Development and validation of innovative hot water spray defrosting method

One of the most common problems in refrigeration cycles is the failure to defrost the evaporator, resulting in decreased performance. This study proposes the hot water defrosting approach as an alternative to the defrosting process using hot gas, an electric heater, and airflow. For this purpose, a hot water box was designed to use the heat from the compressor discharge line, which contains finned tubes through which R290 (propane) refrigerant flows for defrosting. In addition, a defrost control method algorithm was established. The best coefficient of performance (COP) of 4.34 was obtained in Exp. 3. The highest defrosting efficiency was 58.79 % for the hot water defrosting method, while the lowest value was 28.29 % for the airflow. It was observed that the defrosting time could be shortened by using the hot water method, better energy usage could be achieved by using Exp. 4, and a more effective defrosting efficiency could be achieved by using Exp. 5. It was determined that the hot water method can create a difference of up to 44 % in defrost efficiency compared to the hot gas method. Moreover, it was determined that the new approach has almost the same performance compared to the reverse cycle method, but it can provide an advantage because it is not exposed to sudden pressure fluctuations and mechanical shocks. Despite the modest return on investment (0.56–2.22 years) and sustainability for as long as the system is in use, the risk of corrosion that may occur over time during the hot water spraying process should be considered.