Title: Increasing engine efficiency at part load with the exhaust valve control: a simplified modelling approach

Authors: A. Kozina; G. Radica; S. Nižetić

Addresses: Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Department of Heat Engines, University of Split, Split, 21000, Croatia ' Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Department of Heat Engines, University of Split, Split, 21000, Croatia ' LTEF-Laboratory for Thermodynamics and Energy Efficiency, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, University of Split, Split, 21000, Croatia

Abstract: In this study, a new, innovative system based on variable regulation of the exhaust valves in the spark ignited engine was described and analysed. The efficiency of standard spark ignited engines decreases during partial load compared to full load, due to increased losses in the exchange of working medium, precisely, loss of suction. The simplified model of the new system has been developed and a comparison was made between the standard engine, regulated with a valve on the intake system, and an engine that is regulated by dual opening of the exhaust valves. Research was carried out on the model of a four cylinder Otto engine with direct injection into the cylinder. The main results showed a significant improvement over the standard engine with a fixed intake geometry. Specific consumption is reduced between 3.83% and 4.23%, and losses of cylinder gases exchange have decreased between 85% and 87%.

Keywords: engine efficiency; exhaust valve control; cylinder gas exchange; gasoline engine.

DOI: 10.1504/IJEX.2018.092510

International Journal of Exergy, 2018 Vol.26 No.1/2, pp.131 - 153

Received: 28 Aug 2017
Accepted: 21 Dec 2017
Published online: 23 Jun 2018 *

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