U.S. patent application number 12/270668 was filed with the patent office on 2009-06-18 for dedicated heat recovery chiller.
Invention is credited to Benny L. Kincaid, Mark PLATT.
Application Number | 20090151388 12/270668 |
Document ID | / |
Family ID | 40751460 |
Filed Date | 2009-06-18 |
United States Patent
Application |
20090151388 |
Kind Code |
A1 |
PLATT; Mark ; et
al. |
June 18, 2009 |
DEDICATED HEAT RECOVERY CHILLER
Abstract
A heating and/or cooling system which incorporates one or more
modular dedicated heat recovery refrigeration units each of which
includes at least one compressor, an evaporator and a condenser.
The system captures and utilizes condenser circuit heat which would
otherwise be wasted. A variable speed circulating water pump
circulates water through each evaporator/condenser, which are
connected in parallel across the respective supply line and return
line. A master controller activates and deactivates individual
compressors in accordance with load demand. Shut-off valves close
off the water flow through the respective evaporator and/or
condenser of any units deactivated and the resulting changes in the
pressure differential in the supply and return lines is sensed by
sensor which sends a signal to the pump motor speed controller
which changes the output of the pump to restore a predetermined
pressure differential.
Inventors: |
PLATT; Mark; (Sparta,
WI) ; Kincaid; Benny L.; (Awon, IN) |
Correspondence
Address: |
ORUM & ROTH LLC
53 W. JACKSON BLVD., SUITE 1616
CHICAGO
IL
60604
US
|
Family ID: |
40751460 |
Appl. No.: |
12/270668 |
Filed: |
November 13, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61002870 |
Nov 13, 2007 |
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Current U.S.
Class: |
62/498 |
Current CPC
Class: |
F25B 2600/13 20130101;
F25B 29/003 20130101; Y02B 30/70 20130101; Y02B 30/745 20130101;
F25B 2400/06 20130101 |
Class at
Publication: |
62/498 |
International
Class: |
F25B 1/00 20060101
F25B001/00 |
Claims
1. A dedicated heat recovery chiller, comprising: a modular
dedicated heat recovery chiller, a sensor, a dedicated heat
recovery chiller evaporator waste heat line exiting the dedicated
heat recovery chiller, a dedicated heat recovery chiller condenser
coolant line entering the dedicated heat recovery chiller, a
dedicated heat recovery chiller chilled water line, a dedicated
heat recovery chiller return water line, a connection on the
dedicated heat recovery chiller condenser line for exchanging heat
from a main heating unit return water line, a connection on the
dedicated heat recovery chiller evaporator line for exchanging heat
with a main heating unit return water line, a connection on the
dedicated heat recovery chiller chilled water line for exchanging
heat with a return water line to a main chiller unit, a connection
on the dedicated heat recovery chiller return water line for
exchanging heat with a return water line to a main chiller unit,
wherein the dedicated heat recovery chiller supplies heat to the
return water line to preheat return water to the main heating unit,
the sensor sensing the return water line to the main heating unit
and the dedicated heat recovery chiller condenser coolant line
entering the dedicated heat recovery chiller.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to improvements in heating and
cooling systems and relates particularly to improvements in air
conditioning and chilling systems. Particularly, the invention
relates to a dedicated heat recovery chiller and control systems
for such a chiller.
[0003] The dedicated heat recovery chiller and control system of
the present invention utilizes heat otherwise rejected and wasted
from a condenser circuit of a refrigeration system to offset
heating load which would otherwise need to be provided from a
heating source. This system raises the overall thermal efficiency
of a building system, reduces energy consumption overall, and saves
energy costs.
[0004] Recent developments in air conditioning systems involve the
utilization of modular refrigeration units each having an
evaporator and condenser in heat exchange relation with the fluid
to be cooled and/or heated. With the modular system, each
refrigeration unit is provided with headers for supply and return
of the heat exchange fluid. A plurality of refrigeration units is
connected in parallel, and the heat exchange fluid circulates
through each evaporator and condenser heat exchanger.
[0005] The control of such a modular system enables individual
refrigeration units to be operated in accordance with the load on
the system. Thus, in times of high load, all refrigeration units
will be operating to provide a specific heating and/or cooling
capacity. When the load is reduced, refrigeration units may be down
loaded, or made inoperative, thus reducing the operating costs of
the system and resting units which are not required.
[0006] These units are interconnected and coordinated in the
present invention to create a dedicated heat recovery chiller
system. In this system, heat normally rejected to atmosphere from
the condenser circuit of the refrigeration cycle is instead
captured, controlled, and utilized to displace heat load otherwise
provided by a conventional heating circuit.
[0007] 2. Description of the Related Art
[0008] In the past, heat from the condenser circuit of an air
conditioning system would be rejected to atmosphere, and thereby
wasted.
[0009] The modular refrigeration system overcomes a number of
disadvantages of previous systems, particularly with regard to
system breakdowns and system expansion. The modular system also
provides substantial economies in being able to operate only those
refrigeration units necessary for the load at any particular time.
Power is therefore saved in not having to run refrigeration units
which are unnecessary, or in running units at lower than optimum
peak operating efficiency.
[0010] With a modular heating and/or cooling system, however, the
heating and/or cooling heat exchange fluid, which is usually water,
passes through the heat exchange fluid manifolds supplying the heat
exchange fluid to each of the refrigeration units. The pumping
capacity required, therefore, for both heat exchange fluids, i.e.,
the heat exchange fluid through the evaporators and the condensers
of each refrigeration unit, is necessarily that for supplying fluid
through all refrigeration units and, preferably, is of greater
capacity allowing for expansion of the system both in terms of the
number of refrigeration units and/or the load requirements.
[0011] It is desirable to provide a dedicated heat recovery chiller
system to improve the overall thermal efficiency of a building
system.
[0012] It is desirable to provide a heating and cooling system in
which water pressure differentials and water flow through the
heating and/or cooling system is maintained substantially
constant.
[0013] It is also desirable to provide an improved heating and/or
cooling system for a modular refrigeration system having a
multiplicity of refrigeration units in which the flow of heat
exchange fluid through the condenser and/or chiller of each unit is
dependent on the operating state of that unit.
[0014] It is also desirable to optimize the power consumed by a
modular refrigeration system when operated at less than maximum
capacity by reducing the flow of heat exchange fluid through the
system.
[0015] It is further desirable to reduce the flow of heat exchange
fluid through heat exchangers of modular units which are not
operating and, at the same time, maintain substantially constant
pressure differentials throughout the heating and/or cooling
system.
BRIEF SUMMARY OF THE INVENTION
[0016] According to the present invention there is provided a
heating and/or cooling system comprising one or more modular
dedicated heat recovery refrigeration units each of which has at
least one compressor, an evaporative heat exchanger and a condenser
heat exchanger, supply and return manifold on each unit for
conveying a first heat exchange fluid, the manifold being connected
to manifold of adjacent units, supply and return fluid conduit
extending between respective supply and return manifold of each
unit and the associated evaporative heat exchanger so that the
evaporative heat exchangers are connected in parallel across the
interconnected manifolds, pump for the first heat exchange fluid,
said pump including structure to vary the flow of the first heat
exchange fluid, and valve structure to selectively close at least
one of the supply and return fluid conduit structure.
[0017] Preferably, the pump is a variable speed or variable
capacity pump circulating the first heat exchange fluid through the
system. In one particular arrangement, control structure which
controls the operation of the individual duration units determines
changes in load conditions, such as through changes in return water
temperature, conditioned zone temperatures, ambient temperatures,
and the like, and controls the operation of the individual units in
accordance with the load requirements. As the load decreases,
individual refrigeration units are shut down. When a unit
compressor is deactivated, the valve associated with that unit
closes the fluid conduit so that the evaporative heat exchanger is
no longer connected in parallel with the remaining heat exchangers.
This causes a change in the differential pressure between the
supply and return manifolds. The pressure change is sensed and the
pump is varied to return the pressure differential to a
predetermined level.
[0018] By using a variable speed or variable capacity pump, the
power requirements for the pump is able to be reduced during
reduced system load. Thus, as the load decreases and modular units
are made inactive, the valve on those inactive units is selectively
closed to thereby close the heat exchangers thereof to the heat
exchange fluid. The power supplied to the pump is then also reduced
due to the reduced pumping load resulting from a reduced number of
heat exchangers in the circuit.
[0019] In one form of the invention, the valve comprises a valve
provided on the return conduit of each unit. In another form of the
invention, the valve comprises butterfly valves on both or either
the supply and return conduit.
[0020] In a particular, preferred form of the invention, first and
second supply and return manifold are provided for both the
evaporator heat exchanger and the condenser heat exchanger of the
modular units. The manifold comprise header pipes mounted on each
unit with releasable pipe connectors at each end, such as those
produced by Victaulic, which enable the header pipes of adjacent
units to be connected together. However, it is to be carefully
noted that the structure for connecting the pipes may be of any
conventional structure. Welded ends, flanged ends, bolted ends,
compression couplings, chemical adhesives and/or sealants, and any
other standard coupling structure is contemplated by the present
invention. The supply and return conduit are connected into the
respective supply and return header pipes so as to provide a fluid
path from the supply header pipe through the supply conduit, the
heat exchanger and return conduit to the return header pipe.
[0021] The valve is preferably located in the return header pipe
and is actuated to close the return conduit where it connects with
the return header pipe. In one form of the invention the valve has
a valve head to close the entrance of the return conduit into the
return header pipe, a valve stem extending diametrically and
through a seal on the opposite side of the header pipe into a
pressure chamber located thereon, a piston on the end of the valve
stem, and a bleed line extending from the supply header to the
pressure chamber whereby fluid under pressure from the supply
header pipe may be applied to the top of the piston to move the
valve into the closed position. A pneumatic, hydraulic or
electrical actuator valve in the bleed line controls the flow of
fluid from the supply header to the pressure chamber.
