Investigating the Effect of Ambient Temperature on the Defrost Performance of a Refrigerator Operating Under an Adaptive Defrost Strategy

Frost free refrigerators are extensively used worldwide and, due to their continuous operation, consume a considerable amount of energy. The energy consumption of these systems is highly dependent on ambient conditions through several mechanisms. In particular, the temperature difference between the refrigerated cabinet and the surrounding environment governs the rate of heat gain through insulation and door gaskets. Elevated ambient temperatures further increase the condensing temperature, thereby raising the temperature lift between the condenser and evaporator. Additionally, the defrosting process has been identified as a critical factor contributing to increased energy consumption. In this study, an experimental investigation is conducted to evaluate the defrost performance of a 258-L fixed-frequency frost-free refrigerator employing an Adaptive Defrost Method (ADM). The system is tested under varying ambient conditions of 25 °C, 30 °C, and 35 °C to assess the influence of environmental temperature on defrost characteristics, defrost efficiency, and total defrost energy consumption. The results indicated that during the defrost mode, the freezing cabinet temperatures raised by 0.9 °C and 2 °C at 30 °C and 35 °C compared to 25 °C due to increase in defrost mode durations by 2 min and 5 min. Consequently, the total defrost energy consumption increases at 30 °C and 35 °C by 15.2 % and 31.3 %, respectively, when compared to 25 °C. Furthermore, defrost efficiency decreases with increasing ambient temperature, mainly due to the prolonged defrost duration. Overall, the findings demonstrate that the defrost process contributes significantly to additional energy consumption, particularly under higher ambient conditions.