Pool boiling enhancement through induced vibrations in the liquid pool due to moving solid bodies - A numerical study using lattice Boltzmann method (LBM)

Abstract

This study uses a single-component multiphase multiple relaxation time-based lattice Boltzmann method to study the effect of induced vibrations in a liquid pool for enhancement of pool boiling heat transfer. The ebullition cycles of bubbles from a single and multiple nucleation sites with different nucleation densities are modeled in a liquid pool in quiescent condition (SQ) and in fluid motion with the aid of the moving solid boundaries (SMSB), in a periodic motion with a particular frequency f MSB∗ and amplitude A MSB*. The numerical results throw insight into the bubble dynamics, viz., nucleation, growth, and departure in both of these media. It is found that the induced vibrations in the liquid pool lead to a higher growth rate and bubble departure frequency f∗ due to the additional forces acting on the bubble, which facilitates its growth and early detachment. This results in a higher heat flux in SMSB for a given surface superheat. The evolution of the bubble and its shape with time (t*) is represented by the area-equivalent bubble diameter D e∗ and height h*. A force balance analysis on the bubble is conducted to explain the growth rate and shape evolution for both SQ and SMSB. A sensitivity study of the induced frequency (f MSB*) and amplitude (A MSB*) of the MSBs shows that the bubble departure frequency (f*) increases to a maximum value and then decreases with the continuous increase in both f MSB∗ and A MSB*.