U.S. patent application number 12/434469 was filed with the patent office on 2009-11-12 for apparatus and method for modulating cooling.
Invention is credited to Bradford L. Blankenship, Michael J. Dimunation, Dennis S. Gambiana, Dennis R. Maniello.
Application Number | 20090277196 12/434469 |
Document ID | / |
Family ID | 41265756 |
Filed Date | 2009-11-12 |
United States Patent
Application |
20090277196 |
Kind Code |
A1 |
Gambiana; Dennis S. ; et
al. |
November 12, 2009 |
APPARATUS AND METHOD FOR MODULATING COOLING
Abstract
This invention relates to a method and an apparatus for a
modulating air conditioning system having increased energy
efficiency and greater turndown capabilities. A modulating air
conditioning system includes modulating at least one of the
following components: a compressor, a compressor driver, a
condenser fan, an evaporator fan, an effective evaporator surface
area, an effective condenser surface area and/or an expansion
device.
Inventors: |
Gambiana; Dennis S.;
(Bloomington, MN) ; Blankenship; Bradford L.;
(Orono, MN) ; Maniello; Dennis R.; (Bloomington,
MN) ; Dimunation; Michael J.; (Columbia Heights,
MN) |
Correspondence
Address: |
PAULEY PETERSEN & ERICKSON
2800 WEST HIGGINS ROAD, SUITE 365
HOFFMAN ESTATES
IL
60169
US
|
Family ID: |
41265756 |
Appl. No.: |
12/434469 |
Filed: |
May 1, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61049457 |
May 1, 2008 |
|
|
|
Current U.S.
Class: |
62/115 ;
417/410.1; 62/428; 62/508; 62/510; 62/525 |
Current CPC
Class: |
F25B 2600/111 20130101;
F25B 39/028 20130101; F25B 2700/195 20130101; F25B 2700/21173
20130101; F25B 2700/21163 20130101; Y02B 30/70 20130101; F25B
2600/2511 20130101; Y02B 30/743 20130101; F25B 2600/025 20130101;
F25B 2600/112 20130101 |
Class at
Publication: |
62/115 ; 62/510;
62/428; 62/508; 62/525; 417/410.1 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F25B 1/10 20060101 F25B001/10; F25D 17/06 20060101
F25D017/06; F25B 39/02 20060101 F25B039/02; F04B 35/04 20060101
F04B035/04 |
Claims
1. An air conditioning apparatus for a residential or commercial
building and including as components a compressor, a condenser
coil, an expansion device, and an evaporator coil, the apparatus
comprising: a modulating refrigerant distribution and/or expansion
device selected from a group consisting of a variable displacement
compressor device, a modulating expansion device, a modulating
evaporator device, and combinations thereof; and a controller for
modulating the at least one modulating refrigerant distribution
and/or expansion device.
2. The apparatus according to claim 1, further comprising at least
one of a modulating condenser fan or a modulating evaporator
fan.
3. The apparatus according to claim 1, further comprising a
variable stroke compressor as the variable displacement compressor
device.
4. The apparatus according to claim 3, wherein the variable
displacement compressor device has a capacity of less than six
tons.
5. The apparatus according to claim 3, further comprising a motor
for operating the compressor device, wherein the motor is cooled by
air moving over the motor.
6. The apparatus according to claim 5, wherein the motor is
detachably connected to the compressor unit and not cooled by the
refrigerant.
7. The apparatus according to claim 1, further comprising the
modulating evaporator device including more than one evaporator
coil zone and a restriction device for each of the more than one
evaporator coil zone, wherein each restriction device restricts
and/or regulates a flow of refrigerant to a corresponding
evaporator coil zone.
8. The apparatus according to claim 7, wherein the controller
operates the restriction device of each of the more than one
evaporator coil zone.
9. The apparatus according to claim 1, further comprising the
modulating expansion device including more than one expansion
valve.
10. An air conditioning apparatus for a residential or commercial
building, the apparatus comprising: a compressor device for
receiving and compressing a refrigerant; and a motor for operating
the compressor device, wherein the motor is air-cooled; wherein the
compressor device has a capacity of less than six tons or the motor
has a power output of about 5,222 watts or less.
11. The device according to claim 10, wherein the motor is
detachably connected to the compressor unit and not cooled by the
refrigerant.
12. The device according to claim 11, wherein the motor comprises a
motor driveshaft, the compressor device comprises a compressor
driveshaft, and the motor driveshaft is separate from and in
operating combination with the compressor driveshaft.
13. The device according to claim 10, wherein the motor comprises a
brushless DC motor or an electrically commutated motor.
14. The device according to claim 10, wherein the compressor
comprises a variable displacement compressor.
15. The device according to claim 14, wherein the motor comprises a
single speed motor.
16. The device according to claim 14, further comprising a
controller for modulating at least one of the variable displacement
compressor or a speed of the motor.
17. A method of conditioning air for a residential or commercial
building, the method comprising: modulating a compressing of a
refrigerant in a compressor; condensing the compressed refrigerant
within a condenser; running the condensed refrigerant through an
expansion device to cool the refrigerant; absorbing heat from the
residential or commercial building with the cooled refrigerant
within an evaporator device; modulating a flow of the refrigerant
through the expansion device and/or the evaporator device; and
returning the heated refrigerant gas to the compressor.
18. The method according to claim 17, wherein the compressor
comprises a variable displacement compressor.
19. The method according to claim 17, further comprising modulating
a pressure drop of the refrigerant at the expansion device.
20. The method according to claim 17, wherein the evaporator device
comprises more than one evaporator coil zone and further comprising
reducing or stopping for a time period a flow of refrigerant from
one of the more than one evaporator coil zone.
21. The method according to claim 17, further comprising reducing
or stopping an air flow over a portion of the evaporator device.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. application Ser.
No. 61/049,457, filed on 1 May 2008. The co-pending provisional
application is hereby incorporated by reference herein in its
entirety and is made a part hereof, including but not limited to
those portions which specifically appear hereinafter.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This present invention is directed to a method and an
apparatus for modulating cooling in air conditioning and cooling
systems, particularly for residential and commercial buildings.
[0004] 2. Discussion of the Related Art
[0005] There is a general desire for a modulating air conditioning
system with increased energy efficiency and greater turndown
capabilities.
[0006] In a typical closed-loop vapor compression cycle, a heat
transfer fluid (refrigerant) either absorbs or rejects heat to the
environment by changing state between a liquid and a vapor. A
compressor is used to pump and compress the vapor refrigerant. The
refrigerant leaves the compressor as a high pressure, high
temperature vapor, and enters the condenser. As the refrigerant
passes through the condenser, heat is rejected from the refrigerant
into the environment. As heat is rejected, the refrigerant
condenses from a vapor into a liquid. Refrigerant leaves the
condenser as a subcooled liquid, and enters an expansion device,
where it undergoes a volumetric expansion. The expanded low
temperature liquid refrigerant enters the evaporator coil, where it
undergoes a vaporization process as it absorbs heat from the
environment. The refrigerant exits the evaporator as a superheated
low-pressure vapor, then flows through a suction line back to the
compressor.
[0007] An evaporator in a typical air conditioning application
serves a dual purpose of dehumidification as well as temperature
control. A circulator fan forces air over the evaporator coil
surface. As the evaporator coil absorbs heat from the air passing
over its surface, the air is cooled, and exits the evaporator at a
lower temperature than that of the entering air. As the air is
cooled, it loses its ability to hold moisture. If the coil surface
is cooled to a temperature below the dew point temperature of the
passing air, then water will begin to condense on the evaporator
coil surface, thereby reducing the moisture contained in the air.
This reduction in moisture serves to dehumidify the controlled
space.
[0008] Evaporator coil temperature is primarily controlled by the
saturation vapor pressure of the refrigerant, and its corresponding
temperature. As the refrigerant undergoes a state change from a
liquid to vapor, it maintains a constant temperature until the
process has completed. After the change in state of the refrigerant
has completed, the additional absorption of heat will cause the
refrigerant vapor to increase in temperature while remaining at a
constant pressure. This additional temperature rise is a
thermodynamic property known as superheat, and can be used as a
control feedback to regulate the expansion process of the
refrigerant before entering the evaporator coil.
