Performance Analysis Of Organic Rankine Cycle Coupled With Vapor Compression Refrigeration Cycle System Driven By Low-grade Waste Heat

In order to solve the effective use of the low-grade waste heat problem in chemical industry,the organic Rankine cycle?ORC?coupled with the vapor compression refrigeration cycle?VCR?gain more attention in the field of the low-grade waste heat use because of the capacity for changing thermal energy into cold energy.Based on the aim of working fluids selection and the system configuration optimization,the organic Rankine cycle coupled with vapor compression refrigeration cycle system?ORC-VCR?driven by low grade waste heat model was constructed.The performance analysis of ten pure fluids?R245fa,R227ea,R600,R600a,R1234ze,R1234yf,R134a,R601,R601a,R236ea?and four zeotropic mixtures?R245fa/R600,R227ea/R600a,R236ea/R601,R236ea/R601a?were conducted under the system operating condition.At the same time,the effects of boiling temperature,condensing temperature and evaporating temperature to system performance parameters were analyzed,and the effects of the addition of heat regenerator in ORC to system performance parameters were also conducted.The results showed:in ten pure fluids,the HC working fluids performed excellent than HFC working fluids under the certain operating condition.R601 was the prominent working fluids in four HC fluids,and it had the highest system overall efficiency(COP_total),refrigerating capacity per unit mass flow rate of working fluid?CPRm?and compression ratio?CMR?.R245fa isthe best working fluids among the HFC fluids,and its COP_total was only3.367%lower than R601.Four zeotropic mixtures performed better than pure fluids under the fixed condensing dew point and evaporating bubble point.The composition of zeotropic mixtures had a great influence on the temperature glide and the system performance parameters.And the mixtures'temperature glide and the system performance parameters could reach to the maximum under a specific composition.R236ea/R601?0.5/0.5?had the highest system overall efficiency(COP_total=0.9596)and the highest expansion ratio?EPR=4.287?,and its COP_total was 89.87%higher than pure fluid R601 under the same condition.Under the fixed temperature,the COP_total,EPR,CPRm and R of ten pure fluids and four zeotropic mixtures?R245fa/R600?0.9/0.1?,R227ea/R600a?0.4/0.6?,R236ea/R601?0.5/0.5?,R236ea/R601a?0.4/0.6??increased with the increase of the boiling temperature and the evaporating temperature,but decreased with the increase of the condensing temperature.However,the CMR decreased with the increase of the evaporating temperature and increased with the increase of the condensing temperature.When added heat regenerator to the ORC and set the regenerator's pinch point as 5?,the system overall efficiency of seven pure fluids and four zeotropic mixtures were higher than the ORC-VCR system without regenerator.The system COP_total's increase of the zeotropic mixtures in the system with regenerator was higher than pure fluids.When taking zeotropic mixtures as the working fluids in ORC-VCR system,adding regenerator can improve the system performance.