Theoretical And Experimental Investigation On The Working Fluids For Moderate And High Temperature Heat Pumps

One important aspect of the researches on the moderate and high temperature heat pump technology is to find out new alternative working fluids with zero Ozone Depletion Potential and low Global Warming Potential. In this paper, theoretical experimental and simulated methods of evaluating the cycle performances of working fluids were investigated, and some new working fluids with good theoretical cycle performances were proposed, further more the researches of their experimental and simulated cycle performances were carried out at condensing temperature from 80 to 110 oC.In the existed theoretical calculation method of heat pump cycle performances, the compression process had been simply assumed as adiabatic, to make the calculations results more reliable and closer to practical performances, the compression process was developed as a recombining process including isobaric suction heat process, adiabatic compression process and isobaric discharge heat process. The calculations results showed, with the improved theoretical cycle calculation approach, the cycle performances of working fluid were closer to practical ones.The theoretical performances of many fluids had been comparatively assessed, and according to the calculation results, pure fluid R245fa and mixtures M1-M4 were proposed as new working fluids for the moderate and high temperature heat pumps. The calculation results showed that M3 offered the best thermodynamic properties, M1 and M2 also delivered better performances than R114, M4 and R245fa offered higher qv (volumetric heat capacity) and COP (coefficient of performance) values respectively than R114.The unfair factors existed in the current experimental approaches of assessing the cycle performances of various working fluids with the same apparatus were identified. A modified approach was introduced which could effectively eliminate or at least impair the influence of the unfair factors. The same evaporating and condensing temperature of working fluids and mass flux of heat transfer fluid (HTF) should be guaranteed respectively for the improved method during the cycle performances tests. Also the concept and the formula of additional temperature difference were...