Numerical study of heat transfer performance and flow characteristic of water in a multi-wound pipe heat exchanger

The main objective of this study was to evaluate the effects of different flow parameters and structure parameters of the heat exchanger on the flow and heat transfer characteristics of the multi-wound pipe heat exchanger by numerical simulation method. The effects of the screw pitch of the tube (S) changed from 3.5 to 9.5 mm and the tube pitch (L) changed from 100 to 500 mm on Nusselt number (Nu) and the friction factor (f) at different Reynolds numbers were investigated. The results showed that Nu enhances with the decline of L, while f increases significantly with decreasing L, and the performance evaluation criterion (PEC) declines with L decreasing. Within the research range, when S is about 6.5 mm, Nu reaches a minimum of 66.15. Besides, the overall performance of the heat exchanger was compared with that of the straight pipe heat exchanger. The results showed that the overall performance of the novel double-pipe heat exchanger was better than that of the straight pipe heat exchanger, the maximum value of the PEC could reach up to 1.3. The correlations of the Nu and f were developed according to the simulated data, which could provide guidance for designing a heat exchanger.