Effect of variable geometry turbocharger on the performance of the opposed piston engine – An experimental approach

Abstract

The increasing trend of low-carbon policy obligates engine manufacturers to implement new solutions to meet demanded emission reduction. Thus, a growing interest has been in reviving the 2-stroke, opposed-piston engine concept to improve engine thermal efficiency. Although such an engine offers advantages over classic, 4-stroke engines, its application was limited only to the marine sector. Also, recent research activities were mostly limited to scavenging and combustion process simulations due to the lack of available test engines and challenging experimental setup requirements.The authors tested a prototypical 2-stroke, axially opposed-piston engine under various variable turbocharger geometry settings. The author's previous paper on experimental tests with a fixed vane turbocharger influenced the current research activities. The experimental research of a unique axial opposed-piston engine with a wobble-plate mechanism, combined with variable turbocharger geometry application, signified the novelty of such research. The engine test stand accurately measured instantaneous intake and exhaust pressure, in-cylinder pressure and temperature, brake thermal efficiency, and emission. The study demonstrated that the axial opposed-piston engine provides high efficiency of 49.2%. However, the variable turbine geometry actuation increases its efficiency to 51.2% at high load conditions, contributing to CO, HC, and soot emission reduction by 25.1%, 52.5%, and 14.7%, respectively.