Ground cooling potential in a Mediterranean climate : fieldwork and computational modelling

Abstract

The aim of this paper was to explore the potential of exploiting ground source cooling, utilising the high thermal mass of the indigenous sedimentary rock, globigerina limestone, typical of Malta. Based on earlier studies of horizontal and vertical pipe configurations, it was established that the vertical U-tube pipe is more efficient. This demonstrated that at 20m depth ground temperatures were around 20C all year round. This prompted further studies with various refined parameters, this time moving from fieldwork to numerical simulations, facilitating a greater variety of trials. A mathematical model of the system was developed, implemented into a computational model to simulate the heat transfer processes. This model was calibrated using results from the field tests. This was also used to carry out a more elaborate parametric analysis of the system and to simulate its performance in a variety of configurations. Preliminary results already indicate the validity of the numerical model and the applicability of such a system. The same numerical model results and field tests were then used to estimate the potential of such a ground source heat pump system to curtail energy demand for cooling on running the standard HVAC systems.