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Flashing liquid expander energy reduction in refrigeration systems.

Number: pap. 2155

Author(s) : HAYS L. G.

Summary

Expansion valves in refrigeration systems can be replaced with a flashing liquid expander (FLE) to reduce the energy consumption. The original application, pioneered by J.J. Brasz, was for commercial 500 Ton chillers. A reduction in compressor power of 7-8% was obtained (Hays and Brasz, 1996). Some 100 of these chillers have been operating for more than 10 years.

Recent emphasis on the use of environmentally benign refrigerants for cold storage and freezers has created a renewed interest in energy savings. Some refrigerants such as ammonia and propane have high lifts which result in increased inefficiency due to the isenthalpic expansion valve. Useful power is dissipated and the frictional heating results in generation of less liquid for the evaporator. Advances in FLE technology have been made which enable confidence in the use of two-phase impulse turbines for refrigeration and other applications. Performance measurements of FLE expanders and experience in several applications are presented.

Analysis of the power reduction for the above refrigerants and R134A was conducted for a range of variables using proven efficiency of FLE units. The results are presented both for the use of external seals and for the use of canned generators which enable a sealess expander. Increases in the coefficient of performance (COP) were determined and are presented.

A case study of a large ammonia refrigeration system and cogeneration system is presented utilizing the measured FLE efficiencies and canned generators. The electric power generated was 410 kW. The increase in liquid fraction after the flash was 9.9%. An increase in COP of 31% resulted.

This paper substantiates advances in two-phase impulse turbines to enable designers to utilize this type of FLE to improve refrigeration system performance. The results of the analysis are presented in a form to enable estimation of energy savings for the above refrigerants.

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Pages: 10

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Details

  • Original title: Flashing liquid expander energy reduction in refrigeration systems.
  • Record ID : 30024424
  • Languages: English
  • Source: 2018 Purdue Conferences. 17th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2018/07/09

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