[0009] The time required for the refrigerant to change state is
dependent upon both the rate of heat transfer from the evaporator
to the surrounding air, and the flow rate of the refrigerant
through the closed-loop system. Furthermore, the rate of heat
transfer, after incorporating several system constants, is largely
dependent upon the flow rate of the air passing over the evaporator
coil, the surface area of the evaporator exposed to the moving air,
and the temperature differential between the evaporator surface and
the moving air. An increase of air flow, evaporator surface area,
or temperature differential will increase the rate of heat transfer
between the moving air and the evaporator. Conversely, a reduction
in air flow, evaporator surface area or temperature differential
will reduce the rate of heat transfer.
[0010] Accordingly, the heat transfer between the refrigerant and
the evaporator surface is governed by a similar relationship,
involving the flow rate of the refrigerant through the evaporator,
the surface area of the evaporator exposed to the refrigerant, and
the temperature differential between the refrigerant and the coil
surface. As it pertains to this discussion, the thermal mass of the
evaporator itself is assumed to be negligible, and therefore the
heat transfer rate between the refrigerant and the evaporator shall
be assumed equal to the heat transfer rate between the evaporator
and the moving air.
[0011] The refrigerant expansion device provides a restriction in
the refrigerant loop, causing the refrigerant to undergo a
volumetric expansion process as it passes through the restriction.
Typically, the expansion device will incorporate a feedback system
to properly regulate the superheat of refrigerant exiting the
evaporator. This feedback system may consist of a mechanical
thermostatic valve assembly, an electronic temperature sensor,
pressure sensor and corresponding control for an electronically
controlled valve, or various other means. Regardless of the
feedback mechanism incorporated into the system, regulation of
refrigerant superheat is the primary purpose of this device.
[0012] When the refrigerant state change in the evaporator has
completed, the refrigerant is no longer capable of effectively
facilitating heat transfer between itself and the evaporator
surface. Therefore, refrigerant superheat, which begins to occur
immediately after this state change has completed, can be used to
indicate that it is no longer advantageous to allow that specific
quantity of refrigerant to remain in the evaporator.
[0013] Assuming all other temperatures and flow rates remain
constant, the expansion device can be used to regulate the
superheat of the refrigerant exiting the evaporator coil by either
restricting or increasing the flow of refrigerant through the
device. As the refrigerant flow is restricted, the refrigerant flow
rate through the evaporator decreases. The heat capacity of the
refrigerant has not changed, and therefore completion of the
vaporization process of the refrigerant occurs at a point closer to
the inlet of the evaporator. After this point, the refrigerant
begins to absorb heat as superheat until it either exits the coil
or reaches the same temperature as the ambient air, preventing
further heat transfer. Conversely, as the refrigerant flow
restriction is relaxed, the refrigerant flow rate is increased, and
the vaporization process is completed at a point further away from
the inlet. As a result, less evaporator surface area is used to
superheat the refrigerant vapor, and the superheat of the
refrigerant at the exit of the coil is reduced. Through this
process of relaxing and restricting the flow of refrigerant through
the expansion device, the refrigerant superheat can be controlled,
and peak heat transfer efficiency is maintained while correcting
for outside influences.
[0014] A consequence of this flow restriction is a pressure
differential between the refrigerant entering and exiting the
expansion device. As the flow is restricted, the pressure
differential increases, and therefore the pressure of the
refrigerant exiting the expansion device is reduced. This pressure
reduction causes a corresponding temperature reduction, as dictated
by the saturation vapor pressure-temperature relationship.
[0015] In a typical residential or commercial system, the
evaporator fan serves to both transfer heat from the air to the
evaporator, and to distribute the conditioned air throughout the
controlled space. Vapor compression systems with variable fan
control have the ability to reduce the flow of moving air across
the evaporator to better match the operating conditions of the
system. As the fan speed is reduced, heat transfer across the
evaporator is also reduced. Assuming all other factors remain
constant, as the fan speed is reduced, the expansion device must
further restrict the flow of refrigerant in order to ensure that
the vaporization process can be completed before the refrigerant
leaves the evaporator coil.
[0016] Conventional residential air conditioning systems do not
modulate based on cooling requirements, but cycle between an on
state and an off state. Two stage residential air conditioning
systems cycle between a high output, a low output and an off state,
such as utilizing two compressors, de-energizing an unloader valve
or using other capacity reduction devices. Single stage air
conditioning systems are sized only for peak cooling requirements
and operate less efficiently when under partial load. Two stage air
conditioning systems are also sized for peak load when operated at
full capacity, but are typically more efficient when operated at
their second, reduced capacity state.
[0017] Known modulating air conditioning systems available for the
residential and commercial air conditioning marketplace undesirably
make use of an inverter-driven three phase motor with
variable-frequency control to increase and/or decrease a rotational
speed of the attached compressor. Inverter-driven compressors
require the use of specialized and costly electronics to control
the output frequency of the three phase power supplied to the
motor. Furthermore, additional phase conversion hardware is needed
since three phase power is not generally available in most
residential and light commercial installations.
[0018] Known modulating air conditioning systems use proprietary
hardware and/or propriety control systems to allow modulation. The
design of known modulating air conditioning systems cannot be used
with conventional furnaces, evaporator coils and/or thermostat
controls. In a typical installation of a known "ductless
mini-split" modulating air conditioning system, a condenser coil
and a compressor assembly feeds one or more wall-mounted evaporator
coils, each evaporator coil includes a separate control system, a
thermostat and a refrigeration line set.
[0019] Conventional compressor designs available for use in
residential and/or commercial cooling applications include
reciprocating compressors, rotary compressors, rotary vanes, or
scroll compressors. In conventional cooling systems, a
reciprocating compressor uses a crank shaft, connecting rods,
pistons and valves to draw vapor refrigerant into a cylinder and
compress the refrigerant into a condensing coil. In the condensing
coil, the refrigerant transfers heat and/or enthalpy absorbed from
a building as the refrigerant condenses back into a liquid through
a phase change.
[0020] An electric motor drives the crank shaft and a motor speed
controller varies a speed the compressor for modulated capacity.
Undesirably, the motor speed controller is expensive and efficiency
gains are limited by frictional losses from the piston moving
throughout a stroke during turndown. The frictional losses increase
as a percentage of output power when the compressor is slowed,
necessitating a significant increase in heat exchanger surface
area. The net result is a modest efficiency gain at much higher
capital and/or equipment cost.
[0021] In other conventional cooling systems, a scroll compressor
utilizes two interleaved spiral-like vanes to compress a
refrigerant. Typically, scroll compressors can be more efficient
than reciprocating compressors and are the industry standard for
residential and light commercial cooling applications. The scroll
compressor includes limitations for turndown. The vanes of the
scroll compressor generate heat due to the compression process and
are constantly lubricated to prevent premature damage to compressor
components. When the motor is turned down, heat of compression is
still high but the lubricating oil pump in the compressor also
slows down, so the heat of compression is not removed resulting in
premature compressor failure. Other methods and/or attempts for
modulating the scroll compressor, such as dynamically off-setting
the vanes, has proved effective for capacity control, but does not
result in higher efficiency ratings.
[0022] Conventional compressor designs include electric motor
windings imbedded in a compressor housing and cooled by the same
refrigerant used to cool the structure. Heat generated by the motor
is added to the refrigerant cooling load and removed in the
refrigeration cycle resulting in more work for the compressor, more
energy usage by the system and a lower system efficiency. Known
hermetic and semi-hermetic compressor designs result in increased
heat load on the cooling system.
SUMMARY OF THE INVENTION
[0023] A general object of the invention is met at least in part by
a modulating air conditioning system having increased energy
efficiency and greater turndown capabilities than conventional air
conditioning systems. The improved air conditioning system may
include control based on actual and/or real time cooling loads
and/or demands.
[0024] A more specific object of the invention is to overcome one
or more of the problems described above.
[0025] The general object of the invention can be attained, at
least in part by a modulating air conditioning system, where at
least one of the following components includes modulating
capabilities: a compressor, a compressor driver, a condenser fan,
an evaporator fan, an effective evaporator surface area, an
effective condenser surface area and/or an expansion device.
