Patent Application
20130333402
The present invention generally relates to climate control systems, and more particularly relates to climate control systems including a liquid-vapor separator for motor vehicles, motor vehicles including such climate control systems, and methods of operating such climate control systems.
Many motor vehicles, such as automobiles, include climate control systems or air conditioning systems that operate to cool a passenger compartment of a vehicle. These climate control systems typically include a condenser or gas cooler, an evaporator, and a compressor that circulates or pumps a refrigerant between the condenser and the evaporator. In particular, the compressor compresses the refrigerant to a high-pressure, high-temperature gas refrigerant that is sent to the condenser. The condenser condenses the gas refrigerant to a high-pressure, high-temperature liquid refrigerant. Typically, a receiver that has storage capacity is integrated on a side of the condenser. The integrated receiver helps store a portion of the liquid refrigerant so that a column of liquid refrigerant is available at different ambient conditions. The liquid refrigerant is then advanced to an expansion valve, such as a thermostatic expansion valve (TXV), which partially expands the liquid refrigerant and regulates its flow to the evaporator. In the evaporator, the partially expanded refrigerant further expands to a low temperature, low pressure gas refrigerant for indirect heat exchange with air passing over or through the evaporator to cool the air, thereby heating the gas refrigerant. The gas refrigerant is removed from the evaporator as a superheated gas and the cooled air is circulated in the passenger compartment for climate control.
One problem, particularly from an efficiency standpoint, is that the partially expanded refrigerant is typically introduced to the evaporator as a two-phase mixture. The two-phase mixture includes a refrigerant liquid phase and a refrigerant vapor phase which can cause temperature distribution issues in the evaporator. For example, the refrigerant vapor phase can act as an obstacle, e.g., creating back pressure, to the refrigerant liquid phase as the refrigerant liquid phase tries to pass through and expand in the small channels of the evaporator to provide the cooling. As such, less cooling is provided to the air that is passing over or through the evaporator, thereby reducing the efficiency of the climate control system.
Accordingly, it is desirable to provide climate control systems with improved efficiency for motor vehicles, motor vehicles including such climate control systems, and methods of operating such climate control systems. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.
A climate control system for a motor vehicle is provided herein. In one embodiment, the climate control system comprises a refrigeration loop circuit that is configured to advance a refrigerant. A compressor is disposed along the refrigeration loop circuit and is configured to compress the refrigerant to form a high-pressure refrigerant gas stream. A condenser is disposed along the refrigeration loop circuit downstream from the compressor and is configured to condense the high-pressure refrigerant gas stream to form a condensed refrigerant stream. An expansion valve is disposed along the refrigeration loop circuit downstream from the condenser and is configured to expand the condensed refrigerant stream to form a partially expanded refrigerant stream. The partially expanded refrigerant stream comprises a refrigerant liquid phase and a refrigerant vapor phase. A liquid-vapor separator is disposed along the refrigeration loop circuit and is in fluid communication with the expansion valve. The liquid-vapor separator is configured to separate the partially expanded refrigerant stream into a refrigerant liquid stream and a refrigerant vapor stream. The liquid-vapor separator contains a desiccant for removing water from at least a portion of the partially expanded refrigerant stream to form the refrigerant liquid stream that is substantially depleted of water. An evaporator is disposed along the refrigeration loop circuit downstream from the liquid-vapor separator. The evaporator is configured to exchange heat between air passing across or through the evaporator and the refrigerant liquid stream passing internally through and expanding in the evaporator to form a superheated refrigerant gas stream.
