Faster Cool Down of a Reefer Unit by Optimizing the System Losses Through Experimental Investigation

Refrigerated shipping containers are one of the four segments of the cold chain; cooling and storage; refrigerated transport; distribution center, and refrigerated display in supermarkets. The refrigerated shipping containers are commonly known as reefer. It is an emerging area in transport industry. The Covid pandemic has given a push to the development and refinement of reefer unit. The growth in the refrigerated transport has raised the energy demand significantly. With the depleting fossil fuel, it is imperative to develop energy efficient systems. An experimental investigation was conducted in the present paper in order to minimize the energy consumption to run the system at idle condition and to achieve the faster rate of cooling. An existing reefer system was considered for this study. The existing system was designed for small container, size up to 8 ft, and was first evaluated experimentally in the climatic test chamber under different climatic conditions resembling actual ambient usage. The experimental data was analyzed in details and observed that it took more than 2 h to reach the desired cabin temperature. A detailed investigation was made to understand the concerns in the system. Out of all possible root causes, losses in suction lines, ineffective utilization of condenser frontal area, air bypass from evaporator coil, and compressor being exposed to hot air are found to be significant. Appropriate countermeasures were taken to eliminate these losses, and system was modified with these changes. Further the modified system was tested again in climatic test chamber. It was observed that the rate of cooling is much faster than that of existing, and also, the energy consumption to reach to the desired container temperature is significantly lower as compared to the existing system. Energy required to maintain at low speed, e.g., idle is also minimized. Hence, the study was quite useful in establishing design measures at the initial stages of development.