[0026] The invention includes an air conditioning apparatus for a
residential or commercial building that includes as components a
compressor, a condenser coil, an expansion device, and an
evaporator coil. The apparatus further includes a modulating
refrigerant distribution and/or expansion device selected from a
group consisting of a variable displacement compressor device, a
modulating expansion device, a modulating evaporator device, and
combinations thereof. A controller for modulating the at least one
modulating refrigerant distribution and/or expansion device is also
included.
[0027] The invention further includes an air conditioning apparatus
for a residential or commercial building that includes a compressor
device for receiving and compressing a refrigerant and a motor for
operating the compressor device, wherein the motor is air-cooled
and the compressor device has a capacity of less than six tons or
the motor has a power output of about 5,222 watts or less.
[0028] The invention further includes a method of conditioning air
for a residential or commercial building including the steps of:
modulating a compressing of a refrigerant in a compressor;
condensing the compressed refrigerant within a condenser; running
the condensed refrigerant through an expansion device to cool the
refrigerant; absorbing heat from the residential or commercial
building with the cooled refrigerant within an evaporator device;
modulating a flow of the refrigerant through the expansion device
and/or the evaporator device; and returning the heated refrigerant
gas to the compressor.
[0029] The invention further includes an air conditioning apparatus
for a residential or commercial building. The apparatus includes an
expansion device for reducing a pressure of a refrigerant and an
evaporating device for receiving the refrigerant from the expansion
device. The evaporator device includes two refrigerant distribution
assemblies and the apparatus includes a means for alternating a
flow of the refrigerant between though only one of the two
refrigerant distribution assemblies and through both of the two
refrigerant distribution assemblies.
[0030] The invention further comprehends an air conditioning
apparatus for a residential or commercial building including an
evaporating device including two refrigerant distribution
assemblies, a valve assembly in combination the evaporating device
for modulating refrigerant through the evaporating device, and a
controller in communication with the valve assembly for alternating
the valve assembly between delivering the refrigerant to only one
of the two refrigerant distribution assemblies and delivering the
refrigerant to both of the two refrigerant distribution
assemblies.
[0031] A method of conditioning air according to this invention
includes: compressing a refrigerant; condensing the compressed
refrigerant; introducing the compressed refrigerant into an
evaporating device; modulating a flow of the refrigerant within the
evaporating device; moving air over at least a portion of the
evaporating device; and absorbing heat from the air with the
refrigerant within an evaporator device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] These and other objects and features of this invention will
be better understood from the following detailed description taken
in conjunction with the drawings.
[0033] FIG. 1 schematically illustrates an air conditioning
apparatus for a residential or commercial building according to one
embodiment of this invention.
[0034] FIG. 2 shows a partial sectional view of a variable
displacement compressor, according to one embodiment of this
invention.
[0035] FIG. 3 shows internal components of a variable displacement
compressor.
[0036] FIG. 4 shows a view of a compressor input shaft adapter
according to one embodiment of this invention.
[0037] FIG. 5 shows a partial sectional view of a modulating
condensing unit, according to one embodiment of this invention.
[0038] FIGS. 6-13 are schematic illustrations of modulating air
conditioning systems according to embodiments of this
invention.
[0039] FIGS. 14 and 15 are schematic illustrations of modulating
evaporator devices according to embodiments of this invention.
[0040] FIG. 16 is a modulating evaporator device according to one
embodiment of this invention.
[0041] FIGS. 17-19 are schematic illustrations of modulating
evaporator devices according to embodiments of this invention.
[0042] FIG. 20 shows a graph of power consumption and SEER versus
compressor modulation level.
[0043] FIG. 21 shows a compressor input shaft adapter according to
another embodiment of this invention.
DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS
[0044] This invention provides increased efficiency for air
conditioners and/or dehumidification units of fixed structures by
using modulating techniques and/or designs. Modulating techniques
of this invention may also be applied to refrigeration storage
systems and/or applications. Alternately, the modulating techniques
of the invention may also be applied to and/or adapted for heat
pump operations.
[0045] Conventional air conditioning systems do not modulate and/or
have turndown ratios, but provide a constant rate of heat removal
when operated regardless of actual cooling demand. Conventional air
conditioning systems include a fixed speed compressor motor, a
fixed volume compressor, a fixed surface area evaporator coil, a
fixed surface area condenser coil, a fixed speed evaporator fan and
a fixed speed condenser fan.
[0046] Conventional air conditioning systems are sized based on
maximum cooling requirements, such as a peak summer day with high
humidity, but are often inefficient during cooler days requiring
less cooling. Conventional air conditioning systems undesirably
cycle on and off while allowing a temperature inside a building to
fluctuate between feeling hot and cold. Cycling and/or swinging of
the conventional air conditioning system further increases
inefficiencies and/or energy consumption.
[0047] In some embodiments of this invention, the modulating air
conditioning system includes at least one of a variable
displacement compressor, a variable volume compressor, a variable
speed compressor driver, a variable surface area evaporator coil, a
variable surface area condenser coil, a variable speed evaporator
fan driver, a variable volume evaporator fan, a variable speed
condenser fan driver and/or a variable volume condenser fan. The
modulating air conditioning system of this invention may operate
with any suitable refrigerant, such as R-11, R-12, R-14, R-22,
R-32, R-125, R-134a, R-407c, R-410a, R-744, carbon dioxide,
ammonia, propane, hydrogen and/or any other substance with a phase
change.
[0048] By utilizing at least one component with modulating and/or
variable capabilities, the improved air conditioning system
operates to supply an amount of cooling that is needed in real
time, for example. Additional modulating components provide
additional degrees of freedom in an air conditioning system and may
provide a wider operating range, an increased number of operating
points and/or a higher energy efficiency.
[0049] The compressor of this invention may include any suitable
devices, such as reciprocating compressors, swashplate compressors,
variable swashplate compressors, scroll compressors, variable
scroll compressors, rotary compressors, variable rotary
compressors, rotary lobe (Roots-type) compressors, axial
compressors, centrifugal compressors, screw compressors and/or any
apparatus increasing pressure from an inlet and/or suction to an
outlet and/or discharge. Suitable compressors may include multiple
units and/or stages in series and/or in parallel
configurations.
[0050] FIG. 1 schematically illustrates an air conditioning
apparatus for a residential or commercial building according to one
embodiment of this invention. The apparatus 40 includes as
components a compressor 42, a condenser coil 44, an expansion
device 46, an evaporator 48, and an accumulator 50, all connected
by refrigerant lines suitable for passing a refrigerant to and
between the components. It is also common for such systems to
include other components, such as mufflers, liquid line receivers,
filters or dryers in the refrigerant lines.
[0051] In some embodiments of this invention, and as shown in FIG.
1, the compressor 42 is a variable displacement compressor. The
variable displacement compressor of this invention is capable of
modulating the compression of refrigerant by varying the amount
and/or rate of compressed refrigerant for a given period of time. A
variable displacement compressor allows for modulation of
compression output even while using a single speed motor. The
variable displacement compressor can be a variable stroke
compressor that has piston with modulating strokes. Exemplary
variable stoke compressors include swashplate or wobbleplate
compressors.
[0052] One suitable variable stoke compressor can be the swashplate
compressor 60 shown in FIG. 2. Compressor 60 includes a
multi-cylinder reciprocating design utilizing a rotating plate 62
instead of a connecting rod and a crankshaft linkage. The plate 62
is connected to pistons 66 by a bearing plate 65 attached to the
driveshaft 64. The embodiment of FIG. 3 shows a plate 63, a bearing
plate 65, and a driveshaft 64. At no-load conditions, the plate 62
spins on a perpendicular plane and/or axis to the drive shaft 64,
so the pistons 66 remain idle. As an angle of the rotating plate 62
is varied, such as by an external controller function, the pistons
66 are driven up and/or in and down and/or out within corresponding
bores and/or cylinders 68. Desirably, an increased plate angle
results in an increased output of the system.
[0053] Capacity control of modulating air conditioning apparatus
with swashplate compressors can be achieved by, for example,
varying a length of a piston stroke inside the compressor with the
rotating plate 62. The swashplate 62 shifts from near perpendicular
to the drive shaft for low capacity to, for example, about 45
degrees to the drive shaft for high capacity. As the angle of the
swashplate 62 decreases, the stroke of each piston 66 is reduced,
reducing the amount of refrigerant cycled with each corresponding
stroke. Desirably, frictional losses associated with each piston 66
are reduced nearly proportionally with the system capacity for
optimum system efficiency throughout the modulated range of the
swashplate compressor.
