Experimental study on S-shaped fins for high heat flux cooling with supercritical CO2

High heat fluxes from nuclear fusion pose a challenge for heat exchange. Supercritical CO2 and micro-channel heat exchangers offer a way to solve this challenge, however heat transfer correlations for supercritical fluids do not necessarily carry over to higher heat fluxes. This experimental study investigates a promising geometry of S-Shaped fin microchannel heat exchangers at heat fluxes up to 1MW/m2, 10 times hotter than previously tested in the literature. A high temperature test section was heated under laser diodes to represent the heat flux from fusion. A conjugate CFD study was performed, but this did not match the experimental temperatures well. To remedy this, an FE model was made, in which the heat transfer profile from CFD was scaled by a constant factor, giving better agreement with experimental temperatures. A thermal resistance network was developed, and the unknown heat transfer coefficient was varied to minimise the error between the predicted temperatures and experimental ones. This gave heat transfer coefficients that matched well with correlations in the literature, at these elevated heat fluxes. This implies that the design could be used effectively for the heat fluxes found in the blanket of a fusion reactor.