Simulation Study on the Use of Argon Mixtures in the Pressurized Motored Engine for Friction Determination

Mechanical friction and heat transfer in internal combustion engines are two highly researched topics, due to their importance on the mechanical and thermal efficiencies of the engine. Despite the research efforts that were done throughout the years on both these subjects, engine modeling is still somewhat limited by the use of sub-models which do not fully represent the phenomena happening in the engine. Developing new models require experimental data which is accurate, repeatable and which covers wide range of operation. In SAE 2018-01-0121, the conventional pressurized motored method was investigated and compared with other friction determination methods. The pressurized motored method proved to offer a good intermediate between the conventional motored tests, which offer good repeatability, and the fired tests which provide the real operating conditions, but lacks repeatability and accuracy. A 'shunt pipe' was utilized between the intake and exhaust manifolds which reduced significantly the air supply demand. In SAE 2019-01-0930, Argon was used in place of air in the experimental setup which resulted in bulk gas temperatures synonymous to the fired engine. In SAE 2019-24-0141 and SAE 2020-01-1063 mixtures between air and Argon were utilized to investigate the relationship of mechanical friction with a controlled gradual increase in the bulk in-cylinder temperature. In this publication, a one-dimensional engine model is developed to assess the capability of the 1D model to capture the effects on the motored engine imposed by changing the working gas. From the experimental studies on the pressurized motored engine, increasing the proportion of Argon to air showed an increase in the peak bulk gas temperature of around 600°C. This resulted in an increase in the heat losses, a decrease in the pumping losses and no measureable difference in the mechanical friction.