U.S. patent application number 09/882074 was filed with the patent office on 2002-02-21 for capacity control of refrigeration systems.
Invention is credited to Vaisman, Igor.
Application Number | 20020021972 09/882074 |
Document ID | / |
Family ID | 24097410 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020021972 |
Kind Code |
A1 |
Vaisman, Igor |
February 21, 2002 |
Capacity control of refrigeration systems
Abstract
The present invention is directed to a method of reducing
cooling capacity in refrigeration systems. The present invention
provides a refrigeration system comprising a main, an economizing,
and a bypass circuits. The main circuit comprises a compressor, a
condenser unit, an expansion device, an evaporator unit, connecting
piping and appropriate refrigeration control. The compressor
includes an economizer port located in the compression region, and
a variable flow valve associated with the economizer port. A body
of the valve is a part of a body of the housing and a seat of the
valve in a closed position is shaped to be contiguous with internal
portion of the housing. The economizer circuit includes a first
solenoid valve, an additional expansion device and an economizing
heat exchanger. The bypass circuit has a second solenoid valve. A
control system activates the valves based on a capacity demand.
Inventors: |
Vaisman, Igor; (Thornhill,
CA) |
Correspondence
Address: |
Igor B. Vaisman, Ph.D.
R & D Manager
MCC INC.
80 Kincort St.
North York
ON
M6M 5G1
CA
|
Family ID: |
24097410 |
Appl. No.: |
09/882074 |
Filed: |
June 18, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09882074 |
Jun 18, 2001 |
|
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09526453 |
Mar 16, 2000 |
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Current U.S.
Class: |
417/310 |
Current CPC
Class: |
F04C 18/3441 20130101;
F25B 2400/13 20130101; F25B 2309/061 20130101; F25B 41/22 20210101;
F25B 2600/2509 20130101; F04C 29/0014 20130101; F25B 49/022
20130101; F25B 9/008 20130101 |
Class at
Publication: |
417/310 |
International
Class: |
F04B 049/00 |
Claims
I claim:
1. A refrigeration system comprising: (a) a compressor unit
including a housing, a suction side and a discharge side, an
economizer port located at a point after the compression chambers
have been closed for compression; a variable flow valve associated
with said economizer port, which in an opened position provides
communication between said compression chamber and an external
outlet of said economizer port over said economizer port; a body of
said valve being a part of a body of said housing and a seat of
said valve in a closed position is shaped to be contiguous with
internal portion of said housing; (b) a closed main circuit
including said compressor, a condenser unit, an expansion device,
an evaporator unit, connecting piping and appropriate refrigeration
control; (c) a bypass circuit between said external outlet and said
suction side; and (d) an electrical circuit including said variable
flow valve, a control system, and a transducer reading parameters
associated with a system capacity demand.
2. A refrigeration system as recited in claim 11 wherein said
compressor unit is a rotary vane compressor unit.
3. A refrigeration system as recited in claim 11 wherein said
condenser unit is a gas cooler unit providing transcritical heat
rejection.
4. A refrigeration system as recited in claim 11 wherein said port
and said seat of said variable flow valve consists of plurality of
ports and seats.
5. A refrigeration system as recited in claim 11 wherein said
variable flow valve is a solenoid valve.
6. A refrigeration system as recited in claim 11 wherein said
variable flow valve is a control valve.
7. A refrigeration system as recited in claim 11 wherein said
variable flow valve is a pulsing valve.
8. A refrigeration system as recited in claim 11 wherein said
transducer is a refrigerant pressure transducer.
9. A refrigeration system as recited in claim 11 wherein said
transducer is a temperature transducer.
10. A refrigeration system comprising: (a) a compressor unit
including a housing, a suction side and a discharge side, an
economizer port located at a point after the compression chambers
have been closed for compression; a variable flow valve associated
with said economizer port, which in an opened position provides
communication between said compression chamber and an external
outlet of said economizer port over said economizer port; a body of
said valve being a part of a body of said housing and a seat of
said valve in a closed position is shaped to be contiguous with
internal portion of said housing; (b) a closed main circuit
including said compressor, a condenser unit, an expansion device,
an evaporator unit, connecting piping and appropriate refrigeration
control; (c) an economizer circuit between said discharge side
after said condenser unit and said external outlet including an
additional expansion device and an economizing heat exchanger
therebetween; said economizing heat exchanger providing thermal
contact between refrigerant flow in said main circuit after said
condenser unit and between evaporating refrigerant in said
economizer circuit after said additional expansion device; (d) an
electrical circuit including said variable flow valve, a control
system, and a transducer reading parameters associated with a
system capacity demand.
