U.S. patent application number 14/110034 was filed with the patent office on 2014-01-30 for retro-fit energy exchange system for transparent incorporation into a plurality of existing energy transfer systems.
This patent application is currently assigned to ENERGY RECOVERY SYSTEMS INC. The applicant listed for this patent is Aniello Manzo, Sean Douglas Marte. Invention is credited to Aniello Manzo, Sean Douglas Marte.
Application Number | 20140026608 14/110034 |
Document ID | / |
Family ID | 46969597 |
Filed Date | 2014-01-30 |
United States Patent
Application |
20140026608 |
Kind Code |
A1 |
Manzo; Aniello ; et
al. |
January 30, 2014 |
RETRO-FIT ENERGY EXCHANGE SYSTEM FOR TRANSPARENT INCORPORATION INTO
A PLURALITY OF EXISTING ENERGY TRANSFER SYSTEMS
Abstract
A condenser with subcooling is provided. The condenser comprises
apparatus for collecting liquid refrigerant and increasing a
velocity of the liquid refrigerant as the liquid refrigerant
interfaces with at least one wall of a first pass liquid medium
compartment, thereby removing heat from the liquid refrigerant,
subcooling the liquid refrigerant and heating a liquid medium.
Inventors: |
Manzo; Aniello; (Burnaby,
CA) ; Marte; Sean Douglas; (Langley, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Manzo; Aniello
Marte; Sean Douglas |
Burnaby
Langley |
|
CA
CA |
|
|
Assignee: |
ENERGY RECOVERY SYSTEMS INC
Coquitlam
BC
|
Family ID: |
46969597 |
Appl. No.: |
14/110034 |
Filed: |
April 7, 2011 |
PCT Filed: |
April 7, 2011 |
PCT NO: |
PCT/CA11/00406 |
371 Date: |
October 4, 2013 |
Current U.S.
Class: |
62/305 |
Current CPC
Class: |
F25B 40/02 20130101;
F25B 39/04 20130101; F25B 2700/04 20130101; F28B 1/02 20130101;
F25B 2339/047 20130101; F25B 2700/21151 20130101; F25B 6/04
20130101; F28D 7/1607 20130101 |
Class at
Publication: |
62/305 |
International
Class: |
F28B 1/02 20060101
F28B001/02 |
Claims
1. A condenser with subcooling, comprising: a first portion
comprising a refrigerant compartment and a liquid medium
compartment and at least one interface there between, said
refrigerant compartment enabled for receiving refrigerant in a
vapour state, said refrigerant condensing to a liquid state via
latent heat from said refrigerant flowing into said liquid medium
compartment via said interface, thereby heating a liquid medium
flowing there through; and a second portion located below said
first portion for collecting liquid refrigerant, said second
portion comprising: a first pass liquid medium compartment enabled
to receive said liquid medium on a first pass through said
condenser, said first pass liquid medium compartment in
communication with said liquid medium compartment; and apparatus
for collecting said liquid refrigerant and increasing a velocity of
said liquid refrigerant as said liquid refrigerant interfaces with
at least one wall of said first pass liquid medium compartment,
thereby removing heat from said liquid refrigerant, subcooling said
liquid refrigerant and heating said liquid medium.
2. A shell and tube condenser with integral subcooling comprising:
a divider located above a first pass tube carrying a liquid medium,
said divider for collecting liquid refrigerant condensing from a
vapour state on further pass tubes, said divider enabled to direct
said liquid refrigerant towards a header of said condenser and onto
one end of said first pass tube said liquid refrigerant falling to
a bottom of said condenser; and a plurality of baffle plates
between said bottom of said condenser and said divider for reducing
the cross sectional area of the flow of said liquid refrigerant
around said first pass tube, thereby increasing the velocity,
removing heat from said liquid refrigerant, subcooling said liquid
refrigerant and heating said liquid medium.
3. The shell and tube condenser of claim 2, further comprising a
window in a shell of said condenser, said window level with a
portion of said divider, said window for checking a level of said
liquid refrigerant in said bottom of said condenser.
4. The shell and tube condenser of claim 2, wherein said plurality
of baffle plates alternate between extending from first and second
opposing sides of a shell of said condenser, perpendicular to said
divider.
5. The shell and tube condenser of claim 2, wherein said plurality
of baffle plates alternate between extending from said divider
towards said bottom and extending up from said bottom towards said
divider.
6. The shell and tube condenser of claim 2, wherein said plurality
of baffle plates are further enabled to lengthen a path of said
liquid refrigerant along said bottom of said condenser.
7. The shell and tube condenser of claim 2, wherein said first pass
tube and said further pass tubes comprise double walled tubes and
said liquid medium comprises domestic civic water.
8. A condenser system for subcooling liquid refrigerant,
comprising: a condenser for transferring latent heat from a
refrigerant in a vapour state to a liquid medium via at least one
partition between refrigerant compartments and liquid medium
compartments thereby causing said refrigerant to condense to said
liquid refrigerant; and a heat exchanger located below said
condenser, said heat exchanger comprising: first pass compartments
for said liquid medium to flow there through to said liquid medium
compartments of said condenser; liquid refrigerant compartments
enabled to collect said liquid refrigerant from said refrigerant
compartments; and at least one interface between said first pass
compartments and said liquid refrigerant compartments for heat to
flow from said liquid refrigerant to said liquid medium thereby
subcooling said liquid refrigerant and heating said liquid medium;
said liquid refrigerant compartments comprising a cross-section
refrigerant flow area smaller than a cross-section refrigerant flow
area of said refrigerant compartments thereby increasing the
velocity and a heat transfer coefficient of said liquid
refrigerant.
9. The condenser system of claim 8, further comprising piping
connecting said refrigerant compartments and said liquid
refrigerant compartments and further piping connecting said first
pass compartments with said liquid medium compartments.
10. The condenser system of claim 9, wherein said piping and said
further piping is removablely attached to each of said condenser
and said heat exchanger such that that said heat exchanger can be
retrofitted to said condenser.
11. The condenser system of claim 8, further comprising a window
for checking a level of said liquid refrigerant.
12. The condenser system of claim 11, wherein said window is in
piping connecting said refrigerant compartments and said liquid
refrigerant compartments.
13. The condenser system of claim 8, wherein an area of plates
forming said first pass compartments and said liquid refrigerant
compartments is smaller than an area of plates forming said liquid
medium compartments and said first pass compartments.
14. The condenser system of claim 8, wherein each of said condenser
and said heat exchanger comprises a plate heat exchanger.
15. The condenser system of claim 8, wherein each of said condenser
and said heat exchanger comprises a double wall heat exchanger for
heating potable water.
16. A kit for retrofitting a condenser for subcooling, comprising:
a heat exchanger for connection below a condenser, said heat
exchanger comprising: first pass compartments for a liquid medium
to flow there through to liquid medium compartments of said
condenser; liquid refrigerant compartments enabled to collect
liquid refrigerant from refrigerant compartments of said condenser;
and at least one interface between said first pass compartments and
said liquid refrigerant compartments for heat to flow from said
liquid refrigerant to said liquid medium thereby subcooling said
liquid refrigerant and heating said liquid medium; said liquid
refrigerant compartments comprising a cross-section refrigerant
flow area smaller than a cross-section refrigerant flow area of
said refrigerant compartments thereby increasing the velocity and a
heat transfer coefficient of said liquid refrigerant; piping for
connecting said liquid refrigerant compartments of said heat
exchanger with said refrigerant compartments of said condenser; and
further piping for connecting said first pass compartments with
said liquid medium compartments of said condenser.
17. The kit of claim 16, further comprising a window for checking a
level of said liquid refrigerant in said piping for connecting said
liquid refrigerant compartments and said refrigerant compartments.
Description
FIELD
[0001] The present invention relates generally to energy exchange
and distribution systems including heating, ventilation,
air-conditioning and water heating, and more particularly relates
to a retrofit energy exchange system for transparent incorporation
into a plurality of existing energy transfer systems.
BACKGROUND
[0002] It is known to employ energy exchange technologies in order
to, for example, recover excess heat from an air-conditioning
system to provide energy to heat water. The prior art has many
examples of such heat-exchange technologies. A cluster of prior art
references are also found from the early 1980s which reflect the
end of the energy crises of the 1970s. It is interesting to note
that these heat-exchange technologies have not been generally
adopted, despite their apparent advantages.
SUMMARY
[0003] An aspect of this specification provides:
[0004] a first set of valves for connection to a first connection
point of a first energy transfer sub-system; said first energy
transfer sub-system having a potential excess supply of energy
available at said first connection point; said first energy
transfer system connected a first controller; said first controller
configured to receive at least one first input for providing data
to said first controller; said first controller configured to send
at least one output to said first energy transfer sub-system for
selectively instructing activation or deactivation of said first
energy transfer sub-system to thereby generate said potential
excess supply of energy; said first controller having a passive
connection point configured to output a first set data received
from said first input;
[0005] a second set of valves for connection to a second connection
point of a second energy transfer sub-system; said second energy
transfer sub-system having a potential demand for energy at said
second connection point; said second energy transfer system
connected a second controller; said second controller configured to
receive at least one second input for providing data to said second
controller; said second controller configured to send at least one
output to said second energy transfer sub-system for selectively
instructing activation or deactivation of said second energy
transfer sub-system to thereby realize said potential demand for
energy; said second controller having a passive connection point to
output a second set of data received from said second input;
[0006] an energy exchange unit connectable to said first set of
valves via a first conduit; said energy transfer unit connectable
to said second set of valves via a second conduit; an energy
exchange unit controller connectable to said first energy transfer
sub-system and said second energy transfer sub-system to receive
said first inputs and said at least one second input; said energy
exchange unit controller configured to activate said energy
exchange unit when said energy exchange unit controller determines,
based on said first input and said second input, that a present
excess supply of energy from said first energy transfer system is
available to satisfy a present demand for energy at said second
energy transfer sub-system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 shows a prior art complete air-conditioning system
and separate hot water system for a multi-unit structure.
[0008] FIG. 2 shows a retrofit system incorporated into a complete
air-conditioning system and separate hot water system for a
multi-unit structure.
[0009] FIG. 3 shows a schematic representation of an exemplary
energy exchange unit that can be used in the system of FIG. 2.
[0010] FIG. 4 shows a flow-chart depicting an exemplary method of
operating the energy exchange unit of FIG. 3.
[0011] FIG. 5 shows a flow-chart depicting another exemplary method
of operating the energy exchange unit of FIG. 3.
[0012] FIG. 6 shows a schematic representation of a controller for
system of FIG. 2.
[0013] FIG. 7 shows a flow-chart depicting another exemplary method
for controlling energy transfer.
[0014] FIG. 8 shows another retrofit system incorporated into a
complete air-conditioning system and separate hot water system for
a multi-unit structure.
[0015] FIG. 9 shows another retrofit system incorporated into a
complete air-conditioning system and separate hot water system for
a multi-unit structure.
[0016] FIG. 10 shows another retrofit system incorporated into a
complete air-conditioning system and separate hot water system for
a multi-unit structure.
[0017] FIG. 11 shows an exemplary condenser with subcooling,
according to non-limiting embodiments.
[0018] FIG. 12 shows a path of liquid refrigerant around baffles in
the condenser of FIG. 11.
