Design and application of evaporative cooler for a freezer

摘要

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 degrees C/70% RH, 30 degrees C/70% RH, and 35 degrees 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 degrees C, - 4.89 degrees C, 7.36%, and 15.06% and - 5.44 degrees C, - 4.37 degrees 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 degrees 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 degrees C.