[0022] With this arrangement, by operation of the relatively small
electric, pneumatic or hydraulic valve on the pressure bleed line,
fluid under pressure from the supply header pipe is able to be used
to actuate the valve to close the return conduit. The valve may be
opened by closing the electric, pneumatic or hydraulic valve which
enables the pressure of fluid in the return conduit to move the
valve head from the seat.
[0023] In order that the invention is more readily understood,
embodiments thereof will now be described with reference to the
accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS
[0024] FIG. 1 is a schematic fluid circuit diagram showing an
overview of the system,
[0025] FIG. 2 is a fluid circuit diagram showing operation of the
system of the invention,
[0026] FIG. 3 is a simple schematic showing electrical controls for
the system of FIG. 2,
[0027] FIG. 4 is a schematic view indicating one modular
refrigeration unit having supply and return header pipes for both
the evaporator and condenser,
[0028] FIG. 5 is a detailed view of the supply and return header
pipes and the servo valve of FIG. 3, and
[0029] FIG. 6 is a view similar to FIG. 4 but illustrating a
different form of valve.
[0030] FIG. 7 is a schematic of the dedicated heat recovery chiller
logic system.
[0031] FIG. 8 is a schematic illustrating the main elements of the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] The Dedicated Heat Recovery Chiller (DHRC) is designed to
make use of the heat rejected in the condenser circuit of a
refrigeration system to heat/preheat water for domestic and space
heating use in applications such as showers, swimming pools, VAV
reheat, or any other application requiring hot water. The DHRC is
dependent upon the fact that there is an internal cooling
requirement in the building. Typically this cooling requirement
involves a chiller/air conditioner that would reject the heat in
the condenser to the outside ambient by the structure of a water to
refrigerant or air to refrigerant heat exchanger. This heat would
typically be absorbed into the atmosphere and the energy would be
wasted, where as a chiller utilizing the DHRC controls package can
make the most of this energy and can help reduce the dependency of
a water heater/boiler for the hot water requirements of the
building.
[0033] HEAT OVERRIDE: If heat override is selected, the DHRC
controls will stage the compressors ON and OFF based on the
condenser water temperature and the heating mode control setpoints
as configured in the System Variables. As the condenser water
temperature drops below the control setpoint, more compressors will
be called to run one at a time and this staging will continue to
occur until all available compressors are ON and the chiller is at
full load. If the condenser water temperature rises above the
control setpoint, the compressors will be staged OFF and will
continue to do so until all of the compressors in the system are
OFF and the HEATING load is satisfied, This mode of operation
bypasses the COOLING MODE setpoints and associated control
logic.
Cool Override:
[0034] If cool override is selected, the DHRC controls will stage
the compressors ON and OFF based on the evaporator water
temperature and the cooling mode control setpoints as configured in
the System Variables. As the evaporator water temperature rises
above the control setpoint, more compressors will be called to run
one at a time and this staging will continue to occur until all
available compressors are ON and the chiller is at full load. If
the evaporator water temperature drops below the control setpoint,
the compressors will be staged OFF and will continue to do so until
all of the compressors in the system are OFF and the COOLING load
is satisfied. This mode of operation bypasses the HEATING MODE
setpoints and associated control logic.
[0035] Referring to FIG. 1 there is illustrated a cooling system in
which a plurality of refrigeration units 42 are used to chill water
which is circulated through a chilled water circuit 40 by a
circulating pump 41. The chilled water passes through loads 43,
which may comprise cold water coils in an air conditioning system.
The pump 41 is a variable speed pump and is located in the water
supply line 8. Connected in parallel between the water supply line
8 and a return line 22 are evaporator heat exchangers 12 associated
with each of the refrigeration units 42.
[0036] A condenser water circuit has a condenser water pump 14
which supplies water to condenser heat exchangers 16 which are
connected in parallel across supply and return lines 17 and 18,
respectively. The condenser water is circulated through a water
tower 19 where it is cooled, in the usual manner, by airflow and
evaporation.
[0037] Each refrigeration unit 42 includes at least one compressor
21 which circulates refrigerant through a refrigeration circuit 23
which incorporates an evaporator and a condenser.
[0038] A shut-off valve 24 is connected in each of the water return
lines from each evaporator heat exchanger 12 and each condenser
heat exchanger 16. The valves 24 may be of any suitable form, but
in the embodiment illustrated, the valves are servo valves which
are actuated by water under pressure bled from the respective
evaporator water supply line 26 or condenser water supply line 20.
The bleed water passes through a bleed pipe 27 and is controlled by
a solenoid valve 28 actuated in conjunction with the respective
compressor 21.
[0039] A pressure differential sensor 31 is associated with both
the chilled water circuit 40 and the condenser water circuit 15 to
sense the pressure differential between the respective water supply
lines 8 and 17 and the return lines 22 and 18. The pressure
differential sensors 31 provide a signal to respective motor speed
controllers 32 which operate to vary the speed of the respective
pumps 41 and 14 so as to maintain a predetermined pressure
differential.
[0040] Referring to FIG. 2, a 3-phase power supply 33 is provided
for the chilled water circulating pump 41 and the condenser water
pump 14. Each motor speed controller 32 is an inverter which, in
response to signals from the respective pressure differential
sensors 31, varies the frequency of supply to the respective pumps
to thereby vary the pump speed and, thus, the water flow in the
respective circuits which, accordingly, varies the pressure
differential between the respective supply and return lines 8 and
17, and 22 and 18, respectively.
[0041] The system also includes a control circuit incorporating a
master controller 34 which controls operation of the refrigeration
units 42 in accordance with a variety of factors including load
demand, unit operating time, fault diagnosis, maintenance schedules
and the like. In order to detect load changes, the temperature of
the chilled water is measured in the supply line 8 and return line
22 by appropriate temperature measuring devices 36. Each compressor
21 is controlled by a compressor contactor 37 which receives a 24
volt power supply through an outstation controller 38. The
outstation controller 38 receives control signals from the master
controller 34 in response to sensed load conditions and
predetermined system parameters. The solenoid valves 28 for each
servo valve 24 on the respective units 42 are also controlled by
the outstation controllers 38 such that if the compressor contactor
37 is actuated, the associated solenoid valves 28 are de-energized
and, conversely, if a compressor contactor 37 is de-energized the
associated solenoid valves 28 are energized.
[0042] On full load, each of the refrigeration units 42 is
operating and chiller water flows through each of the evaporator
heat exchangers 12. When the load decreases, the temperature of the
chilled water in the chilled water supply and return lines 8 and 22
changes which initiates, through the master controller, operation
of one of the outstation controllers 38 to deactivate a compressor
21. At the same time, the associated solenoid valves 28 are
energized to thereby activate the shut-off valve 24 in the
respective return lines 22 and 18 preventing water flow through the
respective evaporator heat exchanger 12 and condenser heat
exchanger 16. The pressure differential sensors 31 then detect a
change in the pressure differential between the respective supply
and return lines due to one or more of the heat exchangers being
taken out of the water circuits. The pressure differential sensors
31 signal the respective motor speed controllers 32 to thereby vary
the speed of the respective pumps 41 and 14 to decrease the pumping
speed, the flow of water in the respective circuits and, thus,
reduce the differential pressure to the predetermined value.
[0043] It will be seen that the combination of valves and variable
speed pumps enables a substantial reduction in power consumed when
the system is operating at less than full load. Further, by
utilizing servo operated valves, the power requirements for such
valve operations are minimal.
[0044] Referring to FIGS. 3 to 5, there is illustrated a modular
refrigeration unit 42 which comprises a housing 112 mounting a pair
of compressor units 114 which have parallel refrigeration paths 23
including evaporators and condensers. The evaporators are located
in a common evaporator heat exchanger 12 while the condensers are
located in a common condenser heat exchanger 16. The evaporator
heat exchanger is used to chill water which flows from the supply
header pipe 118 through the heat exchanger 12 and to the return
header pipe 119. A supply conduit 121 connects the supply header
pipe 118 to the evaporator heat exchanger 12 while a return conduit
122 connects with the return header pipe 119.
[0045] Similarly, water is supplied to the condenser heat exchanger
16 from the supply and return header pipes 123 and 124,
respectively.
[0046] In an air conditioning system, a plurality of modular
refrigeration units 42 are connected in parallel so that the
chiller water and the condenser water circulates through each of
the evaporator heat exchanger 12 and condenser heat exchanger 16 of
each unit in the system. As previously indicated, the master
controller 34 controls the number of refrigeration units 42
operating at any one time commensurate with the load on the system.
The number of units operating to maintain the chiller water at the
desired temperature is reduced when the load decreases and
individual units are deactivated in accordance with such decreasing
load requirements.
[0047] Similarly, as the load increases, the master controller 34
activates units as necessary to maintain the desired chiller water
(or heating water) temperature.
[0048] When a modular unit 42 is deactivated, one or more valves
are actuated to close off the supply and/or return of chiller
and/or heating water to the evaporative heat exchanger 12 and
condenser heat exchanger 16. In the embodiment illustrated in FIGS.
3 and 4, a valve 126 is provided in the return header pipe 119 to
operate on the return conduit 122. A similar valve is provided in
the condenser water return header pipe 124 to operate on the
condenser return conduit 127.