[0019] FIG. 13 shows another exemplary condenser with subcooling,
according to non-limiting embodiments.
[0020] FIG. 14 shows a path of liquid refrigerant around baffles in
the condenser of FIG. 13.
[0021] FIG. 15 shows a perspective view of a baffle of the
condenser of FIG. 13, according to non-limiting embodiments.
[0022] FIG. 16 shows a cooling curve for at least one of the
condenser of FIG. 11 and the condenser of FIG. 13.
[0023] FIG. 17 shows yet another condenser system with subcooling,
according to non-limiting embodiments.
[0024] FIG. 18 shows a longitudinal cross-section of the condenser
system of FIG. 16.
[0025] FIG. 19 shows a flow-chart depicting another exemplary
method for controlling energy transfer.
[0026] FIG. 20 shows another retrofit system incorporated into a
complete air-conditioning system and separate hot water system for
a multi-unit structure.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0027] The teachings herein have application to a wide variety of
existing energy transfer systems. An example of an energy system is
shown in FIG. 1 and indicated generally at 50. Energy system 50 is
incorporated into a multi-unit structure, such as an apartment
building or office tower. Thus, a plurality of suites 74-1 . . .
74-n are found through-out the structure. Generically, each suite
is referred to as suite 74, while collectively, all suites are
referred to as suites 74. This nomenclature is used elsewhere
herein.) A cooling tower 58 is also provided on the roof of the
structure. The structure also comprises at least one indoor common
area 62, such as a hallway or foyer. In FIG. 1, the structure is
also defined in terms of its context in relation to at least one
outdoor area 66 that is outside the structure. A mechanical room 70
is also provided in the basement of the structure.
[0028] Each suite 74 comprises a heat transfer coil 78, which is
shown in FIG. 1 as operating in an air-conditioning mode whereby
energy within hot air HA passing over coil 78 is absorbed by a cold
coolant CC-1 that passes through coil 78, such that cold air CA
exits coil 78 and into suite 74 and hot coolant HC-1 exits coil 78,
the energy from the hot air HA having been absorbed the cold
coolant CC-1. Each suite 74 also comprises a hot water demand 82.
Hot water demand 82 can be any one of a sink, shower, or bathtub or
other fixture which can receive hot water HW-1.
[0029] Cooling tower 58 comprises a plurality of heat transfer
units such as heat transfer units 86-1 and 86-2, each of which can
receive hot coolant HC-2 and transfer energy therefrom into the
ambient air on the rooftop and then return cold coolant CC-2. It
should be noted that in other embodiments, more or less than two
heat transfer units may be used. Each transfer unit 86-1 or 86-2
also comprises at least one temperature sensor TS1 or TS2
respectively that sends an electronic output therefrom representing
a temperature reading of the ambient air on the rooftop or the
temperature of hot coolant HC-2 or cold coolant CC-2 or all of
them.
[0030] Indoor common area 62 comprises at least one temperature
sensor TS7 that sends an electrical output representing a
temperature reading of the ambient air of that common area. Note
that indoor common area 62 can, in variations, comprise a heat
transfer coil (not shown).
[0031] Outdoor area 66 comprises at least one temperature sensor
TS8 that sends an electrical output representing a temperature
reading of the ambient air respective to the location of that
temperature sensor TS8. Note that where a plurality of temperature
sensors TS8 are provided, each of those sensors may be located on
different sides and heights of the structure, such that the actual
temperature reading from each can vary substantially according to
time of day and when a particular temperature sensor is exposed to
sun, shade, wind or other environmental variables.
[0032] Mechanical room 70 comprises a central energy exchange unit
90 that interconnects cooling tower 58 and transfer coils 78, where
excess energy from hot coolant HC-1 is transferred to cold coolant
CC-2 to thereby generate hot coolant HC-2 and cold coolant CC-1. A
temperature sensor TS3 connects to a cold coolant line to sense the
temperature of cold coolant CC-2 as it enters central energy
exchange unit 90. A temperature sensor TS4 connects to a hot
coolant line to sense the temperature of hot coolant HC-2 as it
leaves central energy exchange unit 90. A temperature sensor TS5
connects to another hot coolant line to sense the temperature of
hot coolant HC-1 as it enters central energy exchange unit 90. A
temperature sensor TS6 connects to another cold coolant line to
sense the temperature of hot coolant CC-1 as it leaves central
energy exchange unit 90.
[0033] A first controller 94 receives input from temperature
sensors TS1 to TS8, and also connects to central energy exchange
unit 90 and to heat transfer unit 86-1 or 86-2 to selectively
activate or deactivate central energy exchange unit 90 or heat
transfer unit 86-1 or 86-2 or all of them according to temperatures
from temperature sensors TS1 to TS8. More specifically, first
controller 94 infers demand for cooling from suites 74 via
temperature sensor TS5 and temperature sensor TS6, while at the
same time infers cooling capacity of cooling tower 58 using
temperature sensors TS1, TS2, TS3, TS4, TS7 or TS8. From such
inferences, first controller 94 can selectively activate pumps,
compressors and fans associated with central energy exchange unit
90 and heat transfer unit 86-1 or 86-2 to satisfy demand from
suites 74. First controller 94 also typically includes an output
port based on a standard format (e.g. RJ45/Ethernet, or Universal
Serial Bus, or RS-232, or the like) for monitoring first controller
94.
[0034] The foregoing description of the structure and operation of
transfer coils 78, central energy exchange unit 90 and heat
transfer unit 86-1 or 86-2 are intended to capture a generic
cooling system that can be employed to provide a cooling system for
suites 74. It is to be understood, however, that the actual
implementations vary according a number of variables, including the
size of suites 74, the size and manufacturer of transfer coils 78,
central energy exchange unit 90, heat transfer unit 86-1 or 86-2,
and first controller 94 and the climate in which the structure is
located. Those skilled in the art will appreciate that first
controller 94 is uniquely programmed according to the unique
installation for a given structure and combination of transfer
coils 78, heat transfer unit 86-1 or 86-2, temperature sensors TS1
to TS8 and central energy exchange units 90. Therefore,
notwithstanding the generic description provided, the specific
embodiment for a given structure will be expected to be different,
and possibly substantially different, for each and every structure.
Table I shows examples of specific manufacturers and model
descriptions that can be employed to implement such a cooling
system for suites 74.
TABLE-US-00001 TABLE I Example components for Cooling System Common
Product Name Manufacturer Model Suitable For Heat pump Carrier
25HNA9 Transfer coil 78 Roof top chiller Carrier 50VL Heat Transfer
units 86 Programmable Honeywell 2MLR-CPUH/F First controller 94
Logic Controller
[0035] Mechanical room 70 also comprises a domestic water heating
unit 100 and water tank 104 and that is configured to receive
domestic cold water from a municipal water supply 108. Temperature
sensor TS9 that is associated with tank 104 and is able to
determine water temperature associated with tank 104. Temperature
sensor TS9 is connected to a second controller 112 which in turn
connects to heating unit 100. Second controller 112 is configured
to activate or deactivate a heating element (e.g. a gas flame)
within heating unit 100 based on temperature sensed at temperature
sensor TS9. Temperature sensor TS9 thus comprises an output line
that sends a temperature signal to second controller 112. Domestic
cold water CW-1 from supply 108 enters tank 104 and can flow into
heating unit 100 as cold water CW-2 where it undergoes an increase
in temperature and then domestic hot water HW-2 flows back into
tank 104. As water demand(s) 82 are activated, hot water HW is
drawn from tank 104 to the activated demand.
[0036] Again, the foregoing description of the structure and
operation of heating unit 100 and water tank 104 and second
controller 112 are intended to capture a generic water heating
system that can be employed to provide hot water to suites 74. It
is to be understood, however, that the actual embodiments vary
according a number of variables, including the size of suites 74,
the size and manufacturer of heating unit 100, water tank 104,
second controller 112, the temperature of water received from
domestic water supply 108, and the climate in which the structure
is located. Those skilled in the art will appreciate that second
controller 112 is uniquely configured according to the unique
installation for a given structure and combination of heating unit
100, water tank 104. Therefore, notwithstanding the generic
description provided, the specific embodiment for a given structure
will be expected to be different, and possibly substantially
different, for each and every structure. Table II shows examples of
specific manufacturers and model descriptions that can be employed
to implement such a water heating system for suites 74.
TABLE-US-00002 TABLE II Example components for Water Heating System
Common Product Name Manufacturer Model Suitable For Water Tank
Rheem GHE100-130 (A) Water tank 104 Aquastat Honeywell L4006 Second
controller 112 Programmable Honeywell 2MLR-CPUF Second Logic
controller 112 Controller Heating Unit Burnham P203 Water heater
100
[0037] In will be noted that is some embodiments of system 50,
second controller 112 can be a dual set-point aquastat. Such a dual
point aquastat may be used in different ways depending on the
existing installation as will be understood by those of skill in
the art.
[0038] Referring now to FIG. 2, a retrofit energy exchange system
is indicated at 200, which becomes part of an energy system 50a.
Like components in system 50a bear like references to their
counterparts in system 50. System 200 comprises an energy exchange
unit 204, an energy exchange controller 208, a first valve 212 for
tapping into the cold coolant line carrying cold coolant CC-2, a
coolant return line (for carrying cold coolant CC-3) to connect
energy exchange unit 204 to first valve 212, a second valve 216 for
tapping into the hot coolant line carrying hot coolant HC-2, a
coolant supply line (for carrying hot coolant HC-3) that connects
energy exchange unit 204 to second valve 216, a third valve 220 for
tapping into the cold water line carrying for cold water CW-2, a
cold water line (for carrying cold water CW-3) connecting energy
exchange unit 204 with third valve 220, a fourth valve 224 for
tapping into the hot water line carrying hot water HW-2, and a hot
water line (for carrying hot water HW-3) connecting fourth valve
224 to energy exchange unit 204.
[0039] As will be discussed in greater detail below, system 200 is
"turn-key" and is configured to connect to any combination of
different individual components that can be used to implement the
components shown in FIG. 1, including, for example, any embodiment
of various combinations of components from Table I and Table II,
without requiring material modification to any of those
components.
[0040] An example energy exchange unit 204 will now be discussed
with reference to FIG. 3. Energy exchange unit 204 generally
incorporates the components of a conventional vapour-compression
refrigeration cycle, namely a compressor 320, a condenser 322, and
an evaporator 324. In addition, energy exchange unit 204 comprises
a heat reclamation unit 326. Heat reclamation unit 326 is placed in
thermal communication with cold water CW-3 to produce hot water
HW-3. Evaporator 324 is placed in thermal communication with hot
coolant HC-3 to produce cold coolant CC-3. Condenser 322 can be
operated in either an air-cooled format, or a liquid-cooled format.
(Where liquid cooled, cold water CW-3 can also be directed to flow
over condenser 322, although this is not shown in FIG. 3.) In the
air-cooled format, the condenser 322 is placed in thermal
communication with ambient air. Each of the above-noted components
is provided with suitable tubing and fittings, to permit the
cyclical flow of a refrigerant through these components.
[0041] Compressor 320 is responsible for moving the refrigerant
through the system, and for compressing the refrigerant into a hot,
high-pressure refrigerant vapour. Exemplary compressors used in
typical vapour-compression systems include reciprocating, rotary
screw, centrifugal, scroll, variable-speed and two-speed
compressors.
