Process intensification for the development of compact heat exchanger with small footprint is greatest challenge of the heat exchanger technology today. In the present study, a heat transfer device, coiled flow inverter (CFI) is revamped for the better heat transfer efficiency with a smaller footprint. The proposed small foot-print coiled flow inverter (SFCFI) is fabricated by bending of helical coil at 90° with equal arm lengths before and after the bend with variable curvature radius. In integration to the improved centrifugal force due to variable curvature, the SFCFI additionally offers a complete 90 flow inversion caused by each 90 bend, which results in higher radial mixing and heat transfer. The velocity and temperature flow fields depict the improved radial mixing under the laminar flow regime for the Dean number ranges from 8 to 1581. The performance of existing CFI of same heat transfer area (0.17 m2) was studied and compared with the novel SFCFI device. The results suggest, the proposed SFCFI device provides three-fold heat transfer enhancement as compared to the straight tube of same heat transfer area at Dean number 400. Additionally, heat transfer coefficient in SFCFI enhanced by 48 % as compared to helical coil. Furthermore, SFCFI provides 18 % higher value of Nusselt number as compared to the CFI. The reason for improved heat transfer may be the enhanced centrifugal force due to additional curvature effect provided in each arm of SFCFI in the plane of vortex formation. It was interesting to note that the proposed device provides 11 % lower pressure drop as compared to the CFI. The present study may aids to the development of a novel design of compact coiled and small footprint heat transfer device.
Papers presented at the 13th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Portoroz, Slovenia on 17-19 July 2017 .