U.S. patent application number 10/157657 was filed with the patent office on 2003-12-04 for expander driven motor for auxiliary machinery.
Invention is credited to Gopalnarayanan, Sivakumar, Griffin, J. Michael, Lewis, Russell G., Neiter, Jeff J., Park, Young K., Rioux, William A..
Application Number | 20030221434 10/157657 |
Document ID | / |
Family ID | 29419652 |
Filed Date | 2003-12-04 |
United States Patent
Application |
20030221434 |
Kind Code |
A1 |
Neiter, Jeff J. ; et
al. |
December 4, 2003 |
EXPANDER DRIVEN MOTOR FOR AUXILIARY MACHINERY
Abstract
The expansion of a high pressure or intermediate pressure
refrigerant in an expansion device in a transcritical vapor
compression system converts the potential energy into usable
kinetic energy. The kinetic energy provides work which is employed
to fully or partially drive an expansion motor unit which is
coupled to rotating auxiliary machinery. By providing work to the
rotating auxiliary machinery, system efficiency is improved. The
auxiliary rotating machinery can be an evaporator fan or a gas
cooler fan to pull the refrigerant through the evaporator and gas
cooler, respectively. Alternatively, the auxiliary rotating
machinery can be a water pump or an oil pump.
Inventors: |
Neiter, Jeff J.; (Coventry,
CT) ; Gopalnarayanan, Sivakumar; (Simsbury, CT)
; Griffin, J. Michael; (Fayetteville, NY) ; Rioux,
William A.; (Willington, CT) ; Park, Young K.;
(Manlius, NY) ; Lewis, Russell G.; (Manlius,
NY) |
Correspondence
Address: |
CARLSON, GASKEY & OLDS, P.C.
400 WEST MAPLE ROAD
SUITE 350
BIRMINGHAM
MI
48009
US
|
Family ID: |
29419652 |
Appl. No.: |
10/157657 |
Filed: |
May 29, 2002 |
Current U.S.
Class: |
62/116 ;
62/498 |
Current CPC
Class: |
F25B 9/008 20130101;
F25B 9/06 20130101; F25B 2400/141 20130101; F25B 2309/061 20130101;
F25B 2400/14 20130101 |
Class at
Publication: |
62/116 ;
62/498 |
International
Class: |
F25B 001/00 |
Claims
What is claimed is:
1. A vapor compression system comprising: a compression device to
compress a refrigerant to a high pressure; a heat rejecting heat
exchanger for cooling said refrigerant; an expansion device for
reducing said refrigerant to a low pressure; a heat accepting heat
exchanger for evaporating said refrigerant; and an auxiliary
machinery coupled to said expansion device and powered by the
expansion of said refrigerant from said high pressure to said low
pressure.
2. The system as recited in claim 1 wherein said auxiliary
machinery is a heat rejecting heat exchanger fan.
3. The system as recited in claim 1 wherein said auxiliary
machinery is a heat accepting heat exchanger fan.
4. The system as recited in claim 1 wherein said auxiliary
machinery is a water pump.
5. The system as recited in claim 1 wherein said auxiliary
machinery is an oil pump.
6. The system as recited in claim 1 further including a heat pump
to reverse flow of said refrigerant.
7. The system as recited in claim 1 further including an expansion
motor, the expansion of said refrigerant powering said expansion
motor to drive said auxiliary machinery.
8. The system as recited in claim 1 wherein said refrigerant is
carbon dioxide.
9. The system as recited in claim 1 wherein said system further
includes an additional compression device, an additional heat
rejecting heat exchanger, an additional expansion device, and an
additional heat accepting heat exchanger.
10. A vapor compression system comprising: a compression device to
compress a refrigerant to a high pressure; a heat rejecting heat
exchanger for cooling said refrigerant; an expansion device for
reducing said refrigerant to a low pressure; a heat accepting heat
exchanger for evaporating said refrigerant; a heat pump to reverse
flow of said refrigerant; an expansion motor powered by the
expansion of said refrigerant from said high pressure to said low
pressure; and an auxiliary machinery driven by said expansion
motor.
11. The system as recited in claim 10 wherein said auxiliary
machinery is a heat rejecting heat exchanger fan.
12. The system as recited in claim 10 wherein said auxiliary
machinery is a heat accepting heat exchanger fan.
13. The system as recited in claim 10 wherein said auxiliary
machinery is a water pump.
14. The system as recited in claim 10 wherein said auxiliary
machinery is an oil pump.
15. The system as recited in claim 10 wherein said refrigerant is
carbon dioxide.
