Frictional pressure drop correlation for condensation of refrigerants in microchannel heat exchangers

ABSTRACT

Condensation of HFC refrigerants in microchannel heat exchangers has gained a lot of interest recently due to high heat transfer coefficient, small size, and reduced refrigerant inventory. Additionally, these microchannel heat exchangers can be conveniently used for extensive ranges of temperature and pressure. Even though numerous research studies have been conducted on the two-phase frictional pressure drop for condensing flows in microchannels, the efforts are continuing to get more experimental data that can be used to develop an accurate frictional pressure drop correlation. The present paper uses 384 experimental data points, which the authors have obtained during the condensation of refrigerants, R134a and R410A, inside multiport rectangular microchannels with hydraulic diameters ranging from 0.66 to 1 mm, at average saturation temperatures of 30°C to 40°C, mass fluxes of 200 to 600 kg/m²s, and average vapor qualities ranging from 0.05 to 0.83. A frictional pressure drop correlation for condensing flows through microchannels has been developed, and the resulting correlation agrees with the experimental data with an MAE of 11.58% and predicts the data almost within the 20% error band. Experimental data were compared with 10 well-known frictional pressure drop correlations from the literature, and it was found that these correlations either over-predict or under-predict the data.

KEYWORDS:

• Frictional pressure drop correlation
• refrigerant
• two-phase flow
• microchannel
• condensation

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Acknowledgments

The present work was supported by DST-SERB, India under the Extra Mural Research scheme from 2015 to 2018. The financial support of the Ministry of Education (India) and NIT Jalandhar is also acknowledged.

Disclosure statement

No potential conflict of interest was reported by the author(s).