Rarefied Gas Flow Through Long Square Tubes

A theoretical model has been developed for gas flow through long square tubes. The continuum differential equation is solved with noncontinuum slip boundary conditions and the “self-diffusion” or normal molecular transport effect is obtained by numerical integration. Specific flow rates as predicted by this theoretical model are compared with experimental data which were obtained using a 0.0985-in-square tube with argon as the test gas. In addition, a comparison is made using a “hydraulic radius” in the equation which Weber developed for rarefied gas flow through cylindrical tubes. Good agreement between theory and experiment give a high confidence level to the theoretical model.