[0049] The valve 126 consists of a pressure chamber 128 located on
the outside of the header pipe 119, a valve stem 129 passing
through a seal 131 in the return header pipe 119, a piston 132 on
the end of the valve stem 129 in the pressure chamber, a valve head
133 on the other end of the valve stem 129, the valve head being of
a size to close the opening to the return conduit 122. A pressure
bleed pipe 134 runs from the supply header pipe 118 to the pressure
chamber 128 to bleed supply fluid to the pressure chamber 128 and
thus cause the piston 132 to move the valve head 133 into the
sealing position, as shown in solid lines in FIG. 4. The pressure
bleed pipe 134 is fitted with a normally closed, solenoid actuated
valve 136 which closes the bleed pipe 134.
[0050] A similar valve arrangement is located on the condenser side
of the modular unit 42.
[0051] In normal operation, when the modular refrigeration unit is
in operation, and the compressors 114 are in operation, the
solenoid is deactivated thus closing the pressure bleed pipe 134.
The pressure of chiller water in the return conduit 122 and the
return spring 120 is sufficient to force the valve head 133 away
from the seat so that the return conduit 122 opens into the return
header pipe 119 as shown in chain dot lines in FIG. 4. Similarly,
the return header pipe on the condenser heat exchanger 117 is open
and heat exchange fluid flows through both the evaporative and
condenser heat exchangers 12 and 16.
[0052] When the modular refrigeration unit is deactivated, the
solenoid valves 136 are actuated to open the bleed pipe 134 and
fluid under pressure from the supply header pipes 118 and 123,
respectively, operate the respective valves 126 so as to close off
the respective return conduits 122 and 127. Thus, water no longer
flows through the evaporative heat exchanger 12 and condenser heat
exchanger 16. By taking these heat exchangers out of the respective
water circuits, the loads on the circulating pumps are reduced
accordingly thus enabling a reduction in pumping power by reducing
pump speed.
[0053] As the solenoid actuated valves 136 operate only on fluid
bleed lines 134, sealing difficulties are avoided and the valves
136 may be of relatively simple construction.
[0054] Referring to the embodiment illustrated in FIG. 5, instead
of using valves of the type illustrated in FIGS. 3 and 4, this
embodiment shows the use of two solenoid actuated butterfly valves
137 and 138 in each of the supply conduit 121 and return conduit
122. With this arrangement, the butterfly valves 137 and 138 are
actuated to directly close off both the supply conduit 121 and
return conduit 122 simultaneously. Such butterfly valves 137 and
138 are located directly in the respective conduits and may, if
desired, be actuated by a single actuating solenoid. Alternatively,
such valves may be pneumatically or hydraulically operated.
[0055] It will be appreciated that although the specific
embodiments described use variable speed pumps for circulating the
chiller water and condenser water, variable capacity pumps, or a
combination of variable speed and capacity pumps may be used.
Alternatively, staged pumps or even a plurality of pumps can be
used for water circulation with one or more stages or individual
pumps of a group being deactivated to reduce water flow as required
by system changes.
[0056] Further, it will be appreciated that the condenser heat
exchanger for each unit may utilize air cooling in which case the
invention will be applicable to the chiller water side of the
units. Conversely, the units may be used for heating purposes in
which case the invention will be applicable particularly to the
condenser water circuit.
Auto Control:
[0057] When AUTO CONTROL mode is selected, the DHRC controls
package will monitor the water temperature in both the condenser
and evaporator sides of the chiller and automatically determine the
maximum load that the chiller can operate at any given time. The
DHRC will initially start in the COOLING MODE of operation when
"enabled" by the end user until the DHRC controls has the
opportunity to better sense the cooling and heating load
requirements in the system. The mode of operation that is
automatically selected by the DHRC controller will be based on the
pre-set System Variables that the end user configures for the
heating and cooling requirements in their system.
[0058] For example: If we have a 100 ton chiller, and there is a 40
ton cooling load and a 60 ton heating load, the DHRC controls will
be in "COOLING MODE" and will limit the 100 ton chiller to a
maximum of 40 tons. This is necessary to prevent the evaporator
from getting too cold, which could possibly cause safety trips or
even damage to the chiller. If the conditions in the building
change and the cooling demand increases to 80 tons but there is
still only a 60 ton requirement for heating, then the DHRC controls
will automatically switch to "HEATING MODE" and will limit the 100
ton chiller to a maximum of 60 tons (in this instance) to prevent
the condenser from running too high in pressure/temperature. This
logic will help prevent the DHRC from tripping on nuisance high
pressure trips. When designed properly, the customer should be able
to utilize the most out of there chiller and get the benefits of
all of the reclaimed heat that would normally be rejected into the
atmosphere.
Sequence of Operations
[0059] The Dedicated Heat Recovery Chiller (DHRC) shall be equipped
with a microprocessor based return water controller. The DHRC shall
have the capability to operate in response to either heating water
or cooling water set points. The selection of these two modes of
operation shall be made automatically by the DHRC's Master
Controller. Alternatively, this mode may be set manually or through
a binary input to the controller.
Heating Mode:
[0060] In Heating Mode the DHRC shall operate to provide maximum
hot water to the building's systems while producing chilled water
as a byproduct and thus reducing the load on the buildings main
chiller system.
[0061] The DHRC will respond to the heating set points while in the
Heating Mode. There shall be three set points which dictate the
staging of compressors in this mode as follows:
TABLE-US-00001 Heating Upper Set Point (HUSP) Heating Lower Set
Point (HLSP) Variable Set Point (VSP)
[0062] The HUSP shall indicate the design leaving hot water
temperature from the DHRC. The HLSP shall indicate the design
entering hot water temperature at the DHRC. The VSP shall indicate
a percentage between 0 and 80 which will allow for a leaving
temperature reset based on entering hot water temperature. (That
is, as the entering hot water temperature begins to rise, the
DHRC's Master Controller may allow the leaving hot water
temperature to fall at a corresponding rate to the VSP. For
example, if the VSP is equal to 50%, then for every 1 degree F.
rise in Entering Water Temperature--above the HLSP--the Leaving
Water Temperature will be allowed to drop a corresponding 1 degree
F. If the VSP is 0% then there will be no corresponding drop in
Leaving Water Temperature on a rise in Entering Water Temperature.
If the VSP is set at its maximum of 80% then for each 1 degree F.
rise in Entering Water Temperature there will be a corresponding 4
degree F. drop in Leaving Water Temperature.
[0063] Any time the actual entering hot water temperature at the
DHRC is below the HLSP the DHRC will operate at maximum
capacity.
[0064] As the entering hot water temperature rises above the HLSP
the DHRC will begin unloading compressor stages based on the
setting of the HUSP and VSP to maintain set point.
[0065] The entering and leaving chilled water temperature will be
monitored and any time any chilled water sensor reads 36.degree. F.
the corresponding portion of the DHRC will be locked-out on a
freeze protection safety.
Cooling Mode:
[0066] In the Cooling Mode the DHRC shall operate to provide the
required chilled water to the building's systems while producing
hot water as a byproduct and thus reducing the load on the
building's main boiler system.
[0067] The DHRC will respond to the cooling set points while in the
Cooling Mode. There shall be three set points which dictate the
staging of compressors in this mode as follows:
[0068] Cooling Upper Set Point (CUSP) Cooling Lower Set Point
(CLSP) Variable Set Point (VSP)
[0069] The CUSP shall indicate the design entering chilled water
temperature at the DHRC. The CLSP shall indicate the design leaving
chilled water temperature from the DHRC. The VSP shall indicate a
percentage between 0 and 80 which will allow for a leaving
temperature reset based on entering chilled water temperature.
(That is, as the entering chilled water temperature begins to drop,
the DHRC's Master Controller may allow the leaving chilled water
temperature to rise at a corresponding rate to the VSP. For
example, if the VSP is equal to 50%, then for every 1 degree F.
drop in Entering Water Temperature--below the CUSP--the Leaving
Water Temperature will be allowed to rise a corresponding 1 degree
F. If the VSP is 0% then there will be no corresponding rise in
Leaving Water Temperature on a drop in Entering Water Temperature.
If the VSP is set at its maximum of 80% then for each 1 degree F.
drop in Entering Water Temperature there will be a corresponding 4
degree F. rise in Leaving Water Temperature.
[0070] Any time the actual entering chilled water temperature at
the DHRC is above the CUSP the DHRC will operate at maximum
capacity.
[0071] As the entering chilled water temperature drops below the
CUSP the DHRC will begin unloading compressor stages based on the
setting of the CLSP and VSP to maintain set point.
[0072] If at any time the entering and leaving water temperatures
exceed the DHRC Design Envelope the corresponding portion of the
DHRC will be locked out on a high compressor discharge pressure
safety.
Automatic Changeover of Control:
[0073] At initiation of the system, the DHRC shall start in Heating
Mode.
[0074] While in Heating Mode, if at any time the system senses that
the cooling side of the load has fallen below set point, the system
will automatically change over to Cooling Mode.
[0075] Similarly, while in Cooling Mode, if at any time the system
senses that the heating side of the load has risen above set point,
the system will automatically change over to Heating Mode.
[0076] The Automatic Changeover Controls will always respond to the
smallest of the cooling and heating load. Therefore, the system
will operate the maximum number available hours over its life
thereby providing maximum economic benefit.
[0077] The Multistack Dedicated Heat Recovery Chiller was developed
to eliminate the common practice (in many large commercial
buildings) of operating electric water chillers for air
conditioning while simultaneously operating a natural gas fired
boiler for heating. There are over 100,000 commercial air
conditioning water chillers installed in North America and in
almost every case those buildings operate some kind of hot water
boiler system (most commonly a natural gas burning boiler) in order
to provide heat at the same time. During the summer months, this
heat is often used for either Domestic Hot Water or Hot Water
Reheat for summertime humidity control. Similarly, in the winter
months when the prevailing requirement in many commercial buildings
is for heating, there are internal building loads that require
cooling. Therefore, in many commercial buildings there is
simultaneous operation of both the air conditioning system and the
heating system.
