Condensation heat transfer of R134a and R410A in multiport rectangular microchannels with different aspect ratio

Experiments were performed to investigate the heat transfer coefficient (HTC) of R134a and R410A condensing in rectangular, parallel microchannels with hydraulic diameter [Dh] between 0.66 and 1 mm. Three microchannels MC-1, MC-2, and MC-3 with aspect ratios of 0.5, 0.7, and 1 respectively, were selected while keeping the constant channel length (30 cm), base area (63 cm2), and channel depth (1 mm). Tests were conducted for mass flux 200 < G < 600 kg/m2s, vapour quality 0.05 < x < 0.83, and saturation temperatures of 30 and 40 degrees C. It was observed that as the refrigerant mass flux and vapour quality increased, the condensation HTC of R134a and R410A increased, but the same decreased as the saturation temperature increased. Data demonstrates that R134a has a higher condensation HTC than R410A, with the maximum value of condensation HTC attained in MC-1 with an aspect ratio of 0.5, followed by MC-2 and MC-3 with an aspect ratio of 0.7 and 1, respectively. Data received from the current experimental research was compared to existing condensation HTC correlations developed for conventional channels and mini/micro channels. A novel correlation has also been proposed for condensation HTC in microchannels, and the resulting correlation agreed to the experimental data with an MAE of 5.40% and predicts the data almost within the 20% error band.