闭式U型地表水换热器传热数值模拟与实验研究

Numerical Simulation and Experimental Study on Heat Transfer Characteristic of Closed-loop U-shaped Surface Water Heat Exchanger

针对工程设计中闭式地表水换热器基础数据缺乏的问题,本文建立了闭式U型地表水换热器的三维传热模型,利用FLUENT软件,分别模拟了夏季与冬季工况下,换热器不同进口温度、不同湖水温度下换热器的传热特性。结果表明,换热器进出口平均温度与湖水温差、换热器进口温度与湖水温差是影响单位管长换热量的根本因素,并根据模拟结果分别拟合了两种温差与单位管长换热量的关系曲线。利用自主设计的实验台,在夏季与冬季分别进行了散热与取热实验,将由拟合公式计算的结果与实验结果进行了对比,误差在±10%以内。本文给地表水换热器的工程设计提供了一条新思路。

Three-dimensional model of closed-loop surface water heat exchanger was built, and heat transfer performance of different inlet water temperature of heat exchanger and lake water temperature were studied based on FLUENT software under summer and winter operation condition. Results indicate that temperature difference between average temperature of inlet and outlet and lake water temperature, and temperature difference between inlet and lake water temperature are the fundamental factor to inflect heat transfer quantity. Relationship curves between two temperature difference and heat transfer quantity per meter were fitted. Field tests on heat rejected to and extracted from lake were carried out based on experimental table developed independently. Results based on curve fitting and experimental results were compared, and relative error is in range of ＋10%. This paper provides a new idea of engineering design and application of closed-loop surface water heat exchanger.