Study On Performance Of Compression-assisted Triple-effect LiBr/H₂O Absorption Refrigeration Cycle

With the worsening of energy and environmental issues,LiBr/H2O absorption refrigeration has received more and more attention due to its advantages of energy conservation and environmental protection.The single-effect and double-effect cycles have poor performance and are more suitable for recovering low-temperature waste heat.In order to improve the utilization efficiency of high-grade heat sources,triple-effect cycle needs to be developed.At present,the main reason for restricting the development of the triple-effect cycle is the corrosion problem which result from over high temperature in the high temperature generator.In order to reduce corrosion,compression-assisted triple-effect cycles was studied in this paper.Firstly,the equations for the thermal physical properties of lithium bromide aqueous solution and saturated water and water vapor are given,and the program for calculation of thermal properties is formulated.the work flow of triple-effect cycle and four types of compression-assisted triple-effect cycle is introduced.Based on energy and mass conservation equation,a thermodynamic calculation model of the compression-assisted triple-effect cycle is established.Then the effects of the compression ratio,the temperature of the high temperature generator,the inlet temperature of the cooling water,and the temperature of the outlet of the coolant water on the performance of the four compression-assisted triple-effect cycles were investigated.The results show that when the other parameters are constant,there is an optimal compression ratio for the four compression-assisted triple-effect cycles with the maximum COPW;compression-assisted triple-effect cycles can operate normally when the temperature of the high-temperature generator is lower than 180 ?.The operation will effectively reduce the corrosion problem and high performance is maintained;in addition,compression-assisted triple-effect cycles can still operate normally when the cooling water temperature is high and the cooltant water temperature is low.Broaden the operating range of the triple-effect cycle.The COPW of the four compression-assisted triple-effect cycles decreases with the decrease of the temperature of the high-temperature generator,decreases with the increase of the cooling water inlet temperature,and decreases with the decrease of the coolant water temperature.Cycle 4 has a smaller cycle ratio and compression ratio,a lower compressor discharge temperature,and a higher COPW,but the compressor delivers a larger volume flow.Finally,based on the second law of thermodynamics,the compression-assisted triple-effect cycle was analyzed.The effects of the compression ratio,the temperature of the high temperature generator,the inlet temperature of the cooling water,and the outlet temperature of the cooltant water on the compression-assisted triple-effect cycle ECOP were studied,and the loss of the components in the cycle was calculated.The results show that there is a compression ratio among the four supercharged three-effect cycles when the other parameters are unchanged,making ECOP the largest.When the temperature of the high-temperature generator is low,the temperature of the cooling water is high,and the temperature of the refrigerant water is low,the compression-assisted thriple-effect cycle can improve the ECOP of the triple-effect cycle;the ECOP of the Cycle 1,Cycle 2 and Cycle 3 rises first and then decreases with the the decrease of temperature high-temperature generator.Cycle 4 maintains a rising trend.The ECOP of four compression-assisted triple-effect cycle decrease with the increase of cooling water inlet temperature,and rise with the decrease of cooltant water outlet temperature.The largest loss of each component is the absorber,followed by the condenser and evaporator.