[0054] The modulating air conditioning apparatus of this invention
may operate with any suitable lubricant and/or lubrication system,
such as mineral oil, synthetic oil, semi-synthetic blend,
polyalphaolefin (PAO), polyolester (POE), polyalkalene glycol (PAG)
and/or any other substance reducing friction. Desirably,
compatibility of a selected refrigerant and/or a lubricant package
provides desired reliability and/or operability of the system.
[0055] The compressors and/or turbomachinery of this invention may
include any suitable sealing design between a rotating shaft and a
refrigerant-containing zone and/or chamber, such as packing glands,
dry packing glands, lubricated packing glands, stuffing boxes,
bellows seals, mechanical seals, double mechanical seals, wet
mechanical seals, labyrinth seals, gas seals, dry gas seals,
hermetic seals, semi-hermetic seals, welded enclosures, bolted
enclosures, gasketed enclosures and/or any other suitable isolating
design. Suitable packing materials may include polymers,
elastomers, fluoropolymers, polyaramids, carbon materials and/or
any other inert relatively flexible materials.
[0056] In one embodiment of this invention, the angle of the plate
62 is controlled by a high pressure refrigerant throttled through a
control valve 70. As the control valve 70 is opened, a force
applied by the high pressure refrigerant on the plate 62 is
increased and the plate angle increases. The control valve 70 can
be electronically controlled by a pulse-width modulated (PWM)
signal, for example. This technique is in common use in modulating
furnaces as the variable furnace control (VFC) may also include
utilize PWM signals with control valves for natural gas flow
applications, for example. Some features of the modulating cooling
system of this invention are similar to features taught by Sigafus
et al., U.S. Pat. No. 6,866,202, and by Sigafus et al., U.S. Pat.
No. 7,293,718, the entire teachings of both commonly assigned
patents are incorporated by reference into this specification.
[0057] Swashplate-type compressors are commonly used in automotive
applications, such as available from several manufacturers
including Denso, Toyota, Visteon, and Delphi. However, for use in
the residential and commercial building applications of this
invention, automobile swashplate compressors are insufficiently
mechanically and fluidically efficient, and are thus unsuitable.
The variable stroke compressors of this invention that incorporate
swashplates have modified structures that include improved valve
mechanisms, piston fit, coatings, oil return mechanisms, seals,
reduced machined parting lines and gaskets; and drive connection
and mounting changes, such as to facilitate mounting, and/or a
fixed speed operation without a clutch mechanism, such as by a
motor driver.
[0058] The variable stroke compressor of this invention may include
any suitable number of cylinders, such as two, three, four, five,
six, seven, eight, nine, ten, twelve and/or fifteen. In one
embodiment, suitable variable displacement compressors of this
invention have a capacity of six tons or less and may include an
output from about 1 to about 225 cubic centimeters per revolution
at operating speeds from about 500 to about 9000 rpm, for example.
Fluid and/or refrigerant contamination may damage swashplate
compressors and/or other compressors, so an optional refrigerant
filter may also be desired.
[0059] As shown in FIG. 1, a compressor drive motor 52 is used for
operating the compressor device 42. The compressor 42 of this
invention may be driven, turned and/or rotated by any suitable
devices, such as electric motors, AC motors, DC motors, synchronous
motors, induction motors, single phase motors, 3-phase motors,
multiphase motors, permanent split capacitor (PSC) motors,
brushless DC motors, electrically commutated motors (ECM), switched
reluctance motors (SRM), variable frequency drive (VFD) controlled
motors, turbines, hydraulic turbines, gas turbines, expanders,
engines, internal combustion engines and/or any other mechanical
driver.
[0060] In one embodiment of this invention, the variable
displacement compressor can be driven by a cost effective,
efficient single-phase PSC motor with a fixed operating speed.
Modulation can be achieved by the variable stroke design of a
variable displacement compressor, allowing the motor run at an
optimal operating state over the entire range of cooling output.
Alternately, an inverter-driven three phase motor system, such as a
VFD, can be used to drive the compressor.
[0061] The compressor drive motor of the modulating air
conditioning system of this invention may include any suitable
fixed and/or variable speed, such as about 1800 revolutions per
minute (rpm), about 3250 rpm, about 3600 rpm, between about 0 rpm
and about 10,000 rpm, between about 0 rpm and about 5,000 rpm
and/or any other suitable value or range. Desirably, the compressor
drive motor has a power output of about 5,222 watts (i.e., about
seven horsepower) or less.
[0062] The compressor of this invention may be directly and/or
indirectly coupled and/or combined with the drive motor by any
suitable devices, such as unitary common drive shafts, rigid
couplings, flexible couplings, fluid couplings, magnetic couplings,
gearboxes, speed increasers, speed decreasers, belts with pulleys
or sheaves and/or any other apparatus. In one embodiment of this
invention and as shown in FIG. 4, the coupling includes a
compressor input shaft adapter.
[0063] As shown in FIG. 1, the apparatus 40 also includes a
condenser fan 54 and an evaporator fan 56. The condenser fan 54 and
evaporator fan 56 of this invention may include any suitable air
moving device, such as a fixed pitch fan, a variable pitch fan, a
damper controlled fan, a multi-ducted fan assembly, a constant
speed fan, a variable speed fan, a propeller, an impeller, a
blower, an axial blower, a radial blower, a rotary lobe blower, an
eductor, an ejector and/or any other suitable motive force. Forced
draft, induced draft and/or combined draft configurations are
possible. Desirably, the condenser fan 54 and/or the evaporator fan
56 is a modulating fan able to be varied in speed and/or blade
pitch by a controller.
[0064] The condenser coil 44 shown in FIG. 1 may include any
suitable heat transfer media and/or configurations, such as pipes,
tubing, coils, extended surface heat transfer materials, finned
tubing and/or any other thermally conducting and/or pressure
containing equipment. In some embodiments of this invention, the
tubing internally includes baffles or twisted ribbons, such as to
create turbulent flow and/or improve heated transfer
coefficients.
[0065] The condenser coil 44 of this invention may be fabricated by
any suitable method, such as by welding, brazing, soldering,
fusing, stamping, rolling, crimping, gasketing, gluing and/or any
other technique to form and/or make a pressure containing conduit.
The condenser coil 44 of this invention may include any suitable
material of construction, such as metal, steel, copper, aluminum,
alloy material, engineered plastic and/or any other thermally
conducting material. Joints and/or connections may be permanent,
semi-permanent and/or removable. Fittings, flanges, valves and/or
any other suitable items may be included in the modulating air
conditioning system, such as to facilitate start up, shut down,
repair and/or operation. The evaporator coil 48 may include any of
the characteristics and/or designs discussed above with respect to
the condenser coil, and can be a modulating evaporator as discussed
further below.
[0066] In some embodiments of this invention, the improved air
conditioning system includes a variable displacement modulating
compressor and/or fan control technology for variable cooling
output levels. The modulating cooling apparatus of this invention
can be a semi-hermetic electronically controlled variable stroke
compressor. A controller and/or logic processor may regulate both
an output of a variable stroke compressor and/or a speed of a
condenser fan, for example. The controller may also interface with
a variable furnace control, for example. The controller regulates
the variable displacement compressor and/or regulates the blower or
fan speed in relation to changing cooling demands of the heating
ventilation and air conditioning (HVAC) system in real time, for
example.
[0067] Benefits of this invention can include reducing and/or
eliminating cycling of the compressor, dramatically reducing fan
and/or compressor noise during partial load operation, eliminating
hard starts of the air conditioner, providing continuous
dehumidification, increasing system efficiency and/or increasing a
seasonal effective energy efficiency ratio (SEER) rating of the
system at all levels of operation.
[0068] In some embodiments of this invention, the modulating air
conditioning system allows equivalent SEER and cooling output
ratings, while reducing coil size. Reduced coil size lowers
material costs and manufacturing labor charges.
[0069] The improved air conditioner of this invention desirably
provides transparent and/or simple operation for HVAC installations
by an end user, such as by utilizing one stage thermostats, two
stage thermostats, available condenser coils, and/or available
evaporator coils.
