Patent Application
20090211293
1. Field of the Invention
The subject of the invention relates generally to the conditioning of air, and more specifically, to improving the heat transfer efficiency of an air conditioning system.
2. Description of the Prior Art
Traditional air conditioning systems utilize the vapor-compression refrigeration cycle to condition ambient air into cool air for cooling a surrounding area. The traditional air conditioning system operating in the vapor-compression refrigeration cycle typically includes a compressor, a condenser, a heat exchanger, and an evaporator for transforming the refrigerant from a low pressure heated vapor into a cool mixed liquid-vapor. As air flows over the mixed liquid-vapor, heat from the air is transferred to the mixed liquid-vapor refrigerant to produce cool conditioned air that may be utilized to cool the surrounding area. The heat transferred to the refrigerant vaporizes the remaining liquid in the mixed-liquid vapor resulting in a low pressure heated vapor. This low pressure heated vapor is returned to the compressor to complete the refrigeration cycle. A thermal expansion valve may also be disposed downstream for decreasing the pressure of the refrigerant prior to delivery into the evaporator. By decreasing the pressure of the refrigerant, the remaining liquid can be vaporized more easily.
The thermodynamic characteristics of a typical refrigerant are illustrated by the pressure-enthalpy diagram shown if
Today, energy used to generate cool conditioned air has become increasingly important. Air conditioning systems are seen as large consumers of power. Therefore, energy efficient air conditioning has become an important area of investigation. Some current investigations have focused on liquid line cooling using the suction line cooling capacity; however, these systems do not reduce energy input. Instead, they merely increase cooling capacity.
In addition to the structure described above, the invention provides for the heat exchanger in fluid communication with the heat mass exchanger for receiving wet working air having a temperature less than the temperature of the high-pressure liquid from the condenser. The working air generated by a heat mass exchanger is flowed through the heat exchanger and over the high-pressure liquid to transfer heat from the high-pressure liquid to the working air for reducing the temperature of the high-pressure liquid.
Accordingly, the evaporative capacity of the evaporator is increased and the overall heat transfer efficiency of the air conditioning system is improved. Additionally, the system leverages the wet working air instead of simply exhausting the working air into the atmosphere to further promote an efficient air conditioning system.
Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
Referring to
The refrigeration cycle beings at the compressor 22 generally indicated. The compressor 22 includes a low-pressure inlet 32 and a high-pressure outlet 34. The compressor 22 receives the refrigerant in a low-pressure heated vapor state and compresses the refrigerant into a high-pressure superheated vapor where it is output from the high-pressure outlet 34.
The condenser 24 generally indicated has a vapor inlet 36 for receiving the refrigerant in a high-pressure heated vapor state and a liquid outlet 38. As the high-pressure heated vapor enters the vapor inlet 36 and flows to the liquid outlet 38, the high-pressure superheated vapor is condensed into a high-pressure liquid having a first predetermined temperature.
The heat exchanger 26 generally indicated has an exhaust air inlet 40 for receiving air and an exhaust air outlet 42. An exhaust channel 44 extends from the exhaust air inlet 40 to the exhaust air outlet 42 for directing the air therethrough. The heat exchanger 26 also has a refrigerant inlet 46 for receiving the high-pressure liquid and a refrigerant outlet 48. The heat exchanger 26 further includes a refrigerant tube 50 having a cross-section defining flat sides and rounded ends. The refrigerant tube 50 extends into the exhaust channel 44 from the refrigerant inlet 46 to the refrigerant outlet 48 through a plurality of U-shapes to form a serpentine pattern for delivering the high-pressure liquid from the refrigerant inlet 46 to the refrigerant outlet 48.
A valve 28, such as a thermal expansion valve 28, is generally indicated and is disposed between the heat exchanger 26 and the evaporator 30. The thermal expansion valve 28 includes a valve inlet 52 having an inlet diameter dINLET and a valve outlet 54 having an outlet diameter dOUTLET greater than the inlet diameter dINLET. The valve inlet 52 is in fluid communication with the condenser 24 for receiving the high-pressure liquid. As the high-pressure liquid flows from the valve inlet 52 to the valve outlet 54, the pressure of the high-pressure liquid is decreased and the refrigerant transforms from a high-pressure liquid into a cool low-pressure mixed liquid-vapor. By decreasing the pressure of the refrigerant prior to delivery into the evaporator 30, vaporization of the remaining liquid is improved. It is also appreciated that although a thermal expansion valve 28 is described, another thermal expansion device and/or valve 28 that decreases the pressure and/or temperature of the refrigerant may used.
The refrigerant cycle ends at the evaporator 30 generally indicated. The evaporator 30 includes a liquid-vapor inlet 56 for receiving the mixed liquid-vapor and a low-pressure outlet 58 for outputting low-pressure heated vapor. A refrigerant channel 60 is included and extends between the liquid-vapor inlet 56 and the low-pressure outlet 58 for delivering the mixed liquid-vapor therethrough. The evaporator 30 includes a product air inlet 62 for receiving air and a conditioned air outlet 64. An air pathway 66 extends perpendicular to the refrigerant channel 60 from the product air inlet 62 to the conditioned air outlet 64 for conveying air over the mixed liquid-vapor. As air flows over the mixed liquid-vapor, heat is transferred from the air to the refrigerant. In response, liquid from the mixed liquid-vapor refrigerant evaporates and the refrigerant is transformed into a high-pressure heated vapor, which is returned to the condenser 24 to complete the refrigeration cycle. Additionally, by transferring heat from the air flowing over the refrigerant, the cool conditioned air is generated. Furthermore, condensate is generated in response to air flowing over the mixed liquid-vapor. The evaporator 30 may include a drain 68 disposed at the bottom 70 of the evaporator 30 for draining the condensate from the evaporator 30.
