Eiyad Abu-Nada

Performance of a spark ignition engine under the effect of friction using a gas mixture model

AbstractThis paper presents the effect of friction on the performance of a spark ignition engine using a gas mixture as the working fluid. The results were compared to a frictionless engine. Engine parameters that were studied include equivalence ratio, engine speed, break mean effective pressure (BMEP), and cycle thermal efficiency. It was found for the frictionless engine operating at 6000 rev min−1 and stoichiometric air–fuel mixture that BMEP and efficiency were about 14 bar and 36% respectively. On the other hand, when friction is included under the same condition BMEP and efficiency were about 10 bar and 27% respectively. However, at lower engine speed and equivalence ratio, the deviations were much smaller. Therefore, it is more realistic to consider the effect of friction using the gas mixture model instead of air as the working fluid for the analysis of spark ignition engines, especially when running at high speeds and/or rich mixtures.

Performance of diesel engine using gas mixture with variable specific heats model

Abstract A thermodynamic, one-zone, zero-dimensional computational model for a diesel engine is established in which a working fluid consisting of various gas mixtures has been implemented. The results were compared to those which use air as the working fluid with variable specific heats. Most of the parameters that are important for compression ignition engines, such as equivalence ratio, engine speed, maximum temperature, gas pressure, brake mean effective pressure and cycle thermal efficiency, have been studied. Furthermore, the effect of boost pressure was studied using both the gas mixture and dependent temperature air models. It was found that the temperature dependent air model overestimates the maximum temperature and cylinder pressure. For example, for the air model, the maximum temperature and cylinder pressure were about 1775u2005K and 93·5u2005bar respectively at 2500u2005revu2005min−1, and the fuel/air equivalence ratio Φ = 0·6. On the other hand, when the gas mixture model is used under the same con...