Flow and heat transfer characteristics of coal-based rocket kerosene in mini-tube with ultra-high parameters

Coal-based rocket kerosene as a new aerospace fuel and active regenerative cooling technology coolant, in order to make it widely used in engineering, the flow and heat transfer experiments were carried out for the first time under the actual working parameters of the rocket engine. The effects of heat flux (2–33.8 MW·m−2), mass flow rate (8000–48,000 kg·m−2·s−1), and inlet temperature (323–473 K) were investigated. The results indicated that as the heat flux increases, the total pressure drop and friction factor first decreased and then increased. With Reynolds numbers 3.1 × 104 and 7.6 × 104 as the boundary, the flow was in the hydraulic smooth tube region, transition region and turbulence rough tube region respectively. Increasing the inlet temperature can inhibit the heat transfer deterioration caused by the entrance effect. Higher heat flux can be maintained by increasing flow rate. When the wall temperature just exceeded the pseudo-critical temperature, the rate at which the heat transfer coefficient increased with the increase of heat flux became higher. Considering the influence of various parameters to modify classic correlation, and using the probability density function to modify the thermophysical properties of coal-based rocket kerosene, a new Nusselt number correlation was proposed. •Flow and heat transfer characteristics of coal-based rocket kerosene under ultra-high parameters were studied.•The probability density function was introduced to improve the accuracy of heat transfer prediction.•Effects of experimental parameters on flow and heat transfer characteristics were discussed.•A well-predicted empirical correlation with the Nusselt number was proposed.