[0070] The modulating air conditioning apparatus of this invention
includes any suitable capacity, such as a capacity of at least
about one ton of refrigeration capacity, and more desirably between
about 2-6 tons of refrigeration capacity, but can be used in
applications having a capacity greater than 6 tons of refrigeration
capacity. Series and/or parallel configurations are also possible
to provide increased capacity, for example. As discussed above, the
variable displacement compressor can operate at industry standard
motor speeds, such as 1800 rpm, 3250 rpm, 3600 rpm and/or any other
suitable rotational velocity.
[0071] The modulating air conditioning system of this invention may
cool any residential or commercial building structure, such as
residential buildings, industrial buildings, commercial buildings,
tents, temporary structures, localized outside settings and/or any
other suitable fixed edifice or stationary location.
[0072] In some embodiments of this invention, the modulating
capabilities of the air conditioning system can be used
interchangeably among an entire line of refrigeration equipment
without any modification, such as for cooling a two-bedroom
townhouse, a five-bedroom home and/or a restaurant. A soft limit
and/or a value in the controller may regulate the compressor output
to match and/or not exceed a coupled motor and/or driver rated
output.
[0073] In some embodiments of this invention, the modulating air
conditioning system meets and/or exceeds requirements and/or
standards from the Department of Energy (DOE) for residential
and/or commercial air conditioning equipment. A higher or increased
SEER rating number indicates a more efficient system. The
modulating air conditioner may have a SEER rating of at least about
13, desirably at least about 15, desirably at least about 20, more
desirably at least about 25 and even more desirably at least about
30.
[0074] Improved SEER ratings may be achieved by replacing the
conventional compressor and motor assembly with a more efficient
unit. Conventional compressor and motor assemblies are a
hermetically sealed as an integrated unit, undesirably requiring
cutting and/or breaking refrigerant lines to change and/or replace
the assembly, the compressor and/or the motor. There is significant
cost and labor associated with compressor and/or motor replacement
of a conventional system. In some embodiments of this invention,
the motor can be replaced without cutting of the refrigerant lines,
such as to allow replacement with a higher efficiency motor.
[0075] Another option to increase SEER rating is to replace the
condenser coil with a larger sized coil, effectively reducing the
size of the compressor relative to the coil. However, replacing the
coil can be cost prohibitive and involve extensive retooling and/or
manufacturing changes.
[0076] Alternately and in some embodiments of this invention, an
improved SEER rating can be achieved by modulating the compressor
and matching the cooling requirements of a space and/or a volume in
real time and/or with minimal delay. If immediate cooling needs do
not include the full system capacity, then modulating the
compressor to reduce output results in a more efficient operating
state and/or mode. In some embodiments of this invention, the
variable displacement compressor and the corresponding driver
assembly mount directly into an existing condensing unit to utilize
existing thermostatic controls with modulation algorithms.
Additional controls may be included, but desirably are not
necessary for improved operation.
[0077] In some embodiments of this invention, the modulating air
conditioning system provides constant dehumidification, even in low
load conditions. Fan and/or compressor noise may be reduced in
partial load states. Alternately, the condensing fan may shut off
when outside conditions provide sufficient convective heat
transfer, such as by a cool breeze. This convective heat transfer
may also sometimes be referred to as gravity flow.
[0078] In some embodiments of this invention, the modulating air
conditioning system provides a simple, transparent upgrade which is
compatible with standard furnaces, existing evaporator coils,
one-stage thermostats, two-stage thermostats, original equipment
manufacturer (OEM) condenser coils and/or conventional fans.
Furthermore, combining a modulating air conditioning system and a
modulating furnace provides additional synergies, functionality
and/or control.
[0079] In some embodiments of this invention, the modulating air
conditioning system includes a compressor designed specifically for
high efficiency cooling modulation in the HVAC industry. Benefits
of a modulating cooling system may be considerably greater than
those available in a modulating heating system. For example,
modulating cooling offers the potential to double the efficiency
over known state of the art systems for residential air
conditioners with a SEER of 13. The high efficiency modulating air
conditioning system of this invention may approach and/or exceed a
SEER of 30.
[0080] In some embodiments of this invention, the modulating air
conditioning and/or cooling system utilizes smaller and/or quieter
equipment, while providing superior temperature and/or humidity
control for the consumer and/or end user.
[0081] During past energy crisis situations some consumers removed
inefficient but still operating and/or functioning cooling
equipment to replace it with newer technology, if the energy saving
benefits were sufficient. Additionally, growing "Green" legislation
focused on energy efficient technology may further prompt equipment
replacements. Modulating air conditioning and/or cooling systems
can be inherently "Green" compared to conventional state of the art
systems.
[0082] Modulating cooling systems of this invention can cut and/or
reduce energy usage in half during the critical summer part of the
year, for example. Modulating cooling systems of this invention may
reduce greenhouse gases affecting climate change by using less
electricity during peak load times and allowing carbon control
and/or capture at central power plants.
[0083] In some embodiments of this invention, the modulating air
conditioning system includes a reciprocating design without fixed
frictional losses and an air-cooled motor. In some further
embodiments of this invention, the electric motor for the
compressor can be removed from the refrigerant path and utilize
ambient air to cool the motor windings.
[0084] In some embodiments of the invention, the compressor drive
motor is an air-cooled electric motor. The air-cooled electric
motor is useful in the modulating air conditioning systems of this
invention, but also can be used in conventional non-modulating
systems to increase efficiency. The compressor motor can be any
motor described herein, but is preferably a brushless DC motor or
an electrically commutated motor. Likewise, the compressor can be a
conventional compressor of a variable displacement compressor of
this invention.
[0085] In the embodiment of FIG. 1, the compressor drive motor 52
is separate from and in operating combination with the compressor
driveshaft 64. The motor 52 includes a motor driveshaft 55 that is
detachably connected to the compressor driveshaft 64 to turn the
compressor driveshaft 64. Conventional compressors include an
integrated motor, that can be contained in a single sealed housing
but more importantly is cooled by the refrigerant in the compressor
and/or adjacent refrigerant line. In one embodiment of this
invention, the separate, non-integrated compressor motor of this
invention is not cooled by the refrigerant, and is instead cooled
by air being moved over the motor.
[0086] The air-cooled compressor motor can be included in a single
housing with the compressor, only separate from the refrigerant and
including a mechanism, such as vent holes, to allow air to pass
over the motor. However, more desirably, the motor is not housed
with the compressor, such as shown in FIG. 5. FIG. 5 is a sectional
view from above that illustrates a common conventional condensing
unit modified to include the compressor and separate motor of this
invention. As shown in FIG. 5, a compressor 80 is mounted with
respect to a separate compressor drive motor 82 on a frame 84. A
drive shaft 86 of the motor 82 is connected to a compressor drive
shaft 88 by a shaft adapter 90, such as shown in FIG. 4.
[0087] A refrigerant flows through a refrigerant line 92, through
accumulator 94, and to compressor 80. The refrigerant is compressed
into the condenser 96. The condenser 96 includes a condenser fan,
generally positioned at a top of the condensing unit, that draws
air over the condenser coils 96. In this embodiment, the condenser
fan also draws air over the motor 82, which in turn cools the
motor.
[0088] Alternately, the condenser fan draws ambient air over the
motor 96 that is at least partially separated from air passing
through the condenser coils 96. A separate and/or alternate air
path maybe provided, and can include a separate inlet, ductwork
and/or shroud. The compressor motor may additionally or
alternatively include an integral fan for cooling. In some
embodiments of this invention, a separate fan and driver
intermittently cool the compressor motor based on a temperature of
the motor windings, such as detected by a thermocouple and/or a
suitable device.
[0089] Open drive compressors, i.e., shaft or pulley driven
compressors with the motor entirely separate from the refrigerant
compressor assembly, with integrated air-cooled motors of this
invention may replace conventional designs and eliminate system
efficiency losses associated with conventional refrigerant-cooled
motor windings, for example.
