Date on Master's Thesis/Doctoral Dissertation


Document Type

Master's Thesis

Degree Name

M. Eng.


Mechanical Engineering

Committee Chair

McNamara, Shamus


Microelectromechanical systems; Pumping machinery


The Knudsen pump works on the principle of thermal transpiration. As a result of requiring a thermal gradient, channel hydraulic diameter smaller than the mean free path of the gas being pumped, and having no moving parts, the Knudsen pump features a simple and attractive design. The focus of this thesis is to develop a general relation for the ideal pump efficiency as well as to quantify thermal losses in the efficiency equation to predict the efficiency of fabricated pumps. Understanding the efficiency will enable a better understanding of the practical limits of the pump's ability to transfer energy from a heat gradient to kinetic energy, in terms of flow rate, potential energy, and pressure gradient, generating a greater understanding of the applications for which the pump is best suited. Test method and results for a MEMS fabricated pump are provided. Thermal simulations of two designs are presented.