Experimental Investigation on the Use of Argon to Improve FMEP Determination Through Motoring Method 2019-24-0141
Mechanical friction is still one of the current topics in internal combustion engine research and development. In the ever increasing challenge of developing more efficient and less polluting engines, friction reduction is of significant importance; whose investigation needs an accurate and reliable measurement technique. The Pressurized Motoring method is one of the techniques used for both friction and heat transfer measurements in internal combustion engines. This method is able to simulate mechanical loading on the engine components similar to the fired conditions. It also allows measurement of friction mean effective pressure (FMEP) with a much smaller uncertainty as opposed to that achieved from a typical firing setup. Despite its advantages, this method of FMEP determination is usually criticized over the fact that the thermal conditions imposed in pressurized motoring are far detached from those seen in fired conditions, hence not able to simulate the complete effects on FMEP. The authors have put forward a modification to the method, employing Argon in place of Air as pressurization medium (SAE paper 2019-01-0930). Due to the higher heat capacity ratio, very high in-cylinder gas temperatures, possibly higher than the fired conditions can be achieved using Argon. This allows better simulation of the fired engine and hence a more representative FMEP measurement. Continuing on the previous work, in this publication, experimental results obtained from a testing campaign with different Argon to Air concentration is presented. Tests were carried out on the fully instrumented test bench consisting of a direct-injection compression ignition, four cylinder engine, at different engine speeds and peak in-cylinder pressures. At each set-point of speed and load, the Argon to Air concentration in the manifolds was varied to achieve different in-cylinder temperatures. The measured FMEP values, their uncertainty and their dependence on the different engine operating parameters are reported in the paper.
Carl Caruana, Mario Farrugia, Gilbert Sammut, Emiliano Pipitone
Univ of Malta, Jaguar & Land Rover, Universita degli Studi di Palermo
14th International Conference on Engines & Vehicles