Investigation on the Simulation of Turbulent Heat Transfer of Liquid Metal Flow in a Narrow Rectangular Channel

Abstract

Liquid metal has the advantages of high boiling point and strong thermal conductivity and is selected as the coolant for a new generation nuclear system. In addition, the narrow rectangular channel is used in the small reactors or research reactors due to its compact structure and high heat transfer capacity. In order to accurately simulate the turbulent heat transfer of liquid metals in narrow rectangular channels, based on the relevant experimental data, this paper explored suitable numerical simulation methods. First of all, according to the research object, the appropriate experimental data was selected, and the geometric modeling, mesh division, and the mesh independence verification were carried out. It was ensured that the y+ meets the requirements of each turbulence model and wall treatment model. Several typical turbulence models and the wall treatment models were evaluated. For the low Prandtl number fluid such as liquid metal, it is necessary to select a suitable turbulent Prandtl number model in the RANS simulation. The sensitivity of the calculation results to the turbulent Prandtl number was analyzed. Finally, the existing turbulent Prandtl number models were evaluated. The suitable Prt at different Pe was given based on experimental value, so that the turbulent heat transfer of liquid metal in a narrow rectangular channel can be accurately simulated.

Study on the turbulent Prandtl number model for liquid metal flow and heat transfer in a narrow rectangular channel

“…The geometric size and boundary conditions fully refer to the above experimental conditions. In previous studies (Zhang et al, 2022b), after comparison and analysis, it was found that the turbulence model that selected the standard k-epsilon model, combined with the enhanced wall treatment model, was more reasonable. After grid independence analysis, the grid division method is as follows: 300 nodes are evenly divided along the flow direction of the channel.…”

“…In previous work, a global turbulent Prandtl number model suitable for narrow rectangular channels was studied (Zhang et al, 2022b). The DNS calculation results of Kawamura et al (1999) showed that there is a certain relationship between the turbulent Prandtl number and position, so it is necessary to research local turbulent Prandtl number models.…”

“…When Pe is greater than 200, the experimental data are highly consistent with an empirical relationship: Nu 5.58 + 0.0003417Pe 1.29 . (34) Figure 4 shows the comparison of Nu calculated by the proposed local Pr t model with experimental data, empirical values, and the previously proposed global model (Zhang et al, 2022b)…”

“…Referring to Jischa's method of solving the turbulent kinetic energy transport equation based on the turbulent heat flux or turbulent momentum flux, the lead-bismuth turbulent Prandtl number model was derived, and a turbulent Prandtl number zoning theoretical model suitable for lead-bismuth was established. Based on the existing experimental data, Zhang et al (2022b) proposed the appropriate turbulent Prandtl number for different Pe in the simulation of liquid metal flow and heat transfer in the narrow rectangular channel. Chen et al (2013) reviewed and assessed the existing turbulent Prandtl number models and various heat transfer correlations in circular tubes, and they evaluated the applicability of various turbulent Prandtl number models for LBE in the circular tube under boundary conditions of constant heat flux and constant wall temperature.…”

Study on flow and heat transfer characteristics of liquid metal flow in narrow rectangular channels under high heat flux

“…The focus of the analysis is on the impacts of the collocation of various models on the Nusselt number, the flow redistribution phenomena, as well as the difference in flow and heat transfer capacity in channels. Our research team recently conducted research on simulation methods for flow and heat transfer of liquid metal in narrow channels, optimized turbulence models, evaluated the applicability of existing Pr t models (Aoki, 1963;Reynolds, , 1974;Jischa and Rieke, 1979;Cheng and Tak, 2006;Keshmiri et al, 2008), and proposed a local Pr t model and a global Pr t model, respectively (Zhang et al, 2022b). The comparison results showed that the local Pr t model had better applicability to changes in the cross-section of the flow channel.…”