Research On Optimal Design Of Solar Assisted Low Temperature Air-source Heat Pump Heating System In A Railway Station Building

In the extreme cold and remote areas of China,the central heating is often lacking in winter.The traditional heat source of public buildings are always being coal-fired boilers or gas fired boilers in such areas,such as the railway station building,which cause high energy consumption and serious pollution.Based on the abundant solar energy resources in this area,a solar energy assisted low temperature Air-source heat pump heating system is proposed in this paper.And the feasibility and optimal design of the combined heating system are studied in order to replace the existing traditional heating heating systems,reduce heating energy consumption and improve the energy efficiency ratio.In this paper,a railway station building along the extreme cold and remote railway is selected as the research object.The heating load calculation model of the station is established by DeST.According to the load characteristics and energy demand of the building,the parallel and series combined heating system are studied respectively.Based on the system operation principle,the heat transfer models of flat panel collector,low temperature Air-source heat pump and plate heat exchanger are established.The simulation platform of parallel and series combined heating system are built based on TRNSYS,and the operation characteristics are analyzed.The operation hours of heat pump and the energy efficiency ratio are taken as optimization targets to optimize the design of the parallel and series combined system.Optimization parameters include the slope of collectors,collector area,collector flow,flow ratio of heat pump and heat exchanger and number of circulating pump.A comparison is made between the combined systems,low temperature air source heat pump and the gas fired boiler heating system,the evaluation and analysis of the combined heating system are carried out from thee aspects of heating performance,system energy consumption and energy efficiency ratio.The results show that the parallel combined heating system is the best choice.The combined heating system can fully meet the heating needs of the station,and the optimal design of the system parameters can obviously improve the system performance.The total energy efficiency ratio of the parallel combined system in the heating season is 2.303,and the solar energy guarantee rate is 22.1%.Compared with series system,heat pump system and boiler system,the energy consumption of the parallel system is reduced by 4.9%,21.4% and 16.8% respectively.Energy efficiency increased by 4.6% and 23.2%,respectively.The effect of energy saving is obvious and operating performance is good,which provides a reference for the practical application of the combined heating system in this area.