Thermal Pprformance Study On Venetian-type Solar Collector Wall System

With the quickly development of economy in our country, the energy demand is also growing. As the biggest developed country in the word, although the total energy is now among the world’s highest, the per capita is still far behind the average level, therefore reduce the energy consumption in our country, especially building energy consumption, which is the largest proportion in the national energy conservation, and break away from the dependence on conventional fossil energy, and spend lots of efforts into the development of new energy and renewable energy are emphases in the future development road in our country.As a kind of renewable energy, solar energy has the advantage of safe, clean and inexhaustible. The development and utilization of solar energy, which has great significance to saving conventional energy, protecting the natural environment, climate change mitigation, etc. Combining solar energy utilization technology application with building, is the important way to reduce building energy consumption。 The two major applications of solar energy in building in current society are solar hot water and solar heating.Now widely applied applications in solar heating are Trombe wall, improved composite Trombe wall, and PV-Trombe wall which is attached with dark blue polycrystalline silicon photocell on the back side of the glass cover of tradition Trombe wall. There are both active heating and passive heating in the systems mentioned above, they mainly aim at the function of heating in winter, without considering overheating problem in the summer. In order to solve this problem, a novel version solar collector wall with venetian blind structure is presented in this paper, which is a combination wall consists of Trombe wall and a venetian blind that can be overturned in an air gap between glazing and wall. One side of the blind slat of venetian blind is covered with high absorptivity coating and the other side is covered with high reflectivity coating, corresponding to winter and summer conditions. What’s more, we build experiment platform and test the thermal performance of venetian-type solar collector wall and the effects of the indoor thermal environment in fully dynamic outdoor environment, we also test its behavior in different blind slat angle. Through analysis and comparison we found out that, without heat source, the highest indoor temperature of the room equipped with a venetian-type solar collector wall can reach more than25℃in winter case, which can afford the requirement of the winter heating. The best heating effect of the venetian-type solar collector wall is when the blind slat angle is set at45℃, the temperature of the room equipped with venetian-type solar collector wall is12.6℃higher than the that of the normal room and26.1℃at the highest, which shows that the venetian type solar collector wall can improve the indoor temperature significantly, lowering the winter indoor heating energy consumption and reduce indoor heat load further.In summer case, we kept the indoor lower air vent and outside upper air vent open, and indoor upper air vent closed, and the temperature of experimental platform was kept at22℃,24℃and26℃, in order to carry out contrast experiment. The venetian-type solar collector wall and the room were treated as a closed system, the average temperature of indoor south wall surface of test room is1.71℃lower than that of comparative room, and the biggest difference is2.02℃. The difference in heat gain between the test room south wall and south wall of comparative room is3.29×103kJ on average, and the biggest difference is3.62x103kJ, which is the reduced cool load. As a result, the venetia-type solar collector wall can reduce the heat gain from south wall, as a result the cool load is reduced and indoor ventilated effect is improved in summer.As the appearance of traditional Trombe wall is poor and the Hui-style building is hot in summer and cold in winter, and the Hui-style building has characteristic of big area of south and small window, we proposed a new structure that compose the venetian-type solar collector wall with Hui-style sunshade eaves, where the outside air vent is hided under the Hui-style sunshade eaves. The combination not only better the appearance of traditional solar collector wall, but also improve indoor temperature and comfort of Hui-style building in winter and ventilation in summer.