In this study, the possibility of the heat transfer control in a vertical channel is analyzed, starting from a numerical solution of the governing equations. The developing convection in connection with an upward forced flow will be characterized by the appropriate parameters. The simulation when the average Nusselt number defined at the cold wall becomes physically insignificant, is presented in detail for different aspect ratios (A=H/L=4;8;16) and Rayleigh numbers (Ra=10~5-10~7). When the incoming fluid temperature is the same as the cold plate, there exists a critical Reynolds number which gives a sharp drop of cold wall Nussel number. For large aspect ratios (A>=8) the values obtained fro this parameter are found to be independent of Ra and proportional to A~2. Analyzing the influence of the fluid temperature entering in the channel on the critical Reynolds number, we found the existence of a minimum cold wall Nusselt number. The minimum Nusselt number, which depends on the entering fluid temperature, follows a curve which eventually converges (for A>8) to the critical value considered for zero entrance temperature, say the value related to the Re_cr for heat transfer.
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机译:在该研究中,从控制方程的数值溶液开始分析垂直通道中的传热控制的可能性。与向上强制流有关的发展对流将通过适当的参数表征。当冷壁上定义的平均露珠数变为物理微不足道时,详细介绍了不同的纵横比(a = h / l = 4; 8; 16)和瑞利数(Ra = 10〜5-10〜7 )。当进入的流体温度与冷板相同时,存在临界雷诺数,其给出了急剧滴落的冷壁鼻子数。对于大的纵横比(a> = 8)来获得该参数的值以与Ra独立于Ra,与A〜2成比例。分析临界雷诺数进入通道中的流体温度的影响,我们发现存在最小的冷壁露珠数。取决于进入的流体温度的最小露珠数遵循最终会聚(对于A> 8)到所考虑的零入射温度的临界值的曲线,例如与传热相关的re_cr相关的值。
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