This study was conducted to figure out the diagnosis basis of cooling performance according to refrigerant charging variation and foreign air and moisture content injected into refrigerant of air conditioner by detecting the temperatures and pressures along the refrigerant circulation line. A car ai...
This study was conducted to figure out the diagnosis basis of cooling performance according to refrigerant charging variation and foreign air and moisture content injected into refrigerant of air conditioner by detecting the temperatures and pressures along the refrigerant circulation line. A car air conditioner of SONATA III(Hyundai motor Co., Korea) was tested at maximum cooling condition at the engine speed of 1500~2000 rpm in the room controlled at 33∼35℃ and 55∼57% air conditionally. Measured variables were temperature differences between inlet and outlet pipe surfaces of the compressor(Tcom), condenser(Tcon), receive drier (Trec) and evaporator(Teva); and high pressure(HP) and low pressure(LP) in the refrigerant circulation line; and temperature difference(Tcoo) between inlet and outlet air of the cooling vent of evaporator. The results can be summarized as follows: 1. Effect of Refrigerant Charging Variations on Temperature and Pressure of Refrigerant Circulation Line in the Car Air Conditioner It seemed possible to diagnose the refrigerant charging condition by measuring each of the temperature and the pressure at the engine speed of 1,500 rpm and 2,000 rpm. Temperature difference(Td) between entrance and outlet air of cooling vent of evaporator was most influenced by refrigerant charge weight(Wr) and next by the high pressure(P1) in the refrigerant circulation line. The optimum refrigerant charge weight(Wr) referred to in the car maintenance book was 720 g, therefore it was considered that the optimum condition of the air conditioner was 15℃ and 1.47 MPa for Td and P1, respectively, under 5% error. The normal condition of Td referred to in the textbook was over 12℃, and therefore P1 at normal condition of the air conditioner was between 1.37 MPa and 1.57 MPa. 2. Cooling Performance Deficiency of Air Conditioning System According to Foreign Air Content in Refrigerant From the test, it was found that the measured values of Tcom, LP and Tcoo were useful in the diagnosis of cooling performance deficiency according to air quantity included in refrigerant of air conditioner. The ranges of Tcom, LP and Tcoo suitable to diagnose cooling performance deficiency were, respectively, less than 55℃, more than 166.7 kPa-g(1.7 kgf/cm2) and less than 13.7℃. In the case of using only external sensors to an air conditioner of normal performance, it was considered that the suitable ranges of LP and Tcoo to diagnose cooling performance deficiency were, respectively, more than 166.7 kPa and less than 12℃. 3. Cooling Performance Deficiency of Air Conditioning System According to Foreign Moisture Content Injected into Refrigerant In this study, changes of the moisture content in the refrigerant injected along the refrigerant circulation line were correlated to the temperature, pressure changes and also foreign moisture content caused by poor air conditioning. The following parameters; temperature, pressure and foreign moisture content appeared reasonable in providing data to diagnose the cooling performance deficiency. With the increase of foreign moisture content in the refrigerant in the air conditioning system, the performance of the cooling or the heat transfer became worse. Average surface temperature was measured on each point along the circulation line of refrigerant, but this alone was not enough to determine foreign moisture content. Temporal variations of the refrigerant in the evaporator outlet point showed patterns that could estimate the foreign moisture content. The tendencies of temperature changes inside the evaporator vent exit points varied and were observed at similar temperatures. Each average temperatures and pressures along the refrigerant circulation line was lower than normal. Low-side pressure and temperature of the pipe were found to vary periodically. Periodic fluctuations of moisture content were more than 0.05 kg and were used to quantify foreign inclusion. Criterion to determine the foreign moisture content in the circulation line was the difference between temperatures of evaporator inlet and outlet pipes when the temperature difference was below 14℃.
This study was conducted to figure out the diagnosis basis of cooling performance according to refrigerant charging variation and foreign air and moisture content injected into refrigerant of air conditioner by detecting the temperatures and pressures along the refrigerant circulation line. A car air conditioner of SONATA III(Hyundai motor Co., Korea) was tested at maximum cooling condition at the engine speed of 1500~2000 rpm in the room controlled at 33∼35℃ and 55∼57% air conditionally. Measured variables were temperature differences between inlet and outlet pipe surfaces of the compressor(Tcom), condenser(Tcon), receive drier (Trec) and evaporator(Teva); and high pressure(HP) and low pressure(LP) in the refrigerant circulation line; and temperature difference(Tcoo) between inlet and outlet air of the cooling vent of evaporator. The results can be summarized as follows: 1. Effect of Refrigerant Charging Variations on Temperature and Pressure of Refrigerant Circulation Line in the Car Air Conditioner It seemed possible to diagnose the refrigerant charging condition by measuring each of the temperature and the pressure at the engine speed of 1,500 rpm and 2,000 rpm. Temperature difference(Td) between entrance and outlet air of cooling vent of evaporator was most influenced by refrigerant charge weight(Wr) and next by the high pressure(P1) in the refrigerant circulation line. The optimum refrigerant charge weight(Wr) referred to in the car maintenance book was 720 g, therefore it was considered that the optimum condition of the air conditioner was 15℃ and 1.47 MPa for Td and P1, respectively, under 5% error. The normal condition of Td referred to in the textbook was over 12℃, and therefore P1 at normal condition of the air conditioner was between 1.37 MPa and 1.57 MPa. 2. Cooling Performance Deficiency of Air Conditioning System According to Foreign Air Content in Refrigerant From the test, it was found that the measured values of Tcom, LP and Tcoo were useful in the diagnosis of cooling performance deficiency according to air quantity included in refrigerant of air conditioner. The ranges of Tcom, LP and Tcoo suitable to diagnose cooling performance deficiency were, respectively, less than 55℃, more than 166.7 kPa-g(1.7 kgf/cm2) and less than 13.7℃. In the case of using only external sensors to an air conditioner of normal performance, it was considered that the suitable ranges of LP and Tcoo to diagnose cooling performance deficiency were, respectively, more than 166.7 kPa and less than 12℃. 3. Cooling Performance Deficiency of Air Conditioning System According to Foreign Moisture Content Injected into Refrigerant In this study, changes of the moisture content in the refrigerant injected along the refrigerant circulation line were correlated to the temperature, pressure changes and also foreign moisture content caused by poor air conditioning. The following parameters; temperature, pressure and foreign moisture content appeared reasonable in providing data to diagnose the cooling performance deficiency. With the increase of foreign moisture content in the refrigerant in the air conditioning system, the performance of the cooling or the heat transfer became worse. Average surface temperature was measured on each point along the circulation line of refrigerant, but this alone was not enough to determine foreign moisture content. Temporal variations of the refrigerant in the evaporator outlet point showed patterns that could estimate the foreign moisture content. The tendencies of temperature changes inside the evaporator vent exit points varied and were observed at similar temperatures. Each average temperatures and pressures along the refrigerant circulation line was lower than normal. Low-side pressure and temperature of the pipe were found to vary periodically. Periodic fluctuations of moisture content were more than 0.05 kg and were used to quantify foreign inclusion. Criterion to determine the foreign moisture content in the circulation line was the difference between temperatures of evaporator inlet and outlet pipes when the temperature difference was below 14℃.
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