Mathematical modelling of cross-flow heat exchangers

The models of cross-flow heat exchangers are n-channel systems through which two heat-exchanging media are flowing, the cross-sections of the channels being rectangular. Based on the pattern of channel interconnections and on the character of cross-mixing of the media, nine basic variants can be distinguished. Mathematical models of these variants are given in the form of differential equations, and the methods of solving the equations are proposed, leading to the temperature profiles and the values of the outlet temperatures in the exchangers. Consequently, a possibility is provided to calculate the mean heat transfer driving force for each of the cases analysed and to give (in analytical, graphical or tabular form) the value of the ratio of this force to the logarithmic mean temperature difference (the so-called 'counter-current correction').