Search Results

In this paper, a novel biodiesel, ethylene glycol monomethyl ether peanut oil monoester, was developed. It was synthesized through transesterification reaction with refined peanut oil and ethylene glycol monomethyl ether as reactants and KOH as catalyst. Its chemical structure was identified through FT-IR, 1H NMR and GPC analyses. Engine test was conducted and the results showed that engine-out smoke emissions were decreased by 25.0% to 75.0%, CO emissions reduced by up to 50.0% and unburned HC emissions lessened significantly. NOx emissions generally did not change noticeably. The new peanut oil monoester has higher cetane number leading to auto-ignition 1.2°CA earlier than diesel fuel during diesel engine operation. Due to more amount of oxygen contained in the new biodiesel, the engine thermal efficiency was improved by 5.5% to 15.4% when fueled with the biofuel compared with diesel fuel.

A new type of swirl generator in a short straight port is developed to get induction swirl in the cylinder. The generator consists of several curvilinear diversion blades and is installed near to the inlet valve. Steady-flow rig tests show that this system is able to generate different strength of swirl in the cylinder when different type of generators is installed. By the control of the airflow rate in another port, variable swirl is achieved. Engine tests prove that variably induced swirl has a significant effect on diesel engine fuel consumption.

This model is developed based on the concept of Hiroyasu's multizone combustion model. It takes nozzle injection (spray) parameters, induction swirl, air and fuel composition into consideration. The models of zone velocity, air entrainment rate, fuel droplet evaporation rate, mixture combustion rate are upgraded according to the latest papers. Various parameters, such as cylinder pressure, heat release rate, NOx and soot emissions, etc. are simulated. The simulated zone velocity and spray tip penetration are compared with those computed by Hiroyasu. The simulation results show good agreement with the experimental data.

Recent advanced technologies in diesel engine FIE(Fuel Injection Equipment) allow high pressure and multiple injection to be used to reduce particulate emissions without significant penalty in NOx emission. It is also well known that diesel engine particulate matter(PM) and NOx emissions can be reduced by the exact injection rate control according to engine conditions. This study was conducted based on such engine conditions as engine speed, load, swirl ratio and solenoid pulse timing and duration. The fast solenoid valve was installed between the connecting part of nozzle and fuel line. The ball valve driven by solenoid is open after the controller generates pulse and it spills the high pressure fuel in the high pressure nozzle chamber. Fuel line pressure, injection rate, cylinder pressure and exhaust emissions were measured with the variation of control method(pulse timing and pulse duration period).

The minimum thickness of the oil film lubricating piston rings was measured successfully under motoring conditions by means of Eddy Current Sensors which were mounted on the liner. The measurements show the influences of engine speed, the viscosity of the oils and the profile of rings on their lubrication. The results also show the effects of hydrodynamic lubrication and oil starvation at the inlet of the rings. Under motoring condition, the minimum oil film thickness has no significant difference for the four strokes and it reaches a minimum value even though the rings are fully lubricated(without oil ring).

The processes of hydrocarbons diffusing into and out of the oil film are studied. The theoretical simulations show that the magnitude of desorbed hydrocarbons from the oil film increases with the increase of the oil film thickness until a critical one at which it reaches a maximum, and the maximum value changes little when the oil film is thicker than the critical one. Under normal operating conditions, the oil film thickness is approximately equal to or greater than the critical one, so that the oil film nearly has its definite and maximum contribution to the exhausted hydrocarbons. The same conclusion can also be drawn from the experimental data. The measured concentration of unburnt hydrocarbons almost has no difference as far as the different petroleum-based oils and the ring packs are concerned, which may cause the oil film thickness to change. The ‘oil-free’ engine test proves that the oil film may contribute about 28 percent to the total hydrocarbon emissions of SI engine.