Analysis of a High-Pressure-Ratio Roots-Type Compressor Producing a Very High-Temperature Outlet Gas Stream
David I. Blekham, Joseph C. Mollendorf, James D. Felske and John A. Lordi
Utilizing the effects of compressive heating, a Multi-Recompression Heater (MRH) is analyzed. Based on the Roots principle, the MRH is capable of producing uniform, uncontaminated, high-temperature gas streams. Potential applications of the MRH include pyrolytic decomposition of chemicals and specialized process heating. To successfully design an MRH a multitude of technical aspects must be resolved. This paper focuses on a gasdynamic model of the basic Roots compression cycle that involves the expansive mixing of gas followed by compression to a minimum volume. In particular, the present analysis uses a variable-volume model to simulate the second phase of this cycle. Numerical results are presented for the compressed gas temperature, pressure and mass flow, plus the work and mass delivered per compression. A range of volumetric compression ratios, gas properties, and values for two new nondimensional parameters are considered. A closed-form analytical solution is given for an adiabatic compression. The present model is compared with experimental data.