Numerical study on turbulent heat transfer of supercritical n-decane in a square regenerative cooling channel

In order to deeply understand the supercritical turbulent heat transfer characteristics of hydrocarbon fuel in the regenerative cooling process, numerical study on flow and heat transfer of n-decane in a square channel with asymmetric heating imposed on the top exterior channel surface was conducted. After the reliability of the numerical methods was fully validated, effects of two operating parameters, including the inlet temperature and pressure, on the distribution of averaged wall temperature and averaged Nusselt number of the top and side internal channel surfaces, have been discussed in detail. Results indicate that under the compositive conditions of the operational pressure being close to the critical pressure and the bulk fluid temperature being in the vicinity of the pseudo-critical temperature, a pseudo-film boiling effect occurs due to the drastic fluid thermophysical properties variations, and thus leads to a significant heat transfer deterioration phenomenon at the top internal wall. Simultaneously, abnormal distribution of the velocity field appears in the channel cross-sections owing to the imbalance pressure difference, further affects the heat transfer performance of near-wall fluid at the top internal wall. Moreover, the pseudo- film boiling effect forces more heat flux from the top to the side wall surface, so the averaged Nusselt number at the side wall greatly increases, and the largest increase amplitude compared to the normal heat transfer is about 50%. © 2015, Journal of Propulsion Technology. All right reserved.