Cost and energy improvement comparison of using electronic expansion valve and vacuum insulation panel in domestic refrigerators

The paper aims to decrease energy consumption (EC) and costs for refrigerators across various climates. Although research on vacuum insulation panels (VIP) in refrigerators is limited, no studies explicitly examine the effects of VIPs and electronic expansion valves (EEV) on EC, thermal efficiency, cost, and insulation aging (for both VIPs and polyurethane) across different climate classes. This research is highly valuable because it compares multiple factors simultaneously. VIPs enhance efficiency by decreasing heat gain, thus increasing the coefficient of performance (COP), while EEVs adjust refrigerant flow to increase COP. However, VIPs are expensive. In this research, six configurations, including VIP and EEV, and without VIP or EEV, were tested on the same refrigerator across four climate classes. Moreover, a 5% annual increase in electricity cost is included. Results revealed that the minimum payback period was 2 years for an EEV-only in its vapor compression cycle with no-VIP. In the subnormal (SN) class, a full-VIP insulated cabinet and an EEV-only cabinet consumed the same energy (166 kWh/year). In the normal (N) class, the door VIP-only with an EEV reduced EC by 2% and shortened the payback period by 3 years. In the subtropical (ST) class, both full-VIP and EEV configurations consumed 221 kWh/year. In the tropical (T) class, full-VIP resulted in the lowest EC, making EEV technology ineffective. This study enables comparisons of cabinet configurations based on EC, cost, heat gain, aging, and EEV technology across climate classes.