Natural convection mass and heat transfer at a horizontal spiral tube heat exchanger

The free convection mass and heat transfer (by analogy) behavior of a spiral tube was studied by an electrochemical technique which involved measuring the limiting current of the cathodic deposition of copper from acidified CuSO4. Variables studied were tube diameter (d), tube separation (s) and physical properties of the solution. The data were correlated for the conditions 1.4 x 10(6) < (Sc . Gr) < 5.74 x 10(8) by the equation: Sh = 0.01 (Sc . Gr)(0.29) (s/d)(-0.5). A comparison of the present data with the data previously obtained for helical tubes and horizontal tubes was made. The importance of the present work for predicting the rate of diffusion controlled metal finishing processes which may be performed on the spiral tube during fabrication such as electroplating, etching, electroless plating and electropolishing was highlighted. Also potential application of the present data for predicting the rate of heat transfer at the outer surface of the spiral tube heat exchanger under stagnant conditions or under weak forced convection where natural convection contributes a great deal to the rate of transfer was pointed out. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.