[0078] The DHRC Chiller, when properly applied, eliminates this
simultaneous operation providing significant energy savings by
reducing the operation of the boiler system (in some cases by as
much as 65%). Since most hot water boilers make heat through the
burning of natural gas, the significant reduction in Natural Gas
Consumption offered by the DHRC not only saves utility costs, but
also reduces the consumption of a limited natural resource.
Furthermore, the most significant contributor to Global Warming is
the burning of Fossil Fuels (like Natural Gas) which causes the
emission Of C02, a Greenhouse Gas. Therefore, the DHRC has the
potential to make a significant positive impact on the environment
through the reduction in Greenhouse Gas Emissions in systems
utilizing this technology.
Operation (See FIG. 1)
[0079] The Dedicated Heat Recovery Chiller (DHRC) is physically
piped in parallel or in series with the main building's central
chilled water and central hot water plants. These main heating and
cooling plants remain an integral and vital part of the building.
Often, the only purpose of the DHRC System is to monitor the
operational temperatures of both of theses main systems and provide
for any simultaneous requirement the building may have for cooling
and heating.
[0080] For example, if there is a very large building cooling load
and simultaneously there is a relatively small building heating
load, the DHRC will provide all of the heat required by the
building, eliminating any operation of the building's main heating
system. At the same time the DHRC will provide cooling in a
corresponding quantity to the heating it is providing to the
building's heating loads. This cooling is supplied to the building
cooling loads and the building's main chiller plant will simply
provide less cooling than it would have in the absence of the DHRC.
Essentially, the DHRC is pumping some of the heat generated by the
building into the building's hot water system (instead of rejecting
it to the atmosphere which is the more common practice) in order to
eliminate boiler operation.
[0081] Similarly, if there is a very large building heating load
and simultaneously there is a relatively small building cooling
load, the DHRC will provide all of the cooling required by
building, eliminating any operation of the building's main chiller
system. At the same time the DHRC will produce heating in a
corresponding quantity to the cooling it is providing to the
building's cooling loads. This heating is supplied to the
building's heating loads and the building's main heating plant will
simply provide less heat than it would have in the absence of the
DHRC. In this case the DHRC is pumping all of the heat generated by
the building into the building's hot water system in order to
eliminate chiller operation.
[0082] The DHRC uses the entering and leaving hot water and chilled
water temperatures (Pipes A, B, C and D in FIG. 1) connected to the
building's hot water and chilled water loads to determine its most
efficient mode of operation. When it is initially enabled the DHRC
will operate in Heating Control Mode. Once initial operation is
established the DHRC will automatically change over from Heating
Control Mode to Cooling Control Mode and vice versa based on its
internal calculations on the most efficient mode of operation.
[0083] In the case of FIG. 1, the system temperatures are defined
as follow:
Pipe A=Entering Hot Water
Pipe B=Leaving Hot Water
Pipe C=Entering Chilled Water
Pipe D=Leaving Chilled Water
[0084] The DHRC uses temperature sensors connected to each of the
above pipes to monitor all four of these temperatures. It also has
installed flow switches in each of the piping systems (that is,
there is a proof of flow switch for both the hot water and chilled
water systems to insure pumping operation is enabled). Proof of
flow is critical because in the absence of chilled or hot water
flow to the DHRC it is impossible for the DHRC to measure the water
temperatures, and the corresponding load, in these systems.
[0085] On initial operation of the DHRC it will utilize the
temperature sensed in Pipe A (Entering Hot Water Temperature),
along with the programmed temperature set points within its
electronic controller, to determine its operating point. The DHRC
will have multiple stages of capacity control. That is, a typical
DHRC will have between two and 24 steps of control. In a two-step
machine, capacity will be capable of being controlled in the
following steps: 0%, 50%, and 100%. In 24-step machine, capacity
will be controlled as follows: 0%, 4%, 8%, 12%, 17%, 21%, 25%, 29%,
33%, 38%, 42%, 46%, 50%, 54%, 58%, 62%, 67%, 71%, 75%, 79%, 83%,
88%, 92%, 96%, and 100%. Each of these steps will have an identical
affect on both total cooling and total heating output of the DHRC.
That is, when the DHRC is operating at 50% of its capacity, it will
be operating simultaneously at 50% of its total cooling capacity
and 50% of its total heating capacity.
Heating Control Mode
[0086] When in heating control mode, a rise in the temperature in
Pipe A indicates a reduction in the building's heating load
requirement. Whenever the temperature in Pipe A is below the
heating set point, the DHRC will operate at full capacity (100%).
As the temperature in Pipe Arises, the DHRC will reduce its
capacity from 100% to 0% corresponding to the temperature measured
in Pipe A, the number of steps of control available in the DHRC,
and the heating set points programmed into the DHRC.
[0087] The three heating mode set points that dictate the loading
and unloading of the DHRC System while in heating mode are:
HUSP: Heating Upper Set Point
HLSP: Heating Lower Set Point
VSP: Variable Set Point
[0088] The HUSP represents the temperature in Pipe B when the DHRC
is operating at its full capacity design point. The HLSP represents
the temperature in Pipe A when the DHRC is operating at its full
capacity design point. The VSP represents a percentage of reduction
in Hot Water Temperature leaving the DHRC (Pipe B) that will be
allowed when the DHRC is operating under part load conditions.
Reducing the leaving hot water temperature from the DHRC under part
load conditions is a common practice that allows for higher
efficiency operation.
[0089] In order to determine the operational curve of the system,
the DHRC's electronic controller calculates a temperature called
the Heating No Load Point (HNLP). The formula for determining the
Heating No Load Point is as follows for the Heating Mode:
HNLP=HUSP-(VSP*(HUSP-HLSP))
[0090] The DHRC then employs its available capacity controls to
correlate the temperatures in Pipe A to a point between the HLSP
and the HNLP.
Example 1
Heating Mode
HUSP=125.degree. F.
HLSP=115.degree. F.
VSP=50%
[0091] The Heating No Load Point (HNLP) is then calculated as
follows:
HNLP=HUSP-(VSP*(HUSP-HLSP)=125.degree. F.-(50%*(125.degree.
F.-115.degree. F.)=120.degree. F.
[0092] Therefore, in this case, the DHRC will operate its capacity
controls based on temperature in Pipe A as it moves between the
HLSP and the HNLP. That is, it will operate its capacity controls
between measured temperatures of 115.degree. F. and 120.degree. F.
in Pipe A. Any time the temperature in Pipe A is at or below the
HLSP (115.degree. F.), the DHRC will operate at 100% capacity. Any
time the temperature in Pipe A at or above the HNLP (120.degree. F.
in this case), the DHRC will operate at 0% capacity. In between
these two temperatures in Pipe A, there will be a linear
relationship between capacity and temperature based on the DHRC's
ability to step down. That is, if the DHRC has five-steps of
capacity control (0%, 20%, 40%, 60%, 80%, and 100%). Then the
following control logic will dictate DHRC loading:
Whenever the temperature in Pipe A is at or below the HLSP of
115.degree. F. the DHRC will operate at 100% capacity If the
temperature in Pipe A is at 116.degree. F. the DHRC will operate at
80% capacity If the temperature in Pipe A is at 117.degree. F. the
DHRC will operate at 60% capacity If the temperature in Pipe A is
at 118.degree. F. the DHRC will operate at 40% capacity If the
temperature in Pipe A is at 119.degree. F. the DHRC will operate at
20% capacity If the temperature in Pipe A is at or above
120.degree. F. (the Heating No Load Point) the DHRC will operate at
0% capacity
Cooling Control Mode
[0093] The three cooling mode set points that dictate the loading
and unloading of the DHRC System while in cooling mode are:
CUSP: Cooling Upper Set Point
CLSP: Cooling Lower Set Point
VSP: Variable Set Point
[0094] The CUSP represents the temperature in Pipe C when the DHRC
is operating at its full capacity design point. The CLSP represents
the temperature in Pipe D when the DHRC is operating at its full
capacity design point. The VSP represents a percentage of rise in
Chilled Water Temperature leaving the DHRC (Pipe D) that will be
allowed when the DHRC is operating under part load conditions.
Increasing the leaving chilled water temperature from the DHRC
under part load conditions practice that allows for higher
efficiency operation.
[0095] In order to determine the operational curve of the system,
the DHRC's electronic controller calculates a temperature called
the Cooling No Load Point (CNLP). The formula for determining the
Cooling No Load Point is as follows for the Cooling Mode:
CNLP=CLSP+(VSP*(CUSP-CLSP))
[0096] The DHRC then employs its available capacity controls to
correlate the temperature in Pipe C to a point between the CUSP and
the CNLP.
Example 2
Cooling Mode
CUSP=55.degree. F.
CLSP=45.degree. F.
VSP=80%
[0097] The Cooling No Load Point (NLP) is then calculated as
follows:
CNLP=CLSP+(VSP*(CUSP-CLSP)=45.degree. F.+(80%*(55.degree.
F.-45.degree. F.)=53.degree. F.
