Analysis Of Solar And Soil Source Heat Pump Heat Storage Characteristics

This paper mainly studies thermal equilibrium problems of solar energy seasonal heat storage in solar-soil source heat pump system.First,use FLUENT software of finite element method to establish the three-dimensional unsteady heat transfer model of buried pipe heat exchanger in FLUENT software after the user-defined function(UDF)write the solar collector system,soil heat storage system,heat pump units terminal devices,such as equipment,floor radiation model,through dynamic them together,realizes the seasonal soil heat storage dynamic process simulation,this paper research content mainly includes the following several aspects:First,analysis and research system run continuously for two years in different soil initial temperature,different soil thermal physical properties and u-shaped tube pipe buried tube heat exchanger under the condition of heat transfer characteristics and COP are affected by the system.The simulation results show that the lower the soil initial temperature can get better performance of heat transfer,the heat accumulation the better,so if you want to the initial temperature of the soil is in cycle is constant,the soil temperature increase to the appropriate level should be appropriate to reduce heat storage,the balance of soil temperature;Heat exchanger heat transfer capacity will be increased with the increase of soil thermal conductivity,so solar energy-soil source heat pump system is more suitable for the soil with large thermal conductivity;Comprehensive engineering cost and heat transfer characteristics,priority should be given high coefficient of heat transfer,high strength,corrosion resistance is strong,long use cycle pipe,high density polyethylene pipe(HDPE)is the best choice of pipe exchanger.Second,the analysis and research system after two years of continuous running heat exchanger under different operation condition of soil temperature field around change and recovery,and the simulation results show that the only with heat storage of solar energy in transition seasons,soil temperature ground-source heat pump system is on the rise,and no other operation condition the soil temperature of the heat storage is more and more low,in shenyang area is not suitable for use with no heat storage system,with the increase of running years short of the heating effect,satisfies the requirement of the thermal comfort of human body.Third,analysis and research system under the condition of running all the year round storage and heat transfer characteristics of the soil changes year by year,and both influence each other are analyzed.Analysis results show that when the system run continuously at the end of eight years,under the condition of the same control,soil temperature trend gradually slow,heat storage and thermal efficiency decline storage has been slowing,and gradually become stable;At the end of the system is running,the heat pump COP increase amplitude is not very big,which may be considered from 3 years began to change in heat storage can effect comparing flatten out appropriately reduce the regenerative operation time and heat storage,so that the soil heat balance,maintain appropriate soil temperature.