Which method can commonly improve energy efficiency in refrigeration systems?

Installing variable speed drives on compressors is a widely recognized method for improving energy efficiency in refrigeration systems. Variable speed drives allow the compressor to operate at varying speeds based on the cooling demand, rather than running at full speed all the time. This optimization means that less energy is consumed during times of low cooling demand, leading to significant energy savings and reduced wear on the compressor. By matching the compressor's output to the actual load requirements, these drives enhance the overall efficiency of the system, leading to lower operation costs and increased service life.

The other methods mentioned do not typically enhance energy efficiency. For instance, removing insulation from pipes can lead to significant heat loss, increasing energy consumption as the system compensates for the loss of cooling. Adding extra refrigerant might temporarily improve cooling performance, but it can also lead to inefficiencies or system malfunctions. Decreasing the size of evaporators would restrict the system's ability to transfer heat effectively, which can further decrease its efficiency. Therefore, the use of variable speed drives stands out as the most effective approach to enhance energy savings in refrigeration applications.