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采用数值模拟的方法,研究锯齿形板翅式换热器在给定壁温、给定热流密度、冷热流体逆流布置和沿壁面长度方向变壁温这四种边界条件的传热特性,得到了在雷诺数为169、415、2725和4095的低压路氦气流动中,不同边界条件下翅片通道的局部努赛尔数沿无量纲高度方向上的分布。结果表明:对于相同Re数下,给定热流密度条件下的壁面温度分布趋势与实际工况下逆流布置时最为接近,其中间位置处局部Nu数沿无量纲高度方向上的变化曲线最为逼近,且计算得到的传热因子j值也最为贴近,所以,仿真时采用定热流边界条件能更好地真实模拟冷热流体逆流换热时的情况。
The heat transfer characteristics of the jagged plate-fin heat exchanger at four given boundary conditions, including given wall temperature, given heat flux, countercurrent placement of hot and cold fluid and variable wall temperature along the length of the wall, were studied by numerical simulation. In the low-pressure helium flow with low Reynolds numbers of 169, 415, 2725 and 4095, the distribution of local Nusselt number along the non-dimensional height direction of the fin passage under different boundary conditions. The results show that for the same Re number, the trend of wall temperature distribution under a given heat flux density is closest to that under counter-flow under actual conditions. The curve of local Nu number along the dimensionless height direction at the middle position is the most approximate, And the calculated value of heat transfer factor j is also the closest, therefore, the simulation using fixed heat flow boundary conditions can better simulate the hot and cold fluid countercurrent heat transfer situation.