Effects of coil diameter and pitch on the flow characteristics of alternative refrigerants flowing through adiabatic helical capillary tubes
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Author list: Chingulpitak S., Wongwises S.
Publisher: Elsevier
Publication year: 2010
Journal: International Communications in Heat and Mass Transfer (0735-1933)
Volume number: 37
Issue number: 9
Start page: 1305
End page: 1311
Number of pages: 7
ISSN: 0735-1933
eISSN: 1879-0178
Languages: English-Great Britain (EN-GB)
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Abstract
This paper presents the effects of various geometries of helical capillary tubes on the flow characteristics of alternative refrigerants flowing through adiabatic helical capillary tubes. The theoretical model is based on the conservation of mass, energy and momentum of fluids in the capillary tube. The two-phase flow model developed was based on a homogenous flow assumption. The model was validated by comparing it with the experimental data of published in literature for R-22, particularly various pairs of refrigerants. It was found conventional refrigerants had lower capillary lengths than alternative refrigerants. For all pairs, the numerical results showed that the traditional refrigerants consistently gave lower pressure drops for both single-phase and two-phase flows, which resulted in longer tube lengths. The results show that coil diameter variation (less than 300. mm) for helical capillary tube geometries affected the length of helical capillary tubes. However, pitch variation (more than 300. mm) had no significant effect on the length of helical capillary tubes. This adiabatic helical capillary tube model can be used to integrate system models working with alternative refrigerants for design and optimisation. ฉ 2010 Elsevier Ltd.
Keywords
Coil diameter, Homogeneous flow, Pitch
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