Abstract
The existing design parameters of hot-air heating for local buildings do not consider the distinctive low-pressure that can be experienced in the plateau regions, resulting in significant inefficiency. In this study, a numerical model based on the Reynolds time-averaged method coupled with the RNG k–ε turbulence model was established by considering the air thermal properties influenced by pressure. Four atmospheric conditions of 101.325 kPa, 84.547 kPa, 70.093 kPa and 57.708 kPa were selected to simulate the velocity and temperature fields of the horizontal and vertical hot-air jets. The influence of low pressure on the flow characteristics of hot-air jets was analyzed subsequently. The results suggest the jet flow patterns are essentially similar under various pressures. The horizontal hot-air jets bent upward more significantly and the diffusion range of the vertical jets was reduced under low pressure. The jet velocity decayed faster at low pressure, and the axial velocity of a vertical jet at 57.708 kPa was 0.26 m/s lower than that at 101.325 kPa. The temperature gradient of the room with a hot-air jet was increased with decreasing pressure, which was 5.0 K/m at 57.708 kPa. This study should be helpful to the detailed design and efficient operation of hot-air heating in buildings in the plateau regions.
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