A climate control system for a motor vehicle is provided herein. In one embodiment, the climate control system comprises a refrigeration loop circuit that is configured to advance a refrigerant. A compressor is disposed along the refrigeration loop circuit and is configured to compress the refrigerant to form a high-pressure refrigerant gas stream. A condenser is disposed along the refrigeration loop circuit downstream from the compressor and is configured to condense the high-pressure refrigerant gas stream to form a condensed refrigerant stream. An expansion valve is disposed along the refrigeration loop circuit downstream from the condenser and is configured to expand the condensed refrigerant stream to form a partially expanded refrigerant stream. The partially expanded refrigerant stream comprises a refrigerant liquid phase and a refrigerant vapor phase. A liquid-vapor separator is disposed along the refrigeration loop circuit and is in fluid communication with the expansion valve. The liquid-vapor separator is configured to separate the partially expanded refrigerant stream into a refrigerant liquid stream and a refrigerant vapor stream. The expansion valve is coupled directly to the liquid-vapor separator such that the liquid-vapor separator receives the partially expanded refrigerant stream directly from the expansion valve and the expansion valve receives the refrigerant vapor stream directly from the liquid-vapor separator. An evaporator is disposed along the refrigeration loop circuit downstream from the liquid-vapor separator. The evaporator is configured to exchange heat between air passing across or through the evaporator and the refrigerant liquid stream passing internally through and expanding in the evaporator to form a superheated refrigerant gas stream.
A method of operating a climate control system for a motor vehicle is provided herein. In one embodiment, the method comprises the steps of expanding a condensed refrigerant stream with an expansion valve to form a partially expanded refrigerant stream. The partially expanded refrigerant stream comprises a refrigerant liquid phase and a refrigerant vapor phase. The partially expanded refrigerant stream is separated with a liquid-vapor separator into a refrigerant liquid stream and a refrigerant vapor stream. Separating the partially expanded refrigerant stream includes removing water from at least a portion of the partially expanded refrigerant stream with a desiccant contained in the liquid-vapor separator to form the refrigerant liquid stream that is substantially depleted of water. Heat is exchanged between air passing across or through an evaporator and the refrigerant liquid stream passing internally through and expanding in the evaporator to form a superheated refrigerant gas stream.
The embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and wherein:
The following detailed description is merely exemplary in nature and is not intended to limit the application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding technical field, background, brief summary or the following detailed description.
Various embodiments contemplated herein relate to climate control systems for motor vehicles, motor vehicles including climate control systems, and methods of operating such climate control systems. Unlike the prior art, the embodiments taught herein provide a climate control system for a motor vehicle with various components arranged along a refrigeration loop circuit. The various components include a compressor, a condenser, an expansion valve, a liquid-vapor separator, and an evaporator. The refrigeration loop circuit is configured to fluidly communicate a refrigerant between these various components. In one embodiment, the compressor compresses the refrigerant to form a high-pressure refrigerant gas stream that is advanced to the condenser. The condenser condenses the high-pressure refrigerant gas stream to form a condensed refrigerant stream. The expansion valve receives and expands the condensed refrigerant stream to form a partially expanded refrigerant stream. The partially expanded refrigerant stream comprises a refrigerant liquid phase and a refrigerant vapor phase and is introduced to the liquid-vapor separator. The liquid-vapor separator separates the partially expanded refrigerant stream into a refrigerant liquid stream and a refrigerant vapor stream. In one embodiment, the refrigerant liquid stream is introduced to and advanced through the evaporator while the refrigerant vapor stream is directed downstream of the evaporator. Heat is exchanged between air passing across or through the evaporator and the refrigerant liquid stream, which is passing internally through and expanding in the evaporator, to form cooled air and a superheated refrigerant gas stream. In one embodiment, the cooled air is directed in a passenger compartment of the motor vehicle for climate control and the superheated refrigerant gas stream is removed from the evaporator and combined with the refrigerant vapor stream upstream of the compressor. By separating the partially expanded refrigerant stream with the liquid-vapor separator, the refrigerant liquid stream is essentially free of the refrigerant vapor phase when the refrigerant liquid stream is introduced to the evaporator. As such, the refrigerant liquid stream can pass more easily through and expand in the small channels of the evaporator without the refrigerant vapor phase acting as an obstacle, thereby improving temperature distribution in the evaporator and increasing the efficiency of the climate control system.
