Combined effect of surface charge and boundary slip on pressure-driven flow and convective heat transfer in nanochannels with overlapping electric double layer

Abstract The electroviscous effect and convective heat transfer of pressure-driven flow in micro/nanochannels have been widely studied in the past decade. However, previous studies often used constant physical parameters in calculations and overlooked the situation of probable overlapping electric double layers (EDL). In this work, we report the combined effect of concentration-dependent surface charge and surface charge-dependent boundary slip on the flow and related heat transfer in nanochannels with overlapping EDL. The results show that the solution concentration-dependent surface charge and boundary slip apparently affect the electric conductivity and velocity distribution in the nanochannel, subsequently affect the fluidic behavior and heat transfer. The dimensionless flow rate and the Nusselt number (Nu) decrease first and then increase with the increasing solution concentration. Besides, the slip significantly improves the dimensionless flow rate and Nu, especially in small nanochannels with thick overlapping EDL. These results provide useful guidelines for the design and performance optimization of micro/nano fluidic devices.