Energy loss and emissions of engine compression rings with cylinder deactivation

Abstract

A novel integrated multi-physics assessment of the piston top compression ring of an internal combustion engine under normal operation mode, as well as subjected to cylinder deactivation is carried out. The methodology comprises ring-liner thermo-mixed hydrodynamics, elastodynamics of ring, as well as combustion gas blow-by and emissions. Therefore, the analysis provides prediction of ring-liner contact’s energy losses and gas power leakage across the piston and ring crevices, as well as the resulting emissions. Cylinder deactivation (CDA) technology reduces the unburnt fuel entering the ring-pack crevices, as well as the emissions. It is also shown that the frictional and gas leakage power losses are exacerbated under CDA by as much as 20%. Although this is much lower than the potential gains in fuel usage when using CDA. The optimisation of the piston compression ring would provide further fuel efficiency and improved emissions, an issue which has not hitherto received the attention which it deserves. The in-depth analysis has also shown that CDA reduces the predicted CO, NOx and HC emissions by nearly as much as 8.5%, 10% and 8.7%, respectively.

Simulation and Analysis of the Impact of Cylinder Deactivation on Fuel Saving and Emissions of a Medium-Speed High-Power Diesel Engine

“…S. Bewsher et al [27] found that the total frictional loss under CDA is 9.53% higher than that under normal operation. Similar results have been achieved in [28][29][30]. However, a decrease in the overall frictional loss under CDA operation has been reported in [31,32].…”

Overview of the potential and limitations of cylinder deactivation

“…As for the other strokes, higher cylinder liner temperature reduces the lubricant viscosity and the power losses in active cylinders are low. However, the viscous friction is higher in deactivated cylinders, where the liner temperature is lower [72].…”

“…The biggest temperature changes on 1.0 l three-cylinder engine occur in the upper section of the cylinder liners and the lower part of the exhaust valves, where the temperature reached 397°C [68]. The highest boundary friction occurs at TDC of the deactivated cylinder, therefore, CDA can cause higher wear, especially due to reduced lubricant film thickness and pressure peaks inside the cylinder [72]. Active cylinders work with higher in-cylinder pressure than in all-cylinder mode.…”

“…After reactivation, the engine oil is burned, which leads to an exhaust smoke problem. The engine oil also contains additives that could reduce the efficiency of exhaust catalyst [72].…”

Multiphysics performance assessment of hydrogen fuelled engines

“…Considering the complexities involved in detailed thermodynamic analysis of the combustion process, achieved mainly through CFD, 31 and development of detailed multiscale in-cylinder tribological models, 32,33 a fully numerical and detailed coupled model can be very time consuming from the computational perspective. This can also prevent wider use of such tools in industry as practical holistic analysis tools for engine designers.…”