Enhancement of condensation heat transfer on integral-fin tubes using radiused fin-root fillets

The paper presents the latest experimental data in a continuing investigation into condensation on horizontal, integral-fin tubes. The effect of radiused fillets at the roots of rectangular-section fins has been investigated. Theory suggested that, for a high conductivity tube, fillets should enhance the heat transfer by preventing retention of condensate in the corners at the base of the fins on the upper "unflooded" part of the tube. Three condensing fluids were used, namely, steam, ethylene glycol and R-113. Vapour-side, heat-transfer coefficients were obtained from accurately measured overall heat-transfer coefficients using a modified Wilson plot. Radiused fillets at the fin root were found to increase the vapour-side, heat-transfer coefficient, the enhancing effect increasing with the surface tension of the condensate