• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>International Journal of Heat and Mass Transfer >Laminar forced and mixed convection heat transfer from a plane vertical isothermal surface to near-critical carbon dioxide
【24h】

Laminar forced and mixed convection heat transfer from a plane vertical isothermal surface to near-critical carbon dioxide

机译：层流强迫混合对流换热从平面垂直等温面传至近临界二氧化碳

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Numerical predictions are made for laminar forced and mixed convection heat transfer from a plane vertical isothermal surface to near critical carbon dioxide. The variation of all the thermo-physical properties with temperature has been taken into consideration. The governing equations are integrated using the Patankar-Spalding implicit finite difference scheme. Computations are made for three pressures.viz., 75 bar (P/P_(cr) = 1.015), 80 bar (P/P_(cr) = 1.083), and 100 bar (P/P_(cr) = 1.354), for different values of △T ranging from 2 K to 30 K. Three free stream velocities and two values of T_∞, T_∞＜T and T_∞=T are chosen so as to give Reynolds numbers, Re_∞ ranging from 10~3 to 4 × 10~5 for forced flow and Gr_∞/Re_∞~2 from 0.004 to 3.4 for mixed convection flows. Based on the results obtained, correlations have been proposed to evaluate the Nusselt numbers both for aiding flow and for opposing flow. The form of the proposed correlation takes into account the variation of the fluid properties in the near-critical region. The Nusselt numbers obtained from the proposed correlations deviate from the numerical predictions within ±10% in the case of forced flow, ±11% in the case of opposing flow and ±15% in the case of aiding flow. The deviation is found to be maximum for pressures close to critical pressure and for those cases for which the surface temperature, Tw is close to the pseudo-critical temperature, T (pseudo-critical temperature is the temperature at which the maximum value of C_p occurs). The predictions also indicate that whenever the property variations are severe, the velocity and temperature profiles deviate considerably from those for constant property cases. However, when the pseudo - critical temperature lies within the boundary layer, the velocity profiles for mixed convection exhibit peaks and there is distortion of the temperature profiles at a location close to the point at which the maximum value of C_p occurs.
机译：对层流强迫和混合对流从平面垂直等温表面到接近临界二氧化碳的传热进行了数值预测。已经考虑了所有热物理性质随温度的变化。使用Patankar-Spalding隐式有限差分方案对控制方程进行积分。针对三个压力进行计算，即75 bar（P / P_（cr）= 1.083），80 bar（P / P_（cr）= 1.083）和100 bar（P / P_（cr）= 1.354），对于2到30 K范围内的不同△T值，选择三个自由流速度和两个T_∞，T_∞＜T和T_∞= T值以给出雷诺数，Re_∞的范围为10〜3强制流量为4×10〜5，混合对流流量的Gr_∞/Re_∞〜2为0.004至3.4。根据获得的结果，已提出相关性以评估辅助流和反向流的Nusselt数。所提出的相关性的形式考虑了在近临界区域中流体性质的变化。从建议的相关性获得的努塞尔特数在强制流动情况下偏离数值预测值在±10％以内，在逆向流动情况下偏离±11％，在辅助流动情况下偏离±15％。对于接近临界压力的压力以及表面温度Tw接近假临界温度T的情况，发现偏差最大（假临界温度是C_p最大值出现的温度）。这些预测还表明，每当特性变化严重时，速度和温度曲线便会与恒定特性情况下的速度和温度曲线发生显着偏离。但是，当准临界温度位于边界层内时，混合对流的速度曲线会出现峰值，并且在接近C_p最大值出现点的位置处温度曲线会发生变形。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号