[0042] In a typical cycle, refrigerant R flows in the directional
order of compressor 320, heat reclamation unit 326, condenser 322,
evaporator 324, and back to compressor 320. The vapour-compression
system generally described above may comprise additional components
for proper and efficient operation. For example, energy exchange
unit 204 also comprises a metering device 332 situated between
condenser 322 and evaporator 324. Metering device 332 provides a
throttling effect to drop the pressure and temperature of the
refrigerant, while also controlling the flow of refrigerant into
the evaporator 324. Exemplary metering devices include expansion
valves (e.g. thermostatic expansion valves) and capillary
tubes.
[0043] In general, during a typical cycle of the water chiller
system, refrigerant R is pressurized at the compressor 320, turning
it into a high-pressure, high temperature vapour. High-pressure,
high temperature vapour then enters the heat reclamation unit 326,
transferring a portion of the heat to a second medium, for example
the cold water CW-3. As such, cold water CW-3 is heated, and
subsequently delivered to tank 104, effectively providing at least
some hot water for tank 104 without using heating unit 100. Next,
the high-pressure, high-temperature refrigerant R in the form of
vapour enters condenser 322 wherein it transfers additional heat to
a comparatively cooler medium, (either air or a liquid), causing
condensation of refrigerant R into a high-pressure,
high-temperature liquid. The high-pressure, high-temperature liquid
then exits condenser 322, and is subject to throttling at metering
device 332 prior to entry into the evaporator 324. As such, heat
transfer from hot coolant HC-3 to refrigerant R occurs evaporator
324, at which point the low-pressure, low temperature liquid is
turned into a low-pressure, low-temperature vapour. As a result of
the heat transfer in the evaporator 324, hot coolant HC-3 becomes
cold coolant CC-3 and is returned to energy exchange unit 90,
effectively providing at least some cold coolant CC-3 without
relying on cooling tower 58. To complete the cycle, the refrigerant
in the form of low-pressure, low-temperature vapour passes back to
the compressor 320 for a subsequent cycle.
[0044] In general, the portion of the cycle between the compressor
320 and the metering device 332 on the side of the condenser 322 is
considered the high pressure high temperature region of the cycle.
In turn, the portion of the cycle on the side of the evaporator 324
is considered the low pressure low temperature region. As such,
energy exchange unit 204 provides for heating at the heat
reclamation unit 326 in the high pressure high temperature region,
and further provides for cooling at the evaporator 324 in the low
pressure low temperature region.
[0045] As mentioned above, an exemplary metering device 332
suitable for use in the water chiller system is an expansion valve.
In one embodiment, metering device 332 is an adjustable expansion
valve. Metering device 332, and metering devices in general, meter
the flow of refrigerant from the high pressure side of the vapour
compression cycle to the low pressure side. With an adjustable
expansion valve, the metering of refrigerant across this threshold
can be varied in accordance with the heat loads of the system.
Under conditions of reduced load, such as where a decreased
temperature differential across the evaporator 324 is required,
less heat is transferred to the refrigerant, reducing the amount of
energy available to convert the refrigerant to vapour. Without
adjusting the metering device 332 to meet the required load,
excessive amounts of refrigerant may pass into the evaporator 324,
with possible liquid refrigerant passing through and onto the
compressor 320. This condition is generally referred to as
"flooding", and can damage the compressor 320. In circumstances
where there is increased load, a greater amount of refrigerant R is
used to handle the increased demand for heat transfer. Insufficient
refrigerant R flow into the evaporator 324 can lead to "starvation"
at the evaporator 324 and compressor 320. Both circumstances result
in reduced overall efficiency, with possible damaging effects to
the system.
[0046] As shown in FIG. 3, a central control unit 350 (which can be
implemented as part of energy exchange controller 208, or central
control unit can be implemented as a stand-alone unit in
communication with exchange controller 208) is used to monitor and
control the metering device 332 during operation of energy exchange
unit 204. Central control unit 350 is configured to signal system
components, for example the metering device 332 and compressor 320,
based on inputs received from one or more sensors placed on the
energy exchange unit 204. The central control unit 350 comprises a
microcomputer comprised of one or more central processing units
connected to volatile memory (e.g. random access memory) and
non-volatile memory (e.g. FLASH memory). Data input, analysis and
functional control processes are received/executed in the one or
more processing units comprising the control unit. The
microcomputer includes a hardware configuration that can comprise
one or more input devices in the form of a keyboard, a mouse and
the like; as well as one more output devices in the form of a
display, printer and the like.
[0047] To assess the heat load of energy exchange unit 204,
refrigerant return tube 334 between is fitted with a temperature
sensor 336. In some embodiments, central control unit 350 may also
receive input from a fluid level sensor 338 within the evaporator
324. Based on inputs from the one or more sensors, the metering
device 332 can be adjusted to meter a more suitable flow of
refrigerant R from the high pressure side of the vapour-compression
cycle, to the low pressure side. With the central control unit 350
monitoring the temperature of the exiting vapour from the
evaporator 324, and the fluid level of the refrigerant contained
therein, a balance between the extremes of "flooding" and
"starvation" of the evaporator 324 and compressor 320 can be
established, thereby improving the overall efficiency of the
system. In one embodiment, incremental adjustments of the metering
device 332 achieve approximately a 5K differential, allowing energy
exchange unit 204 to be efficiently tuned to match the heat load on
the system.
[0048] Energy exchange unit 204 can comprise other suitable
components, such as accumulators (liquid-vapour separators),
compressor (or crankcase) heaters, strainers, driers, and auxiliary
heating elements, as generally known in the art. Energy exchange
unit 204 can also comprise a range of industry-standard fittings,
as well as customized fittings to enable refrigerant maintenance
and replacement, system flushing, refrigerant bypass operations, as
well as a range of industry-standard operations as would be
familiar to one skilled in the art.
[0049] The basic operation of one embodiment of energy exchange
unit 204 is generally shown in FIG. 4 at 400. Upon start-up of the
energy exchange unit 204 (step 410), central control unit 350
activates the system components (e.g. compressor, sensors, etc.),
and establishes an initial set-up of the adjustable metering device
332 that generally matches the expected load encountered on
start-up. At step 420, the central control unit 350 reads inputs
from the temperature sensor 336 of energy exchange unit 204. In
other embodiments more than one temperature sensor may provide this
input. At step 430, central control unit 350 reads inputs from the
fluid level sensor 338 provided in the evaporator 324. At step 440,
central control unit 350 uses these inputs to determine if the
current metering by the metering device 332 matches the heat load
on energy exchange unit 204. If the metering matches the head load,
no adjustments to the expansion valve are necessary. If the
metering does not match the heat load, then at step 450, the
central control unit 350 computes the appropriate metering for the
noted heat load. At step 460, the central control unit 350
generates and sends a valve adjustment signal to the metering
device 332. At step 470, the metering device 332 is adjusted in
accordance with the valve adjustment signal. The central control
unit 350 then returns to step 420 for further monitoring and
adjustment as necessary. The central control unit 350 can be
programmed to assess the inputs from the various sensors at regular
time intervals, for example once every minute, but time intervals
less than, or greater than one minute are contemplated.
[0050] As will be appreciated, the use of one or more temperature
sensors on energy exchange unit 204 need not be restricted to the
configuration described above. The configuration described here is
merely exemplary, and one can choose to use a different assembly of
sensors to provide the central control unit with the necessary
information to effect control over energy exchange unit 204.
[0051] As briefly mentioned above, the screw-type compressor is
quite effective for use in the water chiller system. In some
embodiments, the screw-type compressor, in particular a variable
frequency screw-type compressor can provide additional benefits and
control to the water chiller system.
[0052] As heat loads upon energy exchange unit 204 vary, for
example through changes in the flow of cold water CW-3 or cold
coolant CC-3, then constant compressor capacity may result in a
mismatched flow of refrigerant through the evaporator 224,
resulting in the aforementioned "flooding" or "starvation"
conditions. As such, variable frequency compressors, in particular
variable frequency screw-type compressors can be used to vary the
amount of refrigerant flowing through the evaporator 324 and into
the compressor 320. This form of control is generally known in the
art as capacity control.
[0053] Control of the variable frequency compressor 320 is provided
by the central control unit 350. Based on inputs provided by
sensors, for example the aforementioned temperature sensor 336 and
fluid level sensor 338, central control unit 350 is configured to
determine whether or not the current flow of refrigerant R matches
the given heat load. On detecting a mismatched flow of refrigerant,
the central control unit 350 instructs one or both of the
adjustable metering device 332 and variable frequency compressor
320 to adjust to the new condition.
[0054] (As will be discussed in greater detail below, controller
208 is also configured to ascertain if such control by control unit
350 is no longer sustaining the energy demands of tank 104 or
cooling demands of central energy exchange unit 90 or both of them,
and at which point to automatically disable energy exchange unit
204 such that system 50a operates as described in relation to FIG.
1 so that cold air CA, as demanded, is still provided to suites 74
and hot water HW, as demanded, is provided to suites 74.)
[0055] The operation of energy exchange unit 204 comprising a
variable frequency compressor is shown generally in FIG. 5 at 500.
Upon start-up of energy exchange unit 204 (step 510), the central
control unit 350 activates the system components (e.g. compressor,
sensors, etc.), and establishes an initial set-up of the metering
device 332 and variable frequency compressor 320 that generally
matches the expected load encountered on start-up. At step 520, the
central control unit 350 reads inputs from temperature sensor 336
on energy exchange unit 204. In other embodiments more than one
temperature sensor may provide this input. At step 530, the central
control unit reads inputs from the fluid level sensor 338 provided
in the evaporator 324. At step 540, central control unit 350 uses
these inputs to determine if flow of refrigerant R through matches
the heat load on energy exchange unit 204. If the metering matches
the heat load, no adjustments to the metering device 332 and/or
variable frequency compressor 320 are made. If refrigerant R flow
does not match the heat load, then at step 550, the central control
unit 350 computes an appropriate flow of refrigerant R for the
noted heat load. At step 560, central control unit 350 generates
and sends one or both of a valve adjustment signal and compressor
frequency signal to the respective component. The combination of
adjustments to the expansion valve and compressor frequency are
dependent on a number of factors, including, but not limited to,
maintaining the operation of each component with a range of optimal
efficiency for the required refrigerant flow. At step 570, the
metering device 332 and/or compressor 320 adjusts in accordance
with the respective signals, the system then returns to step 520
for further monitoring and adjustment as necessary. As previously
stated, the central control unit 350 can be programmed to assess
the inputs from the various sensors at regular time intervals, for
example once every minute, but time intervals less than, or greater
than one minute are contemplated.
[0056] In some embodiments, the energy exchange unit 204 can
further comprise other mechanical/electrical components to enhance
the operation and or efficiency of the system. For example, to
facilitate the movement of air across the condenser, one or more
fan units can be implemented. In some embodiments, while presented
above as separate components, the heat reclamation unit 326 and the
condenser 322, may be combined into a single unit.
