Effects of elevation angle on pool boiling heat transfer of tandem tubes

摘要

The effects of an elevation angle and heat fluxes of a lower tube on saturated pool boiling heat transfer of tandem tubes were investigated experimentally. For the test, two smooth stainless steel tubes of 19 mm diameter and the water at atmospheric pressure were used. The elevation angle was varied from the horizontal position to the vertical position in steps of 15°. The heat flux of the lower tube was changed from 0 to 120 kW/m~2. The increases of the elevation angle and the heat flux of the lower tube enhance heat transfer on the upper tube surface. The bundle effect is clearly observed when the elevation angle is greater than 45° and the heat flux of the lower tube is higher than that of the upper tube.