INTEGRATED RECEIVER AND SUCTION LINE HEAT EXCHANGER FOR REFRIGERANT SYSTEMS
A refrigeration system may be provided with a space-saving suction-line heat exchanger. The heat exchanger may be incorporated into a receiver. As heated liquid refrigerant enters and flows through the receiver, it may transfer heat into the heat exchanger. The heat exchanger may be connected to a suction line of the system so that refrigerant vapor and an oil-refrigerant mixture may be heated as it passes from an evaporator and into an inlet of a compressor.
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The present invention generally relates to refrigeration systems. More particularly, the invention relates to a compact refrigeration system which may be advantageously employed in a vehicle.
In some vehicles such as aircraft, refrigeration systems may be employed to perform various cooling functions. In a typical aircraft, where space is limited, it is advantageous to construct on-board refrigeration systems that occupy as little volume as possible. At the same time, it is advantageous to construct aircraft refrigeration systems with low weight and high efficiency.
It is known that incorporating suction line heat exchangers in refrigeration systems may increase temperature of refrigerant vapor at a compressor inlet. The increased temperature may reduce the amount of refrigerant that can be absorbed into lubricating oil and thereby may result in an increase of viscosity of the oil. Higher viscosity oil-refrigerant mixture may provide improved lubrication and longer life for various compressor components. Additionally, the suction line heat exchanger may minimize the amount of liquid refrigerant that enters the compressor thus adding further to higher oil viscosity.
While suction line heat exchangers are a desirable feature for a refrigeration systems, their use has heretofore added substantial volume to a refrigeration system. Typically, effective suction line heat exchangers may have a volume that is about equal to volume of a receiver of the system.
As can be seen, there is a need for an aircraft refrigeration system system in which a suction line heat exchanger may be employed and in which the suction line heat exchanger adds only minimal volume to the system.
SUMMARY OF THE INVENTIONIn one aspect of the present invention, a distributed cooling system for an aircraft may comprise an evaporator; a compressor; a condenser; and a receiver interposed between the condenser and the evaporator for receiving liquid refrigerant from the condenser, the receiver comprising a heat exchanger; and the heat exchanger interposed between the evaporator and the compressor and configured to transfer heat from the liquid refrigerant in the receiver to refrigerant vapor emerging from the evaporator.
In another aspect of the present invention, a receiver for a refrigeration system may comprise an enclosure with an inlet for liquid refrigerant at a first end and an outlet for the liquid refrigerant at a second end; and a heat exchanger with an inlet and an outlet for refrigerant vapor; and wherein the heat exchanger is surrounded by the enclosure.
In still another aspect of the present invention, a method for improving operation of a refrigeration system may comprise passing a vapor and liquid mixture emerging from an evaporator through a heat exchanger incorporated in a receiver; passing heated liquid refrigerant into the receiver and into contact with the heat exchanger; transferring heat from the liquid refrigerant to the vapor; and passing the heated mixture to an inlet of a compressor.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims.
The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Various inventive features are described below that can each be used independently of one another or in combination with other features.
The present invention generally provides a cooling system that uses a space-saving receiver and an integral suction-line heat exchanger incorporated into a single enclosure.
Referring now to
A refrigerant circuit 20 may interconnect the evaporator 16 to a compressor 22 at an inlet side 22-1. In an exemplary embodiment of the invention, the compressor 22 may be a scroll compressor. The compressor 22 may be driven by an AC motor 24 which may be provided with electrical power through a dedicated inverter 26 which may be connected to a DC bus 28 of the aircraft. The compressor 22 may be interconnected, at an outlet side 22-2, to the evaporator 16 through a condenser 30. A receiver 31 may be interposed between the condenser 30 and the evaporator 16.
Referring now to
Referring now to
In an exemplary embodiment, the heat exchanger 32 may comprise a serpentine tube 32-2 and a plurality of baffles 32-4. The heat exchanger 32 may be positioned within the enclosure 31-2. The heat exchanger 32 may be interposed between the evaporator 16 and the inlet 22-1 of the compressor 22 on a suction line 20-1. Refrigerant vapor may be commingled with lubricating oil and liquid refrigerant as it emerges from the evaporator 16. This mixture of lubricating oil, refrigerant vapor and liquid refrigerant may be referred as a suction-line mixture 50. The mixture 50 from the evaporator 16 may enter the heat exchanger 32 at an inlet 32-6 and may exit at an outlet 32-8. The mixture 50 may pass through the tube 32-2 and the liquid refrigerant 40 may pass over the baffles 32-4. The liquid refrigerant 40 may transfer heat to the baffles 32-4 and the tube 32-2 and the mixture 50. This transfer of heat may raise the temperature of the mixture 50 as it passes through the heat exchanger 32 and into the compressor 20.
The heat exchanger 32 may advantageously heat the mixture 50 sufficiently to vaporize any liquid refrigerant that may be contained in the mixture 50 so that any refrigerant emerging from the heat exchanger may be in a vapor state. Additionally, because the heat exchanger 32 may advantageously raise the temperature of the mixture 50, viscosity of an oil-refrigerant component of the mixture may be increased. This may occur because the oil-refrigerant component may become modified to have a higher fraction of oil. Higher viscosity oil-refrigerant may provide improved lubrication and longer life for various compressor components. It may also be noted that because the heat exchanger 32 may minimize the amount of liquid refrigerant that enters the compressor 22, resultant oil viscosity may be increased.