[0057] Referring now to FIG. 6, controller 208 is shown in greater
detail. Controller 208 comprises at least one central processing
unit (CPU) 600 connected to a volatile storage unit 604 (e.g.
random access memory) and a non-volatile storage unit 608 (e.g. a
hard disc drive) by a bus. Controller 208 also comprises a
plurality of input interfaces 612 that connect to CPU 600 and
provide input thereto. Controller 208 also comprises at least one
control interface 616 that connects to CPU 600 and is controlled
thereby. Controller 208 also comprises an administration
input/output interface 620 to which a keyboard and monitor can
connect, either directly or indirectly through a network such as
the Internet, so that controller 208 can be administered.
[0058] CPU 600 is configured to execute a plurality of software
processes, making appropriate use of volatile storage unit 604 and
non-volatile storage unit 608 as needed. It should also be
understood that the term software process is non-limiting, and can
encompass software objects, libraries, classes and generally refers
to any code that configures CPU to perform a particular function.
Likewise non-volatile storage unit 608 is shown maintaining certain
data records that are accessible to CPU 600.
[0059] Thus, in FIG. 6, CPU 600 is shown executing an energy
exchange unit master control application 624 which receives input
data from a plurality of host applications 628, where each host
application 628 corresponds to a respective input interface 612.
(Those skilled in the art will appreciate that other applications
may also be deployed and running on CPU 600.) Also in FIG. 6,
non-volatile storage unit 608 is shown maintaining an application
database 634, which maintains copies of a plurality of host
applications 628, including copies of the host applications 628
represented within CPU 600 of FIG. 6. Application database 634
comprises data files that can maintain a data record for a
plurality of different types of energy transfer equipment (e.g. hot
water heaters, air conditioning units, controllers for the same,
etc.). For example, application database 634 can comprises data
files for each article of equipment that is listed in Table I and
Table II, or data records for additional articles of equipment not
shown in Table I and Table II that can be used as energy transfer
systems. The data records in application database 634 each
correspond to different host applications 628 that are dynamically
loadable onto CPU 600 depending on the type of equipment that is
connected to input interface 612-1 or 612-2.
[0060] Each input interface 612 comprises at least one hardware
port 632, with each port conforming to a different format (i.e.
form factor corresponding to a particular communication protocol).
For example, hardware port 632-1 can be a universal serial bus
(USB) format, while hardware port 632-2 can be Ethernet or RJ-45
format. Other formats are contemplated, including terminal posts to
receive an analog signal representing a temperature from, for
example, temperature sensor TS9. In general, hardware ports 632
correspond to formats that are standard outputs for first
controller 94 and second controller 112, or where a controller does
not have a standard output, then the hardware ports correspond to
an output from a temperature sensor that supplies second controller
112.
[0061] In a specific exemplary embodiment of FIG. 2 through FIG. 6,
assume that first controller 94 is a commercially available with a
standard Ethernet output port, in which case the hardware port
632-1 of input interface 612-1 can be an Ethernet port to receive
the output from first controller 94. By the same token, assume that
while second controller 112 is a commercially available Aquastat
with an input port to receive data from temperature sensor TS9,
while hardware port 632-4 of input interface 612-2 can be identical
to the input on the Aquastat so as to receive input from
temperature sensor TS9.
[0062] Continuing with these examples, CPU 600 is configured to
load an appropriate host application 628 from database 634
according to the specific first controller 94 connected to input
interface 612-1 and the specific temperature sensor TS9 that is
connected to input interface 612-2. CPU 600 can also be configured
to load such a host application 628 automatically (i.e.
Plug-and-play) by detecting a particular type of data stream that
is available from that hardware port 632, if such a data stream is
uniquely identifiable as corresponding to a particular type of
first controller 94 or temperature sensor TS9. If the data stream
is not uniquely identifiable as corresponding to a particular type
of first controller 94 or temperature sensor TS9, then CPU 600 can
be configured to receive a manual indication of same via input
received via administration input/output interface 620.
[0063] In a present embodiment, interface 612-3 is configured to
receive an output signal from central control unit 350 that
monitors activities of central control unit 350. Likewise a host
application 628 executes on CPU 600 corresponding to central
control unit 350. Control interface 616 also sends an input signal
for central control unit 350 via a driver application 636 (which is
also stored in application database 634) that corresponds uniquely
to energy exchange unit 204. In this manner, controller 208 is
dynamically configurable to work with different types of energy
exchange units, other than energy exchange unit 204. Master control
application 624 thus sits between host applications 628 and driver
application 636 to selectively activate or control or deactivate
energy exchange unit 204 according to energy demand and supply
within system 50a.
[0064] Referring now to FIG. 7, a method for controlling energy
transfer in accordance is depicted in the form of a flow-chart and
indicated generally at 700. Method 700 can be used to implement
master control application 624. Block 705 comprises determining
input types. Block 705 can thus be effected as previously
described, whereby master control application 624 examines input
signals received via interfaces 612 to determine the type of
controller or temperature sensor that is connected interface 612.
Where the determination cannot be made automatically, then block
705 can comprise receiving manual input via interface 620 that
identifies the type of input being received via particular
interface 612.
[0065] Block 710 comprises loading applications based on the inputs
detected at block 705. As previously described, block 710 thus
comprises loading appropriate host applications 628 and driver
application 636 from application database 634 to thereby provide
software interfaces to the connected controllers or temperature
sensors. Such applications 628 and application 636 thus provide
master control application 624 with intelligence as to the overall
structure and operational parameters of system 50a.
[0066] Block 715 comprises determining whether there have been any
changes to the input types. In other words, block 715 verifies that
changes have been made since the detection at block 705, and if
such a change is detected, then method 700 cycles back to block
705. If not change is detected then method 700 advances to block
720.
[0067] Block 720 comprises receiving energy supply data via the
respective host application(s). In the example above, block 720
comprises examining input received via interface 612-1, which
includes data from first controller 94. Again, it is to be noted
that the monitoring of first controller 94 is passive--no changes
to first controller 94 are required--and that built-in monitoring
functions of first controller 94 are utilized. The data from first
controller 94 can thus include information from temperature sensors
TS1 to TS8, or information as to whether or not heat transfer unit
86-1 or 86-2 are activated.
[0068] Block 725 comprises receiving energy demand data via the
respective host application(s). In the example above, block 725
comprises examining input received via interface 612-2, which
includes data from temperature sensor TS9. Again, it is to be noted
that the monitoring of temperature sensor TS9 is passive--no
changes to temperature sensor TS9 or second controller 112 are
required. The data from temperature sensor TS9 can thus indicate
whether or not a threshold lower temperature has been reached that
would normally cause second controller 112 to activate heater 100.
Host application 628 can, if desired, be configured with the
operational parameters of second controller 112 so that master
control application 624 can anticipate the operation of second
controller 112 according to the input from temperature sensor
TS9.
[0069] Block 730 comprises determining whether an energy transfer
criteria has been met. A "yes" determination would be reached at
block 730 where, for example, master control application 624
ascertains that one or more heat transfer unit 86-1 or 86-2 are
activated AND where temperature sensor TS9 has fallen below the
threshold lower temperature that causes activation of heater 100.
Other ways of reaching a "yes" determination will now occur to
those skilled. Conversely a "no" determination would be reached at
block 730 where, for example, master control application 624
ascertains that no heat transfer units such as 86-1 or 86-2 are
activated.
[0070] On a "yes" determination from block 730 method 700 advances
to block 735, at which point a determination is made as to whether
the energy transfer unit 204 is capable of meeting the demand that
lead to the "yes" determination at block 730. A "no" determination
can be made at block 735 where, for example, a diagnostic exercise
reveals that energy transfer unit 204 is in need of a repair or
some other fault detection is made. A "no" determination can be
made at block 735 where, for example, a diagnostic exercise reveals
that even if energy transfer unit 204 is activated, the level of
energy required to operate energy transfer unit 204 would not
result in any overall net energy savings in system 50a. A "no"
determination can also be made at block 735 where, for example, a
diagnostic exercise reveals that the particular energy demand and
supply profiles receive via interfaces 612 will likely lead to the
aforementioned "starvation" or "flooding" issues that can occur in
the specific, but purely exemplary embodiment of energy transfer
unit 204 as described above.
[0071] Where a "no" determination is made at block 730, or at block
735, then method 700 advances to block 740 and energy exchange unit
204 will be deactivated (or will remain inactive if it is already
inactive). Method 700 then cycles back from block 740 to block
715.
[0072] Returning again to block 735, a "yes" determination can be
made where, for example, the gap between energy supply and energy
demand is so great that even where energy transfer unit 204
operates inefficiently, there will still be a net reduction in the
amount of energy consumed by heater 100 that more than offsets the
energy consumed by energy transfer unit 204. Those skilled in the
art will now recognize that less cautious criteria can be used to
reach a "yes" determination at block 735.
[0073] A "yes" determination at block 735 leads method 700 to block
745. Block 745 comprises controlling the energy transfer unit. In
the specific example above, block 745 can include invocation of
method 400 or method 500, including the variations thereon, so as
to heat water for water tank 104. Other means of controlling the
energy transfer unit will now occur to those skilled in the
art.
[0074] Block 750 comprises monitoring the operation energy transfer
unit, to detect faults or any aspects of its operation. While not
required, it is generally contemplated that method 700 can comprise
heuristic or artificial intelligence algorithms, whereby
determinations at block 730 and block 735, and control parameters
used at block 745, can change based on historic monitoring at block
750 (including historic data from block 720 and block 725) so that
during subsequent cycling of method 700, the activation, or
deactivation, or control over energy transfer unit 204 will change
so as to provide the most efficient energy savings profile.
[0075] Variants on the foregoing are contemplated. For example, in
addition to temperature sensors, other environmental sensors can be
added, including sensor for barometric pressure, wind speed, rain
fall and the like. As another example, further inputs can be
provided to controller 208, such as a market-feed of daily energy
prices--such as electricity costs for the cooling subsystem or
natural gas prices for operating heater 100. Those daily energy
price inputs can be further used as part of the determinations made
at block 730 or block 735. As another example, first valve 212,
second valve 216, third valve 220 and fourth valve 224 can be
selectively opened, completely or partially, or closed completely,
by remote control from CPU 600 via another control interface (not
shown) so as to provide further control over system 50a. In this
manner, controller 208 can completely remove itself from system 50a
so that system 50a will operate in substantially the same manner as
system 50. Various advantages are contemplated by the teachings
herein. For example, as has been noted the incorporation of energy
transfer units such as energy transfer unit 204 has been virtually
non-existent, despite the basic concepts of such technology being
known. The present teachings permit the transparent, passive,
non-intrusive introduction of such energy transfer technology with
minimal risk for the operator of a multi-unit structure, as much of
the prior art contemplates replacement of existing infrastructure
with an energy transfer unit capable of satisfying all air
conditioning and hot water needs. As another advantage, pricing for
the capital costs of retrofitting system 200 into an existing
system 50 can be based on a cost-savings model, whereby the cost of
system 200 is recouped as a function of overall savings--again
encouraging adoption of system 200 with minimal or no risk to the
operator or owner of a particular multi-unit structure.
