August 21, 2023 - Efficient pumping of liquids by temperature gradients
The standard method to pump a liquid through a channel or duct is to apply a difference in pressure between the inlet and outlet, i.e. a pressure gradient. It is also known that electrolyte solutions such as water can be pumped by applying a temperature gradient, an effect that is termed “thermoosmotic flow”. However, the flow velocities that can be reached using that principle are small, which has so far prevented widespread applications. On the nanoscale, boundary slip needs to be taken into account, which means that in some cases the liquid slips along the channel walls. We were able to derive analytical expressions for the thermoosmotic flow field in slit channels with boundary slip. For channels formed by polarized graphene surfaces, we predict a velocity enhancement factor of up to 250 compared to no-slip channel walls. This may open the door to applications of thermoosmotic flow in nanofluidics. The results were recently published in JFM Rapids.
