Amin Mahmoudzadeh Andwari

Investigation of Cylinder Deactivation (CDA) Strategies on Part Load Conditions

Many efforts have been invested to improve the fuel efficiency of vehicles mainly for the local consumers. One of the main techniques to have better fuel efficiency is cylinder deactivation system. In this paper, the main research area is focus on the investigation of cylinder deactivation (CDA) technology on common engine part load conditions within common Malaysian driving condition. CDA mostly being applied on multi cylinders engines. It has the advantage in improving fuel consumption by reducing pumping losses at part load engine conditions. Here, the application of CDA on 1.6 liter four cylinders gasoline engine is studied. One-dimensional (1-D) engine modeling is performed to investigate the effect of intake and exhaust valve strategy on engine performance with CDA. The 1-D engine model is constructed starts from the air-box cleaner up to exhaust system according to the 1.6 liter actual engine geometries. The model is simulated at various engine speeds with full load condition. The simulated results show that the constructed model is well correlated to measured data. This correlated model is then used to investigate the effect of valves timing configurations on engine performance. The model is then used to determine the optimum intake and exhaust valve lift and timing for CDA application at part load conditions. Also, the effects on the in-cylinder combustion as well as pumping losses are presented. The study shows that the effects of valves strategies are very significant on the engine performance. Pumping losses is found to be reduced, thus improving fuel consumption and engine thermal efficiency.

Controlled Auto-Ignition Combustion in a Two-Stroke Cycle Engine Using Hot Burned Gases

A new combustion concept, which is viewed increasingly as a probable solution to these issues is Controlled Auto-Ignition (CAI) Combustion. In such an engine, a homogeneous mixture of air, fuel and residual gases is compressed until auto-ignition occurs. Due to its significantly low temperature combustion, NOx will be dramatically reduced while the mixture will be under ultra-lean fuel-air condition, thus able to achieve high efficiency and low emission. In the case of two-stroke engine, problem of poor combustion efficiency and excessive white smoke emission can be addressed by the incorporation some features that will ultimately convert a typical two-stroke engine into an efficient CAI engine demonstrating the best of both features. Due to its inherent high internal residual gas rate in partial load operation, the two-stroke engine has been the first application to benefit from the unconventional CAI combustion process. This paper will concisely discuss the utilization of hot burned gas for induction thus imposing a CAI combustion feature onto two-stroke cycle engine. Among the features incorporated are the increasing in the level of Exhaust gas Recirculation and cycle-by-cycle uniformity of the air-fuel ratio (AFR) supplied to cylinder, which will be crucial in creating a suitable temperature within the engine’s combustion chamber.

A New Approach for Ignition Timing Correction in Spark Ignition Engines Based on Cylinder Tendency to Surface Ignition

The performance of Spark Ignition (SI) engines in terms of thermal efficiency can be restricted by knock. Although it is common for all SI engines to exhibit knock from compressed end-gas, knocks from surface ignition remains a more serious problem due to its effect on combustion stability and its obscurity to detect. This paper focuses on predicting the occurrence of knocks from surface ignition by monitoring exhaust gas temperature (EGT). EGT measured during an engine cycle without the spark plug firing. Therefore, EGT rises illustrated any combustion made by surface ignition. Modelling and simulation of a one-dimensional engine combustion done by using GT-Power. The new approach reduces the complexity as EGT monitoring does not require high computational demands, and the EGT signals are robust to noise. The method is validated against a variety of fuel properties and across engine conditions. A new approach is proposed as a measure to predict and detect the knock events.

A Converted Two-Stroke Cycle Engine for Compression Ignition Combustion

A new kind of alternative combustion concept that has attracted attention intensively in recent years is called controlled auto-ignition (CAI) combustion. CAI combustion has been proposed and partially implemented with the aim of both improving the thermal efficiency of internal combustion engines, achieving cleaner exhaust emissions and lower cyclic variation. An experimental study is conducted through a CAI two-stroke cycle engine in order to investigate the influence of internal exhaust gas recirculation (In-EGR) and external exhaust gas recirculation (Ex-EGR) variation in relation to combustion cyclic variability and exhaust emissions characteristics. Results implied that cyclic variation of both combustion-related and pressure-related parameter is substantially improved. Furthermore remarkable decreased exhaust emissions, unburned hydrocarbon (uHC), carbon monoxide (CO) and nitric dioxide (NOX), was observed.