[Paper Review] Hybrid phase-change lattice Boltzmann simulation of the bubble nucleation and different boiling regimes of conjugate boiling heat transfer

Wandong Zhao, Jianhan Liang+3 more|arXiv (Cornell University)|Nov 25, 2019

Lattice Boltzmann Simulation Studies67 references4 citations

TL;DR

This study develops a hybrid phase-change lattice Boltzmann method (LBM) to simulate bubble nucleation and multiple boiling regimes in conjugate heat transfer systems. It demonstrates that conjugate heat transfer significantly alters boiling dynamics, with the model accurately reproducing the critical heat flux and capturing complex behaviors like fluctuating heat flux and transverse bubble motion during transition boiling.

ABSTRACT

Pool boiling characteristics in two computational domains with and without considering conjugate heat transfer (CHT) were numerically simulated by an improved hybrid pseudopotential phase-change lattice Boltzmann method (LBM). The effects of constant temperature boundary condition (BC) with nucleate spots and fluctuant temperature on the boiling process were investigated in detail. It was found that for the computational domain without CHT, the treatment of constant temperature BC with nucleate spots is quite easier to produce film boiling than the temperature BC with small fluctuation. However, the results would be the opposite for the case with CHT. The entire boiling curve from the onset of nucleate boiling to fully developed film boiling was presented using the computational domain considering CHT and constant temperature BC with nucleate spots. The simulated critical heat flux showed an excellent agreement with the existing analytical solutions. Hence, the current hybrid phase-change LBM was quantitatively verified. The highly fluctuant heat flux occurred in the CHF and transition boiling as well as the transverse movement of the bubbles had been observed. Furthermore, the thermal responses inside the heater and heat transfer mechanism in different boiling patterns were also comprehensively studied.

Motivation & Objective

• To investigate the influence of conjugate heat transfer (CHT) on boiling heat transfer mechanisms in pool boiling systems.
• To examine how different temperature boundary conditions—constant with nucleation spots versus fluctuating—affect the onset and progression of boiling regimes.
• To validate the hybrid phase-change LBM model against analytical solutions for critical heat flux (CHF).
• To analyze thermal responses within the heater and heat transfer mechanisms across nucleate, transition, and film boiling regimes.

Proposed method

• An improved hybrid pseudopotential phase-change lattice Boltzmann method (LBM) is employed to simulate multiphase flow and phase change in boiling systems.
• The method couples the lattice Boltzmann equation for fluid dynamics with a pseudopotential model to capture phase transition and interfacial dynamics.
• Conjugate heat transfer is modeled by coupling the fluid domain with a solid heater domain, accounting for thermal resistance and temperature distribution in the solid.
• Two computational domains are compared: one with and one without CHT, under identical boundary conditions to isolate CHT effects.
• Constant temperature boundary conditions with nucleation spots and those with small thermal fluctuations are applied to assess their impact on boiling regime transitions.
• The model is validated by comparing simulated critical heat flux (CHF) against analytical solutions, confirming quantitative accuracy.

Experimental results

Research questions

• RQ1 How does conjugate heat transfer affect the transition from nucleate boiling to film boiling?
• RQ2 What is the impact of temperature boundary condition type—constant with nucleation spots versus fluctuating—on boiling regime development?
• RQ3 Can the hybrid phase-change LBM accurately predict the critical heat flux in pool boiling?
• RQ4 How do thermal responses within the heater and heat flux fluctuations vary across different boiling regimes?
• RQ5 What are the dynamic behaviors of bubbles, such as transverse movement, during transition boiling?

Key findings

• The inclusion of conjugate heat transfer (CHT) reverses the trend observed in non-CHT simulations: CHT suppresses film boiling under constant temperature conditions with nucleation spots.
• The entire boiling curve—from onset of nucleate boiling to fully developed film boiling—was successfully simulated in the CHT case with constant temperature boundary conditions and nucleation spots.
• Simulated critical heat flux (CHF) showed excellent agreement with analytical solutions, validating the quantitative accuracy of the hybrid phase-change LBM.
• Highly fluctuating heat flux and transverse bubble motion were observed during transition boiling and near CHF, indicating strong unsteady thermal and hydrodynamic coupling.
• Thermal responses within the heater revealed significant temperature gradients and time-dependent variations, especially near CHF, highlighting the importance of solid-phase thermal inertia.
• The study demonstrates that CHT fundamentally alters boiling dynamics, particularly in the transition and film boiling regimes, by modifying heat flux distribution and bubble departure behavior.