[0090] The air conditioning apparatus of this invention includes a
controller for modulating the one or more modulating components
such as the variable displacement compressor device, the compressor
motor, a modulating expansion device, and/or a modulating
evaporator device. In some embodiments of this invention, the
compressor control assembly provides modulation with a combination
of a variable speed motor control and a dynamically variable
compressor control in an air-cooled system. The condenser and/or
evaporator heat exchanger surface areas do not need to be grossly
over-sized to achieve the improved efficiencies over conventional
designs. The modulating design of this invention allows a reduced
product size, lower material costs, lower production costs and/or
reduced shipping charges.
[0091] FIGS. 6-13 each illustrate a modulating air conditioning
apparatuses of this invention including a controller. As shown in
FIG. 6 and in some embodiments of this invention, the modulating
cooling system controller includes a logic and control board with a
microprocessor memory, a compressor motor control and a compressor
output control. The apparatus of FIG. 6 also includes a condensing
unit with a semi-hermetic modulating compressor, an external motor,
a condenser fan and a condensing heat exchanger. The apparatus of
FIG. 6 also includes an evaporating unit with an evaporator and/or
circulator fan and an evaporating heat exchanger. The apparatus of
FIG. 6 also includes a mechanical expansion device, a contactor and
the corresponding connections to the above identified items. The
apparatus of FIG. 6 provides modulation by varying the compressor
output.
[0092] As shown in FIG. 7 and in some embodiments of this
invention, the modulating cooling system further includes condenser
fan control based on liquid line subcooling. The apparatus of FIG.
7 includes components described with respect to FIG. 6 and further
includes a condenser fan modulation control with a condenser fan
output and a subcooling input, a liquid line temperature sensor, a
liquid line pressure sensor and the corresponding connections to
the above identified items. The apparatus of FIG. 7 provides
modulation by both varying the compressor output and the condenser
fan output. Desirably, the condenser fan control utilizes all the
available surface area of the condensing heat exchanger, such as
the last vapor bubble collapses at the exit of the condensing heat
exchanger. Alternately, the apparatus of FIG. 7 subcools the
refrigerant below the temperature for condensation.
[0093] As shown in FIG. 8 and in some embodiments of this
invention, the modulating cooling system further includes
evaporator fan control based on discharge air temperature. The
apparatus of FIG. 8 includes components described with respect to
FIG. 7 and further includes an evaporator fan control with an
evaporator fan output and a temperature input, an evaporator
discharge air temperature sensor and the corresponding connections
to the above identified items. The apparatus of FIG. 8 provides
modulation by varying the compressor output, the condenser fan
output and the evaporator fan output. Desirably, the evaporator fan
control maximizes and/or minimizes the evaporator discharge air
temperature. Alternately, the apparatus of FIG. 8 maintains an
evaporator discharge temperature at a set point by varying the
evaporator fan output.
[0094] As shown in FIG. 9 and in some embodiments of this
invention, the modulating cooling system includes expansion valve
control and evaporator fan control based on a combination of
suction line superheat and evaporator discharge temperature. The
apparatus of FIG. 9 includes components described with respect to
FIG. 7 and further includes an expansion valve and evaporator fan
control with an evaporator fan output, a temperature input and an
expansion valve output, an evaporator discharge air temperature
sensor, a suction line temperature sensor, a suction line pressure
sensor and the corresponding connections to the above identified
items. The apparatus of FIG. 9 provides modulation by varying the
compressor output, the condenser fan output, the evaporator fan
output and the expansion valve output. Desirably, the expansion
valve and evaporator fan control optimizes the pressure drop across
the expansion valve, such as with respect to controlling a
refrigerant phase change, and/or while controlling a discharge air
temperature. Alternately, the apparatus of FIG. 9 seeks to utilize
all the available surface area of the evaporating heat exchanger,
such as the last liquid drop vaporizes at the exit of the
evaporating heat exchanger.
[0095] As shown in FIG. 10 and in some embodiments of this
invention, the modulating cooling system includes a multi-outlet
and/or multi-path expansion valve connected with respect to a
plurality of evaporating heat exchanger pathways. The apparatus of
FIG. 10 provides modulation by varying the compressor output, the
condenser fan output, the evaporator fan output, the expansion
valve output and the different paths from the expansion valve.
Desirably, the multi-outlet expansion valve allows use of less than
all the evaporator coils and/or allows uses of different zones for
increased efficiency and/or cooling of different areas. FIG. 11
illustrates an alternative embodiment, where the electronically
controlled expansion valve of FIG. 9 is coupled with an
electronically controlled distribution valve connected with respect
to a plurality of evaporating heat exchanger pathways.
[0096] This invention also includes the refrigerant connections,
electrical connections, control connections and/or other
connections and/or relationships as shown in FIGS. 6-11. Other
embodiments and/or arrangements of equipment are possible without
departing from the scope of this invention. For example, FIG. 12
illustrates the apparatus of FIG. 11, only including a variable
speed hermetically sealed compressor with an integrated motor. FIG.
13 illustrates another alternative of the apparatus of FIG. 11,
including a single or two-stage hermetically sealed compressor and
a mechanical expansion valve.
[0097] As discussed in FIGS. 10-13, the air conditioning apparatus
of this invention can include a modulating evaporating device.
FIGS. 14-18 illustrate exemplary modulating evaporating devices
according to this invention.
[0098] FIG. 14 includes an evaporating device 100 for receiving the
refrigerant from an expansion device. The evaporator device 100
includes an evaporator assembly 102 including a plurality of
refrigerant distribution assemblies 104. The number, size and
configuration of the refrigeration distribution assemblies can vary
depending on need. Each of the refrigerant distribution assemblies
includes a refrigerant distribution inlet 106 at a first end for
receiving the refrigerant from the expansion device and a
refrigerant distribution outlet 108 at a second end opposite the
refrigeration distribution inlet 106. A manifold 110, such as a
suction manifold line, can be used to connect the refrigerant
distribution outlets 108 of each of the refrigerant distribution
assemblies 104 to a means, such as a one or more suction
refrigerant line, for transferring the refrigerant to a compressor
of the air conditioning apparatus. In one embodiment of this
invention, each of the refrigerant distribution assemblies 104
includes one or more evaporator coils 112 extending from the
refrigerant distribution inlet 106 and to the refrigerant
distribution outlet 108. Each assembly 104 is independent and not
interconnected with other adjacent assemblies 104, thereby
providing separate and independent evaporator coil zones.
[0099] In one embodiment of this invention, the modulation of the
evaporator device 100 is provided by alternating a flow of the
refrigerant between various combinations of the refrigerant
distribution assemblies 104. For example, when a reduced cooling or
humidity removal is needed, refrigerant flow through one or more of
the assemblies 104 can be reduced or stopped, thereby effectively
reducing the effective cooling surface area of the evaporator
device 100 when evaporator fan 125 is operated to force ambient
air, water, or a secondary refrigerant across evaporator assembly
102 to facilitate heat transfer.
[0100] In one embodiment of this invention, a restriction device is
used to control the distribution of refrigerant between the
evaporator coils zones. The restriction device can include a
distribution valve in combination with a refrigerant distribution
inlet 106. In FIG. 14, the restriction device is embodied as a
distribution valve assembly 116 including a plurality of
distribution valves 118 each in refrigerant delivering combination
with one inlet 106. An electromechanical valve control assembly
120, such as or in combination with the system controller described
above, can be used to open and close each valve 118 to increase or
decrease the number of refrigeration distribution assemblies 104
receiving refrigerant. Each of the valves 118 operates
independently of the other valves 118.
[0101] Distribution valve assembly 116 can be any type of device or
assembly known by those skilled in the art designed to modify,
restrict, or regulate flow of a heat transfer fluid, such as one or
more needle valves, ball valves, solenoid plunger valves, or any
other type of valve or combination of valves which can be used to
regulate, redirect, or restrict the flow of a heat transfer fluid.
For instance, distribution valve assembly 116 could be a series of
rotary needle valves with a common shaft connecting to valve
control assembly 120. Aforementioned valves may be positioned with
varying offsets designed to reduce refrigerant flow to one or more
discrete evaporator assemblies 104, while allowing other sections
to maintain nominal flow. Valve assembly 116 may also include one
or more ball valves, each controlled through a common linkage, or a
rotating column or sphere with one or more inlet and outlet
passages which align with one or more inlet and outlet ports in the
valve body.
