Adding the Teaching of Claw Rotor Compressors to Fluid Machinery Courses

Abstract

This paper deals with a rotary positive-displacement machine with built-in compression, the study of which is usually neglected in courses on fluid machinery for mechanical engineering students. First, the working principles of the claw rotor compressor are presented; then basic thermodynamic considerations, leading to the formulation of volumetric efficiency, are reported. The volumetric efficiency of the compressor is reviewed as a function dependent on filling and leakages, leading to the definition of the delivery efficiency. Considering the filling efficiency alone, formulated according to a thermodynamic analysis of the closed system, it is possible to determine the limit pressure ratio that causes no flow from the compressor. The ideal work is also formulated and a comparison with the sliding vane compressor is made. Some considerations that deprive the compressor of its ideality are advanced in order to avoid misleading conclusions.