HEAT TRANSFER STUDIES IN A VERTICAL TUBE THERMOSYPHON

Abstract

Prediction of Incipient Point of Boiling (IP U) and Inlet Liquid Velocity in a vertical tube thermosiphon used as a reboiler eases its performance evaluation with respect to its hydrodynamics and heat transfer aspects which are highly interacting. Several empirical and semi-empirical correlations have been proposed for prediction of IPH utilizing heat flux, inlet degree of subcooling, submergence, and pertinent physical properties as parameters. The inlet liquid velocity to the reboiler, in most of the studies, have been based on energy balance calculations using thermal equilibrium model. The present work is an attempt to compare the validity of proposed different correlations/methods [1,4,44] used for the prediction of incipient point of boiling and inlet liquid velocity, using experimental data available in literature El] for five different systems. Utilizing the proposed model of Sarma et al.C443, a computer program was developed for the evaluation of incipient point of boiling and inlet liquid velocity, based on the experimental data of Agarwal El]. For the same experimental data, these variables were also calculated using purely empirical correlations proposed by Agarwal El] and Ali et al.E43. Finally, the comparison of results obtained from three different studies were done and explained in terms of imposed operating parameters. ii