ASHRAE - American Society of Heating@ Refrigerating and Air-Conditioning Engineers@ Inc.
Scope
Commercialand industrial refrigeration systemsconsumea significant portion of U.S. electrical energy. In this research@ advanced expansion valve and control algorithms are evaluated to quantify the potential energy savings due to improved system regulation and efficient start-up of vapor-compression refrigeration systems. The performance of the new micro-electromechanical system (MEMS) actuators with different control strategies is compared with that of the standard mechanical valves and a commercially available superheat controller. Additionally@ thisresearchincludesacomprehensivesetofexperimental tests that identify themosteffective elements ofadvancedvalve control strategies@ including the impact of refrigerant migration control strategies. The experimental results confirm that 30% to 50% improvements in cyclic coefficient of performance (COP) are possible using improved expansion valve controls@ while the benefits of preventing refrigerant migration do not outweigh the additional cooling achieved if refrigerant continues to flow through the expansion valve during the compressor OFF period.