Heat transfer deterioration in vertical sCO2 cooling in 3 mm tube

The steady behavior of the supercritical carbon dioxide natural circulation loop

“…A possible cause for the above is an under-prediction of the viscous losses in the flow in the vicinity of the heat transfer equipment of the setup. As qualitatively described in the work of Wahl et al [17], the alignment of the direction of both forcedand natural convection can result in near-wall velocities that are greater than in an adiabatic setting. For flows of supercritical media, this is the case for downward cooled and upward heated pipe flows.…”

Selected papers from the 5th European conference on supercritical CO2 for energy systems

“…Wahl et al [1] experimentally investigated the cooling heat transfer coefficient in a 3 mm diameter tube with vertical flow orientation using the mixed convection criterion to evaluate the heat transfer deterioration. The results showed an influence of mixed convection at a stepwise reduction of the mass flux.…”