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The climate control system 10 includes a refrigeration loop circuit 16 that is arranged in the motor vehicle 12 and is configured as a closed loop fluid circuit for advancing a refrigerant in a generally counterclockwise direction relative to the view showing in
Arranged along the refrigeration loop circuit 16 in fluid communication with each other are a compressor 18, a condenser 20, an expansion valve 22, a liquid-vapor separator 24, and an evaporator 26. The compressor 18 is operable to draw the refrigerant at a relatively low pressure fluid (e.g., relatively low pressure gas) and to compress the refrigerant to a relatively high pressure, forming a high-pressure refrigerant gas stream 28. The compressor 18 can be, for example, a reciprocating compressor, a scroll compressor, or a rotary vane compressor. The high-pressure refrigerant gas stream 28 exits the compressor 18 through an outlet 29.
The condenser 20 is downstream from the compressor 18 and receives the high-pressure refrigerant gas stream 28. The condenser 20 is operable to condense the high-pressure refrigerant gas stream 28 to form a condensed refrigerant stream 30. In one embodiment, the condenser 20 includes a heat exchanger or coil having an inlet 32 that is adapted to receive the high-pressure refrigerant gas stream 28. The high-pressure refrigerant gas stream 28 rejects heat to ambient air and condenses as the high-pressure refrigerant gas stream 28 flows through the coil and the ambient air passes over an exterior of the coil. A fan 34 may force the ambient air across the coil of the condenser 20 and/or ambient air flowing through a grill of the motor vehicle 12 may flow across the coil of the condenser 20 to facilitate the heat transfer between the ambient air and the high-pressure refrigerant gas stream 28 flowing internally through the condenser 20. As illustrated, the condensed refrigerant stream 30 exits the condenser 20 through an outlet 36. It will be appreciated that the condenser 20 could be a gas cooler, a radiator, or any other heat exchanger known to those skilled in the art for condensing a high-pressure refrigerant gas.
The condensed refrigerant stream 30 advances downstream to the expansion valve 22. As illustrated, the expansion valve 22 is configured as a thermostatic expansion valve (TXV), but alternatively can be an orifice tube or other refrigerant expansion device known to those skilled in the art. The expansion valve 22 is operable to expand the condensed refrigerant stream 30, thereby lowering the pressure and temperature of the condensed refrigerant stream 30 to form a partially expanded refrigerant stream 38. The partially expanded refrigerant stream 38 comprises a refrigerant liquid phase and a refrigerant vapor phase. As illustrated and will be discussed in further detail below, the expansion valve 22 also receives a superheated refrigerant gas stream 44 from the evaporator 26 and in response to conditions, e.g., temperature and/or pressure, of the superheated refrigerant gas stream 44, regulates the amount of the partially expanded refrigerant stream 38 exiting the expansion valve 22.
In an embodiment, the liquid-vapor separator 24 is downstream from and in fluid communication with the expansion valve 22 to receive the partially expanded refrigerant stream 38. The liquid-vapor separator 24 is operable to separate the partially expanded refrigerant stream 38 into a refrigerant liquid stream 40 and a refrigerant vapor stream 42. In one embodiment, the liquid-vapor separator 24 has storage capacity for storing a column of the refrigerant liquid stream 40 at different ambient conditions to ensure a continuous flow of the refrigerant liquid stream 40 to the evaporator 26. Unlike conventional climate control systems, due to the storage capacity of the liquid-vapor separator 24, the condenser 20 does not need an integrated receiver for storing a column of refrigerant at different ambient conditions.
