Impact of liquid coolant subcooling on boiling heat transfer and dryout in heat-generating porous media

TL;DR

This study investigates how coolant subcooling affects boiling heat transfer and dryout in heat-generating porous media, revealing that increased subcooling enhances thermal energy removal and shifts dryout zones inward.

Contribution

It provides a detailed computational analysis of coolant subcooling effects on boiling and dryout in porous media with internal heat generation, an area with limited prior research.

Findings

Higher coolant subcooling increases the power density needed for the same temperature rise.

Subcooling substantially enhances the thermal energy removal capacity.

Dryout zones shift inward with increased subcooling.

Abstract

The present article discusses the impact of liquid coolant subcooling on multiphase fluid flow and boiling heat transfer in porous media with internal heat generation. Although extremely relevant and important, only limited studies are available in the open literature on the effects of coolant subcooling in heat-generating porous media and hence, this requires a detailed analysis. The analysis is carried out using a developed computational model of multiphase fluid flow through clear fluid and porous media considering the relevant heat transfer and mass transfer phenomena. Results suggest that the qualitative nature of boiling heat transfer from the heat-generating porous body, with subcooled coolants, remain similar to that observed with a saturated coolant. Quantitative differences are, however, observed as a result of solid-liquid convective heat transfer, and competing mechanisms of boiling and condensation heat transfer, when subcooled liquid coolant is present. It is observed that a substantially larger heating power density is required - as coolant subcooling is increased - for achieving the same temperature rise in the porous body. Dryout power density at different coolant subcooling is also observed to follow a similar trend. The thermal energy removal limit is, hence, observed to be substantially enhanced in presence of subcooled coolants. Further, the dryout region within the porous body is observed to gradually shift towards its interior as the coolant subcooling is increased.