Abstract:

This paper deals with the phase-change heat transfer in a minichannel. In the investigation, first, an ensemble formula is put forward to calculate the average evolution radius of bubbles based on the known bubble equilibrium diameter and initial value. Next, a random dynamic differential equation describing the growth of bubbles in the minichannel is deduced based on the correlations of random growth factors and the proposed ensemble formula. Then, the potential energy and probability density of the bubble growth system varying with the radius are obtained according to the steady-state solution to the proposed dynamic equation. Furthermore, a formula describing the phase-change heat transfer with nucleate flow boiling is put forward according to the heat soliton expression describing the heat flux of reaction bubbles in the minichannel. Finally, some phase-change heat transfer experiments are carried out for 23 parallel minichannels with the size of 0.3 mm × 2 mm. It is indicated that the proposed formula is feasible because the theoretical results accord well with the experimental ones with an error of less than 7 %.

Key words: minichannel, phase-change heat transfer, heat soliton, Markov process