超长重力热管联合热泵的地热利用系统热力经济性分析

Thermo-Economic Analysis for Exploitation of Geothermal Energy Using Super-Long Gravity Heat Pipe with Heat Pump

深层地热资源储量巨大,采用超长重力热管取热技术对深层地热资源进行开采,将其与热泵系统联合为用户供热是一种高效利用深层地热资源的方法。针对如何调节不同参数下超长重力热管与热泵联合运行以期获得最佳热力经济性的问题,建立了系统热力经济性模型,研究了热泵系统蒸发温度、超长重力热管热阻、井深、地温梯度以及蒸发器面积不同的情况下系统热力经济性变化规律。结果表明存在一个最佳蒸发温度使供热成本最低,如在地温梯度30℃/km、井深3 000 m的条件下,最佳蒸发温度为-2℃;超长重力热管热阻越小或地温梯度越大时可实现供热成本越低且最佳蒸发温度越高;存在最佳的井深和蒸发器面积使得供热成本最低。研究结果可为优化超长重力热管在开采深层地热联合热泵系统性能方面提供理论指导。

The reserves of deep geothermal resources are enormous.An effective method for exploiting deep geothermal resources involves extracting them using a super-long gravity heat pipe combined with a heat pump system to provide heat for consumers.In response to the issue of how to adjust the combined operation of super-long gravity heat pipe and heat pump under different parameters to achieve optimal thermo-economic performance,this study develops a thermo-economic system model.It investigates the changes in thermo-economic performance under different evaporation temperatures,super-long gravity heat pipe thermal resistances,well depths,geothermal gradients,and evaporator areas of the heat pump system.The results indicate that there is an optimal evaporation temperature that minimizes the cost of heating.For instance,under a geothermal gradient of 30℃/km and a well depth of 3000 m,the optimal evaporation temperature is−2℃.When the thermal resistance of the super-long gravity heat pipe is smaller or the geothermal gradient is larger,the heating cost is lower and the optimal evaporation temperature is higher.Additionally,there is an optimal well depth and evaporator area that minimize heating costs.These findings provide theoretical guidance for optimizing the integration of super-long gravity heat pipe and heat pump system in deep geothermal extraction.