[0098] Therefore, in this case, the DHRC will operate its capacity
controls based on temperature in Pipe C as it moves between the
CUSP and the CNLP. That is, it will operate its capacity controls
between measured temperatures of 55.degree. F. and 53.degree. F. in
Pipe C. Any time the temperature in Pipe C is at or above the CUSP
(55.degree. F.), the DHRC will operate at 100% capacity. Any time
the temperature in Pipe C at or below the CNLP (53.degree. F. in
this case), the DHRC will operate at 0% capacity. In between these
two temperatures in Pipe C, there will be a linear relationship
between capacity and temperature based on the DHRC's ability to
step down. That is, if the DHRC has four-steps of capacity control
(0%, 25%, 50%, 75%, and 100%). Then the following control logic
will dictate DHRC loading:
Whenever the temperature in Pipe C is at or above the CUSP of
55.degree. F. the DHRC will operate at 100% capacity If the
temperature in Pipe C is at 54.5.degree. F. the DHRC will operate
at 75% capacity If the temperature in Pipe C is at 54.degree. F.
the DHRC will operate at 50% capacity If the temperature in Pipe C
is at 53.5.degree. F. the DHRC will operate at 25% capacity If the
temperature in Pipe C is at or below 53.degree. F. the DHRC will
operate at 0% capacity
Automatic Changeover of Control Point
[0099] As previously explained, when the DHRC initializes it will
begin operation in the Heating Control Mode. Upon initialization,
the DHRC will immediately calculate both the HNLP (Heating No Load
Point) and the CNLP (Cooling No Load Point). It will perform
capacity control based on the temperature in Pipe A and its Heating
Control Mode Set Points (HUSP, HLSP, and VSP). It will also
continually monitor the temperatures in Pipes B, C and D.
[0100] If while in the Heating Control Mode the DHRC senses that
the temperature in Pipe C drops below the CNLP, the DHRC will
perform a normal shut down and automatically restart in the Cooling
Control Mode.
[0101] Similarly, if while in the Cooling Control Mode the DHRC
senses that the temperature in Pipe A rises above the HNLP, the
DHRC will perform a normal shut down and automatically restart in
the Heating Control Mode.
[0102] It is essential that if the DHRC is to maximize its hours of
operation, which maximizes its energy savings and positive
environmental impact, that it must always use the smaller of the
simultaneous loads (heating or cooling) as its point of control. If
the DHRC were to operate from its Heating Mode controls in the
absence of an adequate building cooling load it would eventually
drive the building's cooling system temperatures so low that the
DHRC system would freeze. Similarly, if the DHRC were to operate
from its Cooling Mode controls in the absence of an adequate
building heating load it would eventually drive the building's
heating system temperatures so high that the DHRC system would
overheat. The ability to automatically sense both the heating and
cooling system loads through the monitoring of the temperatures in
Pipes A and C coupled with the DHRC's ability to continually adjust
its point of control between heating and cooling, in one
embodiment, is critical to its successful operation.
Heat Pump Application
Master Control Requirements:
[0103] Two of the EX inputs may be modified for other purposes. EX1
will be modified so that when it is closed, the controller is in
COOLING mode. EX3 will be modified so that when it is closed, the
controller is in HEATING mode. if both inputs are open, the chiller
is `DISABLED`. If both inputs are closed, the master control will
be i.sub.n HEATING Mode. Both of these inputs will not require a
reset at the master control to resume operation. In addition, no
fault will log in the FAULT REVIEW for these inputs. They will both
be similar to EX2 input. The open line on the second status screen
will display which mode the chiller is in, i.e. COOLING MODE I
HEATING MODE.
[0104] Any time that the control changes from COOLING mode to
HEATING mode all of the compressors will shut off. There will be a
30 second delay same as if the ON key was pressed and then a
compressor will be allowed to start if there is a DEMAND present.
The same will be true if we switch from HEATING mode to COOLING
mode. This will make it obvious if the inputs for COOLING
MODE/HEATING MODE are changing rapidly.
[0105] The other two EX inputs will act as they normally do. EX2
will be used for remote start/stop operations, and will not require
a restart. EX4 will be used only for the Power Phase Monitor (PPM)
system. This input will not require a restart of the chiller, but
will log a fault in the FAULT REVIEW every time EX4 opens.
[0106] The Condenser Water temperature inputs (ECW and LCW) will
not need to be able to read temperatures up to 150.degree. F. The
standard temperature range will be sufficient.
[0107] The Master Control may have separate Upper and Lower
Setpoints for the Cooling Mode and the Heating Mode. The Cooling
Mode setpoints will be the standard setpoints that are in every
Master Control. The Heating Mode setpoints will be:
TABLE-US-00002 Variable Range Default Upper Set Point (Heating)
80--120.degree. F. 100.degree. F. Lower Set Point (Heating)
70--110.degree. F. 90.degree. F.
[0108] When the chiller is in COOLING MODE, the control of the
compressors will be based off the ECHW (Entering Chilled Water)
system sensor. As the ECHW temperature increases more compressors
will be called to start. When the ECHW temperature decreases the
compressors will unload.
[0109] When the chiller is in HEATING MODE, the control of the
compressors will also use the ECHW (Entering Chilled Water) system
sensor. As the ECHW temperature drops, more compressors will be
called to start. When the ECHW temperature increases the
compressors will unload.
[0110] How many compressors are running is based on the Upper and
Lower Set Points for the individual mode of operation along with
the VSP (Variable Set Point) value. For example, if the system
variable were set as such:
Upper Set Point=55
Lower Set Point=45
VSP=50%
Upper Set Point (Heating)=120
Lower Set Point (Heating)=110
[0111] this would mean that in the COOLING MODE, ideally all of the
compressors would be on when the ECHW temperature was 55.degree. or
above, and all of the compressors would be OFF when the ECHW
temperature was 50.degree. or below. When the controller was in the
HEATING MODE, all of the compressors would be on when the ECHW
temperature was 110.degree. F. or below, and all of the compressors
would be OFF when the ECHW temperature was 115.degree. F. or above.
There would also be an at-Jot mode in both the COOLING and HEATING
modes.
[0112] Two sensor inputs may be added to the module boards. These
two sensors may monitor the Leaving Condenser Water Temperature
(LCW) of the two compressor circuits that are controlled by that
module board. The code will incorporate a low temperature cutout on
the Leaving Condenser Water Temperature. It will work exactly like
the Leaving Chilled Water Temp. cutout (at 36.degree. F., reset at
40.degree. F.). This will be active in both the COOLING and HEATING
modes of operation. The fault will need to display as LO LSW. The
present low chilled water temperature display may be changed from
LOCHW to LO LLW.
[0113] The System Condenser Water sensors will now become an active
portion of the control. If the Leaving Condenser Water Temperature
drops to 36.0.degree. F. during operation, a LOW COMMON LSW TEMP
SYSTEM fault will occur. Once the temperature rises to 40.0.degree.
F. the fault will change to a resetable fault. This fault will shut
the entire system down, and a manual reset and restart will be
required to resume operation.
[0114] All of the present cutouts on the module boards may remain
as they are and may be active in both the COOLING and HEATING modes
of operation. This may include the 36.degree. F. cut out on
individual LCHW Temp. and 25 or cut out on the SUCT. Temp. of each
circuit.
[0115] In the Master Control, the CHW Flow Switch inputs may remain
the same as in a standard unit. There is a 4 second delay on the
chilled water flow switch input. If flow is not established in 4
seconds after the chiller is commanded `ON` then the Master Control
will lock the system out, on a fault and will require a manual
reset and proof of flow at the controller before any compressors
will be allowed to start. The chiller will be commanded `ON`
whenever EXI (HEATING MODE) or EX3 (COOLING MODE) is closed. If
both inputs are open, the chiller will be commanded `OFF`, and the
chilled water flow switch will not be monitored. This fault will
display as "WAITING FOR LOAD WATER FLOW" instead of "WAITING FOR
CHILLED WATER FLOW".
[0116] On the condenser side, we need to change the input to
respond the same as the CHW flow switch input. If flow is not
established in 4 seconds after the chiller is commanded `ON` then
the Master Control will lock the system out on a fault and will
require a manual reset and proof of flow at the controller before
any compressors will be allowed to start. The chiller will be
commanded `ON` whenever EX1 (HEATING MODE) or EX3 (COOLING MODE) is
closed. If both inputs are open, the chiller will be commanded
`OFF`, and the chilled water flow switch will not be monitored.
This fault will display as "WAITING FOR SINK/SOURCE WATER FLOW"
instead of "WAITING FOR CONDENSER WATER FLOW
[0117] The Condenser Pump Relay Output may be disabled under
certain conditions.
[0118] The following information may pertain to various screens and
displays:
ECHW will display as ELW. LCHW will display as LLW. ECW will
display as ESW. LCW will display as LSW.
Heat Pump Embodiment:
Master Control Requirements:
[0119] It may be possible to modify two of the EX inputs for other
purposes.
[0120] EX1 will be modified so that when it is closed, the
controller is in COOLING mode. EX3 will be modified so that when it
is closed, the controller is in HEATING mode. if both inputs are
open, the chiller is `DISABLED`. If both inputs are closed, the
master control will be. in HEATING mode. Both of these inputs will
not require a reset at the master control to resume operation. In
addition, no fault will log in the FAULT REVIEW for these inputs.
They will both be similar to EX2 input. The open line on the second
status screen will display which mode the chiller is in (COOLING
MODE/HEATING MODE).
[0121] Any time that the control changes from COOLING mode to
HEATING mode all of the compressors will shut off. There will be a
30 second delay, same as if the ON key were to be pressed, and then
a compressor will be allowed to start if there is a DEMAND present.
The same will be true if there is a switch from HEATING mode to
COOLING mode. This will make it obvious if the inputs for COOLING
MODE/HEATING MODE are changing rapidly.
[0122] The other two EX inputs will act as they normally do. EX2
will be used for remote start/stop operations, and will not require
a restart. EX4 will be used only for the Power Phase Monitor (PPM)
supplied
by Multistack. This input will not require a restart of the
chiller, but will log a fault in the FAULT REVIEW every time EX4
opens.
[0123] The Condenser Water temperature inputs (ECW and LCW) will
not need to be able to read temperatures up to 150.degree. F. The
standard temperature range will be sufficient.
[0124] The Master Control will have separate Upper and Lower
Setpoints for the Cooling Mode and the Heating Mode. The Cooling
Mode setpoints will be the standard setpoints that are in every
Master Control. The Heating Mode setpoints will be:
Variable Range Default Upper Set Point (Heating) 80-120.degree. F.
