Direct injection diesel engine combustion diagnostics

The demand for the protection of the environment from air pollution and reduction of carbon dioxide has resulted in worldwide exhaust emissions regulations imposed on the diesel engines. Fortunately, diesel engine offers the best fuel economy and low emissions of carbon dioxide of most engines currently available. However, the engine's inherent drawbacks are that the engine is heavy, noisy, and expensive, in addition to producing significant level of particulates and nitrogen oxides emissions. The present research attempts to understand the combustion characteristics and emissions trade-off by experimental investigations of the diesel engine using a production Lister Petter 2.97 litres, four-cylinder, high-speed, direct injection diesel engine. The investigation involved the analysis of the in-cylinder pressure data, heat release rate calculation and exhaust gas measurements of various injectors having different nozzle geometry. The engine experiments cover both the investigation of the fuel injection and the engine operating parameters such as injection rate, nozzle geometry, the engine load and speed. The effects of each parameter on ignition delay, heat release rate, nitrogen oxides emissions, smoke density, and total hydrocarbon levels were investigated. Two complementary diagnostic techniques were employed in order to assist in understanding the injection characteristics. The first technique involved the imaging of the fuel sprays from the different injectors in a constant volume spray chamber using a CCD camera. The images were than process using a dedicated image processing software. The second technique involved the measurements of the fuel injection rates from the injectors using the Bosch Tube meter. A three-zone model was developed to determine the heat release rate of combustion. The cylinder pressure data was used to validate the model written in Matlab computer programme. The model is based on the principles of the First Law of Thermodynamics applied to the three zones, formed due to the fuel injection into the combustion chamber. The heat release rate profiles produced by the model were used to analyse the formation of pollutants that were measured in the exhaust gas. The results showed that injectors with large nozzle hole diameters produced high smoke levels, especially at high engine load conditions with small increase in NOx. These injectors also caused the sprays to impinged on the combustion chamber walls at high load conditions. On the other hand, injectors having small nozzle hole diameters produced high levels of NOx while the smoke emission levels were low. The effect of nozzle geometry has little significant on the emissions of THC.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

An Experimental Investigation on the Influence of Port Injection at Valve on Combustion and Emission Characteristics of B5/Biogas RCCI Engine

High unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions, on account of the premixed air-fuel mixture entering the crevices and pre-mature combustion, are setbacks to reactivity-controlled compression ignition (RCCI) combustion at a low load. The influence of direct-injected B5 and port injection of biogas at the intake valve was, experimentally, examined in the RCCI mode. The port injection at the valve was to elevate the temperature at low load and eliminate premixing for reduced pre-mature combustion and fuel entering the crevices. An advanced injection timing of 21° crank angle before top dead centre and fraction of 50% each of the fuels, were maintained at speeds of 1600, 1800 and 2000 rpm and varied the load from 4.5 to 6.5 bar indicated mean effective pressure (IMEP). The result shows slow combustion as the load increases with the highest indicated thermal efficiency of 36.33% at 5.5 bar IMEP. The carbon dioxide and nitrogen oxides emissions increased, but UHC emission decreased, significantly, as the load increases. However, CO emission rose from 4.5 to 5.5 bar IMEP, then reduced as the load increases. The use of these fuels and biogas injection at the valve were capable of averagely reducing the persistent challenge of the CO and UHC emissions, by 20.33% and 10% respectively, compared to the conventional premixed mode

Comparison between tri-fuel (diesel-ethanol-biodiesel) emulsion with and without surfactant

In this project, the overall activities were carried out to compare tri-fuel (diesel-ethanol-biodiesel) emulsions with and without surfactant (Tween 80 and Span 80) in term of stability and physiochemical properties (density, calorific value, surface tension and kinematic viscosity) characteristics. Potential benefit includes micro- explosion phenomenon through mixing diesel fuel and alcohol has inspired researcher to find solution for immiscibility issue. Furthermore, biodiesel add-on apart from as oxygen source, the expectation will be to act as natural surfactant. The effectiveness of biodiesel in the absence of surfactant however is dubious while additional potential benefits compose with surfactant is unfamiliar. Hence, the objective of the study was to compare side by side, tri-fuel emulsion with and without surfactant in term of physicochemical properties. In this study, alternative fuel for CI engine called tri-fuel emulsions were prepared using Hielscher Ultrasonic Processor UP400S. The result of stability study revealed that tri-fuel emulsions with surfactant show promising stability reading compared to the tri-fuel emulsion without surfactant. Evidence was identified by having lower phase separation height and slower phase separation formation. Composition with 5% of ethanol content (D85E5B10) proves to be the best in term of physiochemical properties compared to other composition either with or without surfactant. However, the addition of surfactant in D85E5B10 shows more optimum properties

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