Flow distribution and pressure drop in plate heat exchangers—I U-type arrangement

Abstract

An analytical study is made to calculate the axial velocity and pressure distributions in both the intake and exhaust conduits of plate heat exchangers, the flow distribution in the channels between the plates and the total pressure drop. The analysis shows that there is a general characteristic parameter ( m) for all the plate heat exchangers, which determines the flow behaviour. When m 2 is positive, the channel flow rates will decrease in the direction of the intake stream. When m 2 is negative, the channel flow rates will increase in that direction. In any case, the flow distribution tends to be uniform for low values of m 2 ( ≤ 0.01). If m 2 is kept equal to zero, the flow distribution will be purely uniform. The sign of m 2 may be controlled by the area ratio of the intake and exhaust conduits respectively, its magnitude is affected by the shape and the number of plates. The results show that very low flow rates or even no fluid flow might occur in some of the channels for large positive or large negative values of m 2. The analysis might be useful not only for the proper design of plate heat exchangers but also for many other technical systems with manifold flow distribution and collection problems.