Theoretical And Experimental Cycle Performance Of Natural Working Fluids For Moderate/High Temperature Heat Pump

The moderate/high temperature heat pump technology based on industrial waste heat has wide prospects in enlarging heat pump applications to achieve the higher delivery temperature and utilize waste heat. But the domestic research and development on moderate/high temperature heat pump technology is at the initial stage. Because the moderate/high temperature heat pump system does not exist recognized components and representative refrigerants, one important aspect of the researches on the moderate/high temperature heat pump technology is to screen and propose alternative working fluids with excellent environmental and thermodynamic charactrtistics.Most synthetic refrigerants will spread into the atmosphere,which exist potentially dangerous to the earth's ecological environment,natural working fluid is called the final plan to solve environmental problems.In this thesis, based on R134a system with the principle of matching degree between working fluid and the system, Theoretical performances of natural working fluids with excellent environmental and thermodynamic characteristics in the condensing temperature range of 60 to 105℃,and four circulating temperature rising were carried out with improved theoretical analysis methodology. And two natural working fluids isobutane and butane were proposed.The experimental performances of two natural working fluids isobutane and butane proposed by theoretical performances analysis were carried out with near-fair assessment experimental methodology in the condensing temperature range of 60 to 95℃.It is showed that butane and isobutene present better experimental performances than R245fa. Relative to isobutane, butane have low discharge temperature,small compressor power consumption and high COP, present better experimental performances than isobutane,especially in the high temperature above 80℃condition,butane's performance advantage was more serious than others. With the flammability of isobutene and butane,but if as a component of mixtures,as long as the ratio of the natural working fluid control in a reasonable limit,it is enough to meet safety requirements. The experimental performances of M2 and R245fa were carried out. It is showed that M2 with high COP and cooling capacity present better experimental performances than R245fa. Heat exchanger is a key component of heat pump system,and selecting the appropriate heat exchanger is the main content of the moderate/high temperature heat pumps design. With the rapid development of plate heat exchanger in recent years, optimum selection problem of plate heat exchanger were paid more and more attention.In this paper,selection and analysis of plate heat exchangers was discussed,using steady-state distributed parameter model and numerical simulation of phase separation,combined with energy conservation equation and momentum conservation equations.Theoretical investigations on R22 , butane and isobutene were carried out to check the reliability of program.