100.degree. F. Lower Set Point (Heating) 70-110.degree. F.
90.degree. F.
[0125] When the chiller is in COOLING MODE, the control of the
compressors will be based off the ECHW (Entering Chilled Water)
system sensor. As the ECHW temperature increases more compressors
will be called to start. When the ECHW temperature decreases the
compressors will unload.
[0126] When the chiller is in HEATING MODE, the control of the
compressors will also use the ECHW (Entering Chilled Water) system
sensor. As the ECHW temperature drops, more compressors will be
called to start. When the ECHW temperature increases the
compressors will unload.
[0127] How many compressors are- running is based on the Upper and
Lower Set Points for the individual mode of operation along with
the VSP (Variable Set Point) value. For example, if the system
variable were set as such:
Upper Set Point 55
Lower Set Point=45
VSP=50%
Upper Set Point (Heating)=120
Lower Set Point (Heating)=110
[0128] this would mean that in the COOLING MODE, ideally all of the
compressors would be on when the ECHW temperature was 55. .degree.
F. or above, and all of the compressors would be OFF when the ECHW
temperature was 50.degree. F. or below. When the controller was in
the HEATING MODE, all of the compressors would be on when the ECHW
temperature was 110.degree. F. or below, and all of the compressors
would be OFF when the ECHW temperature was 115.degree. F. or above.
There would also be an abort mode in both the COOLING and HEATING
modes.
[0129] It may be desirable to add two sensor inputs to the module
boards. These two sensors will monitor the Leaving Condenser Water
Temperature (LCW) of the two compressor circuits that are
controlled by that module board. The code will have to encorporate
a low temperature cutout on the Leaving Condenser Water
Temperature. It will need to work exactly like the Leaving Chilled
Water Temp. cutout (at 36.degree. F., reset at 40.degree. F.). This
will be active in both the COOLING and HEATING modes of operation.
The fault will need to display as LO LSW. The present low chilled
water temperature display may be changed from LOCHW to LO LLW.
[0130] The System Condenser Water sensors will now become an active
portion of the control. If the Leaving Condenser Water Temperature
drops to 36.0.degree. F. during operation, a LOW COMMON LSW TEMP
SYSTEM fault will occur. Once the temperature rises to 40.0.degree.
F. the fault will change to a resetable fault. This fault will shut
the entire system down, and a manual reset and restart will be
required to resume operation.
[0131] All of the present cutouts on the module boards will remain
as they are and will be active in both the COOLING and HEATING
modes of operation. This will include the 36.degree. F. cut out on
individual LCHW
[0132] In the Master Control, the CHW Flow Switch inputs will
remain the same as in a standard unit. There is a 4 second delay on
the chilled water flow switch input. If flow is not established in
4 seconds after
the chiller is commanded `ON` then the Master Control will lock the
system out on a fault and will require a manual reset and proof of
flow at the controller before any compressors will be allowed to
start. The chiller will be commanded `ON` whenever EXI (HEATING
MODE) or EX3 (COOLING MODE) is closed. If both inputs are open, the
chiller will be commanded `OFF`, and the chilled water flow switch
will not be monitored. This fault will display as "WAITING FOR LOAD
WATER FLOW" instead of "WAITING FOR CHILLED WATER FLOW".
[0133] On the condenser side, it may be desirable to change the
input to respond the same as the CHW flow switch input. If flow is
not established in 4 seconds after the chiller is commanded `ON`
then the Master Control will lock the system out on a fault and
will require a manual. reset and proof of flow at the controller
before any compressors will be allowed to start. The chiller will
be commanded `ON` whenever EX! (HEATING MODE) or EX3 (COOLING:
,ODE) is closed. If both inputs are open, the chiller will be
commanded `OFF`, and the chilled water flow switch will not be
monitored. This fault will display as "WAITING FOR SINK/SOURCE
WATER FLOW" instead of "WAITING FOR CONDENSER WATER FLOW".
Disable the Condenser Pump Relay Output.
[0134] The following information will pertain to ALL screens and
displays:
ECHW will display as ELW. LCHW will display as LLW. ECW will
display as ESW. LCW will display as LSW.
Master Control Requirements:
[0135] In one embodiment, there must be a modification of two of
the EX inputs for other purposes.
[0136] EX1 will be modified so that when it is closed, the
controller is in COOLING (Summer) mode. EX3 will be modified so
that when it is closed, the controller is in HEATING (Winter) mode.
If both inputs are open, the chiller is commanded `OFF`. If both
inputs are closed, the master control will be in HEATING (Winter)
mode. Both of these inputs will not require a reset at the master
control to resume operation. In addition, no fault will log in the
FAULT REVIEW for these inputs. They will both be similar to EX2
input. The open line on the second status screen will display which
mode the chiller is in (COOLING MODE/HEATING MODE).
[0137] Any time that the control changes from COOLING mode to
HEATING mode all of the compressors will shut off. There will be a
30 second delay, same as if the ON key were to be pressed, and then
a compressor will be allowed to start if there is a DEMAND present.
The same will be true if there is a switch from HEATING mode to
COOLING mode. This will make it obvious if the inputs for COOLING
MODE/HEATING MODE are changing rapidly.
[0138] The other two EX inputs will act as the normally do. EX2
will be used for remote start/stop operations, and will not require
a restart. EX4 will be used only for the Power Phase Monitor (PPM)
supplied by Multistack. This input will not require a restart of
the chiller, but will log a fault in the FAULT REVIEW every time
EX4 opens.
[0139] The Condenser Water temperature inputs (ECW and LCW) will
need to be able to read temperatures up to 150.degree. F. The FAULT
REVIEW will also need to log these temperatures properly in the
case of a fault. This will require a special Master Control with
modified inputs for these two sensors.
[0140] The Master Control will have separate Upper and Lower
Setpoints for the Cooling Mode and the Heating Mode. The Cooling
Mode setpoints will be the standard setpoints that are in every
Master Control. The Heating Mode setpoints will be:
TABLE-US-00003 Variable Range Default Upper Set Point (Heating)
110--140.degree. F. 125.degree. F. Lower Set Point (Heating)
100--130.degree. F. 115.degree. F.
[0141] When the chiller is in COOLING MODE, the control of the
compressors will be based off the ECHW (Entering Chilled Water)
system sensor. As the ECHW temperature increases more compressors
will be called to start. When the ECHW temperature decreases the
compressors will unload.
[0142] When the chiller is in HEATING MODE, the control of the
compressors will change over to the ECW (Entering Condenser Water)
system sensor. As the ECW temperature drops, more compressors will
be called to start. When the ECW temperature increases the
compressors will unload.
[0143] How many compressors are running is based on the Upper and
Lower Set Points for the individual mode of operation along with
the VSP (Variable Set Point) value. For example, if the system
variable were set as such:
Upper Set Point=55
Lower Set Point=45
VSP=50%
Upper Set Point (Heating)=125
Lower Set Point (Heating)=115
[0144] this would mean that in the COOLING MODE, ideally all of the
compressors would be on when the ECHW temperature was 55.degree. F.
or above, and all of the compressors would be OFF when the ECHW
temperature was 50.degree. F. or below. When the controller was in
the HEATING MODE, all of the compressors would be on when the ECW
temperature was 115.degree. F. or below, and all of the compressors
would be OFF when the ECW temperature was 120.degree. F. or above.
There would also be an abort mode in both the COOLING and HEATING
modes.
[0145] All of the present cutouts on the module boards will remain
as they are and will be active in both the COOLING and HEATING
modes of operation. This will include the 36.degree. F. cut out on
individual LCHW Temp. and 25.degree. F. cut out on the SUCT. Temp.
of each circuit.
[0146] In the Master Control, the Flow Switch inputs will remain
the same as our standard unit. There is a 4 second delay on the
chilled water flow switch input. If flow is not established in 4
seconds after the chiller is commanded `ON` then the Master Control
will lock the system out on a fault and will require a manual reset
and proof of flow at the controller before any compressors will be
allowed to start. The chiller will be commanded `ON` whenever EXI
(SUMMER/HEATING MODE) or EX3 (WINTER/COOLING MODE) is closed. If
both inputs are open, the chiller will be commanded `OFF, and the
chilled water flow switch will not be monitored.
[0147] On the condenser side, it is not important to monitor the
flow switch input until a compressor starts. If flow is not
established in 10 seconds after the compressor starts, then the
Master Control will lock the system out on a fault and will require
a manual reset and proof of flow at the controller before any
compressors will be allowed to start. Any time after the 10 second
delay after the first compressor starts there will be only a 4
second delay for this fault.
[0148] The customer would also like a dry contact from a relay for
the ALARM OUTPUT of the Master Control. A relay may be added that
will use the standard Customer Alarm Relay (24V) output on the
Master Control. No changes will be required for this request.
Other Requirements:
[0149] The individual circuits high pressure switches will be set
at 365-370 PSIG which corresponds to a temperature of about
146-150.degree. F. on the condenser side. The will be required
because the chiller must operate at 125.degree. F. condenser
entering water temperature (ECW).
[0150] This design does not fall within the scope of our approval
agency requirements, and such we will not be able to label it ETL
approved.
[0151] In one embodiment, the HRC (Heat Recovery Chiller) will
utilize one input (EX2) for chiller control. EX2 must be closed for
the chiller to operate regardless of the CONTROL MODE. This will
eliminate the use of EX1 and EX3 for determining what mode the
controller should be in. EX1 and EX3 will default back to their
previous configuration.
