关键词: 数值模拟, 对流, 传热, 温度均匀度, 熵产

Abstract:

The temperature uniformity and entropy generation due to heat transfer inside a thermal cycling test chamber are investigated numerically under various operating parameters. Boussinesq approximation and k-ω model are used in the simulation and the result is validated by previous experiment. The result shows that in the range of 4.3×10³ ≤ Re ≤ 8.6×10⁵ and 4.62×10¹³ ≤ Gr ≤ 1.38×10¹⁴, both forced convection and natural convection contribute to the fluid flow and heat transfer. Fluid close to the walls gets heated and rises along the walls due to the buoyancy force while that near the center line accelerates downward to the exit. The temperature at the given height always increases from the center line to the walls. From the top to bottom of the cycling chamber, the temperature increases around the center line while decreases near the walls. The dimensionless standard temperature deviation increases with Reynolds number and changes little with Grashof number. During the mixed convection, the entropy generation due to fluid friction is much smaller than that by heat transfer, and the latter increases with both Reynolds number and Grashof number. In addition, the expressions of wall Nusselt number, dimensionless average temperature, dimensionless temperature standard deviation and dimensionless entropy generation by heat transfer are also provided.

Key words: numerical simulation, convection, heat transfer, temperature uniformity, entropy generation