Effect of refrigerants on the economical optimum insulation thickness for indoor pipelines of split air conditioning systems

Abstract

This study presents investigations of optimum insulation thickness, cost savings and payback periods for gas pipeline and liquid pipeline under the heating operation of 1500 hours and cooling operation of 1500 hours of a split air conditioning system that used flexible insulation foam as insulation material. Analyses are performed for four different refrigerants indicated as R-22, R-134a, R-407C and R-410A. The results indicate that under heating mode, the optimum insulation thickness of gas pipeline varies from 9 to 12 mm depending on the analyzed refrigerants, whereas the optimum insulation thickness of liquid pipeline varies from 6 to 9 mm depending on the analyzed refrigerants. When it comes to cooling mode, while optimum insulation thickness of gas pipelines is 9 mm for all the analyzed refrigerants, optimum insulation thickness of liquid pipelines is 6 mm for all the analyzed refrigerants. Under the given operation conditions, R-407C shows the highest potential for cost savings through the optimization of insulation thickness, since it has the lowest mass flow rate.