A HEAT TRANSFER MODEL TO PREDICT SWIRL FLOW CONDENSING HEAT TRANSFER IN A HORIZONTAL TUBE

Abstract

The performance of heat exchange equipment can be considerably improved by using heat transfer augmentation techniques. Finning of heat transfer surface area is one of the important techniques which is presently used for improving the performance. Though the experimental data on the performance of such equipment are available, analytical equations to calculate the heat transfer rates in such systems are scantily available. This work attempts to develop a prediction equation for finding the heat transfer coefficients in finned tubes for condensation of R-22 and steam. Schlager et al. [10] data on R-22 and Royal and Bergles [11] data on steam have been taken as the experimental values for the development of the model. The plain flow experimental values have been compared with the vai,ues predicted by Azer's plain flow correlation [12]. The swirl flow experimental values of R-22 and steam have also been compared with the swirl flow Azer's correlation [12] and three other's correlations [12]. In all the cases a poor prediction of the experimental data were'noted. Two correlations, based on empirical and physical behaviour of the phenomena, have been developed to predict the swirl flow heat transfer coefficients for R-22 and steam. These are given by the following equations . (iv) Empirical Correlation : h -0.1863 -0.9978 h 0 . 267x1026 [Rem] [r1J Q D AS -0.103x1@3 ...(4.2.5) (D-2H )2 Ap Physical Correlation . h -0.1663 @.166x1 -0.1.667 hs = P .14013x1@2 CF Ref] frr1]: [a E) 0 ...(4.2.6) The above two correlations predict the swirl flow values within + 13percent