STUDY OF HYDRODYNAMICS AND HEAT TRANSFER IN NON-NEWTONIAN LIQUID-GAS TWO-PHASE FLOW IN HORIZONTAL PIPES

Analysis of the reported Newtonian liquid-gas stratified flow data in horizontal circular tubes indicates that an interfacial level gradient (ILG) tends to exist over a wide range of test conditions. ILG reduces the liquid holdup and expands the stratified flow region. Use of the Lockhart-Martinelli parameters (phi)L('2) and (phi)G('2) is invalid in stratified flow when ILG is present because of the unequal pressure gradients in gas and liquid phases. The dimensionless form of the combined one dimensional momentum equations accurately predicts the liquid holdup and the pressure drop for laminar liquid-turbulent gas uniform (no ILG) stratified flow. In future stratified flow experiments, the pressure gradient in both phases should be measured.;Two-phase drag reduction has experimentally been observed in polymer solution-air plug-slug flow in 0.026 and 0.052 m diameter pipes. The Hubbard-Dukler pressure drop model has been extended to non-Newtonian systems. Reasonable agreement between the experiment and the model predictions is obtained. However, more work needs to be done in order to better understand the two-phase drag reduction phenomena. Liquid holdup correlations are developed for both Newtonian and non-Newtonian systems which successfully correlate the holdup over a wide range of parameters.;The Petukhov correlation is found to be better than the Dittus-Boelter correlation in predicting the single phase water heat transfer coefficients. Experimental data obtained in 0.028 and 0.057 m pipes suggest that natural convection is significant in heat transfer to single phase polymer solution flow. During heat transfer experiments for plug-slug flow of both water-air and polymer solution-air systems under constant heat flux conditions, circumferential variation in heat transfer rates has been observed. Two-phase drag reduction can be achieved under heated conditions also.;Non-Newtonian liquid-gas stratified flow data in 0.026 and 0.052 m diameter pipes have been obtained. Interfacial level gradient between the two phases has been observed. The Heywood-Charles model is found to be valid for pseudoplastic liquid-gas uniform stratified flow. Two-phase drag reduction in non-Newtonian systems has not been achieved as the transition to semi-slug flow occurs before the model criteria are reached. Interfacial liquid and gas shear stresses have been compared. A new parameter (SIGMA)('2) is introduced which is a numerical indication of ILG.