Three micro-finned and two smooth multiport tubes having the same tube width and height with the microfin tubes were tested using R-410A. For the smooth multiport tube, the tube with smaller hydraulic diameter yielded both higher heat transfer coefficients and larger pressure drops. However, for the microfin tube, results suggested that, fin configuration (number of fins per channel, fin height, etc.) has to be considered in addition to hydraulic diameter. The trend of the pressure drop generally followed the hydraulic diameter - smaller hydraulic diameter tube yielded larger pressure drop. Data are compared with the predictions by existing correlations.
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