The hot gases produced by the internal combustion engines passes through the exhaust valve and causes high temperatures in the exhaust valve and its seat. To avoid damaging the exhaust valve, heat must be transferred from the valve to its seat during the contact they make at the opening and closing cycle. Heat transfer rate from the exhaust valve to its seat is a function of many factors. One o...

The effects of spark timing and exhaust valve timing change on exhaust gas temperature during cold start of an SI engine are studied through engine bench tests. It is observed that the exhaust gas temperature increases when the spark timing and valve timing are retarded individually or simultaneously, due to late combustion or slow flame speed. However, using COVimep it is also investigated tha...

The tests were carried out with the spark timing adjusted to the maximum brake torquetiming in various equivalence ratios and engine speeds for gasoline and natural gas operations. In thiswork, the lower heating value of gasoline is about 13.6% higher than that of natural gas. Based on theexperimental results, the natural gas operation causes an increase of about 6.2% brake special fuelconsumpt...

Small diesel engines are widely used for commercial vehicle and passenger car applications due to their higher torque requirements, fuel economy, and better thermal efficiency. These engines are exposed to different operating and environmental conditions and hence emissions from these engines are erratic. Strategies are required to enhance performance and reduce engine-out emissions considering...

ABSTRACT Stringent NOx and particulate emission constraints require high levels of exhaust gas recirculation. In this paper we model and analyze a Variable Valve Timing methodology that in steady-state achieves large levels of internal Exhaust Gas Recirculation (iEGR) or residual charge in Compression Ignition Direct Injection (CIDI) engines. Current external Exhaust Gas Recirculation (eEGR) te...

A silencer to attenuate engine exhaust noise using active control methods is developed. The device consists of an electrically driven valve, combined with a buffer volume, which is connected to the exhaust outlet. Using the mean flow through the valve and the pressure fluctuations in the volume, the valve regulates the flow in such a way that only the mean flow passes through the exhaust outlet...

in this paper, the effect of bioethanol- gasoline fuel blends on exhaust emissions of a four-cylinder spark ignition (si) engine was investigated experimentally. pure gasoline fuel was blended with various percentages of bioethanol (0, 20, 40, 60 and 85%), and the hc, co, co2 and nox exhaust emissions were measured at different engine speeds and two throttle valve positions (full throttle and 5...

In internal combustion engines, exhaust valve and its seat gain considerable temperature as the hot gases exit through them. So, the rate of heat transfer should be under control. In this study, the contact heat transfer coefficient has been estimated. An experimental study on an Air-Cooled internal combustion engine cylinder head has been considered. Using the measured temperatures of sensors ...