Thermodynamics of the system “gas turbine - ejector - charge air cooler” in a supercharged diesel engine

From the standpoint of the thermodynamic approach, the structural and functional features of the elements of the ejection air cooling system at the compressor outlet in a diesel engine with a gas turbine boost are considered. The main elements of the system are highlighted: a gas turbine, an ejection device (ejector), an air cooler after the compressor (charge air). Physical processes and their connections in the elements of the system are described. The thermodynamic parameters of the state, the energy of the gas-air flows and their changes in the gas turbine, the ejector installed behind the turbocharger turbine at the outlet, and the air cooler after compression are determined. The relationship between available and actual work performed by exhaust gases at the outlet of the cylinder of a gas turbine supercharged diesel engine is considered. The p, v and i, s diagrams of the state of gas-air flows in the elements of the ejection cooling system at the outlet of the compressor are given. The considered features of determining the energy and thermodynamic parameters of the exhaust gas state in the turbocharger turbine, ejection device and air cooler at the compressor outlet are used to evaluate the effectiveness of their joint operation. The methods of increasing the charge air density with the release of a method using an ejector to realize the low-potential energy of diesel exhaust gases are described. Using the Solid Works software package, the velocities and temperatures of gas and air flows in the elements of the ejection device (nozzle, mixing chamber and diffuser) were determined. The ejection coefficient of the ejection device is determined as a function of the thermodynamic parameters of gas and air flows. The expediency of making compromise decisions is noted, in which the ejection cooling system can provide maximum charge air density with minimal energy consumption for cooling air circulation through the cooler matrix.