[0152] A SYSTEM VARIABLE may be added that has the options of HEAT
OVERRIDE, COOL OVERRIDE, and AUTO CONTROL. This variable will be
called CONTROL MODE. [0153] If HEAT OVERRIDE is selected, the
control will act as it did when EX3 was closed. [0154] If COOL
OVERRIDE is selected, the control will act as it did when EX1 was
closed and EX3 was open. [0155] If AUTO CONTROL is selected, then
control to the following set of parameters.
[0156] Any time the HRC is started (EX2 closed or On/Off button
pushed) it will initially go into "Cooling" control mode.
While the HRC is in "Cooling" Control Mode:
[0157] If the entering heating water temperature (ECW) rises above
the no-load point (default 120.degree. F.) of the Heating Mode,
then the controls will do an automatic change-over to "Heating"
control. This will cause all of the compressors to turn Off, and
start a 30 second count down to start. The control will now display
Heating Mode information.
While the HRC is in "Heating" Control Mode:
[0158] If the entering cooling water temperature (ECHW) drops below
the no-load point (default 50.degree. F.) of the Cooling Mode, then
the controls will do an automatic change-over to "Cooling" control.
This will cause all of the compressors to turn Off, and start a 30
second count down to start. The control will now display Cooling
Mode information.
[0159] In the case that the ECW is above the no load point of
Heating Mode, and the ECHW is below the no load point of Cooling
Mode everything should be OFF and the controller would be in
Cooling. Mode. [0160] It may be necessary to modify the CPR output.
This output will need to be energized as soon as EX2 closes, or any
time the Chiller is Commanded ON instead of when a compressor
starts. This will occur in all modes of operation. There should be
a 10 second delay after the start of the pump before a fault
condition can occur, and 4 seconds any time thereafter. Manual
reset and restart of chiller may be necessary to resume operation.
You will need to remove the portion of code that requires proof of
flow in order to reset this fault. [0161] It may be possible to add
one SYSTEM FAULT to the control. HIGH ECW TEMP. This fault would
occur if the ECW reached 150.degree. F. If this fault occurs,
command the chiller OFF. This will turn all of the compressors OFF
as well as the CPR output. Manual reset and restart may be
necessary to resume operation.
[0162] In one embodiment, the need for an external signal to tell
what mode the system is operating in could be eliminated.
Heat Recovery Chiller Auto-Changeover Controls
When the HRC is in "Cooling" Control Mode:
[0163] If the entering heating water temperature drops below the
no-load point, then the controls will
change-over to "Heating" control
When the HRC is in "Heating" Control Mode:
[0164] If the entering cooling water temperature drops below the
no-load point, then the controls will
change-over to "Cooling" control
[0165] The HRC will be utilize EX2 for remote start/stop. Any time
the HRC is started it will initially go into "Cooling" control.
Specific Applications:
70/90 Ton Heat Recovery Controls
External Inputs: (EX Inputs)
[0166] The customer inputs (EX Inputs) will not need to be modified
for this program. EX1 and EX3 will be closed circuit to operate,
open to stop. These two inputs would require manual resets to
resume operation. EX2 would be utilized as the Customers Remote
Start/Stop contact. Open to stop operation, closed to start the
chiller. No reset required to resume operation. EX4 will be used
for the PPM input (Power Phase Monitor).
System Variables:
[0167] The System Variables may be expanded to encorporate a COOL
MODE and HEAT MODE set of variables for the following: UPSETPT,
LOSETPT VSP VALUE, T-DIFF. The COOL MODE setpoints will be the same
as in all 70/90 Ton standard program chips. Which are:
TABLE-US-00004 Variable Range Default Upper Set Point (Cooling)
45-80.degree. F. 125.degree. F. Lower Set Point (Cooling)
35-70.degree. F. 115.degree. F. VSP VALUE 0-80% 50 T-DIFF 15-210
Secs. 90 Secs.
[0168] The HEAT MODE setpoints will need to be adjustable as
follows:
TABLE-US-00005 Variable Range Default Upper Set Point (Heating)
110-130.degree. F. 125.degree. F. Lower Set Point (Heating)
100-120.degree. F. 115.degree. F. VSP VALUE 0-80% 50 T-DIFF 15-210
Secs. 90 Secs.
[0169] There may also be an additional System Variable called
CONTROL MODE. The options for this variable will be: HEAT OVERRIDE,
COOL OVERRIDE, and AUTO CONTROL. This point may be able to be
written to by a BAS controller through the RS232 port.
Status Screens:
[0170] Move the display of current faults from the first screen to
the second status screen (center bottom). Replace the current
faults on the first (main) status screen with the display of the
mode of operation of the chiller. (HEATING or COOLING)
[0171] The condenser water temperature inputs (ECW and LCW) may be
able to read temperatures up to 150.degree. F. The FAULT REVIEW
will also need to log these temperatures properly in the case of a
fault. This will require the use of a special Master Control with
modified inputs for these two sensors.
Oct. 6, 2003
Logic of Operation:
[0172] Anytime the HRC (Heat Recovery Chiller) is started (EX2
closed or On/Off button pushed) it will initially go into "Cooling"
control mode. There will be a 30 second countdown to start before
any compressor will start. Also, ideally anytime the controller
changes from one mode to another, there should be a 30 second count
before any compressor will be allowed to start.
While the HRC is in "Cooling Control Mode:
[0173] If the entering condenser water temperature (ECW) rises
above the no-load point (default 120.degree. F.) of the Heating
Mode, then the controls will do an automatic change-over to
"Heating" control. This will cause all of the compressors to turn
Off, and start a 30 second count down to start. The control will
now display Heating Mode information.
While the HRC is in "Heating" Control Mode:
[0174] If the entering chilled water temperature (ECHW) drops below
the no-load point (default 50.degree. F.) of the Cooling Mode, then
the controls will do an automatic change-over to "Cooling" control.
This will cause tall of the compressors to turn Off and start a 30
second count down to start. The control will now display Cooling
Mode information.
[0175] In the case that the ECW is above the no load point of
Heating Mode and the ECHW is below the no load point of Cooling
Mode, everything should be OFF, and the controller would be in
Cooling Mode.
[0176] How many compressors are running is based on the Upper and
Lower Set Points for the individual mode of operation along with
the VSP (Variable Set Point) value. For example, if the System
Variables were set as such:
Upper Set Point (Cooling)=55 Lower Set Point (Cooling)=45 VSP
(Cooling)=50 Upper Set Point (Heating)=125 Lower Set Point
(Heating)=115
VSP (Heating)=50
[0177] This would mean that in the "Cooling" mode of operation,
ideally all of the available compressors would be on when the ECHW
temperature was 55.degree. F. or above, and all of the compressors
would be OFF when the ECHW temperature was 50.degree. F. or below.
When the controller was in the "Heating" mode of operation, all of
the compressors would be on when the ECW temperature was
115.degree. F. or below, and all of the compressors would be OFF
when the ECW temperature was 120.degree. F. or above. There would
also be an abort mode in both the Cooling and Heating modes of
operation similar to the standard program.
[0178] It would also be possible to modify the CPR output so that
it is energized as soon as EX2 closes (or anytime the Chiller is
commanded ON) instead of when a compressor starts. This should
occur in all modes of operation. There should be a 10 second delay
after the start of this CPR output before a CW FLOW fault can
occur. Any time after the initial 10 seconds, if the CW FLOW input
(TB11-pin 9) is open for 4 seconds, a CW FLOW fault will occur.
Manual reset and restart of chiller may be required to resume
operation. It may be necessary to remove the portion of the code
that requires proof of flow in order to reset this fault.
[0179] An additional SYSTEM fault may be added to the control
logic. Its name is HIGH ECW TEMP. This fault would occur if the ECW
temperature reached 140.degree. F. If this fault occurs, command
the chiller OFF. This will turn all of the compressors OFF as well
as the CPR output. Manual reset and restart may be required to
resume operation.
Oct. 6, 2003
[0180] All other safeties from the module boards will remain as
they are and will be active in both the COOLING and HEATING modes
of operation. This will include the 36.degree. F. cut out on
individual LCHW Temp. and 25.degree. F. cut out on the SUCT. Temp.
of each circuit.
Other Requirements:
[0181] The individual circuits high pressure switches will need to
be set to 330 psig, which corresponds to a temperature of about
138.degree. F. on the condenser side. The rated load amps for the
compressors will be preliminarily set as:
TABLE-US-00006 RLA's 208 V 230 V 460 V 575 V 70 TON 219 amps 198
amps 99 amps 80 amps 90 TON 297 amps 268 amps 134 amps 108 amps
OCT. 6, 2003
[0182] The system may also include the following features.
[0183] A heating and/or cooling system comprising at least one
modular dedicated heat recovery refrigeration units each of which
has at least one compressor, an evaporator heat exchanger and a
condenser heat exchanger, supply and return fluid conduit on each
unit for conveying a heat exchange fluid through the evaporator
heat exchanger, said supply and return fluid conduit being
connected to respective supply and return manifold so that the
evaporator heat exchangers of the system are connected in parallel
across the manifold, pump disposed in said manifold for circulating
the heat exchange fluid through the manifold, said pump including
pump control to vary the flow of said heat exchange fluid, and
valve associated with each unit to selectively close at least one
of the supply and return fluid conduit.
[0184] The system may include differential pressure sensing
structure to sense the pressure differential between the supply and
return manifold, said pump control being responsive to said sensing
structure to vary the flow of said heat exchange fluid to maintain
a predetermined pressure differential.
[0185] The system may include a master controller to monitor system
operating parameters and control the modular units, the pump and
each valve, said master controller receiving signals from
temperature sensors in the supply and return manifold, compressor
contactors for each compressor which are activated or deactivated
by the master controller in response to manifold temperatures, and
structure to operate the valve structure of those units which are
deactivated to close the respective supply and/or return fluid
conduit structure.
