Matematický model rázové komprese a expanze

Abstract

The presented dissertation thesis deals with the research of the shock compression and the shock expansion at the displacement compressors with the rotary movement of the piston(s) and the built-in pressure ratio. The shock compression and the shock expansion are negative phenomena that may occur under certain operating conditions when operating said compressors. The production of compressed air or other technical gases is an integral part of the modern industry. This is a very energy-intensive process with approximately 19% utilization of the input energy. Given the fact that electricity consumption in human civilization is showing steady growth, the trend is nowadays to look for possible savings even in applications that have not been characterized by significant “losses” of electric energy. The process of compressing air is often unduly underestimated in technical practice because air is free but compressed air is one of the most expensive forms of energy. The essence of the dissertation is to enrich the scientific field with the knowledge of the influence of shock compression and shock expansion based on the creation of mathematical models and laboratory experiments. The dissertation thesis is structured into several parts, the continuity of which forms a coherent process leading the fulfillment of the stated goals of the dissertation. The first part of the thesis deals with the compressed air issues in contemporary society and industry, the accident of the screw compressor unit initiating the shock phenomena research at the VŠB-TUO, a summary of theoretical knowledge of compressor thermodynamics and a summary of current knowledge about the shock compression and the shock expansion. The second part of the thesis deals with the creation of mathematical models. The ideal mathematical model simulates the ideal working process with the implementation of ideal shock phenomena. The advanced mathematical model simulates the polytropic processes with different values of polytropic exponents with working medium with real gas properties. The simulations confirm changes in the specific compression work, power consumption, specific heat, and the work-ability in combined processes with subsequent shock compression or shock expansion. The third part of the thesis deals with the preparation and realization of shock phenomena influence measurements at the compressor unit with the screw compressor. In general, the results of experiments coincide with the results of mathematical models. At the end of this part of the thesis, experimental measurement stands for future shock phenomena research are designed. The prototype of the experimental measuring stand for measuring the Roots blower was realized in the framework of the thesis. The final part of the thesis deals with the interpretation of results and their evaluation, discussion and comparison of simulation results with measurement results. There are summarized the benefits of the dissertation for the scientific discipline and for the practice and also suggested recommendations for further research on this issue.