Thermodynamic performance assessments of a district heating system with geothermal by using advanced exergy analysis

Abstract

This paper relates to thermodynamic performance assessment of a geothermal district heating system (GDHS) using advanced exergetic analysis to identify the interactions among system components and the potential for improvement. It is introduced four new exergetic parameters, namely the exergetic fuel depletion ratio, the exergetic productivity lack ratio, the exergetic rehabilitation ratio, and the exergetic improvement potential for a GDHS. This analysis and new exergetic parameters are applied to the Bursa GDHS in Turkey. The results show that the advanced exergetic analysis is a more meaningful and effective tool than the conventional one for the system performance evaluation. The exergetic efficiencies for the conventional and advanced ones are 25.24% and 26.34%, respectively. The highest priorities for improvement of system components are in descending order of importance: the heat exchangers and the pumps for the conventional analysis, and only the heat exchangers for the advanced analysis. New exergetic parameters appear to be key indicators to show how much the system is improvable and apparently sustainable. The ratios of these parameters in the order given above are respectively 4.19%, 16.60%, 33.23% and 4.19%, for the Bursa GDHS. The heat exchangers have the highest values of exergetic rehabilitation ratio. Thus, there are improvement priorities of the heat exchangers.