Numerical investigation on boiling mechanism under periodic wave pulse heating by lattice Boltzmann

Abstract

The heating power of electronic chips varies with time periodically during operation. The current research on electronic chip heat dissipation mainly focuses on the constant heating boundary conditions, while boiling under continuous periodic pulse heating conditions is scarcely studied. In this paper we employed the lattice Boltzmann model (LBM) to explore the boiling mechanism of the chip under periodic pulse heating. The effects of square-wave pulse heating conditions on boiling heat transfer were explored. The differences under different pulse heating conditions and constant heating conditions were discussed. Firstly, we studied the effects of square-wave pulsed heating conditions on individual boiling nucleation points. The simulation results show that the boiling bubble detaching time gradually increases and the detaching area gradually decreases as the pulse period increases. t T = 100 is a transition pulse period. In comparison with the constant heating conditions, the maximum bubble detaching time is shortened by 10.75% and the maximum bubble detaching area is increased by 64.30% at t T ≤ 100 , while the maximum bubble detaching time is extended by 113.98% and the maximum bubble detaching area is reduced by 81.82% at t T > 100 . Then we studied the boiling heat transfer under the periodic pulse heating with fluid-solid interface conjugate at the bottom, discussed the effects of different pulse factors, and plotted the boiling curves. The results show that the critical heat flux (CHF) under pulse heating conditions is lower than that under constant heating condition. At A = 0.57 T c , t T = 30 , the minimum reduction of CHF 1.76% occurs, while at A = 0.77 T c , t T = 170 , the maximum reduction of CHF 9.94% occurs. In addition, the periodic pulse heating has a strong influence on the bubble motion in the nucleate boiling regime but little influence on the transition boiling regime.