An experimental study on thermal performance evaluation and effectiveness of geothermal heat exchange system in various standing column well types

Abstract

The technology proposed in this study aims to improve the performance characteristics and coefficient of performance (COP) of a geothermal system by fundamentally preventing underground water discharge and maintaining a constant temperature of the underground heat exchanger composed of bleed discharge water that utilizes two balancing wells using cross-mixing methods. The results of the cooling and heating operations of the existing standing column well (SCW) and the balancing well cross-combined heat exchange systems show that the measured COP increases by 23% during the cooling operation and 12% during the heating operation. When operating with a balanced well-cross-mixed heat exchange system, the initial temperature of the underground is constant with a small standard deviation of 0.08–0.12 °C. The results of the measured values using this technology show that, if the operational method is changed from the ordinary SCW-type heat exchange system to a balanced well-intersected heat exchange system, the COP of the cooling and the heating system using geothermal heat not only improves but also ensures a stable supply of geothermal sources by maintaining a constant initial temperature. This finding is useful to fundamentally eliminate the ultimately wasted bleed water.