A modified convective heat transfer model for heated pipe flow of supercritical carbon dioxide

Supercritical carbon dioxide (sCO2) is a promising working fluid for heat transfer applications. But the complex nature of heat transfer and fluid flow, especially in near critical region hinders the development of heat transfer equipment. In this study, the two-layer model for heat transfer to supercritical fluids used in Ref. [29] is improved by inclusion of the buoyancy and acceleration effects. Results were then calibrated with direct numerical simulation (DNS) data for refinement and were validated with the available experimental data for sCO2. The model is improved qualitatively in terms of capability to predict heat transfer deterioration and quantitatively in terms of reduction in mean relative error. A parametric study is also performed to identify the effects of different variables such as mass flux, pipe diameter and inlet temperature on heat transfer. In the end, the need of further DNS and experiments pertaining to heating and cooling of sCO2 is briefly discussed.