单井循环热泵系统冬季运行特性的数值模拟

Numerical Simulation for Winter Operation Characteristics of Heat Pump System with a Standing Column Well

建立了单井循环系统中井水与土壤的传热数学模型,采用有限差分法对单井循环热泵系统冬季运行特性进行了数值模拟分析。在热泵运行初期,出水温度下降较快,井水从土壤中的吸热量少,热泵的吸热量基本来自井水自身的蓄热。井水初始温度对井壁处热流密度没有影响。相同运行工况下,在一定范围内,井的尺寸越大,井壁处热流密度越小。出水质量流量越大,对井水和周围土壤的传热越有利,但会缩短井的供热时间。

A mathematical model for heat transfer between soil and well-water of standing column well system is established, and the numerical simulation analysis for winter operation characteristics of heat pump system with a standing column well is conducted using finite difference method. At the initial phase of heat pump operation, the outlet water temperature is rapidly decreased and heat is seldom absorbed by well-water from soil. The heat pump absorbs mainly heat stored in well-water. The initial well- water temperature does not have significant influence on heat flux density at the well wall. Under the same operation condition, the bigger the well diameter is, lower heat flux density at the well wall is within a certain range. With the increasing of mass rate of the outlet water, more heat is exchanged between well-water and the surrounded soil, but the heat-supply time of well is decreased.