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'Ilhis paper deals with a numerical analysis of the heat transfer behavior in gasketed plate heat exchangers with an odd number of parallel arranged channels (case of half-unsymmetrical channels). The calculations are carried out under varying the number of transfer units, the heat capacity rate ratios and the number of channels for both cuses of co-current and countercurrent flow regimes. A computer program is established to predict the temperature distribution in the channels, the heat exchanger effectiveness and the correction factor of the logarithmic mean temperature dzfference. For this purpose, a com bination of Jacobian iteration method and Gaussian elimination method is applied to solve exactly the system of coupled dzflerential equations governing the temperature distribution in terms of exponential Jirnctions. m e computer program is extended to cover the case of even number of channels (case of complete unsymmetrical channels) for the sake of comparison. Furthermore, deduced formulae for predicting the limit values of the correction factor as a finction of the number of channels and the heat capacity rate ratio are also presented It is shown that both the effectiveness and the correction factor have high values in case of counter-$law specially at equal capacity rates than in case of parallel Jlow. The results indicate also that the correction factor falls slowly with increasing the eflectiveness, the total number of transfer units and the total heat qac i ty rate ratio to reach certain higher limit values in case of countercument flow regimes, while it falls down steeply to approach very low values in case of co-current flow regimes. Manuscript received from Dr. M. Khalil Bassiouny Accepted on : 23 1 6 1 2001 Engineering Research Journal Vol 24,No 3, 2001 Minufiya University, Faculty Of Engineering , Shebien El-Kom , Egypt , ISSN 1110-1180 The rate of heat tram$er with plate units of odci number of channels is more than that with even number in all cases except in units undergoing evaporation or condensation processes we have the other way round at the limit case. This means an d i t i o n of another thermal plate causes a substantial change in the heat transfer characteristics of plate heat exchangers. Keywords= Plate heat dangers, heat transfer, perf~mance, mathematical model, numen'cal methods.

PERFORMANCE OF PLATE HEAT EXCHANGERS WITH ODD NUMBER OF CHANNELS