**ABSTRACT**

The coaxial microtubes, which can be transparent, flexible, and biocompatible, are often part of micro-electro-mechanical systems. This paper examines the steady, subsonic rarefied gas flow through an axisymmetric microtube with an annular cross-section, induced by pressure difference. The flow is considered compressible and non-isothermal, with constant inner and outer wall temperatures. The study uses continuum approach based on continuity, momentum and energy equations together with slip and temperature jump boundary conditions. The perturbation method is used and enables including effects of inertia, convection and expansion work. Hence, analytical solutions for velocity, pressure and temperature are obtained, which allows analysis of all named effects along with annular microtube geometry. These results provide optimizing microtube designs in practical applications. Regarding solutions are analytical, they can be useful as a criterion for validating the accuracy and reliability of numerical solutions of similar problems.

**KEYWORDS**

PAPER SUBMITTED: 2024-06-27

PAPER REVISED: 2024-08-12

PAPER ACCEPTED: 2024-08-19

PUBLISHED ONLINE: 2024-09-12

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