Improving spark-ignited engines efficiency by heat energy recovery system

The current trends in regulations changes focus more and more on emissions reduction. Earlier environment protection mechanisms covering emissions limits of particulates, nitrogen oxides, sulphur oxides and carbon monoxide were recently extended also to cover carbon dioxide emissions. One way to reduce carbon dioxide emission is the improvement of the efficiency of a powertrain system or main driver efficiency. This paper explains main limitations for efficiency improvement when conventional methods are used. The effective heat energy recovery system principles and its technical specification are described including its control principles. System was initially tested in the engine laboratory and experience from the laboratory tests is included in the paper. After successful and promising laboratory tests the solution was transferred to commercial operation which covered already period of more than 2 years. Statistics and operational data from commercial operation is shown with relevant examples of various operational modes. At the end of the paper simple feasibility study is shown. Alternative applications with basic evaluation of their feasibility and efficiency improvement potential are included in this paper as well.