[0102] In one embodiment of this invention, as shown in FIG. 14,
the restriction device can be a multi-outlet and/or multi-path
expansion valve. Referring to FIG. 14, each of the valves 118 can
be an expansion valve controlled by the electromechanical valve
control assembly 120. FIG. 15 illustrates an alternative embodiment
of the invention where a separate expansion device, embodied as
expansion valve 122 is disposed upstream from the distribution
valve assembly 116. The expansion valves of this invention can be a
thermostatic expansion valve, an automatic expansion valve, a
single orifice valve, or electronic expansion valve.
[0103] FIG. 16 illustrates an exemplary evaporator device 100
according to one embodiment of this invention. The evaporator
device 100 includes a triangular evaporator assembly 102 including
six refrigerant distribution assemblies or zones. A valve assembly
116 including three valves 118, with each valve 118 feeding two
zones, is in combination the evaporator assembly 102 for modulating
refrigerant through the evaporator assembly 102. A control assembly
120 is in communication with the valve assembly 116 for alternating
the valve assembly between delivering the refrigerant to all or
less than all of the evaporator coils 112.
[0104] FIG. 17 illustrates another embodiment of a restriction
device according to this invention. In FIG. 17, two expansion
valves are used in combination with the evaporator assembly 102. A
first expansion valve 122 is in refrigerant delivering combination
with a first one or plurality of refrigerant distribution
assemblies 104. A second expansion valve 122' is in refrigerant
delivering combination with a second one or plurality of
refrigerant distribution assemblies 104. Each of the expansion
valves 122 and 122' is preferably controlled by a dedicated
electromechanical valve control assembly 120. FIG. 18 illustrates
an alternative variation of the embodiment in FIG. 17. In FIG. 18,
one of the two expansion valves, e.g., valve 122, is a primary
mechanical expansion valve, such as a conventional expansion valve,
and the other expansion valve 122' is an electromechanical
expansion valve, as shown in FIG. 17.
[0105] The modulating evaporator device of this invention, such as
shown in FIGS. 14-18, allows for a modulating conditioning of air
by modulating the flow of the refrigerant within the evaporating
device. In this manner, only the portion of the air moving over the
portion of the evaporator device including refrigerant is cooled.
In another embodiment of this invention, the modulation can be
obtained or assisted by reducing or stopping an air flow over a
portion of the evaporator coils. The moving air can be isolated
from portions of the evaporator coil by a damper, cover, or other
method to restrict air flow, and preferably the refrigerant flow to
those portions is halted, or redirected to other portions of the
evaporator coil.
[0106] As discussed above, the modulating evaporator of this
invention can also be used in combination with other modulating
components discussed herein, such as the variable displacement
compressor, which can be used to provide more or less compressed
refrigerant depending on the number of evaporator coil zones to be
used.
[0107] In some embodiments of this invention with a multi-outlet
valve, different zones of the evaporator coil include a check valve
and/or other suitable backflow preventing device. Alternately,
individual control valves may be included on the inlet and/or
outlet of the evaporator zone coils.
[0108] In some embodiments of this invention, a home and/or a
building heat pump system, air conditioning system,
dehumidification system and/or cooling system includes an apparatus
for controlling refrigerant distribution and/or expansion, the
apparatus includes a compressor, a condenser coil, an expansion and
distribution device, an evaporator coil, and corresponding and/or
applicable wiring, tubing and/or piping adapted to connect the
components and provide communication between the components. The
apparatus of this invention can include refrigerant distribution
tubes, pipes, channels, conduits, headers, and/or manifolds
connected to discrete sections of the evaporator coil, such as to
allow modulating based on refrigeration load. Each refrigerant
distribution tube can include a restriction device installed to
restrict and/or regulate a flow of refrigerant through the
corresponding refrigerant distribution tube. Suitable restriction
devices include valves, control valves, thermostatic valves,
expansion valves, orifices, multiple hole orifices, variable open
area orifices, multiple-outlet valves and/or any other flow
controlling device. The orifice may include a plate and/or a part
with one or more bores, holes and/or passages.
[0109] In some embodiments of this invention, the orifices and/or
passages of the restriction device may provide both refrigerant
direction and expansion characteristics and/or features using one
assembly. In other embodiments of this invention, a first device
provides expansion of the refrigerant, such as by Joule-Thomson
effect and a second device and/or devices provide direction and/or
distribution of refrigerant flow. The second device may be after
and/or downstream of the first device, for example.
[0110] Joule-Thomson effect and/or Joule-Kelvin effect describes
the increase and/or decrease in the temperature of a real gas when
it is allowed to expand freely at constant enthalpy, such as that
no heat transfers to and/or from the gas and no external work is
extracted. Alternately, a turbo expander may recover work from the
refrigerant while lowering a pressure from an inlet pressure to an
outlet pressure, for example.
[0111] The air conditioning apparatus may include an expansion
valve to expose one or more evaporator tubes to an input side
and/or upstream side of the expansion valve. In some embodiments of
this invention, the input side of the expansion valve connects
through a tube and/or a fitting to a refrigerant circuit and/or
loop. The expansion valve may include two or more fittings attached
to the evaporator coil for supplying refrigerant to the evaporator
coil and/or corresponding bank or sections of the evaporator
coil.
[0112] In some embodiments of this invention, the refrigerant
distributes to corresponding discrete sections of the evaporator
coil by controlling the restriction exposure, such as with a
multi-outlet valve. Desirably, but not necessarily, the
multi-outlet valve simultaneously controls expansion of the
refrigerant and/or flow of the refrigerant through the evaporator
coils and/or sections of the evaporator coils. Alternately, the
multi-outlet valve includes flow direction and flow throttling
features.
[0113] In some embodiments of this invention, control of the
refrigerant flow maintains a sufficient velocity and/or mass flow
with respect to an effective cross sectional area of a utilized
section of the evaporator coils and/or condenser coils, such as to
provide sufficient oil return and/or improve heat transfer by
reducing oil film. Desirably, the refrigerant flow is controlled in
a way to increase refrigerant velocity through the coil so an oil
return process remains consistent with the other levels of
operation regardless of turndown, for example. According to another
embodiment of this invention, a separate lubrication unit with a
separate oil pump and/or driver operates to supply adequate
lubrication to the air conditioning system and/or the compressor
independent of operating rate.
[0114] In some embodiments of this invention, the modulating
cooling system includes selective evaporator coil defrosting and
de-icing, such as allowing one bank to warm to ambient conditions
with and/or without a condenser fan circulating air, while a second
evaporator bank provides and/or meets a needed refrigeration load
capacity. Additional heat sources may assist in deicing procedures.
The above features of a zoned evaporator may also be applied to a
zoned condenser, such as to allow for deicing and/or thawing of
frosted coils.
[0115] In some embodiments of this invention, a thermostatic
expansion valve, an automatic expansion valve, a single orifice
and/or an electronic expansion valve controls refrigerant expansion
and a separate multi-outlet valve assembly serves as a distribution
device, such as to multiple evaporator coils.
[0116] In one embodiments of this invention, such as shown in FIG.
19, a expansion valve 122, such as a thermostatic expansion valve,
an automatic expansion valve, a single orifice and/or an electronic
expansion valve controls refrigerant expansion, while a valve or
series of valves 124, connected by a saturated vapor line manifold
126 in FIG. 19, are used to selectively distribute refrigerant to
one or more areas or banks of the evaporator device. Suitable
valves 124 include solenoid valves, ball valves, needle valves,
diverter valves, or any other valve or device which may be used to
redirect, restrict or stop the flow of refrigerant. Furthermore,
these valves may be operated in such a way as to alternate or cycle
between different areas and/or banks of the evaporator coil on a
timed, controlled, or random basis. This cycling process can be
used to control the latent and sensible heat loads on the
evaporator or specific areas of the evaporator.
[0117] A method of operating the air conditioning system of this
invention may include diverting refrigerant to one and/or more
discrete areas and/or banks of the evaporator coil, leaving other
areas and/or banks of the evaporator coil free of refrigerant flow
and/or essentially free of refrigerant. Alternately, non-flowing
areas and/or banks of the evaporator coils remain filled with
refrigerant, such as in a liquid and/or a vapor state.
[0118] The method of operating the air conditioning system of this
invention may further include isolating portions of the evaporator
coil from a circulator and/or evaporator fan air flow by a damper,
a cover, and/or any other suitable device to restrict air flow.
