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

Abstract

The manufacturing process and architecture of three Knudsen type micropumps are discussed and the associated flow performance characteristics are investigated. The proposed fabrication process, based on the deposition of successive dry film photoresist layers with low thermal conductivity, is easy to implement, adaptive to specific applications, cost-effective, and significantly improves thermal management. Three target application designs, requiring high mass flow rates (pump A), high pressure differences (pump B), and relatively high mass flow rates and pressure differences (pump C), are proposed. Computations are performed based on kinetic modeling via the infinite capillary theory, taking into account all foreseen manufacturing and operation constraints. The performance characteristics of the three pump designs in terms of geometry (number of parallel microchannels per stage and number of stages) and inlet pressure are obtained. It is found that pumps A and B operate more efficiently at pressures higher than 5 kPa and lower than 20 kPa, respectively, while the optimum operation range of pump C is at inlet pressures between 1 kPa and 20 kPa. In all cases, it is advisable to have the maximum number of stages as well as of parallel microchannels per stage that can be technologically realized.

Transport Reagents through the Pore Structure of a Membrane Catalyst under Isothermal and Non-Isothermal Conditions

“…In the compressor, the temperature gradient on the surface wall of the channels is created by artificial heating and cooling of the chamber (Q1–Q2), and in the membrane reactor, by the endothermic effect of the reactions (∑ F i ΔH reaction ) occurring on the catalyst deposited on the porous support. It was shown in [ 25 ] that the transpiration phenomenon on a membrane catalyst can also be initiated by artificial creation of a temperature gradient in the channels of the pore structure. In the same place, the values of transpiration air flow through the channels of the pore structure of the membrane catalyst and the pressure drop arising across it were estimated.…”

Knudsen pumps: a review

“…However, for mixed cellulose esters with the same pore diameters and porosity, the maximum pressure differences reported by different articles [100][101][102] have large differences. These differences are probably the result of factors such as gas species, membrane thickness, input power, and differing manufacturing techniques and structures of the pumping systems [181][182][183] . In fact, these factors affect KP pressure characteristics significantly.…”

Thermal Characterization of Rarefied Flows in Rhombic Microchannels

“…In particular, temperature gradients play a leading role in the performance evaluation of Knudsen pumps. Operating this kind of micro-pump only requires a temperature gradient; therefore, Knudsen pumps are reliable and they do not require any maintenance, because they do not have moving parts [45]. In this context, the numerical outcomes of this work can be useful for designers and technicians involved in the sizing of Knudsen pumps.…”