Design and application of evaporative cooler for a freezer

In this study, a self-designed evaporative cooler (EC) was used to coat the compressor of an R404A freezer (internal volume: 540 L) to cool the compressor through evaporative cooling and thus to improve the freezer performance. The EC was constructed using a moisture-transferring and quick-drying textile (MTQDT) to provide superior evaporative cooling. The unloaded pull-down, loaded pull-down, and 24-h on-load cycling characteristics of the freezer were measured under different ambient temperatures and relative humidity conditions (27 °C/70% RH, 30 °C/70% RH, and 35 °C/75% RH) to evaluate the freezer performance with and without the EC. The results showed that the installation of the EC could effectively reduce the case temperature (T_case) and discharge temperature (T_dis) of the compressor and improve the slope of pull down (SPD) for the freezer temperature (T_f) and coefficient of performance (COP) of the freezer. The effects of the EC on T_case, T_dis, SPD of T_f, and SPD of COP during the pull-down tests were enhanced by increasing the ambient temperature (T_a). T_case, T_dis, SPD of T_f, and SPD of COP of the freezer with an EC were −5.99 °C, −4.89 °C, 7.36%, and 15.06% and −5.44 °C, −4.37 °C, 7.19%, and 14.73% compared with those of the original machine in the unloaded pull-down and loaded pull-down tests at a T_a value of 35 °C, respectively. In addition, in terms of the 24-h on-load cycling test results, the difference ratio of the operating time of the compressor (R_tr) and energy factor of the freezer (EF) with the EC was −2.36% and 1.54% compared with those of the original machine at a T_a value of 35 °C.