The Study On The Small Cross Seasonal Thermal Storage Heating System

Nearly 70% of our country needs heat supply.Most of them rely on coal.It provides a comfortable living for human beings.Meanwhile,it increases the consumption of fossil fuels and pollution.Therefore,the search for renewable energy has become a trend.As a renewable energy,the solar energy meets the requirements of reduction of energy consumption and environmental protection.Through the research of climate and solar energy distribution in Tianjin,we proposed a new rural residential from perspective of building energy efficiency.We designed the construction of 200m2.We used the DeST to simulate building load.Form simulation,we got maximum heat load of 7.58 KW and annual heat load of 10691.17 KW.Consideration of this building,the medium of the seasonal storage of solar energy consists of phase change materials,soil and water.We proposed three different heat storage ways of solar energy storage heating system.Based on the characteristics of seasonal heat storage,these systems were detailed designed in heat collection system,heat storage system and heat supply system.Meanwhile,we described the operation principle and control mode.Three systems based on the TRNSYS simulation software were run throughout the year and long-term.Analyze the operating characteristics of the system under different forms and found that phase change thermal storage system performs better than the other two systems in heating season.Annual heating system with phase change storage system is 2.72;soil thermal storage heating system is 2.32.The COP of thermal storage tank heating system is 2.10.From a long-term simulation results,without considering the phase change material solid-liquid separation and super cooling phenomenon,the characteristics of phase change thermal storage system will not change,but in reality,the phase change temperature of the phase change material will be reduced year by year which will resulting in the system COP decreases.For trans-seasonal soil solar thermal storage system to select the appropriate collector area can maximize the use of the soil self-recovery capabilities,and the average soil temperature does not change much in the long run.For tank thermal storage system,selecting the appropriate collector area and the tank volume,the average temperature of the tank will be maintained at an initial temperature around at the end of the heating season each year.We analyzed economic benefit in these systems with annual cost method.The annual cost of the soil heat storage system is RMB 4167.14.The annual cost of the phase change heat storage system is RMB17480.97.The annual cost of the tank storage system is RMB 30340.02.The cost of the soil heat storage system is the lowest.The cost of the phase change heat storage system is about 4.2 times of the soil heatstorage system.The cost of the tank storage system is about 7.2 times of the soil heat storage system.It can be seen that the soil heat storage system will be most possibly carried out in villages.Consideration of the future about rural heat supply,we think the phase change heat storage system is the most potential for village.