Experimental Investigations of a Screw Liquid Chiller

• Main Authors: WU WU CHIEH, 吳武杰
• Other Authors: 李宗興
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/99542118549703993653

碩士 === 國立臺北科技大學 === 電機工程系碩士班 === 90 === This thesis presents the results of performance test of a water chiller at various operating conditions. The study was proceeded in a R-22 semi-hermetic twin-screw direct-expansion water-cooled water chiller. The performances were addressed on the compressor power consumption, cooling capacity, and energy efficiency ratio (EER). Refrigerant superheat at compressor suction line, the inlet water temperature of evaporator, and the inlet water temperature of condenser were the three major factors used to measure the performance. The results showed that the superheat and inlet water temperature of evaporator were the key factors to the cooling capacity, while the inlet water temperature of condenser dominated the compressor power consumption. As to EER, it was found that all the three factors mentioned above would simultaneously affect it. The test data showed that decreasing superheat by 1 K would contribute to EER by 2%. The maximum EER was found at a state of no superheat, however, the refrigerant at wet conditions was found detrimental to EER. In additions, it was also found that increasing 1K of the inlet water temperature for evaporator and condenser would change EER by +3.2% and —3.8%, respectively. According to the test data, a correlation was performed as follow: 1/COP = 0.0482(1/Qe)+0.0275 From the study, suggestions for promoting the efficiency of water chiller were also made. Key word: screw type water chiller, energy efficiency ratio, direct-expansion evaporator