The refrigerant liquid stream 40 exits the liquid-vapor separator 24 and is directed downstream to the evaporator 26. The evaporator 26 is operable to exchange heat between air passing across or through the evaporator 26 and the refrigerant liquid stream 40 passing internally through and expanding in the evaporator 26 to form the superheated refrigerant gas stream 44. In one embodiment, the evaporator 26 includes a heat exchanger with channels, e.g., small channels, and an inlet 46 that is adapted to receive the refrigerant liquid stream 40. The refrigerant liquid stream 40 absorbs heat from ambient air as the air flows across or through the heat exchanger. Notably, by separating the partially expanded refrigerant stream 38 with the liquid-vapor separator 24, the refrigerant liquid stream 40 is essentially free of the refrigerant vapor phase when the refrigerant liquid stream 40 is introduced to the evaporator 26. As such, the refrigerant liquid stream 40 can pass more easily through and expand in the small channels of the evaporator 26 without the refrigerant vapor phase acting as an obstacle, thereby improving temperature distribution in the evaporator 26 and increasing the efficiency of the climate control system 10.
As illustrated, a fan 48 may force the ambient air across or over the outside of the channels of the evaporator 26 to facilitate heat transfer between the ambient air and the refrigerant liquid stream 40. Air forced across or through the evaporator 26 may be, for example, subsequently directed through one or more ducts to the passenger compartment 14 of the motor vehicle 12 to provide cooling.
In one embodiment, the superheated refrigerant gas stream 44 exits the evaporator 26 through an outlet 50 and is advanced back to the expansion valve 22. The expansion valve 22 is configured such that as the superheated refrigerant gas stream 44 passes through a control portion of the expansion valve 22, the expansion valve 22 regulates the outgoing flow of the partially expanded refrigerant stream 38 in response to the pressure and/or temperature of the superheated refrigerant gas stream 44. This allows the amount of the partially expanded refrigerant stream 38 being introduced to the liquid-vapor separator 24 to be adjusted to meet the demands of the evaporator 26 for ensuring a more complete expansion of the liquid refrigerant stream 40 in the evaporator 26 to the gaseous phase for enhanced cooling. The superheated refrigerant gas stream 44 exits the expansion valve 22 and is directed downstream to a section 54 of the refrigeration loop circuit 16 that is upstream from the compressor 18.
In an embodiment, the refrigeration loop circuit 16 includes a bypass section 52. The bypass section 52 fluidly couples the liquid-vapor separator 24 to the section 54 of the refrigeration loop circuit 16. As such, the refrigerant vapor stream 42 exits the liquid-vapor separator 24 and is advanced along the bypass section 52 to the section 54 and is introduced to the superheated refrigerant gas stream 44 to form a combined refrigerant stream 56. The combined refrigerant stream 56 is passed along the refrigeration loop circuit 16 and is received at an inlet 58 of the compressor 18 to repeat the refrigeration cycle as described above.
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As illustrated, the internal heat exchanger 60 has a fluid conduit 62 that is arranged downstream from the condenser 20 and upstream from the expansion valve 22 and a fluid conduit 64 that is arranged downstream from the evaporator 26 and upstream from the compressor 18. The fluid conduits 62 and 64 are arranged adjacent to each other in the internal heat exchanger 60 to allow heat transfer between the two fluid conduits 62 and 64. As such, the internal heat exchanger 60 is operable for indirect heat exchange between the condensed refrigerant stream 30 and the superheated refrigerant gas stream 44.
In one embodiment and as illustrated, the bypass section 52 directs the refrigerant vapor stream 42 to the superheated refrigerant gas stream 44 upstream from the internal heat exchanger 60 so that the combined refrigerant stream 56 is introduced to the fluid conduit 64 of the internal heat exchanger 60. The condensed refrigerant stream 30 passing through the fluid conduits 62 is at a higher temperature and pressure than the combined refrigerant stream 56 and therefore, heat transfers from the condensed refrigerant stream 30 to the combined refrigerant stream 56 to cool the condensed refrigerant stream 30.
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While at least one embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the embodiment or embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the embodiment or embodiments. It should be understood that various changes may be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.
