Swirling effect of jet impingement on heat transfer from a flat surface to CO2 stream

The heat transfer of swirling and conventional CO2–air submerged jet impingement was experimentally studied with thermo-chromic crystal liquid technique. The experiment is focused on the verification of the swirling jet effect on the distribution of the local heat transfer coefficient on the impinged target surface. In the range of Re = 7500–28 300, distributions of the local Nusselt number were obtained and compared with other researcher’s results. It is revealed that the swirling of the jet improves the radial uniformity of the heat transfer significantly. The heat transfer deteriorates in the stagnation region but gets enhanced in the wall jet region. The relative magnitude of the Nusselt number for the swirling and non-swirling jets reverse in the range of r/D = 0.35–0.95. In addition, the swirling jet also enhances the heat transfer in terms of the mean Nusselt number in a larger r/D area.