Abstract
A non-isothermal formulation of the Poisson–Nernst–Planck with Navier–Stokes equations is used to study the influence of heating effects in the form of Joule heating and viscous dissipation and imposed temperature gradients on a microchannel/nanochannel system. The system is solved numerically under various cases in order to determine the influence of temperature-related effects on ion-selectivity, flux and fluid flow profiles, as well as coupling between these phenomena. It is demonstrated that for a larger reservoir system, the effects of Joule heating and viscous dissipation only become relevant for higher salt concentrations and electric field strengths than are compatible with ion-selectivity due to Debye layer overlap. More interestingly, it is shown that using different temperature reservoirs can have a strong influence on ion-selectivity, as well as the induced electrohydrodynamic flows.
Highlights
Ion-transport phenomena are at the foundation of many technical solutions in future water treatment and energy scenarios
The results demonstrated the importance of temperature on the resulting electroosmotic flow (EOF) and friction factors for pure EOF, as well as EOF with pressure gradients, finding that viscous dissipation became comparable to Joule heating (JH) for channels smaller than 50 nm [26]
In this paper the influence of temperature on the electrohydrodynamic and electrokinetic behaviour in microchannel/ nanochannel systems was investigated through a theoretical framework based on a non-isothermal formulation of the Poisson–Nernst–Planck with Navier–Stokes equations
Summary
Ion-transport phenomena are at the foundation of many technical solutions in future water treatment and energy scenarios. The role of temperature effects in nanochannels on the resulting ion-selectivity, fluxes and induced flow profiles in the case of double layer overlap or high surface charges/wall potentials has not been examined in depth It is the aim of this study to numerically investigate the effects of temperature on the resulting electrokinetic and electrohydrodynamic behaviour of nanochannels. In order to accomplish this goal, a theoretical framework based on a non-isothermal formulation of the Poisson–Nernst–Planck equations, Navier–Stokes and energy balance has been formulated in order to determine the couplings between temperature, ion-species concentration, fluid velocity and electrical potential Using this framework, numerical simulations were undertaken to investigate the role of temperature effects on ion-selectivity, flux and induced fluid flows
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