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Flow boiling heat transfer and pressure drop of R245fa inside horizontal 1.62 mm and 2.43 mm tubes under hypergravity.

Author(s) : LI C., FANG X., LUO Z., DAI Q.

Type of article: IJR article

Summary

Experimental investigation of refrigerant R245fa flowing inside horizontal 1.62 mm and 2.43 mm tubes under different gravity levels were carried out to study effects of gravity level, tube diameter, and heat flux on flow boiling heat transfer and pressure drop. The experimental parameter range is the mass flux of 351 kg m−2 s−1, heat fluxes of 32 and 64 kW m−2, system pressure of 217.8 kPa, average vapor qualities of 0.007–0.915, and gravity levels from 1 to 2.77 g. The flow boiling heat transfer and pressure drop of R245fa in different tube sizes under hypergravity are first reported. The results show that the heat transfer was enhanced significantly for both tubes when the turntable starts to rotate (from 1 to 1.04 g), which attributes to the fluid disturbance and secondary flow generated by the Coriolis force. With the further increase in hypergravity (from 1.04 to 2.77 g), the heat transfer coefficient may be enhanced or deteriorated. The reason is that the effect of centripetal acceleration, which increases much faster with increasing rotational speed of the turntable than the Coriolis acceleration, offsets the contributions made by the Coriolis force. The effect of heat flux on flow boiling heat transfer interacts with other factors. It is possible for the heat transfer coefficient at lower heat flux to be greater than that at higher heat flux due to the compound flow and heat transfer mechanisms. Under hypergravity, the pressure drop in the small tube is slightly larger than that under normal gravity, while in the large tube it may be smaller than that under normal gravity. The experimental data are compared with the predictions of existing correlations of saturated flow boiling heat transfer and frictional pressure drop, and those which can provide the most agreeable predictions are identified.

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Pages: 96-107

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Details

  • Original title: Flow boiling heat transfer and pressure drop of R245fa inside horizontal 1.62 mm and 2.43 mm tubes under hypergravity.
  • Record ID : 30031148
  • Languages: English
  • Subject: Technology
  • Source: International Journal of Refrigeration - Revue Internationale du Froid - vol. 148
  • Publication date: 2023/04
  • DOI: http://dx.doi.org/10.1016/j.ijrefrig.2023.01.004

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