Determining optimum insulation thickness by thermoeconomic analysis for a pipeline system in a subway central cooling system

Highlights: • Determine OIT of a pipeline system using thermoeconomic analysis. • OIT is higher for exergoeconomic optimization than for energoeconomic optimization. • The cooling loss and the OITs significantly differ between the FCW and UCW. • EC method is a good way for economic impacts considered. • EPC method is a better choice for environmental advantages considered. Thermoeconomic analysis combines exergy and economic analysis to evaluate and improve the performance of energy systems. This study utilized exergetic production cost (EPC), based on combined exergy and life-cycle cost analysis (LCCA), to optimize the insulation thickness of a pipeline system with a variable secondary pump in a subway central cooling system. The effects of the selected variables on insulation thickness optimization were also investigated. The results of the EPC and energetic cost (EC) methods were compared using payback period and total environmental impact of the pipe system, respectively. Results showed that the optimum insulation thickness (OIT) is higher for exergoeconomic optimization than for energoeconomic optimization. EC method is a good way for economic impacts considered, while EPC method is a better choice for environmental advantages considered. Moreover, cooling loss and the OIT significantly differ between fresh and used chilled water. Therefore, the characteristics of the supply and return pipes should be jointly considered in calculating the insulation thickness.