Two-phase frictional pressure drop of R134a and R410A condensing inside multiport rectangular microchannels with different aspect ratio

ABSTRACT

This paper presents the experimental result of R134a and R410A (without lubricating oil) pressure drop condensing along three parallel, rectangular microchannels with the aspect ratio varying from 0.5 to 1 and D_h from 0.66 to 1 mm, while maintaining the constant channel depth (1 mm), base area (63 cm²), and channel length (30 cm). All the factors accountable for change in pressure through microchannels were determined for all the configurations separately, i.e. contraction, expansion, frictional, and deceleration. Two distinct saturation temperatures were used in the present experimental study, with vapor quality 0.05 < x < 0.83 and mass flux 200 < G < 600 kg/m²s. Frictional pressure drop estimations were found to be greater than 90% of overall pressure drop. Condensation pressure drop for both the refrigerants increases directly with increasing mass flux and vapor quality, whereas it decreases with the channel aspect ratio and saturation temperature increase. At constant mass flux, R134a has a higher condensation pressure drop than R410A, and the highest value of condensation pressure drop was obtained in MC-1 having an aspect ratio of 0.5, followed by MC-2 and MC-3 having aspect ratios of 0.7 and 1, respectively.

KEYWORDS:

• Channel aspect ratio
• condensation
• frictional pressure drop
• microchannel
• two-phase flow

Disclosure statement

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

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Additional information

Funding

The study reported in this research article was funded by DST-SERB India research project funded under the EMR scheme in the period 2015-2021.