Critical Heat Flux Analysis With Single-Side Heated Swirl Tube Under Subcooled Flow Boiling Conditions

Abstract

Critical heat flux (CHF) is regarded as one of the major problems in cooling system design. Specifically, because the tokamak is loaded with heat flux of several megawatts per square meter, carefully considering the CHF is crucial. This study analyzes the subcooled flow boiling CHF of the swirl tube under one-side high-heat load condition. The CHF parametric analysis results indicate that smaller swirl tape twist ratios yield higher swirl flows. As the subcooling increases, the CHF increases because the vapor inside the channel condensates more rapidly due to the lower bulk temperature. And the increase of the mass flow rate also increases the CHF because it enhances the forced convection heat-transfer performance. However, the CHF slightly decreases as the latent heat decreases with the increase in pressure. The assessment of existing CHF subcooled flow boiling indicates that the formulated correlations based on the smooth tube mainly tend to yield under-predicted results. However, most of the correlations developed according to the swirl tube tend to over-predict. Among these, the Nariai and Inasaka swirl CHF correlation has the lowest error rate; nevertheless, it tends to slightly under-predict results because of the difference between uniform and one-side heating. Accordingly, a new modified Nariai and Inasaka correlation is formulated using a Python code and artificial intelligence technology to reflect the one-side heating effect.