Abstract
Heat transfer rates in a single tube natural circulation evaporator were studied for a range of inlet velocities and heat fluxes, distilled water being used as the feed throughout. Three tube diameters were used, 1/2", 2", and 4" these being regarded as covering an industrial range. The tubes were divided into six sections, and the heat transferred to each, measured separately. Tube wall, and axial stream temperatures were measured at 18 positions along the tube length. From these and a knowledge of the local heat fluxes, values of the boiling side heat transfer coefficient for each section were obtained. The heat transfer results from all tubes, and boiling lengths from to 9 feet were correlated by means of a dimension less equation viz. [mathematical equation]. This applies to bulk boiling regions in an evaporator tube. An equation was also produced for the calculation of pressure losses in the two phase region viz. [mathematical equation] This utilised data from all three tubes and lengths from 3 to 9 feet.