Numerical Simulation On Heterogeneous Heat And Flow Transfer In Water At Supercritical Pressures In Circular Tubes

Supercritical boiler and supercritical water cooled reactor system is one of the hot spot in development of efficient utilization of clean energy at present and future. Both of the devices are using the characteristics of high heat efficiency when supercritical pressure water in the process of doing work. So, Studying the heat transfer and flow characteristics of supercritical pressure fluid has important practical significance in using supercritical water.Because of the higher of supercritical water pressure, more complicated of Heating conditions and the limited of experimental testing technology, we can’t observe the the flow of the fluid state in flow passage, So we can’t intuitive analysis the effect of supercritical water flow on heat transfer. In recent years, due to the continuous development of computer technology and computational fluid dynamics, it is possibility to use computer numerical simulation of the supercritical flow characteristics. Making it to be a effective methods to study the supercritical fluid flow and heat transfer characteristics.In this paper, using computational fluid dynamics software CFX, numerical analysis of flow and heat transfer characteristic of supercritical water in a pipe by different ways of place. By the analysis of simulation results, it confirms that the physical model and numerical method are reasonable. It analyzed the effect of the heat load and quality state of flow velocity on the flow and heat transfer of supercritical water in pipe when the pipe inclination, vertical and horizontal.Numerical simulation results show that, it can accurately predict supercritical water flow and heat transfer process in the large diameter round tube by using RNG k-ε model, the buoyancy model and water and steam IAPWS-IF97equation in computational fluid dynamics software CFX. Among them, it occur fluid stratified and uneven distribution of wall temperature phenomenon in inclined half cycle heating tube.It forms a secondary flow vortex within the cross section, increasing fluid of fusion, the secondary flow relative intensity is bigger in the inclined full cycle heating tube, but the intensity decreased quickly after the mainstream temperature across the pseudo critical temperature. It is similar to the effect of the heat load and mass flow rate on heat transfer coefficient in vertical pipe flow up and down, and the heat exchanged capacity in vertical is stronger than in horizontal pipe, and the vertical rise flow is worse than vertical flow down in heat transfer. Supercritical water flow in horizontal tube stratification phenomenon is more serious, the supercritical water stratification phenomenon is more serious in horizontal tube, and there are two symmetrical flow vortex along the midperpendicular, the four stages of Fluid heat transfer is obvious, and the effect of secondary flow heat-exchange is remarkable.