Analysis Of The Influences Of Indoor Heat Source Surface Temperature On Performances In Thermal Natural Ventilation Rooms

Building energy efficiency and indoor air quality improvement are two main themes in the way of sustainable development of architecture. Natural ventilation, driven by wind pressure and thermal pressure, is an important technology to achieve sustainable architecture. Natural ventilation driven by thermal pressure is the only factor considered in the current design specifications because the instability of the outdoor air pressure. Therefore, research on the natural ventilation driven by thermal pressure is very important for its control and effective use.In this dissertation, a set of experiments have been conducted under three circumstances, namely, the initial indoor temperature is above, equal to and below the outdoor temperature, respectively. While the initial distributions of the indoor temperature and the pollutant(co2as a tracer pollutants) are uniform, square type heat sources with difference surface temperature are placed in the room to change the distribution of temperature and pollutant. The total heat release of the heat source and other conditions are kept the same in the three circumstances during the test to study the influence of the indoor heat source surface temperature on the distribution of temperature and pollutant.Results show that the higher the temperature of the heat source surface, the shorter time it requests to clear away the pollutant. Stratifications of the pollutant concentration in the vertical direction are obvious while the indoor temperature is above and equal to the outdoor temperature, and the stratifications remain the same during the test. Temperature stratifications will also emerge under these two circumstance, and the stratification is much more obvious in the bottom of the room. The difference between the measuring temperature and the outdoor temperature will decrease through increasing the temperature of the heat source surface, which indicates that it takes shorter time for air from the bottom outlet to replace indoor air with higher temperature. While the indoor temperature is below the outdoor temperature, the stratifications of both temperature and pollutant are not significant, much more indistinct than other two circumstances. But conclusion can be made that in each circumstances, the higher the temperature of the heat source surface, the better the efficiency of the natural displacement ventilation and the stratifications of the pollutant are much more obvious and stable under natural ventilation driven by thermal pressure.