Study On Coupling Characteristics Of Small Solar-ground Source Heat Pump System In Severe Cold Region

The development and progress of human society mainly dependent on energy.With the rapid development of China's economy,the demand for energy is increasing day by day,which makes the trend of developing and using renewable energy urgent.At present,in terms of energy consumption,building energy consumption accounts for a large proportion of China's total energy consumption,and primary energy efficiency is low,so building energy conservation becomes particularly important.Solar energy is an inexhaustible source of clean energy.Combined with ground-source heat pump technology,it can be used to heat,cool and supply domestic hot water for buildings in cold regions.It not only makes up for the shortcomings of the two clean energy,but also realizes the efficient use of energy.This article takes a small office building in Harbin as the research object,and divides the annual operation mode of the system into quarters based on the principle of the solar-ground source heat pump coupling system.On the basis of the traditional operation plan(plan 1),an optimized plan is proposed,namely plan 2: Add solar auxiliary heating in winter and perform soil heat storage mode;In summer,when the unit intermittently stops cooling in the cooling condition,solar energy is added for soil heat storage mode.The domestic hot water is heated by the auxiliary heater throughout the year as a guarantee,so as to prevent the domestic hot water from being heated to the demand of hot water supply due to the thermal storage tank storing heat on the soil.Initially calculate the maximum cooling and heating load of the building by the area heat index method,select the system equipment and build the experimental platform.The transient simulation software TRNSYS is used as the platform,and appropriate modules are selected according to the design scheme to build a simulation model of the coupled system,and the reliability of the model is verified based on experiments.The dynamic characteristics of the system operation scheme are mainly analyzed from the following aspects:room temperature in winter and summer,collector performance,heat pump performance,hot water storage tank performance,heat storage of underground heat exchangers throughout the year,characteristics of soil temperature change in one and ten years of system operation,system energy consumption.Finally,the annual cost method is used to analyze the economy of the two schemes,and the lowest annual cost scheme is obtained,which is compared with the traditional coal-fired boiler system.The optimal operation scheme of the coupling system in severe cold regions is studied.The results show that after one year of operation of the system,in scheme 1,the heatingguarantee rate is 97% in winter and the cooling guarantee rate is 100% in summer,and the average soil temperature decreases by 0.21°C.The guarantee rate of heating and cooling in scheme two reached 100%,and the average soil temperature increases by 0.09°C.The energy consumption of scheme two in the whole year saves 1080.1kWh compared with scheme one.Scheme two is superior to scheme one in improving the energy supply performance of heat pump units.In the comparison of annual cost,the system controlled by option 2 is more economical than option 1 and traditional coal-fired boilers.Therefore,the second scheme proposed in this paper is the relatively optimal operation scheme for the application of the coupled system in severe cold regions,and it can provide theoretical basis and important reference for the practical application of the solar-ground source heat pump coupled system in severe cold regions.