Distribution of exhaust gas energy between the elements systems “gas turbine - ejector - charge air cooler” in a supercharged diesel engine

The expediency of distributing exhaust gas energy between the elements of the “gas turbine - ejector - charge air cooler” system in a diesel engine with a gas turbine boost when using an ejector to circulate cooling air through a cooler in order to cool the air after the compressor is substantiated. The relevance of the redistribution of exhaust gas energy between the system elements is noted in order to mprove the charge air cooling systems in the direction of reducing the cost of power for operation and simplifying the design of their elements. The functional and design features of the elements of the charge air ejection cooling system are considered. The incompleteness of studying the functioning of the ejector at the outlet for intensive circulation of cooling air through the cooler matrix when placing the ejector after the turbocharger turbine is noted. The criteria for evaluating the effectiveness of the “turbine - ejector - charge air cooler” system and the conditions of their use are determined. It is noted that it is necessary to solve a system of criteria equations when finding the optimal value of the degree of pressure reduction in the turbine. Possible ways of switching on a gas turbine and an ejector in the exhaust tract of a diesel engine, in particular, a sequential and parallel method, are considered. The necessity of rational distribution of exhaust gases between the gas turbine and the ejector has been established. The main factors characterizing the relationship between the functional and geometric parameters of the system elements are given. The features of a comprehensive assessment of the ejection cooling system of the charge air in a diesel engine using mathematical modeling of processes in various elements of the system to find reserves and compromise solutions to reduce the cost of power for its operation are reflected. The results of a comprehensive assessment of the efficiency of the charge air ejection cooling system by numerical modeling are presented graphically in the form of dependences of the parameters of its elements on the degree of pressure reduction in the turbocharger turbine. Analysis of the results of the comprehensive efficiency assessment shows that the most effective method is the sequential installation of the ejector behind the turbine of the turbocharger. It is noted that the cost of diesel power to the ejector must be less than the reduction of its power from the decrease in the density of the superheated air in the fall of πk due to the redistribution of the energy of the exhaust gases between the turbine and the ejector. The maximum values of the degree of cooling, charge air density and effective diesel power are achieved at various degrees of pressure reduction in the turbine or ejector. In this regard, it is concluded that it is advisable to set the degrees of pressure reduction in the turbine or ejector on a compromise basis.