A numerical investigation on heat transfer dynamics of a periodically forced boiling channel in low amplitudes

In this article, the authors report wall-heat transfer characteristics of a periodically forced vertical boiling channel with the help of numerical simulation based on four-equation drift flux model. The periodic forcing on the boiling channel was initiated by the sinusoidal perturbation of the inlet velocity. The effect of the frequency ω and the amplitude ã of the forcing on the heat transfer enhancement were studied to formulate a mechanism for the enhancement of wall heat flux qw″. qw″ increases with ã in the range of ω less than a critical value ωcrit. The comparison of the numerical solution and the asymptotic solution of a reduced-order model through harmonic balance method (HBM) shows that both the solutions for the amplitude of exit mixture enthalpy decrease with ω consistently and asymptotically, when ω is greater than the characteristic frequency ωc of the channel. The enhancement is also facilitated by chaotic instability (mixing) at higher ã and higher external heat flux.