Influence Of Bidirectional Radiation On The Thermal Environment In Industrial Buildings With High-temperature Heat Sources

Within an industrial building, the high-temperature heat sources release excess heat. There are differences in the environment control and the energy efficiency design between industrial buildings and civil buildings. In China, the industrial building is in rapid development, but the study about environmental control and energy efficiency design of the industrial buildings relatively lag behind. Based on the classification form of the industrial buildings, the paper investigates the thermal environment in industrial buildings with high-temperature heat sources. The main works are as follows:The architectural form and the basic environment properties of industrial buildings with high-temperature heat sources are obtained through investigation and measurement. It is observed that the directional mean radiant temperature in an industrial building is close to 100℃, compared with outdoor integration temperature in summer, there are the same effects on the heat transfer of the envelope. Therefore, the heat transfer of the envelope and the thermal environment are influenced by the bidirectional radiation of indoor heat source radiation and solar radiation.The characteristics of convection and radiation from the heat source are firstly studied. The mechanism of secondary convection due to the radiation effect is revealed. The ratio between radiation and convection from the heat source is proposed as a basic parameter for predicting the effects of heat transfer. And the heat transfer method has an important effect on the thermal environment. The heat flux by convection and radiation the convection are presented for different temperature heat source. The ratio between radiation and convection from the heat source is investigated for different temperature heat source and surface emissivity. The temperature and flow distributions, the heat transfer on the heat source surface and the ventilation rate for different Grashof numbers and surface emissivity are discussed. It is observed that the wall-attachment flow is formed obviously due to radiation effects at Gr = 1010-1011.The flow field features are studied by numerical simulations for both pure convection model and combined convection and radiation model. The effects of radiation on predictive accuracy in the numerical simulations are clarified. For pure convection model, the resulting lower zone temperature is underestimated and the upper zone temperature is overestimated compared to the experimental results. The distribution of the vertical temperature from the simulation for combined convection and radiation model agrees better with the experimental results as compared to the pure convection model. The radiation effect redistributes the heat within the building, reduces the vertical temperature gradient and decreases the ventilation rate. In the practical industrial buildings, taking protection measures to limit the radiation effects from a heat source will have a beneficial influence on the environment of the occupied zone.On the basis of the investigation of the characteristics of heat sources and the thermal environment on the effect of radiation from heat sources, the heat transfer mechanism and the flow field features on the effect of bidirectional radiation are studied. At noon in summer, the temperature in inner wall with the effect of solar radiation is lower than that of with the effect of bidirectional radiation, but the temperature in inner roof is higher than that of with the effect of bidirectional radiation. The effects of thermal performance of the envelope on the heat transfer are further studied through numerical simulation. And on this basis, the optimal design parameters of the envelope in industrial buildings with high-temperature heat sources are given. The results supplied the basic theory for energy efficiency and optimal design of the industrial buildings.