[0076] As a still further variation, it should be understood that
controller 208 can be configured to work with a plurality of
different types of energy supply, and energy demand, and energy
transfer technologies. Furthermore, controller 208 can be
configured to work with a plurality of energy transfer units and
also provided additional inputs to work with a plurality of energy
supply sources (e.g. air conditioners, furnaces, ovens, chimneys)
and a plurality of energy demands (e.g. hot water heaters, hot air
supply sources). Indeed the present specification can be modified
for application to space heating and combined space heating and
domestic water heating system. In this manner controller 208 can
dynamically route different excess energy sources to different
energy demands.
[0077] Referring now to FIG. 8, another retrofit system
incorporated into a complete air-conditioning system and separate
hot water system for a multi-unit structure is indicated generally
at 50b. System 50b is a variation on system 50a, and therefore like
elements bear like references, although certain elements bear
references followed by the suffix "b" to denote particular features
of system 50b.
[0078] Of note is that in system 50b, first valve 212b is provided
for tapping into the hot coolant line carrying hot coolant HC-2.
First valve 212b is positioned closer to the heat transfer units
86-1 and 86-2 than central energy exchange unit 90, down-stream
from second valve 216b. (In a variation, not shown, second valve
216b may be located downstream from first valve 212b, but this
configuration is presently less preferred as it increases the
amount of flow in the portion of the existing conduit that lies
between the second valve 216b and first valve 212b.)
[0079] Also of note is that system 50b comprises a pump 217b. (As
will be apparent from further discussion below, pump 217b can be
implemented using a flow-restrictor, though presently, this is not
preferred.) Pump 217b is positioned on the conduit between second
valve 216b and energy exchange unit 204b. Pump 217b is configured
to control the flow rate through energy exchange unit 204b.
[0080] It can be noted that the conduit between second valve 216b
and energy exchange unit 204b can be characterized as having an
inlet pressure at second valve 216b, reflecting the pressure of hot
coolant HC-2 as it travels to energy exchange unit 204b from second
valve 216b. Likewise it can be noted that the conduit between
energy exchange unit 204b and first valve 212b can be characterized
as having an outlet pressure at first valve 212b, reflecting the
pressure of hot coolant HC-2 as it travels to first valve 212b from
energy exchange unit 204b and towards heat transfer unit 86-1 or
86-2. Pump 217b is therefore sized so that the inlet pressure at
second valve 216b and the outlet pressure at first valve 212b are
substantially equal. In this manner, the placement of energy
exchange unit 204b is substantially transparent to the regular
operation of energy exchange unit 90.
[0081] The choice of inlet pressure at valve 216 is generally
selected according to the overall height of the building within
which system 50b is situated. A person skilled in the art will
appreciate that other mechanical means can be provided to achieve
the same result as pump 217b, such as a flow restrictor.
[0082] In order to help further assure that the outlet pressure
from first valve 212b is substantially equal to the inlet pressure
at second valve 216b, first valve 212b is preferably physically
located near second valve 216b along the conduit that runs between
energy exchange unit 90 and heat transfer unit 86-1 or 86-2. For
example, where the conduit that runs between energy exchange unit
90 and heat transfer unit 86-1 or 86-2 is about fourteen inches in
diameter, and where the conduits running between valves 212b and
216b and energy exchange unit 204b are about six inches in
diameter, then valves 212b and 216b may be spaced about two feet
apart. This configuration is, however, a non-limiting example. In
any event the addition of valves 212b and 216b are effected so as
not to disrupt the pre-existing line pressures at those points and
thereby not disrupt normal operation of energy exchange unit
90.
[0083] At this point it can also be noted that, in system 50b no
control signals from first controller 94 are required or received
from controller 208b, thereby simplifying system 50b in relation to
system 50a, and also further highlighting one of the advantages of
the present invention, in that energy exchange unit 204b can be
transparently incorporated into an existing system, without
requiring material modification to the existing system. System 50b
is thus presently configured for environments where the ambient
temperature of outdoor area 66 is substantially warm enough such
that central energy exchange unit 90 operates substantially
constantly, and therefore such continuous operation is presumed by
controller 208b.
[0084] However, it can be noted that system 50b can be implemented
in environments where the ambient temperature of outdoor area 66
varies and system 50b will still function, though perhaps less
optimally. Where system 50b is implemented in a climate with
varying ambient temperature of outdoor area 66, then it can be
desired to provide at least one control signal from first
controller 94 to controller 208b that indicates whether or not
energy exchange unit 90 is operating, so that when energy exchange
unit 90 is not operating, then controller 208b would be configured
to deactivate energy exchange unit 204b.
[0085] System 50b also comprises a temperature sensor TS10 that is
located along the outlet conduit that runs between energy exchange
unit 204b and first valve 212b. Temperature sensor TS10 provides
input to controller 208b. In variations, temperature sensor TS10
could be placed along the inlet conduit that runs between second
valve 216 and energy exchange unit 204b, or a temperature sensor
could be placed along both conduits.
[0086] When temperature sensor TS10 is positioned as shown in FIG.
8, and where temperature sensor TS10 falls below a particular
temperature, then controller 208b is configured to deactivate or
reduce the current operating capacity of energy exchange unit 204b.
When controller 208b is deactivated, then controller 208b may also
be configured to maintain (either constantly or periodically)
operation of pump 217b and thereby ensure a flow of coolant past
temperature sensor TS10 so that readings therefrom are
substantially accurate. For example, controller 208b could be
configured to periodically activate pump 217b, take a reading from
temperature sensor TS10, and then reactive pump 217b. In another
embodiment, a temperature sensor may be installed downstream of
first valve 212b (not shown), although this may lead to a
practically longer cabling run between temperature sensor TS10 and
controller 208b, but can obviate the need to periodically cycle
pump 217b.
[0087] Note, however, if system 50b was configured with another
temperature sensor in addition to temperature sensor TS10 (not
shown) placed along the inlet conduit that runs between second
valve 216b and energy exchange unit 204b, then the temperature
difference between those sensors, as well a measurement of the flow
rate can provide good indication of the amount of heat transferred
from hot coolant HC-2. Note that the flow rate could be assumed
where pump 217b is a constant speed pump. For a variable speed
pump, the flow rate would be assumed based on the pump control
signal from controller 208b.
[0088] Thus, once the following energy input conditions are
provided: A) the amount of heat transferred from hot coolant HC-2;
B) the amount of power consumed by the energy exchange unit 204b
(and accounting for or neglecting ambient losses) then the amount
of heat being transferring to hot water HW-2 could be determined
(due to the fact that energy exchange unit 204b consumes electrical
energy to remove thermal energy from hot coolant HC-2) with the sum
of these energy inputs being substantially moved to hot water
HW-2.
[0089] Also of note in system 50b, is that the municipal cold water
supply CW-1 is split, with one feed providing an input of municipal
cold water to energy exchange unit 204b, and the second feed
providing an input of municipal cold water to heating unit 100.
Also of note in system 50b is that a hot water return line from hot
water demands 82 feeds back into the heating unit 100 or energy
exchange unit 204b. By maintaining a flow of hot water HW-1 in a
feedback loop, hot water may be provided to all hot water demands
82 quickly. Those skilled in the art will now appreciate that if
both heating unit 100 and energy exchange unit 204b are active,
municipal cold water supply CW-1 is directed to energy exchange
unit 204b and the hot water return line from hot water demands 82
is preferentially directed to heating unit 100.
[0090] System 50b also comprises a three-way valve 219b positioned
at the input to tank 104. Three-way valve 219b is configured to
selectively receive hot water input from energy exchange unit 204b
or heating unit 100. A temperature sensor TS11 is also located
between three-way valve 219b and the input of tank 104. Three-way
valve 219b is under the control of controller 208b, so that
controller 208b can selectively direct hot water from either
heating unit 100 or energy exchange unit 208b into tank 104.
[0091] When three-way valve 219b is positioned to direct hot water
from energy exchange unit 204b into tank 104, then controller 208b
is configured to monitor the temperature of temperature sensor
TS11. In the event that the temperature detected in temperature
sensor TS11 falls below a certain threshold of about 120.degree.
F., then controller 208b activates three-way valve 219b so as to
direct hot water from heating unit 100 into tank 104, and thereby
shutting off flow of hot water from energy exchange unit 204b to
tank 104.
[0092] Controller 208b may also be configured to monitor
temperatures detected at temperature sensor TS10 during times when
the threshold temperature at temperature sensor TS11 is reached
such that controller 208b reaches the decision to direct water from
heating unit 100 into tank 104. In this manner, based on the
historical temperatures detected at temperature sensor TS10 and
temperature sensor TS11, controller 208b can increase its ability
to reliably predict which temperatures at temperature sensor TS10
are sufficient to provide a desired level of heating to municipal
cold water supply 108.
[0093] Other criteria may also be used to determine when to
activate three-way valve 219b. For example, where the heat source
for heating unit 100 uses a fuel that is ultimately cheaper than
the cost of electricity used to operate energy exchange unit 204b,
then three-way valve 219b may be set to direct hot water from
heating unit 100 to tank 104, even though there may be sufficient
energy for energy exchange unit 204b to satisfy the hot water
demand.
[0094] It is also contemplated that valve 219b can be variable, so
that a first portion of hot water is directed from heating unit 100
into tank 104, and a second portion of hot water is directed from
energy exchange unit 204b. Where such a variable three-way valve
219b is provided, energy exchange unit 204b offloads some of the
carbon-intensive resources required to heat water using heating
unit 100 onto energy exchange unit 204b, while recognizing that
energy exchange unit 204b may not be able to satisfy the entire hot
water demand of system 50b.
[0095] In a variation to system 50b where valve 219b is variable,
an additional temperature sensor (not shown), either in addition
to, or instead of temperature sensor TS11, can also be positioned
between energy exchange unit 204b and three-way valve 219b. Such an
additional temperature sensor can also be used to provide input to
controller 204b to provide further input for determining when
three-way valve 219b should be adjusted to direct hot water from
energy exchange unit 204b into tank 104.
[0096] In another variation to system 50b, three-way valve 219b may
be omitted and a conduit can be provided to connect the hot water
outlet of energy exchange unit 204b to a water input of heating
unit 100. In this manner, energy exchange unit 204b acts as a
pre-heater for heating unit 100. This variation can be desired to
further simplify a retro-fit installation of energy exchange unit
204b.
[0097] Those skilled in the art will now appreciate that method 700
can also be modified to operate system 50b or its variants. As
noted above, block 705 comprises determining input types. When
applying block 705 to system 50b, controller 208b performs an
initialization sequence to determine which types of inputs are
connected to controller 208b. In the specific, but non-limiting
example of FIG. 8, controller 208b receives inputs from temperature
sensor TS10 and temperature sensor TS11.
[0098] Referring back to FIG. 7, block 710 comprises loading
applications based on the inputs detected at block 705. As
previously described, block 710 thus comprises loading appropriate
host applications and driver applications from application database
634 to thereby provide software interfaces to the connected
controllers or temperature sensors. When applying block 710 to the
example in FIG. 8, then master control application 624 will be
configured to monitor the inputs in relation to temperature sensor
TS10 and temperature sensor TS11.
[0099] Again, as desired, controller 208b can be configured to
either have fixed expectations as to the locations and functions of
temperature sensor TS10 and temperature sensor TS11 within system
50b, or controller 208b may be manually configured as part of an
initialization process as to the locations and functions of
temperature sensor TS10 and temperature sensor TS11.
