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Konferensartikel

Experimental comparison of the dynamic evaortor response using homogeneous and slip flow modeling

Martin Ryhl Kærn
Technical University of Denmark, Department of Mechanical Engineering, Denmark \ Danfoss A/S, Refrigeration and Air-Conditioning, Denmark

Brian Elmegaard
Technical University of Denmark, Department of Mechanical Engineering, Denmark

Danfoss A/S, Refrigeration and Air-Conditioning, Denmark

Linköping Electronic Conference Proceedings 63:28, s. 246-255

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ISBN: 978-91-7393-096-3

ISSN: 1650-3686 (tryckt), 1650-3740 (online)

Abstract

The dynamic response from an evaporator is important for control of refrigeration and air-conditioning systems. Essentially; the prediction of refrigerant charge inside the evaporator is crucial for the dynamic behavior. The prediction of refrigerant charge follows from suitable void fraction correlations from the literature. A chosen set of void fraction correlations (slip flow) and the assumption of homogeneous flow will be investigated in this paper and compared to experiments on a simple coaxial type evaporator. The numerical model of the evaporator is a dynamic distributed mixture model; where different void fraction correlations can be applied. It is shown that the dynamic response of the homogeneous model is too fast; whereas the slip flow models agree well with the experiments. Another difference is that the charge prediction of the homogeneous model is approximately 2-3 times less than the slip flow models.

Nyckelord

refrigeration; air-conditioning; evaporator; two-phase flow; modeling; Modelica; transient; dynamic; simulation

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