[0186] The system may have a master controller which activates or
deactivates selected compressor structure in response to manifold
temperatures and so that all units operate substantially
equally.
[0187] The system may have a valve structure mounted on each unit
so as to selectively close only the return fluid conduit
structure.
[0188] The system may have a valve structure mounted on each unit
so as to selectively close only the return fluid conduit
structure.
[0189] The system may have a valve structure which are mounted on
each unit so as to selectively close only the return fluid conduit
structure.
[0190] The system may have second supply and return conduit
conveying condenser fluid to the condenser heat exchanger of each
unit, said second conduit being connected to condenser fluid
manifolds which are interconnected so that the condenser heat
exchangers are connected in parallel, second pump for circulating
said condenser fluid, said second pump having second pump control
structure to vary the flow of said condenser fluid, and condenser
valve structure to selectively close at least one of the second
supply and return conduit on each unit.
[0191] The system may have valve structure comprising a servo valve
having a valve head movable to substantially seal against a valve
seat in the respective return fluid conduit, a piston connected to
the valve head, a pressure line to convey fluid from the supply
manifold to said piston, and closure structure to selectively close
the pressure line.
[0192] The system may have closure structure comprising an inline
solenoid valve in the pressure line.
[0193] The system may have a solenoid valve which is a normally
closed valve which opens the pressure line when energised.
[0194] The system may have an outstation controller which switches
a supply voltage to either the solenoid valve or compressor
contactor in response to the presence or absence of a control
signal for actuation of the respective compressor.
[0195] The system may have pump control structure comprising motor
speed controller structure to vary the speed of said pump.
[0196] The system may have a condenser heat exchanger which is an
air-cooled heat exchanger.
[0197] The dedicated heat recovery air conditioning system
according to the present invention may include a plurality of
modular refrigeration units each having at least one compressor in
a refrigeration circuit which includes an evaporator and a
condenser, a chiller water circuit including water supply and
return manifold pipes and a water circulating pump, a motor speed
controller to control the speed of the pump motor, a pressure
differential sensor to sense the water pressure difference between
the supply and return manifold pipes, differential signal to supply
a control signal to the motor speed controller in response to a
predetermined sensed pressure differential, a chiller water supply
and return conduit for each evaporator to convey water from the
chiller water circuit to a heat exchanger associated with the
evaporator such that the heat exchangers are connected in parallel,
a valve in at least one of each supply and return conduit, and
valve actuating structure to close the valves when the respective
at least one compressor is deactivated.
[0198] The system may have a valve which is a servo valve actuated
by supply manifold water through a bleed pipe and controlled by a
solenoid valve in the bleed pipe.
[0199] The system may have a temperature measuring device which
measures the temperature of the water in the supply and return
manifold pipes, and a master controller activates or deactivates
compressors of the system in response to measured temperatures and
pre-programmed instructions to effect a decrease or increase,
respectively, of the temperatures and, at the same time deactivates
or activates, respectively, the valve actuating structure.
[0200] The present invention may include a heating and/or cooling
system comprising a plurality of modular refrigeration units each
of which has at least one compressor, an evaporator heat exchanger
and a condenser heat exchanger, supply and return fluid conduit
being connected to respective supply and return manifold so that
the evaporator heat exchangers of the system are connected in
parallel across the manifold, pump for circulating the heat
exchange fluid through the manifold, said pump including pump
control structure to vary the flow of said heat exchange fluid,
valve structure associated with each unit to selectively close at
least one of the supply and return fluid conduit, second supply and
return conduit structure conveying condenser fluid to the condenser
heat exchanger of each unit, said second conduit being connected to
condenser fluid manifolds which are interconnected so that the
condenser heat exchangers are connected in parallel, second pump
for circulating said condenser fluid, said second pump having
second pump control to vary the flow of said condenser fluid, and
condenser valve to selectively close at least one of the second
supply and return conduit on each unit.
[0201] The system may include second pump control which includes a
condenser fluid pressure differential sensor to sense the pressure
differential between the condenser fluid supply manifold and return
manifold, and is responsive to the sensor to vary the flow of
condenser fluid to maintain a predetermined pressure
differential.
[0202] The system may function such that condenser fluid is
circulated through a cooling tower.
[0203] The present invention may include a heating and/or cooling
system comprising at least one modular dedicated heat recovery
refrigeration unit each of which has at least one compressor, an
evaporator heat exchanger and a condenser heat exchanger supply and
return fluid conduit on each unit for conveying a heat exchange
fluid through the evaporator heat exchanger, said supply and return
fluid conduit being connected to respective supply and return
manifold so that the evaporator heat exchangers of the system are
connected in parallel across the manifold, pump for circulating the
heat exchange fluid through the manifold, said pump including pump
control to vary the flow of said heat exchange fluid, valve
associated with each unit to selectively close at least one of the
supply and return fluid conduit, and differential pressure sensing
structure to sense the pressure differential between the supply and
return manifold, said pump control structure being responsive to
said sensing structure to vary the flow of said heat exchange fluid
to maintain a predetermined pressure differential.
[0204] The system may include a master controller to monitor system
operating parameters and control the modular units, the pump and
each valve, said master controller receiving signals from
temperature sensors in the supply and return manifold, compressor
contactors for each compressor which are activated or deactivated
by the master controller in response to manifold temperatures, and
structure to operate the valve of those units which are deactivated
to close the respective supply and/or return fluid conduit.
[0205] The system may include valve which are mounted on each unit
so as to selectively close only the return fluid conduit.
[0206] The present invention may include a heating and/or cooling
system comprising at least one modular dedicated heat recovery
refrigeration unit each of which has at least one compressor, an
evaporator heat exchanger and a condenser heat exchanger, supply
and return fluid conduit on each unit for conveying a heat exchange
fluid through the evaporator heat exchanger, said supply and return
fluid conduit being connected to respective supply and return
manifold so that the evaporator heat exchangers of the system are
connected in parallel across the manifold, pump for circulating the
heat exchange fluid through the manifold, said pump including pump
control to vary the flow of said heat exchange fluid, valve
associated with each unit to selectively close said return fluid
conduit, a master controller to monitor system operating parameters
and control the modular units, the pump and each valve, said master
controller receiving signals from temperature sensors in the supply
and return manifold, compressor contactors for each compressor
which are activated or deactivated by the master controller in
response to manifold temperatures, and structure to operate the
valve of those units which are deactivated to close the respective
supply and/or return fluid conduit.
[0207] The present invention may include a heating and/or cooling
system comprising at least one modular dedicated heat recovery
refrigeration units each of which has at least one compressor, an
evaporator heat exchanger and a condenser heat exchanger, supply
and return fluid conduit on each unit for conveying a heat exchange
fluid through the evaporator heat exchanger, said supply and return
fluid conduit being connected to respective supply and return
manifold, so that the evaporator heat exchangers of the system are
connected in parallel across the manifold, pump for circulating the
heat exchange fluid through the manifold, said pump including pump
control structure to vary the flow of said heat exchange fluid,
valve associated with each unit to selectively close said supply
fluid conduit, a master controller to monitor system operating
parameters and control the modular units, the pump and each valve,
said master controller receiving signals from the temperature
sensors in the supply and return manifold, compressor contactors
for each compressor which are activated or deactivated by the
master controller in response to manifold temperatures, structure
to operate the valve of those units which are deactivated to close
the respective supply and/or return fluid conduit, wherein said
master controller is arranged and constructed to activate or
deactivate selected compressor in response to manifold temperatures
so that all units operate substantially equally.
[0208] The present invention may include a heating and/or cooling
system comprising at least one modular dedicated heat recovery
refrigeration units each of which has at least one compressor, an
evaporator heat exchanger and a condenser heat exchanger, supply
and return fluid conduit on each unit for conveying a heat exchange
fluid through the evaporator heat exchanger, said supply and return
fluid conduit being connected to respective supply and return
manifold so that the evaporator heat exchangers of the system are
connected in parallel across the manifold, pump for circulating the
heat exchange fluid through the manifold, said pump including pump
control to vary the flow of said heat exchange fluid, valve
associated with each unit to selectively close at least one of the
supply and return fluid conduit, said valve comprising a servo
valve having a valve head movable to substantially seal against a
valve seat in the respective return fluid conduit, a piston
connected to the valve head, a pressure line to convey fluid from
the supply manifold to said piston, and closure structure arranged
and constructed to selectively close the pressure line, said
closure structure comprising an inline solenoid valve in the
pressure line, wherein an outstation controller switches a supply
voltage to either the solenoid valve or compressor contactor in
response to the pressure or absence of a control signal for
actuation of the respective compressor.
[0209] The dedicated heat recovery chiller sensor monitors both
sides, heating and cooling. The dedicate heat recovery chiller
reacts to the smaller demand. The result is no wasted heat and no
wasted cooling. The dedicated heat recovery chiller acts to control
the load which is smaller. In the present invention, all of the
otherwise wasted heat is used to supply the heat input for the main
building heating supply. The overall effect is to reduce the
outside energy needed to create the correct temperature hot water
for the building heating input circuit by preheating the input
water to the main boiler.
[0210] The dedicated heat recovery chiller is sized to run at full
load all year. The dedicated heat recovery chiller supplies all
heat requirements to the building in the summer while cooling at
the same time and also may be sized to substitute all cooling load
in the winter. In one embodiment, the dedicated heat recovery
chiller is sized to the larger of either the entire summer heating
load or the entire winter cooling load. The dedicated heat recovery
chiller acts to pre-cool the main chiller water and to preheat the
main boiler water.
[0211] The sensor senses and controls based upon the return water
line characteristics from the building to the main heating unit,
and the cooled condenser water line in the dedicated heat recovery
chiller.
* * * * *