Study On Thermal Environment Of Passive Solar House With Collecting Wall System In Severe Cold Area

Solar collector wall is a kind of building envelope structure of passive house.It can make full use of solar energy,improve indoor thermal comfort and effectively reduce building energy consumption.Although the relevant technology of solar collector wall has been basically mature,there are still some problems to be solved urgently,such as low indoor temperature in winter,large temperature difference between day and night,and uneven distribution of indoor warm air.Objectives of this study were(i)to uses CFD software to establish the physics model of a room with traditional solar wall and(ii)to solves the model in transient and steady state respectively.There are four aspects are discussed in depth,first one is the winter heat collection characteristics of the outer surface of the collector wall,the second is the ventilation outlet and the indoor temperature field,the third is the distribution characteristics of wind speed field,the fourth is the influence of wall size parameters and the wall surface structure on the thermal environment.Both the optimization of wall size and the added blinds reconstruction project can improve the collection efficiency.The simulation results show that(i)the geographic location and thermal inertia of the wall affect the opening and closing time of the air vents.The air vents should be opened about 2 hours after sunrise and closed 1-2 hours before sunset in Xinjiang,so as to prevent cold air from"backfilling"and affect indoor thermal comfort;(ii)in steady state,both the isoline of temperature and density are symmetrical distribution.The warm air upward flow and gathers near the center of the solar wall.The warm air is forced to flow around both sides after being blocked by the top of the wall.The density distribution near the outlet is in a vortex shape.It can be understand that the heat absorption and airflow movement of air in the air interlayer are greatly influenced by the structure of the external surface of the wall;(?)the temperature of the upper middle area of the wall is about 10 degrees higher than that of the outlet area,so it is suggested that the vent should be added here to improve the indoor thermal cycle efficiency,make the temperature distribution relatively uniform and improve the indoor thermal environment;(?)for the 2.8m high and 3m wide solar wall,the optimum size of the vent is 0.18m,0.16m-0.18m is suitable for the thickness of air gap.The renovated project of adding blinds improves the heat collecting effect of the solar wall.It can reduces the fluctuation of indoor temperature day and night and plays the role of heat preservation and insulation.Based on the simulation results,the heat collection efficiency of the new type of collector wall was confirmed.The experimental room with traditional collector wall system built in Shihezi University Test Site has been partially renovated.A new type collector wall system has been formed by hanging louvers on the outside surface of the collector wall.By means of comparative tests,the winter collection of the new type collector wall system has been tested on site.The file experiment of the novel system thermal performance verifies the rationality of the simulation study.Field tests show that the maximum temperature difference between the new louvered collector wall system room and the room with the traditional solar wall is 4.4 and 2.2?,respectively,when the solar radiation intensity is 480 W/M~2 and 420 W/M~2.Within 72 hours,the average temperature difference between the new louvered wall system room and the control group room is 3.1?.The maximum daily temperature difference of the new louvered wall system room is lower than that of the traditional solar wall room is about2.4?.Under the same weather conditions,at the daytime,the average indoor temperature of the new louvered wall system room is higher than that of the control room about 13.2?.At night,the average indoor temperature of the new louvered wall system room is higher than that of the control room about 13.2?.The average indoor temperature is higher than that of the control room about 9.1?.The study results of thermal environment of passive solar collector wall system,in severe cold area,can provides a reference for the optimization and transformation of new or existing passive house in this area.