Large enclosure means a space of high ceiling and large floor. Designing the heating system, many thermal conditions exist, such as thermal comfort, IAQ, heating load and energy efficiency etc. The prediction of the temperature distribution is carried out according to some of the diffuser angle. The simulation conditions are 7 m high diffuser, 4/2 inlet/outlet diffusers, 39 °C discharge air temperature, and 6 m/s exit velocity. The results show that 45° diffuser provides an optimal thermal environment, and the reason is that the temperature is closed to the designed temperature 22 °C at 1.18m elevation plane. As the diffuser angle is decreased, the temperature of the upper region is increased for the thermal buoyancy effect. And the asymmetry of the temperature distribution is increased.

teacher s efficiency is an important factor. Recently, some schools installed an air conditioner in classroom, while most schools selected the built-in type air conditioner. However, the study on a valuation of thermal environment is not sufficient, especially in classroom. It is insufficient that the study is a valuation of thermal environment which considered valuation about indoor thermal environment diffusion angle and air volume. In this work, the change of thermal environment was investigated for five kinds of air diffusion angle(15∘, 30∘, 45∘, 60∘, 90∘) for ceiling type air conditioner. The vector and temperature distributions of air in the room were calculated by a 3-dimensional numerical method. This study was also conducted to calculate the Mean Age of Air and Predicted Mean Vote(PMV). This analysis showed that 30-45° is the optimum angle of diffusion in cooling mode and in heating mode.