A comparative study on exergetic assessment of two ground-source (geothermal) heat pump systems for residential applications

Ground source heat pumps (GSHPs), also known as geothermal heat pumps (GHPs), have been widely used for years in developed countries due to their higher energy utilization efficiencies than those of both conventional heating and cooling systems. However, they have been applied to the Turkish residential buildings since 1997. This study deals with the exergetic performance evaluation of two types of GSHP systems installed in Turkey based on the actual operational data. The fist one is a GSHP system designed and constructed for investigating geothermal resources with low temperatures, while the second one is a GSHP system with a vertical ground heat exchanger. In the analysis, four balance (mass, energy, entropy and exergy) equations are applied to the two GSHP systems considered for modeling purposes in a tabulated form. Exergy (second law) efficiency values for both systems are given, while exergy destructions in each of the system components are determined to assess their individual performances by presenting the potential for improvements. It may be concluded that the exergetic evaluation method presented here may be applied to other GSHP systems worldwide as a useful tool, which is a way to sustainable development. (c) 2006 Elsevier Ltd. All rights reserved.