11. A refrigeration system as recited in claim 20 wherein said
compressor unit is a rotary compressor unit.
12. A refrigeration system as recited in claim 20 wherein said
condenser unit is a gas cooler unit providing transcritical heat
rejection.
13. A refrigeration system as recited in claim 20 wherein said port
and said seat of said variable flow valve consists of plurality of
ports and seats.
14. A refrigeration system as recited in claim 20 wherein said
variable flow valve is a solenoid valve.
15. A refrigeration system as recited in claim 20 wherein said
variable flow valve is a control valve.
16. A refrigeration system as recited in claim 20 wherein said
variable flow valve is a pulsing valve.
17. A refrigeration system as recited in claim 20 wherein said
transducer is a refrigerant pressure transducer.
18. A refrigeration system as recited in claim 20 wherein said
transducer is a temperature transducer.
19. A refrigeration system as recited in claim 20 wherein said
refrigeration system further includes a first solenoid valve in
said bypass circuit, an economizer circuit between said discharge
side after said condenser unit and said external outlet including a
second solenoid valve, an additional expansion device and an
economizing heat exchanger therebetween; said economizing heat
exchanger providing thermal contact between refrigerant flow in
said main circuit after said condenser unit and between evaporating
refrigerant in said economizer circuit after said additional
expansion device; said first and second solenoid valves are
electrically connected to a control system.
20. A refrigeration system as recited in claim 29 wherein said
compressor unit is a rotary compressor unit.
21. A refrigeration system as recited in claim 29 wherein said
condenser unit is a gas cooler unit providing transcritical heat
rejection.
22. A refrigeration system as recited in claim 29 wherein said port
and said seat of said variable flow valve consists of plurality of
ports and seats.
23. A refrigeration system as recited in claim 29 wherein said
variable flow valve is a solenoid valve.
24. A refrigeration system as recited in claim 29 wherein said
variable flow valve is a control valve.
25. A refrigeration system as recited in claim 29 wherein said
variable flow valve is a pulsing valve.
26. A refrigeration system as recited in claim 29 wherein said
transducer is a refrigerant pressure transducer.
27. A refrigeration system as recited in claim 29 wherein said
transducer is a temperature transducer.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application to the patent
application "Capacity Control of Compressors" Ser. No. 09/526,453
dated Mar. 16, 2000.
FIELD OF THE INVENTION
[0002] The invention relates to refrigeration systems using
unloading rotary compressors.
BACKGROUND OF THE INVENTION
[0003] The main problem of controlling compression system capacity
is to reduce both the capacity of the compressor and the power
required to drive the compressor rotor to the same extent.
[0004] One commonly utilized means of achieving a capacity
reduction is to bypass a portion of the fluid from the discharge
side of the compressor back to the suction side. This method
requires an auxiliary pipe connecting the discharge and suction
sides of the compressor with a valve located in the pipe. Such an
arrangement reduces the system capacity since a smaller amount of
fluid is directed to the main system circuit, but it does not
reduce the power consumption since the compressor pumps the same
amount of fluid.
[0005] On the other hand, in many refrigeration or refrigerant
compression applications, there are other times when it would be
more desirable to have the ability to also achieve increased
capacity. One way of achieving increased capacity is the inclusion
of an economizer circuit into the refrigerant system. Typically,
the economizer fluid is injected through an economizer port at a
point after the compression chambers have been closed.
[0006] In one design, the system is provided with an unloader valve
which selectively communicates the economizer injection line back
to suction. In this arrangement, the fluid ports and passages
necessary to achieve the economizer injection are also utilized to
achieve suction bypass unloading, and thus the compressor and
system design and construction are simplified. However, operating
in regular mode, the compressor chamber communicates with the
additional volume of the passages, thus impacting compressor
efficiency. If the passages are made too small to reduce the impact
on compressor efficiency, unloading capacity would not be
enough.