A plurality of conduits 72, 74, 76, 78, 80 are used to connect the compressor 22, the condenser 24, the heat exchanger 26, the valve 28, and the evaporator 30 to one another in order to complete the air conditioning system 20. Although conduits 72, 74, 76, 78, 80 are described to connect the air conditioning system 20, any means for providing fluid communication between each of the compressor 22, the condenser 24, the heat exchanger 26 and the valve 28 may be used. Specifically, a first conduit 72 is included having one end connected to the high-pressure outlet 34 of the compressor 22. The opposite end is connected to the vapor inlet 36 of the condenser 24 for delivering the high-pressure superheated vapor from the compressor 22 to the condenser 24. A second conduit 74 is included having one end connected to the liquid outlet 38 of the condenser 24. The opposite end is connected to the refrigerant inlet 46 of the heat exchanger 26 for delivering the high-pressure liquid from the condenser 24 to the heat exchanger 26. A third conduit 76 is included having one end connected to the refrigerant outlet 48 of the heat exchanger 26. The opposite end is connected to the valve inlet 52 of the valve 28 for delivering the high-pressure liquid from the heat exchanger 26 to the valve 28. A fourth conduit 78 is included having one end connected to the valve outlet 54. The opposite end is connected to the liquid-vapor inlet 56 of the evaporator 30 for delivering the mixed liquid-vapor from the valve 28 to the evaporator 30. Lastly, a fifth conduit 80 is included having one end connected to the low-pressure outlet 58 of the evaporator 30. The opposite end is connected to the low-pressure inlet 32 of the compressor 22 for returning the refrigerant being in the low-pressure heated vapor state to the compressor 22.
Traditionally, the air conditioning system 20 thermally conditions ambient air to generate cool conditioned air utilized to cool the surrounding area. However, it is generally understood that the temperature of the air introduced into the evaporator 30 plays an important role in the overall efficiency of the air conditioning system 20. By reducing the temperature of the air prior to input into the evaporator 30, the overall load on the evaporator 30 may be reduced. Accordingly, a heat mass exchanger 82 may be used to provide the air conditioning system 20 with pre-cooled product air. By providing pre-cooled air to the air conditioning system 20, the temperature of the conditioned air generated by the evaporator 30 is further decreased.
Referring to
The air channels 92 also include wet channels 96 disposed between the dry channels 94 and being closed at the front ends. The wet channels 96 extend to one of the working air outlets 86 for flowing wet air therethrough. A first plurality of the dry channels 94 have a plurality of apertures 98 in the walls 88 for conveying air out of the respective dry channel 94 and into at least one adjacent wet channel 96 to cool the air in the adjacent dry channels 94. A second plurality of the dry channels 94 are included alternating with the first plurality of dry channels 94. The second plurality of dry channels 94 are disposed between two of the wet channels 96 and have a plurality of product air outlets 100 in the tops 90 thereof for directing pre-cooled product air from the second plurality of alternating dry channels 94. Each of the wet channels 96 are lined with a wicking material 102 for retaining a liquid.
The liquid is evaporated in response to airflow conveyed by the apertures 98 in the walls 88 of the dry channels 94 for extracting heat from the adjacent dry channels 94, thereby generating the dry air in the adjacent dry channels 94. The product air inlet 62 of the evaporator 30 is in fluid communication with the product air outlets 100 of the heat mass exchanger 82 for receiving the pre-cooled product air and flowing the pre-cooled air over the mixed liquid-vapor to generate the conditioned air from the conditioned air outlet 64.
The heat mass exchanger 82 may further include a reservoir 104 in fluid communication with the drain 68 of the evaporator 30 for collecting the condensate. The reservoir 104 supplies the condensate to the wicking material 102 of each of the wet air channels to wet the wicking material 102. Although one embodiment of a heat mass exchanger 82 is described above, any device for cooling air while generating wet working air as a by-product of the heat exchanging process may be used.
Traditionally, the wet working air generated by the heat mass exchanger 82 was viewed as being too humid to be utilized and was simply exhausted into the atmosphere. However, the air conditioning system 20 is distinguished by providing a means of flowing the wet working air exhausted from the heat mass exchanger 82 over the refrigerant flowing through the heat exchanger 26. The wet working air exhausted from the heat exchanger 26 has a temperature less than the high-pressure liquid from condenser 24, which flows through the heat exchanger 26. To maximize the air flow delivered to the high-pressure liquid flowing through the heat exchanger 26, the exhaust air inlet 40 of the heat exchanger 26 is disposed against the heat mass exchanger 82 and in fluid communication with the working air outlets 86, as shown in
Accordingly, the heat exchanger 26 receives the wet working air having a temperature less than the high-pressure liquid from the condenser 24. The wet working air flows through the exhaust channel 44 and over the high-pressure liquid to transfer heat from the high-pressure liquid to the working air for reducing the temperature of the high-pressure liquid. Therefore, the evaporative capacity of the evaporator 30 is increased and the overall efficiency of the air conditioning system 20 is improved. Additionally, the system leverages the wet working air generated by the heat mass exchanger 82 instead of simply exhausting the working air into the atmosphere, thereby further promoting an efficient air conditioning system 20.
While the invention has been described with reference to an exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
