Experimental Study of Boiling Heat Transfer in a Thin Film on Horizontal Tube.(Dept.M)

Abstract

Boiling heat transfer process in thin film on horizontal tubes is, experimentally. investigated . The effect of the operating parameters on the boiling heat transfer coefficient is studied and accordingly the optimum operating conditions is deduced. The operating parameters such as heat flux. mass flow rate, feed water height and test tube configuration are considered. To carry out this experimental work, a suitable test rig hag been constructed such that the effect of these operating parameters can be investigated. The test tube is heated by & heating steam flowing inside it in a stratified flow pattern. A perforated distributer sprays a thin water film on a test tube forming dripping flow, The considered ranges of the investigated parameters are heat flux from 20 to 300 kw/m2 , mass flow rate from 0.02 to 0,1 kg/m.s. height to diameter ratio from 0.1 to 1 , and tube diameter from 12.2 to 38 mm. The effect of test tube configuration in case of circular , horizontal elongated oval shape and vertical elongated oval shape is studied. It is found that the heat transfer coefficient in case of circular cross sectional tube is the best one specially , compared with horizontal elongated oval shape.