Refrigeration, Energy, Efficiency, Two-Phase, Expander
Expansion valves in refrigeration systems can be replaced with a flashing liquid expander (FLE) to reduce the energy consumption in refrigeration systems. The original application, pioneered by J.J. Brasz, was for commercial 500 Ton chillers. A reduction in compressor power of 7-8% was obtained. Some 100 of these chillers have been operating for more than 10 years. Recent emphasis on the use of environmentally benign refrigerants have created a renewed interest in energy savings. Some refrigerents such as ammonia, carbon dioxide and propane have high lifts resulting in increased inefficiency due to the isenthalpic expansion valve. Useful power is disipated and the frictional heating results in generation of additional vapor for the compressor. Analysis of the power reduction for the above refrigerants was conducted for a range of variables using state of the art flashing liquid expanders. The results are for the use of canned generators which enable a sealess expander. Power generation and reduction of vapor load are presented. A case study of a large ammonia refrigeration system is presented. A reduction of compressor power of 27.5% resulted. The electric power generated was 410 kW. The reduction in vapor fraction after the flash was 12%. Performance measurements of FLE expanders in several other applications are presented. The results of the analysis are presented in a form to enable estimation of energy savings for the above refrigerants.