Exergoeconomic analysis of a district heating system for geothermal energy using specific exergy cost method

• Exergoeconomic evaluation of a GDHS using SPECO method for the first time.
• Displaying cost flows for all streams and components of the system.
• The unit exergy cost of heat produced by the GDHS is calculated as average 5624 $/h.
• The HEX-III among all components should be improved quickly.
• Its heat production costs decrease while the well head and ambient temperature increase.

This study presents the exergoeconomic analysis and evaluation in order to provide cost based information and suggests possible locations/components in a GDHS (geothermal district heating system) for improving the cost effectiveness. The analysis is based on the SPECO (specific exergy costing) method, and used to calculate exergy-related parameters and display cost flows for all streams and components. As a real case study, the Afyon GDHS in Turkey is considered based on actual operational data. The obtained results show that the unit exergy cost of heat produced by the Afyon GDHS is calculated as average 5624 $/h. The HEX (heat exchanger)-III among all components should be improved quickly due to the high total operating cost rate and relative cost difference. The HEX-I and PM (pump)-V have the highest exergoeconomic factors among all other system components due to the high owning and operating costs of these components. The heat production costs per exergy unit for all the HEXs decrease due to the high exergy destruction cost rate of the system, while the well head temperature and ambient temperature increase. The SPECO method may be used to improve the cost effectiveness according to exergy rates in GDHSs as a thermal system.