[0100] Block 715 comprises determining whether there has been any
change to the input types. Again, block 715 verifies that changes
have been made since the detection at block 705, and if such a
change is detected, then method 700 cycles back to block 705. If no
change is detected then method 700 advances to block 720.
Accordingly, if additional temperature sensors (not shown in FIG.
8) or other types of inputs that can be provided to controller 208b
are provided, then block 705 and block 710 can be repeated to
accommodate.
[0101] Note that block 705 and block 710 can also be modified to
accommodate the various types of output controls that controller
208b may be configured to access. For example, in FIG. 8,
controller 208b may be configured with applications and drivers to
issue output commands that control three-way valve 219b, or pump
217b, or both of them.
[0102] Block 720 comprises receiving energy supply data via the
respective host application(s). In the example for system 50b,
block 720 comprises examining input received via temperature sensor
TS10 and temperature sensor TS11. Again, it is to be noted that the
monitoring is passive--no changes to the existing air conditioning
or water heating systems are required.
[0103] Block 725 comprises receiving energy demand data via the
respective host application(s). In the example above, demand is
presumed to exist. (However, optionally, not shown, temperature
sensor TS9 may also be connected to provide input to controller
208b, and thus the reaching of a lower threshold temperature may be
used to determine that a demand exists).
[0104] Block 730 comprises determining whether an energy transfer
criteria has been met. A "yes" determination would be reached at
block 730 where, for example, controller 208b determines that an
upper threshold temperature of temperature sensor TS10 has been
reached, indicating that an excess of energy supply is available
from energy exchange unit 90 that can be used to satisfy hot water
demands 82. Conversely a "no" determination would be reached at
block 730 where, for example, controller 208b ascertains that a
lower threshold temperature of temperature sensor TS10 has been
reached.
[0105] On a "yes" determination from block 730 method 700 advances
to block 735, at which point a determination is made as to whether
the energy transfer unit 204 is capable of meeting the demand that
lead to the "yes" determination at block 730. A "no" determination
can be made at block 735 where, for example, a diagnostic exercise
reveals that energy transfer unit 204b is in need of a repair or
some other fault detection is made. A "no" determination can be
made at block 735 where, for example, a diagnostic exercise reveals
that even if energy transfer unit 204b is activated, the level of
energy required to operate energy transfer unit 204b would not
result in any overall net energy savings in system 200a. A "no"
determination can also be made at block 735 where, for example, a
diagnostic exercise reveals that the particular energy demand and
supply profiles will likely lead to the aforementioned "starvation"
or "flooding" issues that can occur in the specific, but purely
exemplary embodiment of energy transfer unit 204b as described
above.
[0106] Where a "no" determination is made at block 730, or at block
735, then method 700 advances to block 740 and energy exchange unit
204b will be deactivated (or will remain inactive if it is already
inactive). Likewise block 740 may comprise activation of three-way
valve 219b so as to direct hot water from heating unit 100 into
tank 104. Method 700 then cycles back from block 740 to block
715.
[0107] Note that, according to one of the advantages of this
specification, the reaching of a "no" determination at block 730
need not have any impact on either the pre-existing air
conditioning or hot water systems.
[0108] Returning again to block 735, a "yes" determination can be
made where, for example, the gap between energy supply and energy
demand is so great that even where energy transfer unit 204b
operates inefficiently, there will still be a net reduction in the
amount of energy consumed by heater 100 that more than offsets the
energy consumed by energy transfer unit 204b. In optimal and
typical conditions, it would normally be expected that a "yes"
determination would be reached at block 735. Indeed, those skilled
in the art will now recognize that less cautious criteria can be
used to reach a "yes" determination at block 735.
[0109] A "yes" determination at block 735 leads method 700 to block
745. Block 745 comprises controlling the energy transfer unit 204b.
Block 745 can include, by way of non-limiting example, activation
of three-way valve 219b so as to direct hot water from energy
exchange unit 204b into tank 104, and additionally invoking method
400 or method 500, or variations thereon, so as to provide hot
water for water tank 104. Other means of controlling the energy
transfer unit will now occur to those skilled in the art.
[0110] Block 750 comprises monitoring the operation energy transfer
unit, to detect faults or any aspects of its operation. While not
required, it is generally contemplated that method 700 can comprise
heuristic or artificial intelligence algorithms, whereby
determinations at block 730 and block 735, and control parameters
used at block 745, can change based on historic monitoring at block
750 (including historic data from block 720 and block 725) so that
during subsequent cycling of method 700, the activation, or
deactivation, or control over energy transfer unit 204b will change
so as to provide the most efficient energy savings profile.
[0111] Further variations, combinations, and subsets of the
foregoing are contemplated. Indeed, aspects of system 50a can be
incorporated into system 50b, and vice versa. For example, the hot
water feedback loop of system 50b that provides instant hot water
to demands 82 can also be incorporated into system 50a. As another
example, it should be understood that a single controller can be
developed that includes the functionality of both controller 208
and controller 208b to provide an even further flexible retrofit
energy exchange system.
[0112] As another example variation, energy exchange unit 204b can
be configured to tap into hot coolant line HC-1, to thereby
pre-cool coolant before it enters energy exchange unit 90.
[0113] Referring now to FIG. 9, another retrofit system
incorporated into a complete air-conditioning system and separate
hot water system for a multi-unit structure is indicated generally
at 50c. System 50c is a variation on system 50a, and therefore like
elements bear like references, although certain elements bear
references followed by the suffix "c" to denote particular features
of system 50c. System 50c may be desired to recognize that energy
exchange unit 204c can operate more efficiently by heating cold
inlet water rather than warm water, as less electricity is required
to transfer the same amount of heat from hot coolant line HC-3.
[0114] System 50c can be generally described as comprising two pipe
heat recovery with inlet CW-1 preferentially directed to energy
exchange unit 204c before entering tank 104. Inlet CW-1 directs
water towards energy exchange unit 204c via line CW-3. Also valve
228c joins line HW-3 with line CW-3. When energy exchange unit 204c
is deactivated, then valve 228c can be opened under the control of
controller 208 allowing cold water CW-1 to flow directly into
storage tank 104. Note, however, if the pressure drop through
energy exchange unit 204c is acceptable even though energy exchange
unit 204c is deactivated, then valve 228c can be eliminated.
[0115] A check-valve 232c prevents back flow of cold water from
line CW-1 into heater 100 or tank 104. By the same token, water
from line CW-2 can overcome the check valve 232c and flow into
energy exchange unit 204c.
[0116] An optional, though presently preferred, recirculation line
CW-4c is provided from suites 74 and back to line CW-3.
Recirculation line return CW-4c can be also piped directly into
tank 104, or as shown to directly join with line CW-1.
[0117] Cold water line CW-3 contains a mixture of water from cold
water line CW-1 and cold water line CW-2. During relatively low
demand, water line CW-3 will be warm, and during higher demand
water in line CW-3 will be colder.
[0118] Second controller 112c may be a dual set-point aquastat
responsive to data received from temperature sensor TS9. The use of
such a second controller 112c is contemplated in system 50c. In
system 50c, the wiring of second controller 112c is configured so
that energy exchange unit 204c is activated when the temperature
from sensor TS9 falls below the upper threshold (e.g. about
140.degree. F.), and heater 100 is activated when the temperature
from sensor TS9 falls below the lower threshold (e.g. about
120.degree. F.), such that only when sensed temperature of sensor
TS9 falls below the lower threshold are both energy exchange unit
204c and heater 100 activated. Control outputs from second
controller 112c indicating the upper threshold thus provide input
to controller 208c and thereby activate energy exchange unit 204c,
while control outputs from second controller 112c indicating the
lower threshold thus provide inputs to heater 100 to activate
heater 100.
[0119] Referring now to FIG. 10, another retrofit system
incorporated into a complete air-conditioning system and separate
hot water system for a multi-unit structure is indicated generally
at 50d. System 50d is a variation on system 50a and system 50b, and
therefore like elements bear like references, although certain
elements bear references followed by the suffix "d" to denote
particular features of system 50d. System 50d can be generally
described as a heat recovery system that preferentially directs
municipal water CW-1 towards energy exchange unit 204d before
entering tank 104.
[0120] System 50d also comprises a temperature sensor TS12 that is
connected to the cold coolant line to sense the temperature of cold
coolant CC-2. Temperature sensor TS12 provides input to controller
208d. When temperature sensor TS12 falls below a particular
temperature, controller 208d is configured to deactivate or reduce
the current operating capacity of energy exchange unit 204d. It
will be appreciated by a person skilled in art that placing
temperature sensor TS12 on the cold coolant line will be
advantageous for accurately measuring the temperature of cold
coolant CC-2 entering the central energy exchange unit 90.
[0121] Of note is that energy exchange unit 204d can optionally
include a sub-cooler, which is separately shown in FIG. 10 as
sub-cooler 250d, which is configured to transfer a portion of
excess energy from central energy exchange unit 90 as described
above. Municipal cold water CW-1 is directed initially to
sub-cooler 250d, and then exits therefrom and enters the main
portion of energy exchange unit 204d as described above.
[0122] In addition, cold water CW-2 circulating out of tank 104 is
split into two lines, with one line entering heater 100 and the
second line directed back into energy exchange unit 204d.
[0123] Municipal cold water CW-1 can also be directed into tank 104
via the path labeled cold water CW-1d by the selective activation
of a solenoid valve 254d that is under the control of controller
208d. Solenoid valve 254d can also be deactivated so that all
municipal cold water CW-1 is directed towards energy exchange unit
204d.
[0124] In system 50d, water from hot water line HW-1 is
re-circulated back to cold water line CW-2 via cold water line
CW-4d. As is the case with the other embodiments discussed herein,
it should be understood that such a recirculation line is optional
and its presence depends on the existing hot water infrastructure
since controller 208d and energy exchange unit 204d are configured
to retrofit into such an existing hot water infrastructure.
However, when such a recirculation line is provided, choices can be
made where it connected back into the hot water system components
as those components are located within mechanical room 70.
[0125] Referring to FIG. 11, a shell and tube condenser 900 with
integral subcooling according to a non-limiting embodiment is
generally shown. Shell and tube condenser 900 is also referred to
as condenser 900 hereafter. In some embodiments, energy exchange
unit 204, 204b, 204c, or 204d may comprise condenser 900. However,
it is appreciated that use of condenser 900 is not limited, and
that condenser 900 can be used in any suitable system where heat
exchange and/or subcooling is desired.
[0126] A fluid inlet 16 is provided in a connection header 36 for
entry of a liquid medium, such as water, glycol, or the like to be
heated. The liquid medium proceeds to an inlet compartment 24 where
the liquid medium is distributed to at least one first pass tube
44, located near the bottom of a shell 10 of condenser 900. The
liquid medium travels down at least one first pass tube 44 to a
compartment 26 which is located in a plain header 22 and connects
to a plurality of tubes 20 (also referred to as tubes 20), and
specifically the lowest set of tubes of the plurality of tubes 20
(though above at least one first pass tube 44). The lowest tubes
terminate in compartment 28. The liquid medium then travels through
the next highest set of tubes of the plurality of tubes 20 to
compartment 30 and back down the highest set of tubes of the
plurality of tubes 20 to compartment 32. As the liquid medium
travels through each set of tubes of the plurality of tubes 20 up
through condenser 900, the liquid medium is heated by the
condensing of a refrigerant as described below. A fluid outlet 18
is provided in connection header 36 for exit of the liquid medium
after it has been heated. Tubesheets 34 are provided at either end
for securing the ends of tubes 20 and 44.
