Design and Efficiency Analysis of a Dual-Purpose Refrigeration System for Domestic Water Heating

The escalating global energy demand necessitates innovative solutions for waste energy recovery in domestic appliances. This study presents the design and experimental analysis of a system that repurposes waste heat from a refrigerator's condenser for water heating. A conventional domestic refrigerator was modified by integrating a custom heat exchanger with its condenser circuit. The system utilizes a 135 W compressor and a copper-based heat transfer system to maximize thermal exchange. Experimental results demonstrate the system's capability to heat 5 liters of water from 26°C to 65°C within 120 minutes, utilizing only the otherwise wasted thermal energy. An energy consumption analysis reveals the proposed system consumes 0.27 kWh for this task. In contrast, a conventional 2500 W electric water heater requires 0.2075 kWh to perform the same duty but relies solely on grid electricity. The annual energy savings are projected to be approximately 912 kWh for a typical household, translating to significant cost reduction and lower carbon emissions. This research confirms the technical viability and economic benefits of integrating waste heat recovery systems into household refrigeration units, promoting a sustainable approach to energy utilization.