[0007] As a further development a pulsed flow capacity control is
achieved by rapidly cycling solenoid valves in the suction line,
the economizer circuit, and in a bypass line with the percent of
"open" time for the valve regulating the rate of flow. The
provision of three modulating valves results in an increased
complexity and a reduced reliability of the whole refrigeration
system.
SUMMARY OF THE INVENTION
[0008] The present invention is directed to a method of reducing
cooling capacity in a refrigeration system with a rotary compressor
in such a way that the power requirement to drive the rotor is
reduced to the same extent (or close to) as capacity is reduced. In
an aspect of the invention this is accomplished without any impact
on compressor efficiency at regular mode. In another aspect, this
is accomplished without excessive complexity or low
reliability.
[0009] The present invention provides a refrigeration system
comprising a main circuit, and a bypass circuit. The main circuit
comprises, in a closed loop, a compressor, a condenser unit, an
expansion device, an evaporator unit, connecting piping and
appropriate refrigeration control. The compressor includes a
housing, an inlet, an outlet, a compression region therebetween, an
economizer port located in the compression region at a point where
the port is in communication with the compression chamber after it
has been closed for compression, and a variable flow valve
associated with the economizer port. A body of the valve is a part
of a body of the housing and a seat of the valve in a closed
position is shaped to be contiguous with internal portion of the
housing. The bypass circuit has a second solenoid valve located
between the economizer port and the suction side of the compressor.
The variable flow valve, a control system, and a transducer,
reading parameters associated with a system capacity demand, are
wired in an electrical circuit. The control system activates the
valves based on the capacity demand.
[0010] One more aspect of the invention there is provided a
refrigeration system comprising a main circuit, and an economizer
circuit. The main circuit comprises, in a closed loop, a
compressor, a condenser unit, an expansion device, an evaporator
unit, connecting piping and appropriate refrigeration control. The
compressor includes a housing, an inlet, an outlet, a compression
region therebetween, an economizer port located in the compression
region at a point where the port is in communication with the
compression chamber after it has been closed for compression, and a
variable flow valve associated with the economizer port. A body of
the valve is a part of a body of the housing and a seat of the
valve in a closed position is shaped to be contiguous with internal
portion of the housing. The economizer circuit includes a first
solenoid valve, an additional expansion device and an economizing
heat exchanger and is connected to the economizer port. The
economizing heat exchanger provides thermal contact between
refrigerant in the main circuit after the condenser unit and
evaporating refrigerant in the economizer circuit after the
additional expansion device. The variable flow valve, a control
system, and a transducer, reading parameters associated with a
system capacity demand, are wired in an electrical circuit. The
control system activates the valves based on the capacity
demand.
[0011] When the economizer and bypass circuits are applied together
the refrigeration system includes a first solenoid valve in the
bypass circuit and a second solenoid valve in the economizer
circuit.
[0012] According to the invention the refrigeration system has an
advantage in terms of the system simplicity and reliability since
only one variable flow valve is required.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Preferred embodiments of the present invention are
illustrated in the attached drawing, which is:
[0014] FIG. 1 is a schematic diagram of a Refrigeration System
utilizing capacity control.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] A refrigeration system, realizing abilities to increase and
decrease capacity, consists of three circuits: a main circuit, an
economizer circuit for the increased capacity mode, and a bypass
circuit for the decreased capacity mode.
[0016] The main circuit includes a compressor 1, a condenser 2, a
high pressure side 3 of a regenerative heat exchanger 4, an
expansion valve 5, and an evaporator 6. The compressor 1 has the
economizer port 7, the variable flow (including a solenoid type)
valve 8, and the outlet 9. A seat of the valve 8 in a closed
position is shaped to be contiguous with the wall portion of the
compression chamber.
[0017] The compressor could be provided with a plurality of the
economizer ports and seats providing contiguous shape of seats
providing contiguous shape of seats in respect to the wall portion
of the compression chamber.
[0018] The economizer circuit includes a solenoid valve 10, an
auxiliary expansion valve 11, and a low pressure side 12 of the
regenerative heat exchanger 4.
[0019] The bypass circuit includes a solenoid valve 13.
[0020] Both economizer and bypass loops, communicate with the
economizer port 7 over the valve 8 and outlet 9 at one end. The
economizer circuit at the other end is connected either to an
outlet 14 of the high pressure side 3 of the regenerative heat
exchanger 4 or, as an option, to an inlet 15 of the high pressure
side 3 of the regenerative heat exchanger 4. The bypass loop
circuit at the other end is connected to the compressor suction
line.
