U型垂直地埋管换热器性能的影响因素分析

为了了解不同的设计参数对于换热器性能的影响,本文通过建立流体力学三维模型模拟了管长60²00m的地埋管换热器性能。研究结果显示,流体进口温度、流体速度和初始地下温度都对换热器性能有显著的影响,考虑到热通量和压降2个因素,推荐流速为0.5m/s。回填物和土壤的密度及比热对性能的影响小于导热率的影响。文中开发了一个简单的数学模型用于预测回填物和土壤,比热和导热率以及热通量的影响,预测结果与CFD结果高度符合。当换热器的长度从60m增加到200m,热通量下降,影响半径也变小。

Analysis on Influence Factor for the Performance of Vertical Ground Source U-tube Heat Exchanger

In order to understand the influences of different design parameters on the performance of heat exchanger,a three dimensional computational fluid dynamics simulation for the performance of ground source heat exchanger with tube length ranging from 60 m to 200 m was performed.The research results show that,the fluid inlet temperature,the fluid velocity and initial ground temperature significantly affect the heat exchanger performance.The recommended fluid velocity is about 0.5 m / s by considering both the heat flux and pressure drop.The influences of density and specific heat of backfill and soil are smaller than that of thermal conductivity.The simple mathematic models for predicting the influences of density,specific heat and thermal conductivity of backfill and soil on heat flux are developed,and agree well with the CFD results.With the increase of heat exchanger length from60 m to 200 m,the heat flux decreases,and the influencing radius decreases.