Analysis of the effect of a closed crankcase ventilation system on the fuel efficiency of a compression ignition engine

Abstract

This article provides relevant information regarding the analysis of the effect of crankcase gas bypass from the crankcase ventilation system into the intake manifold of a highly boosted compression-ignition engine with turbocharging. The information on the breakthrough of crankcase gases into the crankcase through a cylinder-piston group is provided. The data on the types of execution of crankcase ventilation systems, their features and environmental impact are presented. State standards and international standards for the development and requirements for closed and open crankcase ventilation systems are shown. The article reveals the need to evaluate the engine workflow when developing a closed crankcase ventilation system. The development and verification of a mathematical model of the engine workflow with a closed ventilation system was carried out. The reliability of the mathematical model is confirmed by a maximum deviation of up to 1 % from the results of full-scale engine tests, in terms of specific fuel consumption, maximum combustion pressure and crankcase gas consumption. A description of the methodology of the design study and the elements of the design of thermodynamic model of the engine with a closed and open crankcase ventilation system is described. An analysis of the design study and comparison of two versions of the engine ventilation system is made. The influence of an open and closed ventilation system on the effective engine performance in terms of specific fuel consumption and maximum combustion pressure is presented. There is evidence that confirms that the supply of crankcase gases to the intake manifold impairs the fuel economy of the engine, especially at low operating modes, and the difference can go up to 1 g/kWh.