The influence of the processes of utilization of exhaust gases of reciprocating internal combustion engines on the gas dynamic and acoustic characteristics of noise silencers

Abstract

The scientific basis for the design of noise suppressors for internal combustion engines with exhaust gas heat recovery, providing the release of gas flows with improved gas-dynamic and acoustic characteristics, is presented. The thermodynamic analysis of the processes of energy utilization of exhaust gases has been studied. Thermodynamic analysis showed that the utilization of exhaust gas heat leads to an increase in the coefficient of performance (COP) of the Otto cycle. An exergy analysis of heat exchange processes in the muffler was also carried out, and ways to increase its thermodynamic efficiency were determined. It has been established that a noise silencer with a heat exchanger-coil installed inside, from the position of the second law of thermodynamics, expressed by means of exergy analysis, is a more advanced thermodynamic system compared to a conventional silencer. A mathematical description of the recycling processes under conditions of external thermal exposure is given, while the nature of the influence of thermal exposure on changes in pressure, temperature and density is established. Based on the method of L.A. Vulis analytical equations for changes in pressure, temperature and density are obtained. Exhaust gas energy recovery processes contribute to a decrease in gas temperature, an increase in density, a decrease in flow velocity and a pressure drop, i.e. there is an effect (law of L.A. Vulis) of thermal stagnation of the gas flow, which causes a decrease in the noise level with less back pressure and an increase in engine efficiency.