Experimental study on forced convective heat transfer of supercritical carbon dioxide in a horizontal circular tube under high heat flux and low mass flux conditions

Abstract

This study focuses on the convective heat transfer characteristics of supercritical carbon dioxide flowing in a horizontal circular tube under high heat flux and low mass flux conditions. The influences of thermophysical property, buoyancy effect, and thermal acceleration on the heat transfer characteristics are discussed. The parameters are as follows: system pressure is 7.6-8.4 MPa, mass flux is 400-500 kg/m 2 s, heat flux is 30-200 kW/m 2 , fluid temperature is 20°C 262°C, and Reynolds number is 1.23 3 10 4 to 4.3 3 10 4 . The wall temperature and heat transfer coefficient of supercritical carbon dioxide are obtained. The results show that, under the condition of high heat flux and low mass flux, heat transfer deterioration would happen, in which thermophysical property and buoyancy effect are the main factors. When the pressure is 7.6 MPa, the buoyancy factor is greater than 10 23 in the whole heat transfer area, and the buoyancy effect cannot be ignored, while the thermal acceleration factor is 9.5 3 10 28 to 4 3 10 26 and the effect of thermal acceleration can be negligible. The experimental data are compared with the predictions using seven empirical correlations, in which the Liao-Zhao correlation shows the best performance.

Effect of heat flux and mass flux on the heat transfer characteristics of supercritical carbon dioxide for a vertically downward flow using computational fluid dynamics and artificial neural networks

“…Properties of supercritical fluids vary drastically near the critical point. These property variations can be incorporated into the ANSYS FLUENT by establishing an interface between FLUENT and NIST REFPROP [12] database. Stainless steel 316L properties are used for the solid domain.…”

“…Ye et al [11] have used artificial neural networks (ANN) to develop a correlation to predict heat transfer coefficient (h), with an absolute percentage error of 0.97%, but neglecting the significant effects of buoyancy and flow acceleration in their model, restricts the applicability of the proposed model in buoyancy-driven flows. Wang et al [12] conducted parametric studies on sCO 2 at low mass fluxes and at high heat fluxes in a horizontal tube where the mass flux ranges from 400-500 kg/m 2 s and heat flux ranges from 30-200 kW/m 2 . The studies highlight the main reason for heat transfer deterioration as the buoyancy difference between the top wall and bottom wall.…”

A Review of Heat Transfer of Co2 at Supercritical Pressure in the Critical and Pseudo-Critical Region

“…The developed very compact and higher-integrity core is ideally suited to high pressure and high temperature applications, particularly for CO2 systems [49,50]. Kruizenga et al [30,31], Li et al [32] and Ren et al [38] investigated the heat transfer and pressure drop of CO2 within PCHEs. Comparison of experimental data with standard correlations for circular tubes showed significant differences near the pseudocritical temperature region, while modelling predictions using computational fluid dynamics (CFD) and the SST k-ɛ turbulence model showed good agreement between experimental and simulation results of heat transfer near the pseudo-critical region.…”