Comparison of compressor control strategies for energy efficient refrigerated counters

Abstract

• Energy label improvements for refrigerated counters are evaluated using simulations. • Improvements are evaluated based on compressor power and product temperature. • 70% reduction of the compressor power can be attained. • Reduction of the compressor power infers higher product temperature fluctuations. • Tradeoff between power consumption and temperature fluctuation should be identified. Small scale hermetic compressors with built-in frequency converters for compressor speed adjustment are an emerging technology on the commercial market. These compressor technologies offer the ability to impose innovative compressor control strategies, such as variable speed drive or adaptive energy optimization, for small scale commercial refrigeration systems. These strategies may both reduce power consumption and increase the temperature stability of the stored goods. Both of which are a necessity for the refrigerators to abide EU regulations 2015/1095 and 2015/1094 of 5 May 2015 and thus pass the test described in EN 16825. The influence of the applied compressor control strategy was investigated in combination with improvements to the cabinet envelope and improvements to the condenser and evaporator design. The investigation was performed using a validated dynamic model of a refrigerated counter using R290 and R600a, under the EN 16825 test conditions. Both variable speed drive and adaptive energy optimization yield significant reductions in power consumption compared to the conventional On-Off control. A more constant product temperature was achieved by variable speed drive, while the product temperature fluctuated slightly more when applying adaptive energy optimization.