Film Boiling Conjugate Heat Transfer during Immersion Quenching

Abstract

Boiling conjugate heat transfer is an active field of research encountered in several industries, including metallurgy, power generation and electronics. This paper presents a computational fluid dynamics approach capable of accurately modelling the heat transfer and flow phenomena during immersion quenching: a process in which a hot solid is immersed into a liquid, leading to sudden boiling at the solid–liquid interface. The adopted methodology allows us to couple solid and fluid regions with very different physics, using partitioned coupling. The energy equation describes the solid, while the Eulerian two-fluid modelling approach governs the fluid’s behaviour. We focus on a film boiling heat transfer regime, yet also consider natural convection, nucleate and transition boiling. A detailed overview of the methodology is given, including an analytical description of the conjugate heat transfer between all three phases. The latter leads to the derivation of a fluid temperature and Biot number, considering both fluid phases. These are then employed to assess the solver’s behaviour. In comparison with previous research, additional heat transfer regimes, extra interfacial forces and separate energy equations for each fluid phase, including phase change at their interface, are employed. Finally, the validation of the computational approach is conducted against published experimental and numerical results.

Analysis of the Causes of the Emergency Shutdown of Natural Gas-Fired Water Peak Boilers at the Large Municipal Combined Heat and Power Plant

“…If the heat flow rate on the heated surface of the pipe becomes too high, nucleate boiling turns into film boiling [28,29]. This leads to the formation of a vapor layer across the entire inner surface of the tube, insulating it from the coolant.…”

“…The model, which incorporated a thin vapor layer, merely highlighted the pipes' incapability to cool properly, resulting in overheating and eventual failure. If the heat flow rate on the heated surface of the pipe becomes too high, nucleate boiling turns into film boiling [28,29]. This leads to the formation of a vapor layer across the entire inner surface of the tube, insulating it from the coolant.…”