THE EFFICIENCY OF HEAT-EXCHANGERS WITH ROTATING INNER PIPES

Heat transfer correlations are given in terms of Nusselt, Reynolds and Rossby numbers, the flow mode (parallel or countercurrent) and the in ner rotating-pipe surface area. The effects of these parameters on the pressure drop have also been evaluated. The results are compared with values for conventional systems. Rotation of the helically threaded i nner pipe leads to Nu numbers which may be several times higher than t hose found for a smooth stationary pipe. Although the rotation of the inner pipe caused some increase in pressure drop, this effect was unim portant compared with the improvement in heat-transfer capacity. Copyr ight (C) 1996 Elsevier Science Ltd.