[0021] In the regular mode the valves 8, 10 and 14 are closed and
the refrigeration system operates as follows. The compressor 1
induces vapor at low pressure from the evaporator 6, compresses it
to high pressure, and discharges the compressed vapor into
condenser 2. In the condenser vapor is liquefied. Liquid
refrigerant after the condenser 2 passes the high pressure side 3
of the regenerative heat exchanger 4, expands in the expansion
valve 5 from high pressure to low pressure turning the liquid into
a mixture of vapor and liquid, and enters the evaporator 6. In the
evaporator 6, the liquid phase of the mixture is boiled out,
absorbing heat from objects to be cooled. Vapor, appearing at the
evaporator outlet, is induced by the compressor and the
thermodynamic cycle is reproduced.
[0022] In the increased capacity mode, the valves 8 and 10 are
opened and the valve 13 is closed. In this mode a part of
refrigerant flow at the outlet 14 (or at the inlet 15 as shown with
a dashed line) of the regenerative heat exchanger 4 is expanded in
the expansion valve 11 from high pressure to low pressure turning
the liquid to a mixture of vapor and liquid. Then the mixture
enters the low pressure side 12 of the regenerative heat exchanger
4. In the heat exchanger 4 the liquid phase is boiled out,
subcooling liquid refrigerant flow in the high pressure side 3.
Vapor, appearing at the heat exchanger outlet 14, is introduced
into compression process over the economizer port 7 without any
effect on refrigerant flow induced by the compressor 1 from the
suction line. This additional subcooling increases total cooling
capacity.
[0023] If the valve 8 is a solenoid one, then the system generates
two levels of system capacity: a nominal capacity, when the valve
is closed, and a maximal capacity, when the valve is opened.
[0024] If the valve 8 is a control valve, then the system generates
any intermediate capacity from the nominal one, when the valve is
completely closed, to the maximal one, when the valve is completely
opened. The intermediate capacity between the nominal and maximal
ones is provided at intermediate positions of the valve seat
depending on the capacity demand.
[0025] If the valve 8 is a pulsing one, then the system generates
any intermediate capacity from the nominal one, when the valve is
closed for the full pulsing cycle, to the maximal one, when the
valve is opened for the full pulsing cycle. The intermediate
capacity between the nominal and maximal ones is provided by the
relation between the time or portion of the pulsing cycle when the
valve seat is at an opened position, to the time or portion of the
pulsing cycle when the valve seat is at a closed position,
depending on the capacity demand.
[0026] In the decreased capacity mode the valve 10 is closed and
the valves 8 and 13 are opened. In this mode a part of the
refrigerant flow from the economizer port 7 is returned back to the
suction line, decreasing the amount of refrigerant circulating over
the main circuit.
[0027] If the valve 8 is a solenoid one, then the system generates
two levels of system capacity: a nominal capacity, when the valve
is closed, and a minimal capacity, when the valve is opened.
[0028] If the valve 8 is a control valve, then the system generates
any intermediate capacity from the nominal one, when the valve is
closed, to the minimal one, when the valve is opened. The
intermediate capacity between the nominal and maximal ones is
provided at intermediate positions of the valve seat depending on
the capacity demand.
[0029] If the valve 8 is a pulsing one, then the system generates
any intermediate capacity from the nominal one, when the valve is
closed for the full pulsing cycle, to the minimal one, when the
valve is opened for the full pulsing cycle. The intermediate
capacity between the nominal and maximal ones is provided by the
relation between the time or portion of the pulsing cycle when the
valve seat is at an opened position, to the time or portion of the
pulsing cycle when the valve seat is at a closed position,
depending on the capacity demand.
[0030] If a transcritical refrigerant (such as carbon dioxide) is
applied, than instead of the condenser 2, a gas cooler is applied
since instead of the condensation process the transcritical heat
rejection process takes place.
[0031] The refrigeration system described above has only one
variable flow valve, which is an advantage in terms of the system
simplicity and reliability.
[0032] While certain preferred embodiments of the present invention
have been disclosed in detail, it is to be understood that various
modifications in its structure may be adopted without departing
from the spirit of the invention or the scope of the following
claims
* * * * *