Diffusion Approximation for the Knudsen Compressor Composed of Circular Tubes

Design Guidelines for Thermally Driven Micropumps of Different Architectures Based on Target Applications via Kinetic Modeling and Simulations

“…Overall, it is observed that for a multistage pump with N≥100 the pressure difference generated is very significant and may be of the same order as the inlet pressure or even several times higher, when Pin≤20 kPa. It is noted that the present results are in excellent qualitative agreement with the corresponding ones reported in [10]. Furthermore, running the present code for some of the geometrical and operational parameters in [10], it has been found that the deviation in the numerical results is small (about 10%) and is due to the corresponding deviation between the kinetic coefficients obtained by the ES and Shakhov models.…”

“…It is noted that the present results are in excellent qualitative agreement with the corresponding ones reported in [10]. Furthermore, running the present code for some of the geometrical and operational parameters in [10], it has been found that the deviation in the numerical results is small (about 10%) and is due to the corresponding deviation between the kinetic coefficients obtained by the ES and Shakhov models.…”

“…In each case the computed mass flow rate m˙ with the associated pressure difference ΔP=Pout−Pin between the inlet and the outlet fully characterize the pump performance. It is noted that a very close kinetic type analysis of pump B, based on the ellipsoidal‒statistical (ES) model, and the one presented here, based on the Shakhov model, has been performed in [10].…”

“…Thermal transpiration (or thermal creep) has been known for more than 100 years, since the first studies of Maxwell [3], Reynolds [4], and Knudsen [5,6]; however, functional pumping prototypes based on this phenomenon have been developed only during the last 20 years with the massive development and adoption of microfabrication techniques. The Knudsen pump, which is one of the devices exploiting the thermal transpiration phenomenon, is able to generate a macroscopic gas flow by applying exclusively a tangential temperature gradient along a surface without any moving parts or external pressure gradient [7,8,9,10,11,12]. The induced thermal transpiration flow is useful for technological purposes, provided that the flow is through microscale channels, since the phenomenon is intensified as the characteristic length of the system is decreased.…”

Numerical study on effective configurations of the Knudsen pump for separation and compression

“…Numerical simulations of the experiment were performed by the use of the convection-diffusion system for the pump composed of circular pipes prepared in [9,10]. We treated the pumping system as 10 units cascade, thus ignoring the curved glass pipe connecting two subsystems.…”