Study On Temperature Distribution Characteristics Of Photo-thermal Integrated Trombe Wall

China is currently the world’s largest energy consumer,and with the progress of country’s productivity and economic development,the rate of energy consumption will continue to increase.At the same time,with the acceleration of China’s urbanization process,building energy consumption is rising rapidly,therefore,the work of building energy conservation is urgent.In the world’s increasingly tight energy environment,the development of integrated solar and thermal building technology is an effective method to reduce the demand for energy consumption and achieve sustainable economic development.The climate characteristics of hot summer and cold winter areas require the wall to have better heat preservation performance in winter,better heat-insulating capacity in summer and transitional seasons,so as to discharge indoor waste heat to the outdoors at certain times.Trombe wall is well suited to the needs of the area,while most of the existing technologies adopt the method of opening vents on the Trombe wall,and realize the temperature regulation of the Trombe wall with natural ventilation,which has some problems such as poor architectural aesthetics,inconvenient operation and poor temperature regulation effect.For the sake of improving the thermal insulation performance of the building envelope and make full use of solar energy,a combination of Trombe wall and a photo-thermal collector was proposed in this study.The thermal characteristics of the wall could be adjusted by changing the water flow of the heat collecting plate,which could effectively solve the above problems.In the hot climate of Xiangtan(China),the influence of variation in solar irradiance and water flow of the collector on the temperature of each material layer and vertical temperature gradient of Trombe wall were studied.Meanwhile,the unit heat transfer model of the wall system was established and verified using the experimental data.Furthermore,the distribution characteristics of vertical temperature gradient of the wall and the adjustment method were simulated using the heat transfer model.In addition,the temperature distribution and heat transfer characteristics of the wall system under different working conditions were simulated.The results showed that:1)under the action of solar irradiance,a large vertical temperature gradient occurred in the Trombe wall.For the simulated no-load condition,the vertical temperature gradient of the outer surface of the massive wall can reach 33.6℃/m,whereas that in the inner surface is 7.6℃/m.Furthermore,the amount of heat transferred per unit area passing through the upper part of the massive wall is 3.2 times that of the lower part.Trombe walls with independent air circulation between the floors are set in each layer of multistoried buildings,which will facilitate the uniform use of solar energy in each layer.If the air interlayer in Trombe wall is connected,it will be beneficial for the upper layer to get more solar energy.2)The vertical temperature gradient of the massive wall and the amount of heat transfer through it could be changed by adjusting the water flow and water capacity of the collector.And with the increase of the water flow and water capacity of the heat collecting plate,vertical temperature difference between the inside and outside of the main wall layer would be smaller,and so as the temperature difference between the inside and outside of the main wall layer.Thence,the temperature distribution of the wall was more uniform,and the indoor thermal comfort was higher.When the water flow was less than 100 L/(h.m~2),adjusting the water flow had a significant effect on heat transfer temperature difference between the inner and outer surfaces of the wall.3)The material and thickness of the main wall layer had great influence on heat transfer temperature difference between inside and outside of the wall.When the thermal conductivity of massive wall was small,increasing the thickness of massive wall could effectively reduce the heat transfer through the massive wall.However,when the thermal conductivity was great,the influence of changing the thickness of massive wall on the heat transfer was not obvious.Meanwhile,it was necessary to consider the economic and practical premise to determine the best main wall layer thickness according to the use requirements of the wall.