Study On Thermal Insulation Performance Of A Trombe Wall In Hot Summer And Cold Winter Zone

China is the world’s largest energy consumer,where building energy consumption accounts for a large proportion.With the further development of economy,China’s building energy consumption will continue to grow.Under the situation of increasingly tense of global energy,promoting solar thermal energy utilization technology and building integration is an important way to solve the continuous increase in China’s building energy consumption and achieve sustainable economic development.In hot summer and cold winter zone of China,the building envelopes not only need to meet the requirements of winter and summer insulation,but also need to enhance heat dissipation during transitional seasons.Applying the technology of soalr thermal integrated with buildings,it will affect the heat transfer of envelopes greatly.Thus,it is significant to consider the efficiency of photo-thermal utilization and envelopes’ insulation performance,as well as the mutual influence between these two.This paper presents a new designed Trombe wall which was able to meet the requirements of thermal insulation in hot summer and cold winter area.In the wall system,a solar collector plate,thermal radiation reflection layer and indoor radiation panel were designed.To study thermal insulation performance of the wall system in summer,both southward and westward directions were investigated numerically and experimentally in Xiangtan weather conditions.According to the results,affected by the solar radiation,collector temperature had a larger value under no load condition and made a more obvious impact on the heat transfer of the wall.The simulations and experiments results under no load condition in winter showed that the maximum temperature of the collector reached 89.3 ℃ and 92.2 ℃,respectively.As collector temperature was higher than indoor and outdoor ambient temperatures,it was beneficial to the thermal insulation performance in winter.Besides,vertical temperature differences were generated on the surface of each layer of the wall,and the temperature differences increased with the increase in solar radiation and decreased with the increase in air interlayer thickness.In summer,simulations and experiments results of collector temperatures reach maximum values of 93.7 ℃ and 84.8 ℃,respectively.Meanwhile,the corresponding values of inner surface of massive wall were 29.6 ℃ and 28.4 ℃,respectively.Those indicated that the wall had an excellent insulation performance in summer.Besides,varying the reflectivity of massive wall outer surface was beneficial to improving the thermal insulation performance.The higher the collector temperature,the higher the effect of reflectivity variation of outer surface on thermal insulation performance.Evaluating the parameters of the wall showed that thickening of the massive wall was beneficial to reducing heat transfer through the wall and the economic thickness of it is related to collector temperature.As for the massive wall studied herein,the increment of massive wall thickness will have an inconspicuous influence over the thermal insulation performance when the following two situations are confronted:i.e.40 ℃ collector with a corresponding wall thickness more than 100mm,65 ℃ collector with a corresponding wall thickness more than 140mm,and 90℃ collector with a wall thickness more than 180mm.The test results also indicated that heat transfer capacity and thermal insulation performance of the wall could be controlled by varying the collector temperature under different operating conditions.