The Influence of Aquifer Parameters on the Design of Extraction and Recharge Wells for Heat Pump Systems

Abstract

Groundwater can be considered a non-polluting, renewable energy source. It can be used as a fluid in industrial, commercial, and residential building heating and airconditioning systems. Usually the water table is deep enough, so atmospheric conditions have a negligible influence on water temperature. Consequently, annual temperature variation is minor, and groundwater can therefore also be considered a reliable energy source. This paper presents some aspects of the groundwater heat pump (GWHP) wells design and addresses problems that can occur during their exploitation. The heat pump system consists of two types of wells: extraction wells and recharge wells. This paper shows that the distance between the two is a crucial parameter that affects the efficiency of the whole system. An example of wells design for a production hall groundwater heat pump is given. The wells are constructed is in the northern part of Croatia. Geological and hydrogeological conditions at the site, regarding water temperature and soil hydraulic conductivity, are highly favorable. Due to insufficient distance between wells thermal breakthrough occurred, i.e. water temperature in the extraction well rose, which resulted in a lower efficiency of the GWHP system.