High Temperature Heat Pump Technology And System Performance Study

There are many kinds of low temperature heat source in our country, which maycause the heat pollution and the energy waste. If they can be recycled by heatexchange, high temperature heat pump or electricity generation, then the energy useefficiency will be improved obviously. Being an energy-saving equipment with greatdevelopment potential, high temperature heat pump is becoming one of the researchhotspots in recent years.In this paper, new refrigerant mixture BY-3is conducted. Theoretical andexperimental analysis is processed to find out the optimal operation temperature rangeand to analysis the operation performance. Combined with engineering operation, thestability and security of long term operation is tested. At last, the economicperformance, environmental performance and comprehensive performance is analysisfor the central heating system.(1) A new refrigerant mixture BY-3was conducted based on the theoreticalcalculation, which is suitable for the situation of temperature difference between thelow temperature and high temperature heat source is about60℃and the condensingtemperature is between60-85℃. The temperature glide model of the mixturerefrigerants is built to offer the parameter for the unit design. The impact to theperformance of leakage is also analyzed using the phase equilibrium model and massequilibrium model, and the result shows that the leakage of BY-3impacts the specificmass performance little. A kind of mixture refrigerant supplement method is alsoproposed to solve the mixture refrigerant leakage problem.(2) The BY-3performance is tested by the experiment and engineeringoperation. The comparing result shows that the BY-3is not suitable for theair-conditioning condition and equivalent to R22unit in moderate heat pumpcondition. However, the BY-3system has better performance in the high temperatureheat pump condition. It can produce85℃hot water when the low temperature is20℃with high efficiency. Under this condition, the discharge temperature is lowerthan105℃, and the refrigerant vapor pressure keeps lower than1.98Mpa. Theoperation results match the experimental results well, which shows the BY-3performance is suitable for the stability and security of the long term operation. (3) The cost, environmental performance and comprehensive performance is putforward to compare the different heating systems. The cost analysis shows that, whenthe COP=3, the heat pump system cost almost the same money with gas boiler systembut higher than coal boiler heat system; when the COP>3, heat pump system savescost compared to boiler heat systems. For example, it saves10%and14%costcompared to the gas boiler heating system and coal boiler heating system respectivelywhen COP=4. The environmental performance analysis use the life cycle analysismethod, and the results show that when the COP>2.5, the heat pump system hasadvantage to the boiler heating systems. The comprehensive analysis is based on theeco-efficiency method, and the result shows that, if COP>3, the heat pump heatingsystem would have best comprehensive performance, i.e. it has lower cost and lessenvironmental impact than the other systems. This method can avoid the impact of theheating source, building area and so on.