Application Research Of Active-Passive Combined Solar Heating System For Small Residential Buildings In Xinjiang Region

By the end of 2016,12.39 million people still lived in rural areas in Xinjiang,and the living houses were mainly small residential building with three or less floors and an area of not more than 300 m~2.These buildings usually do not have central heating system,and they use household coal-fired boilers to keep indoor temperature.This heating method not only has low coal-burning efficiency,but also has poor indoor thermal comfort and serious pollution to the living environment.Xinjiang has abundant solar energy resources.The research on the utilization of solar energy in buildings is mostly concentrated on passive solar houses,and on active solar energy provides domestic hot water.This paper studies the active-passive combined solar heating system,which can efficiently use solar energy,especially suitable for small residential buildings,to alleviate the dependence on coal combustion during heating period,and provide a practical reference for Xinjiang to use solar energy resources.Based on the above analysis,this paper mainly carried out the following work:(1)Choose an ordinary small residential building as the research object of this subject,and by DEST-H modeling to calculate the basic data of the winter heating load;(2)The small residential building was designed and transformed into a passive solar house;not only a external insulation system was added,but also a passive solar collector wall system was added.According to the heat transfer analysis inside the air layer of the heat collecting wall,and the mathematical model of the heat obtained by circulating inside the air layer,the passive solar collector wall design is carried out by orthogonal test;(3)On the basis of the passive solar house,a vacuum tube type solar collector and an air source heat pump heating system was added to complete the active-passive combined solar heating system.The low temperature radiant floor heating system was selected as heat radiator,and the operation of the heating system was controlled by indoor temperature;(4)The test was carried out on the completed experimental platform;(5)Energy-saving effect analysis of active-passive combined solar heating system.Through the research work of this project,the conclusions are as follows:(1)The annual average thermal load of the small residential building before renovation is15008.88KW·h,and the thermal load index during heating period is 37.65W/m~2;(2)The maximum operating condition of the wall collector system:the diameter of the vent hole is150mm,the thickness of the air interlayer is 100mm,and the distance between the upper and lower vent holes is 2.4m;(3)The optimal installation angle of the solar collector in the heating period of the Shihezi area is 47.6°,and the average daily radiation value of the heating period is 2755.7 Wh/m~2.Considering the economic factors of the system and the value of the solar guarantee rate,the value of the solar collector area of the system is 24m~2 through TRNSYS software.Through the modeling and analysis of PHOENICS simulation software,the low temperature radiant floor heating form was choose as radiator of the active-passive combined solar heating system.The heating system is controlled by the indoor temperature;(4)The test results show that the active-passive combined solar house can meet the heating requirements only by the collector wall system and the active solar collector system under the clear weather conditions at the initial stage and final stage of the heating period,without need auxiliary heating.In the medium term of heating period,the indoor temperature control mode causes the working time of the air source heat pump to be not fixed,and the heating power consumption is large.In this paper,the time control mode is proposed,and the time control mode is designed according to the heat load.When adopt the time control mode compared with the traditional coal-fired boiler heating form,the active-passive combined solar heating system can save 5.37 kWh of electricity and the energy saving rate is 6.72%;(5)Compared with the traditional coal-fired boiler heating system,the active-passive solar heating system saves an average of 5.37 kWh of electricity per day,which is equivalent to reducing CO2emissions by 5.35 kg per day,and reducing CO2 emissions by 481.5 kg during the entire heating period.The active-passive combined solar heating system not only has economic advantages,but also has significant energy saving and emission reduction effects,and can be widely used in small residential buildings in Xinjiang and northern regions.