Abstract
M.Ing.
The two-phase heat transfer and pressure drop coefficients of pure R22, the mixtures 80% R22/20% R142b and 60% R22/40% R142b within a helix coiled tube-in-tube heat exchanger are presented in this study. Experimental data was presented in the form of average heat transfer coefficient and two-phase friction factor. Comparison of the experimental heat transfer coefficient with the predicted values obtained from the Jung, Murata and Thome methods confirms a good accuracy of these methods although they were developed for the straight tube-in-tube heat exchanger. The predicted two-phase friction factor values obtained from the Martinelli correlation deviates more than 50% from the experimental results for the three working fluids. This confirms that the Martinelli method is not accurate enough for the helix coiled tube-in-tube heat exchanger.