A general correlation for critical heat flux in horizontal channels

While horizontal channels are widely used in heat exchangers involving boiling, no well-verified method for predicting CHF (critical heat flux) in them is available. Presented here is a general correlation for CHF in horizontal channels. It provides the ratio of CHF in horizontal channels to CHF in vertical channels. It has been verified with a very wide range of test data that include 10 fluids (water, refrigerants, and hydrocarbons) in single channels and multi-channels of diameters 0.13-24.3 mm, reduced pressures from 0.005 to 0.9, mass flux from 20 to 11,390 kg/m(2)s, inlet qualities from -1.05 to 0.72, and critical qualities from -0.2 to 0.99. Data include uniform and non-uniform heat fluxes. With CHF for vertical channels calculated by the author's published correlation, it predicts 878 data points from 39 data sets from 18 sources with a mean absolute deviation of only 15.4%. The new correlation is presented and other predictive techniques are also discussed. (C) 2015 Elsevier Ltd and International Institute of Refrigeration. All rights reserved.