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Development of an accumulator liquid-level estimator to enable zero-superheat control and active charge management in vapor-compression systems.

Author(s) : LIU H., CAI J.

Type of article: IJR article

Summary

Vapor-compression system efficiency increases with reduced superheat but excessively low superheat settings may cause wet compression and jeopardize reliable system operations. Accumulators are commonly used to intercept liquid refrigerant before it reaches the compressor and can also be used as a refrigerant reservoir to assist active charge management. For zero-superheat and active charge control, accurate measurement or estimation of the accumulator liquid level is required. This paper presents an accumulator liquid level estimation approach based on a nonlinear state observer combined with a gray-box dynamic model of the evaporator and accumulator. This approach affords virtual detection of the liquid level in real-time from refrigerant pressure and temperature measurements, which are readily available in modern vapor-compression systems, and supports zero-superheat and dynamic charge control to maximize system efficiency. Both numerical and experimental tests of the proposed liquid level estimation and charge control strategies were carried out with a 3-ton variable-speed heat pump. The tests have demonstrated the accuracy of the accumulator liquid level estimator and shown that the zero-superheat and active charge control strategy could improve the system efficiency by up to 10.5%.

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Pages: 264-274

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Details

  • Original title: Development of an accumulator liquid-level estimator to enable zero-superheat control and active charge management in vapor-compression systems.
  • Record ID : 30030524
  • Languages: English
  • Subject: Technology
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 144
  • Publication date: 2022/12
  • DOI: http://dx.doi.org/10.1016/j.ijrefrig.2022.08.003

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