竖直地埋管换热器内两相流动传热影响因素分析
Influence factors of two-phase flow and heat transfer in vertical ground heat exchangers
摘要：
为了给直接膨胀式地埋管地源热泵U形铜管地埋管换热器的优化设计提供理论依据，利用自定义函数添加相界面质量和热量传递源项，建立了修正的两相流混合物模型，对地下换热系统供热工况下的三维流场和换热过程进行了数值模拟，分析了工质不同进口干度和流量对地埋管换热器内流体流动及换热性能的影响。结果表明，该模型符合工程精度要求；U形铜管内温升主要集中在距进口0～15 m管段；在一定的质量流量条件下存在最佳干度，或者干度一定时存在最佳流量，使得换热性能最优。
Abstract：
Aiming at optimizing U-pipe heat exchangers in direct expansion ground-source heat pump systems, utilizes user defined functions adding the quality and heat transfer source between phase interfaces, establishes a modified two-phase flow mixture model, simulates three dimensional steady flow field and heat transfer of underground exchangers in heating conditions, and analyses the influences of inlet dryness and flow of working fluid on flow and heat transfer in ground source heat exchangers. The results show that the model can meet the requirement of engineering in accuracy; temperature rise in the U-pipe mainly occurs in 0 to 15 m section from the inlet; in a certain quality flow condition, there exists an optimum dryness making heat transfer rate optimal, or in a certain dryness condition, there is an optimum quality flow.
Keywords:directexpansionground-sourceheatpump,groundheatexchanger,two-phaseflow,dryness,flow