[0127] It is appreciated that a pass of liquid medium between
header 22 and header 36 can be referred to as a "pass" through
condenser 900. Hence, at least one first pass tube 44 can be
referred as first pass tube 44. Further, it is appreciated that
there are four passes through condenser 900 and hence condenser 900
can also be referred to as a four pass condenser and/or a condenser
with an even number of passes. Hence, liquid medium enters and
exits condenser 900 from the same side via header 36. In a
condenser with an odd number of passes, the liquid medium enters
and exits from opposite sides. Both even and odd pass condensers
are within the scope of present embodiments. Additionally, while
only one first pass tube 44 is depicted, it is appreciated that
condenser 900 can comprise any suitable number of first pass tubes.
Further, condenser 900 can comprise any suitable number of tubes 20
for each successive pass.
[0128] A refrigerant inlet 12 is provided in a top of shell 10 for
entry of refrigerant in a vapour state from a compressor discharge
(e.g. compressor 320). While inlet 12 is depicted adjacent
connection header 36, it is appreciated that the location of inlet
12 is not particularly limiting. For example, in another embodiment
(not shown), an inlet can be located substantially midway between
connection header and plain header. In yet another embodiment (also
not shown), an inlet can be located towards header. Inside shell
10, the refrigerant contacts tubes 20 where sensible heat and then
latent heat is removed from the refrigerant causing the refrigerant
to condense into a liquid state. It is appreciated that tubes 20
carry the liquid medium that enters condenser via first pass tube
44 near the bottom of condenser 900, and thereafter flows through
tubes 20 exchanging heat with a refrigerant on each pass through
condenser 900. It is further appreciated that refrigerant enters
shell 10 in a vapour state and initially transfers sensible heat
and then latent heat to tubes 20. The refrigerant condenses on
tubes 20 to form liquid refrigerant.
[0129] After condensing, the liquid refrigerant falls off tubes 20
and collects on a divider 40 located towards a bottom of shell 10,
and above at least one first pass tube 44. Indeed, it is
appreciated that divider 40 is located between at least one first
pass tube 44 and second pass tubes (i.e. the lowest of tubes 20).
Divider 40 is enabled to direct the liquid refrigerant towards a
plain header 22 of condenser 900, divider 40 extending towards
header 22 with a gap there between of any suitable size allowing
the liquid refrigerant to fall to the bottom of shell 10 and onto
at least one tube 44. Alternatively, one or more holes are provided
in divider 40 for the liquid refrigerant to pour there through.
Divider 40 is generally parallel to the bottom of shell 10 and a
height difference of liquid refrigerant from connection header 36
to plain header 22 causes the liquid refrigerant to flow towards
plain header 22. It is appreciated that the height difference
occurs due to the flow of liquid refrigerant as it falls onto at
least one tube 44. In another embodiment (not shown), a divider may
be sloped at an angle for directing liquid refrigerant towards a
header.
[0130] Referring to FIG. 11, divider 40 is rectangular in cross
section (e.g. flat). However, in another embodiment, the divider
can comprise any suitable number of channels of any suitable shape
to aid the liquid refrigerant flow towards header 22. It is
appreciated that divider 40 comprises dimensions that enable
divider to fill the space between the sides of shell 10. Divider 40
extends to both sides of shell 10 as well as tubesheet 34 adjacent
connection header 36. In other embodiments, the divider may also
extend to tubesheet 34 adjacent plain header 22, however in these
embodiments, the divider includes at least one aperture proximate
to plain header 22 for liquid refrigerant to flow onto at least one
first pass tube 44.
[0131] It is appreciated that in embodiment shown in FIG. 11,
divider 40 directs liquid refrigerant towards plain header 22. In
general, it is appreciated that divider 40 directs liquid
refrigerant away from a refrigerant outlet 14 such that when the
liquid refrigerant is flowing across first pass tube 44, the liquid
refrigerant is flowing towards outlet 14.
[0132] A plurality of baffle plates 42-42a, 42b, 42c, and 42d
(collectively baffles 42 and generically a baffle 42) are located
between divider 40 and the bottom of shell 10. Baffles 42 are
enabled to route the liquid refrigerant along the bottom of shell
10. It is appreciated that a first baffle 42a extends from divider
40 towards the bottom of shell 10, leaving a gap between the end of
baffle 42a and the bottom of shell 10. A second baffle 42b extends
from the bottom of shell 10 towards divider 40, leaving a gap
between the end of baffle 42b and divider 40. Baffle 42c is similar
to baffle 42a and baffle 42d is similar to baffle 42b. Hence,
baffles 42 alternate between extending from divider 40 towards the
bottom of shell 10 and extending up from the bottom of shell 10
towards divider 40. It is appreciated that while four baffles are
depicted in FIG. 10, other embodiments may comprise any suitable
number of baffles, including at least one baffle. It is further
appreciated that the shape of baffles 42 is generally non-limiting,
though in some embodiments, baffles are complementary to the shape
of divider and/or shell. In addition, it is appreciated that, first
pass tube 44 passes through baffles 42, for example, through
suitable aperture in each of baffles (not shown).
[0133] Baffles 42 are generally enabled to cause liquid refrigerant
to flow around at least on first pass tube 44, and reduce the cross
sectional area of the flow of the liquid refrigerant around at
least one first pass tube 44, thereby increasing the velocity of
the liquid refrigerant such that heat (e.g. sensible heat) is
removed from the liquid refrigerant, subcooling the liquid
refrigerant and heating the liquid medium in at least one first
pass tube 44. For example, it is appreciated that increasing the
velocity of a liquid refrigerant results in an increase in the
liquid refrigerant's heat transfer coefficient. Hence, by
increasing the velocity of the liquid refrigerant with baffles 42,
the flow of sensible heat from the liquid refrigerant to the liquid
medium in first pass tube 44 becomes more efficient.
[0134] Referring to FIG. 12, a schematic diagram of a subset of
features of condenser 900, including a portion of shell 10, divider
40, baffles 42, at least one first pass tube 44, divider 40 and
outlet 14 is shown. It is appreciated that while other elements of
condenser 900 are not depicted in FIG. 10, the other elements are
nonetheless present in condenser 900 (e.g. plain header 22). In any
event, it is appreciated from FIG. 10 that baffles 42a, 42b, 42c,
and 42d alternately extend from divider 40 and the bottom of shell
10 resulting in a path 1001 for liquid refrigerant around baffles
42. It is further appreciated that path 1001 is longer than a path
along a longitudinal axis of condenser 900 in the absence of
baffles 42. Furthermore, baffles 42 also result in a smaller
cross-sectional area of path 1001 as compared to a path along a
longitudinal axis of condenser 900. The smaller cross-sectional
area of path 1001 causes the velocity of the liquid refrigerant to
increase, which in turn leads to an increase in the liquid
refrigerant's heat transfer coefficient, improving the heat
transfer efficiency between the liquid refrigerant and the liquid
medium in first pass tube 44 over a similar condenser without
baffles 42. This in turn leads to an improvement in the subcooling
of condenser 900. Further, the longer length of path 1001 increases
interaction between the liquid refrigerant and first pass tube 44,
which further improves the efficiency of subcooling in condenser
900.
[0135] Referring now to FIG. 13, a condenser 1100 similar to
condenser 900 is shown with like elements having like numbers,
however with a prime mark appended thereto. For example, divider
40' is similar to divider 40. Condenser 1100 comprises baffles
42'a, 42'b, 42'b, and 42'd (collectively baffles 42' and
generically a baffle 42'). However, baffles 42' extend under
divider 40' from one side of shell 10' to an opposite side of shell
10', substantially along a transverse axis of shell 10' (and/or
divider 40'). For example, each baffle 42' is substantially
perpendicular to a longitudinal axis of shell 10' (and/or divider
40').
[0136] Referring to FIG. 14, liquid refrigerant follows a path
1001' around baffles 42' and out of outlet 14'. Similar to baffles
42, baffles 42' are generally enabled to cause liquid refrigerant
to flow around at least on first pass tube 44', and reduce the
cross sectional area of the flow of the liquid refrigerant around
at least one first pass tube 44', thereby increasing the velocity
of the liquid refrigerant such that heat (e.g. sensible heat) is
removed from the liquid refrigerant, subcooling the liquid
refrigerant and heating the liquid medium in at least one first
pass tube 44'. For example, it is appreciated that increasing the
velocity of a liquid refrigerant results in an increase in the
liquid refrigerant's heat transfer coefficient. Hence, by
increasing the velocity of the liquid refrigerant with baffles 42',
the flow of sensible heat from the liquid refrigerant to the liquid
medium in first pass tube 44' becomes more efficient. In any event,
it is appreciated that the cross-sectional area of path 1001' is
smaller than the cross-sectional area of the path of liquid
refrigerant in the absence of baffles 42'.
[0137] Referring to FIG. 15, a perspective view baffle 42' is
shown. Baffle 42' is appreciated to be substantially complementary
to a shape of the bottom of shell 10, and is further enabled to
extend from divider 40 to the bottom of shell 10, with the
exception of a baffle "window" 1102 through which the liquid
refrigerant can flow. Baffle 42' further comprises at least one
aperture 1101 through which at least one first pass tubes 44 can
pass. As depicted in FIG. 15, baffle 42' comprises 22 apertures
such that 22 first pass tubes can pass there through. It is
appreciated that the number of apertures 1101 is preferably matched
to the number of first pass tubes 44.
[0138] Returning now to FIG. 11, refrigerant outlet 14 connects
condenser 900 to an expansion control device (not shown) within a
vapour compression cycle, for example expansion valve 332. The
expansion control device can compensate for any pressure drop
penalty introduced by increasing the velocity of the liquid
refrigerant. Furthermore, the amount of refrigerant in condenser
900 is controlled such that the liquid refrigerant level is matched
to divider 40. Shell 10 comprises an optional window 38 (e.g. a
sight glass) at the level of divider 40 such that the height of the
liquid refrigerant can be visually confirmed. In other words,
window 38 can be used to confirm that condenser 900 contains the
correct amount of refrigerant. When condenser 900 does not contain
the correct amount of refrigerant, corrective action can be taken
to increase or decrease the amount of refrigerant in condenser
900.
[0139] Referring to FIG. 16, a graph showing a cooling curve 1301
for the refrigerant as it enters and condenses in a condenser such
as condenser 900 or condenser 1100 and a heating curve 1302 for the
liquid medium as it flows through the condenser is shown generally
at 1300. The arrows on each of curves 1301, 1302 indicate the
direction of flow through the condenser. For example, liquid medium
enters condenser on a first pass through at least one tube 44, and
is heated by the condensing refrigerant on subsequent passes. Curve
1302 represents an idealized and/or average of heating of the
liquid medium in the condenser. The liquid medium (e.g. water),
enters the condenser at about 25.degree. C. and exits the condenser
at about 60.degree. C., a rise of about 35K. However, it is
understood that in embodiments where the liquid medium is water
from a civic water supply, the entry temperature of the water can
vary. For example, the temperature may be dependent on climate,
with water in cooler climates being approximately 15.degree. C.
while water from warmer climates can be as high as about
30-35.degree. C.