Referring now to
Referring particularly to
Referring now to
It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.
Claims
1. A distributed cooling system for an aircraft, comprising:
- an evaporator;
- a compressor;
- a condenser; and
- a receiver interposed between the condenser and the evaporator for receiving liquid refrigerant from the condenser, the receiver comprising an integral heat exchanger; and
- the heat exchanger interposed between the evaporator and the compressor and configured to transfer heat from the liquid refrigerant in the receiver to a suction-line mixture emerging from the evaporator.
2. The cooling system of claim 1, further comprising a head pressure control valve interposed between the compressor and an inlet of the receiver.
3. The cooling system of claim 1, further comprising a bypass line through which liquid refrigerant can flow into the receiver without passing through the condenser.
4. The cooling system of claim 1:
- wherein the receiver comprises an enclosure;
- wherein the heat exchanger comprises: a serpentine tube; and one or more baffles in contact with the serpentine tube; and wherein the baffles are in contact with an interior of the enclosure.
5. The cooling system of claim 4:
- wherein the baffles have outer peripheries; and
- wherein a portion of the outer peripheries are spaced away from the interior of the enclosure so that flow passages for liquid refrigerant are interposed between the enclosure and non-contact portions of the outer peripheries of the baffles.
6. A receiver for a refrigeration system comprising:
- an enclosure with an inlet for liquid refrigerant at a first end and an outlet for the liquid refrigerant at a second end; and
- a heat exchanger with an inlet and an outlet for refrigerant vapor; wherein the heat exchanger is surrounded by the enclosure.
7. The receiver of claim 6 wherein the heat exchanger comprises:
- a tube for passage of refrigerant vapor; and
- one or more baffles in contact with the tube for defining a flow path for the liquid refrigerant through the receiver.
8. The receiver of claim 7 wherein the tube is a serpentine tube.
9. The receiver of claim 7 wherein the baffles have a outer periphery, a first portion of which conforms in shape to a shape of an interior of the enclosure and a second portion of which does not conform to the shape of the interior of the enclosure so that a flow passage for the liquid refrigerant is present in a space between the second portion of the outer periphery and the interior of the enclosure.
10. The receiver of claim 9 wherein the first portion of the outer periphery of the baffle is in contact with the interior of the enclosure so that flow of the liquid refrigerant is directed to the flow passage.
11. The receiver of claim 9, wherein the baffle is provided with one or more holes though which the tube passes.
12. The receiver of claim 11 wherein the tube is in contact with the baffle at the hole so that flow of the liquid refrigerant is directed to the flow passage.
13. The receiver of claim 12 further comprising:
- at least two of the baffles; and
- wherein a first one of the flow passages formed by the a first one of the baffles is at a first side of the enclosure; and
- wherein a second one of the flow passages formed by a second one of the baffles is at a second side of the enclosure so that the liquid refrigerant is constrained to flow from the first side of the enclosure to the second side of the enclosure to effectively transfer heat to the tube.
14. A method for performing suction line heating in a refrigeration system comprising:
- passing a vapor and liquid mixture emerging from an evaporator through a heat exchanger incorporated in a receiver;
- passing heated liquid refrigerant into the receiver and into contact with the heat exchanger;
- transferring heat from the liquid refrigerant to the vapor; and
- passing the heated vapor and liquid mixture to an inlet of a compressor.
15. The method of claim 14 wherein the step of transferring heat increases viscosity of an oil-refrigerant mixture entering the compressor.
16. The method of claim 14, wherein the step of passing heated liquid refrigerant into the receiver comprises passing liquid refrigerant from a condenser of the refrigeration system into the receiver.
17. The method of claim 14, wherein the step of passing heated liquid refrigerant into the receiver comprises passing liquid refrigerant from a bypass line connected to an outlet of the compressor into the receiver.
18. The method of claim 14, wherein the step of passing heated liquid refrigerant into the receiver comprises the step of flowing the liquid refrigerant over one or more baffles.
19. The method of claim 18:
- wherein the liquid refrigerant flows laterally across a first one of the baffles to a first side of the receiver;
- wherein the liquid refrigerant flows laterally across a second one of the baffles to a second side of the receiver.
20. The method of claim 19, wherein the liquid refrigerant flows past a tube through which the vapor and liquid mixture passes so that heat is transferred from the liquid refrigerant into the tube.
Type: Application
Filed: Oct 27, 2010
Publication Date: May 3, 2012
Applicant: HONEYWELL INTERNATIONAL INC. (MORRISTOWN, NJ)
Inventors: RICKY GOV (Monterey Park, CA), RANJIT DARKE (Los Angeles, CA), PETER ZHENG (Rancho Palos Verdes, CA)
Application Number: 12/912,965
International Classification: F25B 41/00 (20060101); F25D 11/00 (20060101); F25B 39/04 (20060101);