Desirably, the refrigerant flow to isolated portions of the
evaporator coil stops, halts and/or redirects to other portions of
the evaporator coil. The evaporator coil can by made up of several
discrete coils and each coil can include one or more refrigerant
paths.
[0119] In some embodiments of this invention, a home and/or
building heat pump and/or air conditioning system provides
modulation of the air conditioning system by controlling
refrigerant distribution and/or expansion. The air conditioning
system includes a compressor, a condenser coil, an expansion and/or
distribution device, an evaporator coil and/or applicable and/or
corresponding wiring, tubing and/or piping to connect components of
the air conditioning system. The modulating air conditioning system
may include a motor that is physically separated from the
compressor, such as including a separate motor shaft and a separate
compressor shaft. Desirably, the compressor is directly coupled the
motor, such as without any change in speed and/or gearing. The air
conditioning system may further include a device for receiving a
modulating signal, such as from a controller to modulate the motor
and/or the compressor while providing variable refrigeration
capacity and/or output for the air conditioning system.
[0120] The modulation of the air conditioning system may include
any suitable continuous and/or discrete amounts and/or increments
over suitable operating ranges and/or parameters. In some
embodiments of this invention, modulation includes and/or is
defined as three or more distinct and/or discrete operating levels
and/or speeds other than zero. Any suitable number of operating
levels is possible.
[0121] In some embodiments of this invention, the compressor
includes a variable displacement compressor, such as a variable
swashplate compressor and/or a scroll compressor. The motor driver
for the compressor may include a brushless DC motor and/or an
electrically commutated motor. In some other embodiments of this
invention, a single speed motor drives the variable displacement
compressor and modulation can be achieved with the variable
displacement compressor. Desirably, the compressor motor can be
cooled by outside air, such as to remove a motor coil heat loading
from the refrigeration loading and the SEER calculation.
Alternately, the compressor includes a swashplate compressor with
an external motor and/or a scroll compressor with an external
motor.
[0122] Desirably, a method of controlling the modulating air
conditioning system of this invention includes a control scheme
and/or system to maximize dehumidification during the air
conditioning cycle, for example.
[0123] In some embodiments of this invention, a control scheme uses
pre-defined and/or preset values and/or functions for a compressor
output, an expansion valve pressure drop and/or an orifice open
area. The compressor output may be controlled in response to and/or
based on a thermostat algorithm and/or a separate controller. The
expansion valve may be controlled to provide the most efficient
operating mode of the system, such as for system dehumidification
at an evaporator coil by regulating the evaporator coil temperature
based on a combination of compressor output and/or expansion
pressure drop. Desirably, a relationship between the temperature of
the evaporator coil, the compressor output and the expansion valve
pressure drop can be used to determine and/or control the
evaporator coil temperature.
[0124] In some embodiments of this invention, the air conditioning
system regulates evaporator coil superheat so liquid refrigerant
does not escape and/or exit the evaporator coil before a change in
state, such as to a vapor and/or a gas. Alternately, the air
conditioning system regulates evaporator coil superheat so the
evaporator coil remains filled with liquid refrigerant.
[0125] In some embodiments of this invention, a system temperature
is controlled by a dew point and/or humidity sensor and/or probe.
Alternately, other psychrometric parameters and/or measures can be
used to control the air conditioning system. Psychrometrics and/or
psychrometry includes the field of engineering concerned with the
determination of physical and thermodynamic properties of gas-vapor
mixtures. Alternately, the air conditioning system can be
controlled by a temperature sensor configured to identify a dew
point temperature, such as in a living space.
[0126] In some embodiments of this invention, the air conditioning
system includes a shell and/or a cover welded and/or sealed around
the compressor to prevent refrigerant leaks. The shell may include
two or more pieces to at least partially surround the compressor
and/or the driver.
[0127] The compressor and the motor may be mechanically connected
and/or coupled in any suitable manner. The compressor and the motor
may be sealed in any suitable manner, such as to prevent
refrigerant leaks. In some embodiments of this invention, an
adapter connects the motor to the compressor.
[0128] Any suitable control system may modulate the compressor,
such as a hard wired circuit, an integrated circuit, a programmable
logic controller (PLC) with ladder logic, a central processor unit
with software instructions and/or any other comparator or decision
making device.
[0129] In some embodiments of this invention, a sequence and/or
order of modulation includes any suitable order, such as optimizing
the expansion device, the compressor, the condenser fan and the
evaporator fan, for example.
EXAMPLES
Example 1
[0130] A computer simulation showed the benefits of a modulating
compressor design in an air conditioning system. A simulation was
written in the Engineer Equation Solver compiler to accurately
model the operation of a reciprocating compressor at different
speeds and compression ratios. In the simulation, the compressor
powered a refrigeration cycle with a variety of refrigerant types,
air temperatures, coil heat transfer coefficients, coil sizes, fan
speeds and/or expansion pressure drops. This simulation was
developed to test and/or compare modulating air conditioning system
designs to conventional systems.
[0131] A set of experimental parameters were refined to include air
conditioning systems ranging from 2.5 to 3 tons of refrigeration
capacity, with an indoor temperature of 70 degrees Fahrenheit (21.1
degrees Celsius) and an outdoor temperature of 80 degrees
Fahrenheit (26.7 degrees Celsius). The coil sizes, heat transfer
coefficients, compressor speed, compression ratio, physical
geometry and air flow velocity were derived from a standard model
conventional air conditioning system with a SEER of 12. During the
simulation, the compressor modulation level was adjusted from 10
percent to 100 percent capacity and the results were charted versus
the instantaneous SEER and the power consumption of the system, as
shown in FIG. 20. The simulation showed at a 30 percent modulation
level, the air conditioning system achieved its highest efficiency
and a SEER increase of over three points. The SEER increased from
11 to 14.3 for an increase of 30 percent over a conventional air
conditioning system.
Example 2
[0132] A variable displacement modulating air conditioner was
fabricated and used for testing. A Denso 7SEU16C swashplate
compressor was mounted on a test platform and was driven by a 5 HP
Dayton motor with a variable speed pulley drive. The compressor was
controlled by a Labview console developed specifically for the
modulating air conditioner test. The test included refrigerant
compatibility, oil compatibility, power requirements, system state
temperatures, system state pressures and/or control response.
[0133] Initial testing was performed on an R-22 based system, with
a mineral oil lubricant having a light viscosity. The test was
conducted with rubber quick-disconnect hose and suction line
filters. After satisfactory results were achieved on the variable
speed test platform, a direct coupling from the motor to the
compressor was engineered and machined. The compressor utilized a
screw-on pulley with a set screw on the attaching hub. A converting
shaft replaced the pulley with a 5/8'' keyed shaft attached
directly to the motor by a rubberized power coupling. The direct
drive provided nearly silent operation at no-load conditions.
Further testing utilized a customized compressor driveshaft as
shown in FIG. 21, designed to replace the existing internal
driveshaft while providing a keyed drive suitable for mounting of a
pulley sheave, or direct drive coupling.
[0134] Further testing includes using a smaller welded base to
allow the entire motor-compressor assembly to be mounted inside an
existing condenser cabinet and both R-22 and R-410 refrigerant
varieties. Additional and/or expanded experimental variables may
include mass flow, crankcase pressures, condenser fan mass air
flow, blower fan mass air flow, water removal volume and/or
dehumidification percentage. Particularly, test procedures may
include SEER ratings and efficiency over comparable conventional
units and/or compressor types.
[0135] It will be appreciated that details of the foregoing
embodiments, given for purposes of illustration, are not to be
construed as limiting the scope of this invention. Although only a
few exemplary embodiments of this invention have been described in
detail above, those skilled in the art will readily appreciate that
many modifications are possible based at least in part on the
exemplary embodiments without materially departing from the novel
teachings and advantages of this invention. Accordingly, all such
modifications are intended to be included within the scope of this
invention, which is defined in this specification and all
equivalents thereto. Further, it is recognized that many
embodiments may be conceived that do not achieve all of the
advantages of some embodiments, particularly of the preferred
embodiments, yet the absence of a particular advantage shall not be
construed to necessarily mean that such an embodiment is outside
the scope of the present invention.
* * * * *