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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 light-duty direct-injection diesel engine with dimethyl ether (DME) fuel was studied experimentally. The effects of fuel injection parameters and in-cylinder air motion, such as the pump plunger diameter, nozzle type, fuel injection timing, nozzle tip protrusion, nozzle opening pressure and swirl ratio, on performance and emissions of the DME engine were investigated. Cylinder pressure, needle valve lifts, and emissions were measured after optimization of the fuel-injection and combustion system parameters. By installing a low-pressure pump, a fuel pressure regulator, and a buffer in the fuel supply system, the vapor lock of DME in the fuel system is eliminated. The engine runs smoothly on DME over a wide range of speeds and loads. Thermal efficiency with DME fuel shows 3% higher than that with diesel fuel. The measured injection delay with DME is longer than that with diesel fuel due to the lower acoustic velocity in the liquid DME.

Compared with bathtub combustion chamber which is widely used in SI engines especially in China, this paper introduces an experimental investigation on the performances of SI test engine with a new squish jet-turbulence combustion chamber. The new chamber can combine inlet swirl and squish effectively. Results show that the engine with the new chamber gives better comprehensive performances. The combustion process shortens, and the lean burn limit extends.

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.

A zero-dimensional computation model for the heat release rate of a swirl chamber diesel engine is established in this paper. With the aid of control volume analysis method of variable mass thermodynamic system, the instantaneous discharge coefficent of the connecting passage of combustion chambers is accurately determined by calculating the motored indicator diagrams of main and swirl chambers. A deeper study is also made on the heat release rate and other combustion characteristics under various conditions of the swirl chamber diesel engine such as connecting passages with different structural parameters, different shapes of main combustion chambers and different operating conditions. Thus some beneficial conclusions are reached, that is, the combustion delay in the main combustion chamber of the swirl chamber diesel engine is an important reason for its fuel economy lower than that of a DI diesel engine besides its greater losses of flow and heat.

This paper presents the results of experimental studies carried out on a spark-assisted, direct-injection, diesel engine operating on methanol, ethanol and gasoline (all having low cetane numbers) as well as on diesel fuel. The key measures that ensure reliable ignition and stable flame propagation through the inhomogeneous mixture are the character and location of the fuel spray in the combustion chamber relative to the location of the spark in both the vertical and horizontal directions, the spark plug gap, and the timing of injection and spark. When these parameters are optimized, the engine runs smoothly over a wide range of speeds and loads. The ignition characteristics, rates of heat release, cycle-to-cycle variations, NOx emissions, and thermal efficiencies of the engine operating on these four fuels are analyzed and compared in detail.