16. A method of powering an auxiliary machinery of a vapor
compression system comprising the steps of: 1) compressing a
refrigerant to a high pressure; 2) cooling said refrigerant; 3)
expanding said refrigerant to a low pressure; 4) providing energy
provided by step 3) to said auxiliary machinery; 5) powering said
auxiliary machinery; and 6) evaporating said refrigerant.
17. The method as recited in claim 16 wherein said auxiliary
machinery is a heat rejecting heat exchanger fan.
18. The method as recited in claim 16 wherein said auxiliary
machinery is a heat accepting heat exchanger fan.
19. The method as recited in claim 16 wherein said auxiliary
machinery is a water pump.
20. The method as recited in claim 16 wherein said auxiliary
machinery is an oil pump.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to a means for
increasing the cycle performance of a vapor compression system by
using the work produced by the expansion of high or intermediate
pressure refrigerant to drive an expander motor coupled to
auxiliary rotating machinery.
[0002] Chlorine containing refrigerants have been phased out in
most of the world due to their ozone destroying potential.
Hydrofluoro carbons (HFCs) have been used as replacement
refrigerants, but these refrigerants still have high global warming
potential. "Natural" refrigerants, such as carbon dioxide and
propane, have been proposed as replacement fluids. Unfortunately,
there are problems with the use of many of these fluids as well.
Carbon dioxide has a low critical point, which causes most air
conditioning systems utilizing carbon dioxide to run transcritical
under most conditions.
[0003] When a typical vapor compression system runs transcritical,
the high side pressure of the refrigerant is high enough that the
refrigerant does not change phases from vapor to liquid while
passing through the heat rejecting heat exchanger. Therefore, the
heat rejecting heat exchanger operates as a gas cooler in a
transcritical cycle rather than as a condenser. The pressure of a
subcritical fluid is a function of temperature under saturated
conditions (where both liquid and vapor are present).
[0004] In a transcritical vapor compression system, refrigerant is
compressed to a high pressure in the compressor. As the refrigerant
enters the gas cooler, heat is removed from the high pressure
refrigerant. Next, after passing through an expansion device, the
refrigerant is expanded to a low pressure. The refrigerant then
passes through an evaporator and accepts heat, fully vaporizes, and
re-enters the compressor completing the cycle.
[0005] In refrigeration systems, the expansion device is typically
an orifice. It is possible to use an expander unit to extract the
energy from the high pressure fluid. In this case, the expansion of
the refrigerant flowing from the gas cooler or condenser and into
the evaporator converts the potential energy in the high pressure
refrigerant to kinetic energy, producing work. If the energy is not
used to drive another component in the system, it is lost. In prior
systems, the energy converted by the expansion of the refrigerant
drives an expander motor unit coupled to the compressor to either
fully or partially power the compressor. The expansion of
pressurized cryogen has also been used in prior systems to drive
mechanical devices in refrigerant units, but not in vapor
compression systems.
SUMMARY OF THE INVENTION
[0006] A reversible vapor compression system includes a compressor,
a first heat exchanger, an expansion device, an expansion motor
unit coupled to auxiliary rotating machinery, a second heat
exchanger, and a device to reverse the direction of refrigerant
flow. By reversing the flow of the refrigerant with the heat pump,
the vapor compression system can alternate between a heating mode
and a cooling mode. Preferably, carbon dioxide is used as the
refrigerant. Because carbon dioxide has a low critical point,
systems utilizing carbon dioxide as a refrigerant usually require
the vapor compression system to run transcritical.
[0007] The high pressure or intermediate pressure refrigerant
exiting the gas cooler is high in potential energy. The expansion
of the high pressure refrigerant in the expansion device converts
the potential energy into useable kinetic energy which is utilized
to completely or partially drive an expansion motor unit. The
expansion motor unit is coupled to drive auxiliary machinery. By
employing the kinetic energy converted by the expansion of the high
pressure or intermediate pressure refrigerant to fully or partially
drive the expansion motor unit coupled to the auxiliary machinery,
system efficiency is improved. The auxiliary machinery can be an
evaporator fan or a gas cooler fan which draw the air through the
evaporator and gas cooler, respectively. Alternatively, the
auxiliary machinery can be a water pump which pumps the water or
other fluid through the evaporator or gas cooler that exchanges
heat with the refrigerant. The auxiliary machinery can also be an
oil pump used to lubricate the compressor.