[0140] Curve 1301 shows that refrigerant enters a condenser such as
condenser 900 or condenser 1100 in a vapour phase and first
interacts with tubes 20 carrying liquid medium on the fourth pass.
Sensible heat is removed from the vapour refrigerant until the
refrigerant condenses. On the third and second pass latent heat is
removed from the refrigerant and the refrigerant changes state as
it condenses resulting in the "flat" portion of curve 1301 when the
refrigerant is present in both liquid and vapour phases. It is
appreciated that the position of change between removal of sensible
heat and removal of latent heat can occur at any suitable point on
the third or fourth pass, though as depicted the change is on the
fourth pass, indicating that the refrigerant can exist in both
liquid and vapour phases in the fourth pass as well. However, the
position of this point is understood to be substantially
non-limiting. It is appreciated that a small degree of subcooling
can occur in the second pass, however the substantial portion of
subcooling of the liquid refrigerant occurs in the first pass as
will now be described. However, it is understood that whether
subcooling occurs or does not occur in the second pass is
substantially non-limiting.
[0141] Furthermore, it is further appreciated that a significant
portion of the subcooling occurs in the first pass (e.g. about 15K
to 30K) as the liquid medium is heated; Indeed, in heat exchange
systems, in which civic water is heated using heat recovered from,
for example, a central energy exchange unit (such as central energy
exchange unit 90), more heat can be transferred with a large degree
of subcooling. A larger degree of subcooling is possible relative
to cooling condensers used in chiller water applications due to the
larger temperature change of the water (e.g. cooling condensers are
generally appreciated to be typically heated only about 3K to 8K).
For example, in many water chillers, the inlet condenser water is
at about 30.degree. C., while the condenser saturation temperature
is around 35.degree. C. for an approximate maximum possible 5K of
subcooling. In heat recovery systems installed in a hot climate the
inlet condenser water can be at about 20.degree. C. while the
condenser saturation temperature at full load is around 60.degree.
C. for a maximum possible subcooling amount of about 40K.
[0142] Referring now to FIG. 17 a condenser system for subcooling
liquid refrigerant is shown generally at 1400. System 1400
comprises a first condenser 1450 for transferring sensible and
latent heat from a refrigerant in a vapour state to a liquid medium
via at least one partition (not depicted) between refrigerant
compartments and liquid medium compartments thereby causing the
refrigerant to condense to liquid state. System 1400 further
comprises a second heat exchanger 1460, located below first
condenser 1450. Heat exchanger 1460 comprises first pass
compartments for a liquid medium to flow there through to liquid
medium compartments of first condenser 1450. As will be described
below, the liquid refrigerant compartments of heat exchanger 1460
are enabled to collect liquid refrigerant from refrigerant
compartments of condenser 1450. It will be appreciated that
condenser 1450 is located vertically above heat exchanger 1460 to
allow gravity to assist in the flow of liquid refrigerant from
condenser 1450 to heat exchanger 1460. Heat exchanger 1460 further
comprises at least one interface between first pass compartments
and liquid refrigerant compartments for heat to flow from liquid
refrigerant to liquid medium thereby subcooling the liquid
refrigerant and heating the liquid medium on a first pass through
system 1400. It is appreciated that the refrigerant velocity in
condenser 1450 decreases rapidly as it condenses and the density
increases by a factor of approximately 12 times. The refrigerant
velocity in heat exchanger 1460 is nearly constant but can be
significantly faster than the liquid refrigerant velocity at the
bottom of condenser 1450 but may be similar to the vapour velocity
at the top of condenser 1450. Hence, it is appreciated that the
smaller cross-section refrigerant flow area of refrigerant
compartments of heat exchanger 1460 cause the velocity of liquid
refrigerant to increase thereby increasing the heat transfer
coefficient of the liquid refrigerant.
[0143] A refrigerant inlet 1452 is provided in condenser 1450 for
entry of refrigerant in the vapour state from a compressor
discharge (e.g. compressor 320). Inside condenser 1450, sensible
and latent heat is removed from the refrigerant vapour causing it
to condense into a liquid. Liquid refrigerant proceeds from outlet
1454 in condenser 1450 through refrigerant piping 1472 to a
refrigerant inlet 1462 in heat exchanger 1460. The amount of
refrigerant in system 1400 is controlled such that heat exchanger
1460 is flooded with liquid refrigerant. An optional sight glass
1470 located in refrigerant piping 1472, can be used to confirm the
correct amount of refrigerant in a system such as system 50a, 50b,
50c, or 50d. It is appreciated that the refrigerant charge is
enough to completely flood one heat exchanger. Sensible heat is
removed in heat exchanger 1460 subcooling the liquid refrigerant.
Refrigerant outlet 1464 connects heat exchanger 1460 to an
expansion control device (such as expansion valve 332) within the
vapour compression cycle.
[0144] A fluid inlet 1466 is provided in heat exchanger 1460 for
entry of the liquid medium to be pre-heated by subcooling of liquid
refrigerant. Examples of liquid medium are water, such as civic
water, glycol or the like. The liquid medium is piped in a counter
flow fashion where the liquid refrigerant exiting condenser 1460
would be near the incoming liquid medium. The liquid medium
proceeds from outlet 1468 in heat exchanger 1460 through fluid
piping 1474 to a fluid Inlet 1456 in the condenser 1450. The liquid
medium is further heated in condenser 1450 as it absorbs latent
heat from the refrigerant as the refrigerant condenses from a
vapour to a liquid state. The liquid medium is further heated in
condenser 1450 as it absorbs sensible heat from the refrigerant
vapour. A fluid outlet 1458 is provided in condenser 1450 for exit
of the liquid medium after it has been fully heated.
[0145] It is appreciated that at least one of condenser 1450 and
heat exchanger 1460 can comprise a plate heat exchanger. In
embodiments where the liquid medium is potable water, for example
from a civic water supply, each of condenser 1450 and heat
exchanger 1460 can comprise a double walled heat exchanger.
[0146] Referring now to FIG. 18, a portion of a longitudinal cross
section of condenser 1450 and a portion of longitudinal cross
section of heat exchanger 1460 is shown. It is appreciated that in
condenser 1450, refrigerant flows through refrigerant compartment
1501 and exchanges heat with the liquid medium flowing through
liquid medium compartment 1503, exchanging heat via partition 1509,
causing the refrigerant to condense from a vapour phase to a liquid
phase and the liquid medium to heat up. In heat exchanger 1460,
liquid refrigerant flows through liquid refrigerant compartment
1505 and exchanges heat with the liquid medium flowing through
first pass compartment 1507, exchanging heat via interface 1511,
causing the liquid refrigerant to subcool and the liquid medium to
heat up in the first pass through system 1400. It is appreciated
that while only a single refrigerant compartment 1501 and a single
liquid medium compartment 1503 of condenser 1450, other embodiments
may comprise any suitable number of refrigerant compartments and
any suitable number of liquid medium compartments. Similarly, it is
appreciated, that while only a single liquid refrigerant
compartment 1505 and a single first pass compartment 1507 of heat
exchanger 1460, other embodiments may comprise any suitable number
of refrigerant compartments and any suitable number of liquid
medium compartments.
[0147] It is further appreciated that a cross-section refrigerant
flow area of liquid refrigerant compartment 1505 is smaller than a
cross-section refrigerant flow area of refrigerant compartment
1501. In other words, as a cross-sectional area of heat exchanger
1460 is smaller than a cross-sectional area of condenser 1450, such
that the refrigerant compartments of heat exchanger 1460 are
smaller than the refrigerant compartments of condenser 1450. Such a
difference in cross-section causes the liquid refrigerant to
increase in velocity as it collects in heat exchanger 1460. Hence,
the difference in cross-section causes an effect similar to baffles
42 of condenser 900.
[0148] It is further appreciated that heat exchanger 1460 and
piping 1472, 1474 can be provided as a kit for retrofitting
condenser 1450 for subcooling. Hence, the efficiency of an existing
condenser can easily be retrofit for subcooling using such a kit.
It is appreciated that piping 1472, 1474 can be any suitable piping
for respectively piping liquid refrigerant from condenser 1450 to
heat exchanger 1460 and piping the liquid medium from heat
exchanger 1460 to condenser 1450.
[0149] Referring to FIG. 19, a method for operating systems 50c and
50d is shown generally at 700a. In system 50d, second controller
112d may be a dual set-point aquastat used in a similar manner as
described in 50c. Method 700a generally contemplates that energy
exchange unit 204c or 204d may be activated on its own, or
activated in conjunction with heater 100, using second controller
112c or 112d and controller 208c or 208d to effect the various
decision boxes in method 700a and the resulting controls from those
decisions. For example, a "no" decision from box 737a is made by
second controller 112c or 112d when the lower threshold temperature
is sensed, thereby leading to activation of heater 100. It will
thus be apparent that box 737a, box 738a and box 739a are
ultimately effected without involvement of controller 208c or 208d
or energy exchange unit 204c or 204d, and thus reflect the
transparent retro-fit possibilities of the teachings herein.
[0150] It should be understood that method 700a can also be used to
operate other variants of system 50a, and not just system 50c and
50d. Such a variant is shown as system 50e in FIG. 20. System 50e
is a variant of system 50a that contemplates the use of dual
set-point second controller 112e. System 50e also contemplates a
pump 260e and a flow-switch 264e, although pump 260e and
flow-switch 264e could also be incorporated directly into energy
exchange unit 204e. System 50e also expressly shows a pump 268 on
conduit HW-2, though it should be understood that such a pump 268
can be part of a pre-existing hot water system.
[0151] In system 50e, as part of effecting block 735a, pump 260e is
activated and then controller waits for confirmation of flow of
water through conduit HW-3 by way of a signal from flow-switch
264e. If no flow of water is detected, then a "no" determination is
made at block 735a and then controller 208e does not activate
energy exchange unit 204e. Thus, flow-switch 264e is a safety
mechanism to ensure pump 260e is working or that there is not some
other failure preventing water from flowing into energy exchange
unit 204e and out through conduit HW-3. If a flow of water is
detected, then a "yes" determination can be made at block 735a and
method 700a advances to block 736a so that energy exchange unit
204e is activated.
[0152] When energy exchange unit 204e is activated at block 736a,
then at block 737a a determination is made if all of the hot water
heating demand is being met. In system 50e, a "yes" determination
at block 737a is reached if the temperature detected by second
controller 112e of temperature sensor TS9 is more than the lower
threshold, in which case at block 739a the heater 100 remains off.
A "no" determination at block 737a is reached if the temperature
detected by second controller 112e of temperature sensor TS9 is
less than the lower threshold, in which case at block 738a the
heater 100 is turned on. In this circumstance, energy is being
provided by both heater 100 and energy exchange unit 204e. However,
in the event of a failure of energy exchange unit 204e, second
controller 112e can continue to control and activate heater 100 in
the usual manner, thereby providing a transparent and uninterrupted
supply of hot water.
[0153] The claims attached hereto solely define the scope of
monopoly sought.
* * * * *