Research on the effect of bubble dynamics and turbulent kinetic energy on heat transfer in mini-channels filled with metal foam

This paper presents an investigation of the boiling heat transfer of R141b in a mini-channel with a 2.42-mm inner diameter filled with metal foam. Investigations are performed at velocity of 0.01 m s⁻¹ and temperature of 450 K. The coupled level set and volume-of-fluid method is applied to simulate flow boiling in metal foam. It considers that the bubble number and the average bubble area have influence on the heat transfer coefficient. The simulation model is verified by experimental data with an emphasis on the effect of boiling bubbles and turbulent kinetic energy on heat transfer. The simulation results show that even though the bubble motion range and vortices area is smaller, more vortices appear in the channel filled with foam metal, which increase the mixing frequency and improve the heat transfer performance. Meanwhile, the heat transfer coefficient is inversely proportional to the average bubble area but proportional to the bubble number. The relationship between turbulent kinetic energy and heat transfer coefficient is also compared. Results indicate that the differentiation of turbulent kinetic energy to time appears consistent with the heat transfer coefficient in the mini-channel filled with metal foam.