[0008] These and other features of the present invention will be
best understood from the following specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The various features and advantages of the invention will
become apparent to those skilled in the art from the following
detailed description of the currently preferred embodiment. The
drawings that accompany the detailed description can be briefly
described as follows:
[0010] FIG. 1 illustrates a schematic diagram of a prior art vapor
compression system;
[0011] FIG. 2 illustrates a thermodynamic diagram of a
transcritical vapor compression system; and
[0012] FIG. 3 illustrates a schematic diagram of auxiliary
machinery coupled to the expansion motor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0013] FIG. 1 illustrates a schematic diagram of a prior art
reversible vapor compression system 10. The system 10 includes a
compressor 12, a first heat exchanger 14, an expansion device 16, a
second heat exchanger 18, and a reversible heat pump 20.
Refrigerant circulates though the closed circuit system 10, and the
heat pump 20 changes the direction of refrigerant flow to switch
the system between cooling mode and heating mode.
[0014] As shown in FIG. 1, when operating in a cooling mode, after
the refrigerant exits the compressor 12 at high pressure, the heat
pump 20 directs the refrigerant into the first heat exchanger 14,
which acts as a heat rejecting heat exchanger or a gas cooler. The
refrigerant flows through the first heat exchanger 14 and loses
heat, exiting the first heat exchanger 14 at low enthalpy and high
pressure. As the refrigerant passes through the expansion device
16, the pressure drops. After expansion, the refrigerant flows
through the second heat exchanger 18, which acts as a heat
accepting heat exchanger or evaporator and exits at a high enthalpy
and low pressure. The refrigerant then flows through the heat pump
20 and re-enters and passes through the compressor 12, completing
the system 10. By reversing the direction of the flow of the
refrigerant with the heat pump 20, the system 10 can operate in a
heating mode. A thermodynamic diagram of the vapor compression
system 10 is illustrated in FIG. 2.
[0015] In a preferred embodiment of the invention, carbon dioxide
is used as the refrigerant. While carbon dioxide is illustrated,
other refrigerants may benefit from this invention. Because carbon
dioxide has a low critical point, systems utilizing carbon dioxide
as a refrigerant usually require the vapor compression system 10 to
run transcritical. Although a transcritical vapor compression
system 10 is disclosed, it is to be understood that a conventional
sub-critical vapor compression cycle can be employed as well.
Additionally, the present invention can also be applied to
refrigeration cycles that operate at multiple pressure levels, such
as systems having more than one compressors, gas cooler, expander
motors, or evaporators.
[0016] The high pressure or intermediate pressure refrigerant
exiting the gas cooler 14 is high in potential energy. The process
of expansion of the high pressure refrigerant in the expansion
device 16 to low pressure converts the potential energy into
useable kinetic energy. As shown in FIG. 3, the kinetic energy
provides work which is used to fully or partially drive an expander
motor unit 24. The expander motor unit 24 is coupled to auxiliary
machinery 26a-26e, and the work is provided to operate and reduce
the power requirements of the auxiliary machinery. The structure,
control and operation of the expansion device 16 and the drive
connection to the auxiliary machinery is well within the level of
ordinary skill. It is the use of the expansion device 16 to drive
the auxiliary machinery which is inventive. By employing the
kinetic energy converted by the expansion of the high pressure or
intermediate pressure refrigerant to drive the expander motor unit
24 for the operation of the auxiliary rotating machinery 26, system
efficiency is improved.
[0017] The auxiliary rotating machinery coupled to the expander
motor unit 24 can be an evaporator fan 26a or a gas cooler fan 26b.
The heat exchanger fans 26a and 26b draw the refrigerant through
the evaporator 18 and the condenser 14, respectively, during
operation of the system 10. The auxiliary machinery 26 can also be
a water pump 26c or 26d. The water pumps 26c and 26d pump water
through the gas cooler 14 and evaporator 18, respectively. The
water exchanges heat with the refrigerant drawn through the gas
cooler 14 and evaporator 18. Water pumped by the evaporator water
pump 26c rejects heat which is accepted by refrigerant. Water
pumped by the gas cooler water pump 26d accepts heat which is
rejected by the refrigerant. The work produced by the expansion of
the refrigerant can also be utilized to power an oil pump 26e which
pumps oil through the compressor 12 to provide lubrication.
[0018] The foregoing description is only exemplary of the
principles of the invention. Many modifications and variations of
the present invention are possible in light of the above teachings.
The preferred embodiments of this invention have been disclosed,
however, so that one of ordinary skill in the art would recognize
that certain modifications would come within the scope of this
invention. It is, therefore, to be understood that within the scope
of the appended claims, the invention may be practiced otherwise
than as specially described. For that reason the following claims
should be studied to determine the true scope and content of this
invention.
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