Experimental results from single-phase refrigerant mixture flow in smooth and micro-coil enhanced meso-channels are presented. R-407C — a mixture of R-32 (23%)/R-125 (25%)/R-134a (52%) — is used as the working fluid and different micro-coils are used in conjunction with two meso-channels (2.78mm and 3.97 mm) to obtain distinct roughness parameters. The flow was varied over a range of Reynolds numbers and experiments were conducted over a heat flux range of 2 to 11 kW/m2. The heat transfer coefficient was found to be dependent on both the heat flux as well as mass flux levels. Results show that heat transfer characteristics are comparable to R-113, and that micro-coil inserts enhanced the heat transfer performance compared to the performance in smooth meso-channels.

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