Further Experimental Investigation of Motored Engine Friction using Shunt Pipe Method 2019-01-0930
Mechanical friction is one of the significant power dissipaters in the internal combustion engine. In the effort of designing more efficient and less pollutant engines, friction reduction is certainly on the agenda to be investigated. Such investigation cannot be possible without an accurate measurement of the same quantity. This publication regards a continued study on the mechanical friction determination in an internal combustion engine using the Pressurised Motoring Method. In this work, the friction mean effective pressure of a four-cylinder compression ignition engine was investigated with varying engine speed and manifold pressurisation, using a dedicated high precision sensor for the correct determination of the cylinder Top Dead Centre position. Two different measurement sessions were carried out; in the first, air was employed as pressurisation medium, testing 32 different setpoints; in the second, instead, with the aim to test the effect of the variation of thermochemical properties of fluids on the thermodynamic loss angle, Argon was used in place of air in 18 different setpoints. The 2000 rpm region was explored with particular attention with the aim to investigate the high motoring torque observed in a previous work from the same authors . An investigation of the volumetric efficiency effect on motoring torque is also presented in the paper. To understand further the instantaneous motoring torque whilst having a repeated torque measurement, a simple and inexpensive DAQ system was developed which allows wireless torque measurement on the shaft coupling the engine to the AC motor. Values of IMEP, BMEP, FMEP, peak in-cylinder pressure, loss angle and other parameters are given. The loss angle measured at each setpoint using the TDC sensor is compared with the loss angle evaluated by the use of two thermodynamic methods developed by Stas  and Pipitone .
 Caruana, C., Farrugia, M., and Sammut, G., "The Determination of Motored Engine Friction by Use of Pressurized ‘Shunt’ Pipe between Exhaust and Intake Manifolds," SAE Technical Paper 2018-01-0121, 2018, https://doi.org/10.4271/2018-01-0121.
 Sta s̒, M., "Thermodynamic Determination of T.D.C. in Piston Combustion Engines," SAE Technical Paper 960610, 1996, https://doi.org/10.4271/960610.
 Pipitone E., Beccari A., “Determination of TDC in internal combustion engines by a newly developed thermodynamic approach”, Applied Thermal Engineering, Vol. 30, Issues 14-15, October 2010, Pages 1914-1926, DOI: 10.1016/j.applthermaleng.2010.04.012
Carl Caruana, Mario Farrugia, Gilbert Sammut, Emiliano Pipitone
University of Malta, Jaguar & Land Rover Ltd., University of Palermo