Quantifying Efficiency Gains of Refrigeration Systems Using Advanced Expansion Valve Technology (ST-16-009)

Commercial and industrial refrigeration systems consume a significant portion of US electrical energy. In this paper, 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 MEMS actuators with different control strategies is compared with the standard mechanical valves and a commercially available superheat controller. Additionally, this research includes a comprehensive set of experimental tests that identify the most effective elements of advanced valve control strategies, including the impact of refrigerant migration control strategies. The experimental results confirm that 30-50% improvements in cyclic 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.