Electric field on bubble dynamics and heat transfer during flow boiling in a vertical microchannel under different gravity conditions

In this study, a horizontal electric field was applied to a vertical microchannel to explore the flow boiling heat transfer under varying gravitational accelerations. The effects of the electric field strength, gravitational acceleration, surface wettability, Reynolds (Re) number, and superheat degree on bubble dynamics and heat transfer characteristics were investigated using a hybrid lattice Boltzmann model that integrates the pseudopotential model, finite-difference method, and leaky dielectric model. The results indicated that an increase in Re enhances bubble growth, movement, and detachment on the hydrophilic wall while exerting only a minimal influence on the hydrophobic wall. Furthermore, the higher Re facilitates heat transfer on the hydrophilic wall but decreases it on the hydrophobic wall. The superheat and contact angle are the key factors influencing bubble nucleation during the initial stage of wall heating, while gravitational acceleration primarily affects subsequent bubble interactions and detachment. Under hyper-gravity, flow boiling heat transfer is enhanced at lower Re for the hydrophobic wall, while at higher Re, the hydrophilic wall demonstrates superior performance. As the electric field intensifies, heat transfer increases, primarily because the electric field enhances heat transfer during the initial stage of the flow boiling. When an electric field is applied to the hydrophilic wall under hyper-gravity at higher Re, it can yield the highest flow boiling heat transfer.