Comparative Study on Two-Stage Absorption Refrigeration Systems with Different Working Pairs

Abstract

Abstract:The objective of this paper is to present a simulation study on the two-stage absorption refrigeration systems of 2.5 kW capacity using LiBr-H₂O, NH₃-H₂O and R124-DMAC as working pairs. Under the design condition that the generating, absorbing, evaporating and condensing temperatures are 75 °C, 45 °C, 5 °C and 40 °C, respectively, the high and low pressure side solution circulation ratios and the coefficient of performance (COP) for the systems are calculated. Then the influences of medium, generating, absorbing, evaporating and condensing temperatures on system performances are analyzed. The results show that under the design condition, the COP of the LiBr-H₂O system can reach 0.49, superior to those of the NH₃-H₂O and R124-DMAC systems, which are 0.32 and 0.31, respectively. Furthermore, the medium temperature for higher COP lies in an interval of 64—67 °C for the LiBr-H₂O, NH₃-H₂O and R124-DMAC systems. High generating temperature and low absorbing temperature can decrease the high and low pressure side solution circulation ratios, and can also increase the COP. High evaporating temperature can decrease the low pressure side solution circulation ratio and increase the COP. Low condensing temperature can decrease the high pressure side solution circulation ratio and increase the COP.

Key words:absorption refrigeration| two-stage system| working pair| cycle characteristics

摘要：The objective of this paper is to present a simulation study on the two-stage absorption refrigeration systems of 2.5 kW capacity using LiBr-H₂O, NH3-H₂O and R124-DMAC as working pairs. Under the design condition that the generating, absorbing, evaporating and condensing temperatures are 75 °C, 45 °C, 5 °C and 40 °C, respectively, the high and low pressure side solution circulation ratios and the coefficient of performance (COP) for the systems are calculated. Then the influences of medium, generating, absorbing, evaporating and condensing temperatures on system performances are analyzed. The results show that under the design condition, the COP of the LiBr-H₂O system can reach 0.49, superior to those of the NH₃-H2O and R124-DMAC systems, which are 0.32 and 0.31, respectively. Furthermore, the medium temperature for higher COP lies in an interval of 64—67 °C for the LiBr-H₂O, NH₃-H₂O and R124-DMAC systems. High generating temperature and low absorbing temperature can decrease the high and low pressure side solution circulation ratios, and can also increase the COP. High evaporating temperature can decrease the low pressure side solution circulation ratio and increase the COP. Low condensing temperature can decrease the high pressure side solution circulation ratio and increase the COP.

关键词:absorption refrigeration| two-stage system| working pair| cycle characteristics

CLC Number:

TB 61

KONG Xiangqiang (孔祥强), MENG Xiangxi (孟祥熙), LI Jianbo (李见波), SHANG Yanping (尚燕平), CUI Fulin (崔福林) . Comparative Study on Two-Stage Absorption Refrigeration Systems with Different Working Pairs[J]. J Shanghai Jiaotong Univ Sci, 2021, 26(2): 155-162.

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