Estimation of Relative Resource Circulation for Heat Exchangers Using Material Flow Analysis for Air Conditioners

Abstract

The demand for resource circulation of heat exchangers in air conditioners is expected to grow rapidly; however, the market stocking time is relatively long. Therefore, this scenario was used as a case study for sustainable products design. A material flow analysis was conducted to estimate the balance between global relative resource consumption for shipment, waste, and installed stock from publicly available information up to 2050. Based on the projected demand through 2050, the shipment volume for each year was calculated on a cooling capacity basis. From this analysis, the waste volume was calculated. Using the shipment volume on the basis of yearly cooling capacity, the shipment volume on a resource basis was calculated considering the heat transfer coefficient. The balance between the waste volume and the installed stock was estimated. The resource circulation was simulated by defining variables such as the ratio of units that can be converted from waste to shipment and the ratio of heat exchangers using circulated resources in the total number of shipments. The results indicate that the shipment, waste, and installed stock of resources projected for 2050 were greater than those at the 2021 levels by factors of 2.2, 2.8, and 2.9, respectively. In addition, they were greater than those of the 2021 levels in the scenarios by factors of 1.8, 2.2, and 2.8 accounting for the increase of heat transfer coefficient into account, indicating the importance of improvement of heat transfer. The simulation of circulation showed that a fully closed loop in 2050 would be difficult to achieve owing to the shortage of heat exchangers for waste-to-shipment. Sensitivity analysis also indicated that even under conditions where there is no predicted shortage of circulated resources for 2050, achieving the target in a short period of time may cause a rapid increase in demand for circulating resources. This would subsequently, lead to a shortage of supply compared to demand. Thus, it is important to account for these dynamics relating resource circulation and strategy planning during analysis.