| High temperature heat pump technology can be used in the industry in the presence of a large number of 30?60? waste heat resources,produce high temperature water or steam can be applied to industrial production again,greatly expanding the application range of heat pump technology,effectively avoid this part of the waste heat caused by direct emissions of environmental pollution,but also plays an important role on the energy conservation.In this paper,the research on high-temperature heat pump technology is carried out from two aspects of circulating working medium and heat pump system.When it comes to the research on working fluid,the requirements of high-temperature heat pumps for their circulating working fluids have been put forward,that is,the working fluid of high-temperature heat pump must not only be equipped with good physical and chemical characteristics and environmental protection,but also be able to maintain low condensation pressure and exhaust gas temperature at high temperature etc.Besides,the author,through the field analysis of the heat pump,set up a theoretical calculation model of the heat pump cycle,and also wrote the calculation program in MATLAB programming language,during which the physical parameters of the working fluid were obtained by REFPROP.After the theoretical calculations of six pure working fluids,such as R152 a,R245fa,R134 a,and R1234 ze,which were initially screened in the previous period and the analysis of the calculation results of the cycle performance parameters,it was found that the condensing pressure and exhaust gas temperature of R245 fa were lower while its COP was higher,indicating that R245 fa has an advantage of operating performance at the high temperature.In the perspective of system research,in order to explore the effect of Intermediate air supply technology used in high temperature heat pump on system performance,from the theoretical simulation and experimental testing of two aspects.A mathematicalmodel of compressor,condenser,evaporator,economizer and other components is established,and a theoretical calculation program is written by MATLAB.Theoretical calculations with different values of the primary volume ratio to simulate the effect of the compressor air supply port position on system performance,and selected Intermediate air supply technology calculates a volume ratio of 1.3.Comparing the cycle performance parameters of the Intermediate air supply technology and the single-stage system,it is found that the air supply system has higher heating capacity and COP,and the exhaust gas temperature is reduced.On the basis of the physical properties of R245 fa and the operating conditions of the unit,the unit was modified,including the design and selection of the condenser evaporator.What is more,the circulation flow of the working fluid and the superheat at the evaporator outlet were controlled by the Danfoss electronic expansion valve.After that,the expansion valve control system was characterized by more adjustment steps,faster response and more accuracy.In order to make the outlet of the heat pump unit higher in temperature,a pressurized water system is set on the condensing side of the test one,making it possible that the system provides a maximum pressure of 0.5Mpa,and the outlet of the condenser is liquid at the maximum temperature of 150 ? though.The use of high-temperature heat pump unit after the transformation,in the low temperature heat source temperature 50?,condenser water temperature 70?100?conditions were experimental tests on the air supply system and single-stage system,found that high-temperature heat pump unit to increase the intermediate air supply process can effectively improve the heating capacity and COP,effectively reducing the compressor discharge temperature,using air supply system water temperature experiments,the condenser water temperature up to 110?,this time there are still 2.41 COP,and the exhaust gas temperature is only 114.1?,showing a good prospect of application. |
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