Experimental study of the flow and heat transfer characteristics of thin water films on a large diameter horizontal tube

Heat transfer coefficients from a single, steam heated, large diameter aluminum tube to thin water films, together with water film thicknesses and the distribution of heat flux around the tube periphery were measured. The tube used had a nominal diameter of 127 mm. Cooling water temperatures were varied from 17°C to 50°C and cooling water film Reynolds numbers were varied from Rer = 1150 to Rer = 5250. Four different water flow rates were chosen and for each water flow rate the temperature of cooling water was raised in steps. Heat transfer coefficients were calculated from the weight of steam condensed in a certain period of time. Temperature distribution around the periphery of the tube was measured by thermocouples embedded at intervals of 15°. Dial calipers were used for measuring water film thicknesses; and heat flux distribution around the tube periphery was measured using heat flux meters embedded at intervals of 45°. The experimentation was used for the verification of theoretical equations for the prediction of heat transfer coefficients and film thicknesses developed earlier at Carleton University. While the scope of the experiments and equations is general, typical CANDU reactor conditions were kept in mind.