Condensation heat transfer and flow pattern inside a herringbone-type micro-fin tube

Condensation heat transfer and pressure drop of R410A and R22 in a newly proposed herringbone-type micro-fin tube are measured and compared to those of a helical micro-fin tube and a smooth tube. The heat transfer coefficient of the herringbone micro-fin tube is higher than that of the helical micro-fin tube in the high mass velocity region, while it has slightly lower value in the low mass velocity region. Pressure drop of the herringbone micro-fin tube is, however, higher than that of the helical micro-fin tube. Flow patterns of the herringbone micro-fin tube are observed and the heat transfer enhancement mechanism is discussed. The heat transfer coefficient and pressure drop of the helical micro-fin tube is predicted well with previously proposed correlations, while those of the herringbone-type micro-fin tube has higher value than the predicted values. Preliminary correlations for the pressure drop and the heat transfer coefficient are proposed for the herringbone micro-fin tube.