直接空冷凝汽器空气侧热流性能的跨尺度模拟

doi:10.3969/j.issn.1000-7229.2015.08.003

摘要/Abstract

摘要：

针对冬季直接空冷凝汽器的防冻工业需求，将翅片管和空冷单元这2个尺度的模型耦合起来，既考察翅片管束的整体流动换热性能，又考察直接冷却翅片管内凝结水的冲击换热特性，为确定冬季低温运行条件下空冷凝汽器管内凝结换热甚至结冰计算提供第3类热边界条件。建立了空冷单元模型和翅片管模型，然后，将三维进口风条件下的翅片管级数值模拟结果简化成输入-输出代理模型；从空冷单元系统级数值模拟中获得系统级边界-迎风面的速度分布；进而将翅片管数值模拟代理模型应用到系统边界上，得到了系统边界上翅片管冲击换热特性以及翅片管平均对流换热特性的空间分布。数值计算结果表明，冲击换热系数比平均对流换热系数大一个数量级；在迎风面上冲击换热系数和平均对流换热系数均呈现出上低下高、左右不对称的特点；冲击换热系数随着转速的下降而下降。

关键词: 直接空冷凝汽器, 跨尺度模拟, 传热, 冻结

Abstract:

For the antifreezing industrial demand of direct air-cooling condenser in winter, the model on finned tube scale was coupled with that on air-cooling unit scale, both the whole heat transfer characteristics in finned tube bundle and the impingement heat transfer characteristic of condensate water in air-cooling finned tube were studied, which could provide the third thermal boundary condition for the calculation of the in-tube condensation heat transfer and freezing in direct air-cooling condenser under the condition of low temperature operation in winter. The air-cooling condenser cell model and finned tube model were constructed. Then, the simulation results of finned tube under 3D inlet wind velocity boundary condition was simplified as input-output type agent model. The velocity distribution at the windward surface and symmetric boundary was obtained from air-cooling condenser cell numerical simulation. Then the finned tube agent model was applied in the symmetric boundary to obtain the spatial distribution of the impingement heat transfer characteristics and average convective heat transfer characteristics of finned tube at symmetric boundary. The numerical calculation results show that, the impinging heat transfer coefficient has a larger magnitude than the average convective heat transfer coefficient； at the windward surface, the distributions of those two coefficients are both up-down asymmetrical and left-right asymmetrical； and the impinging heat transfer coefficient decreases with the decrease of the rotational speed.

Key words: direct air-cooling condenser, cross-scale simulation, heat transfer, freezing

中图分类号:

程通锐，杜小泽，杨立军. 直接空冷凝汽器空气侧热流性能的跨尺度模拟[J]. 电力建设, 2015, 36(8): 15-21.

CHENG Tongrui, DU Xiaoze, YANG Lijun. Cross-Scale Simulation for Air-side Thermo-Fluid Performance of Direct Air-Cooling Condenser[J]. ELECTRIC POWER CONSTRUCTION, 2015, 36(8): 15-21.

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