Current Issue : July - September Volume : 2017 Issue Number : 3 Articles : 5 Articles
This paper presents the investigation of engine optimisation when plastic pyrolysis oil (PPO) is used as the primary fuel of a direct\ninjection diesel engine. Our previous investigation revealed that PPO is a promising fuel; however the results suggested that control\nparameters should be optimised in order to obtain a better engine performance. In the present work, the injection timing was\nadvanced, and fuel additiveswere utilised to overcome the issues experienced in the previouswork. In addition, spray characteristics\nof PPO were investigated in comparison with diesel to provide in-depth understanding of the engine behaviour.The experimental\nresults on advanced injection timing (AIT) showed reduced brake thermal efficiency and increased carbon monoxide, unburned\nhydrocarbons, and nitrogen oxides emissions in comparison to standard injection timing. On the other hand, the addition of\nfuel additive resulted in higher engine efficiency and lower exhaust emissions. Finally, the spray tests revealed that the spray tip\npenetration for PPO is faster than diesel.The results suggested that AIT is not a preferable option while fuel additive is a promising\nsolution for long-term use of PPO in diesel engines....
In this work, the influence of internal combustion engine parameters (cylinder-\npiston clearance, piston head height, the first segment position, gap of the\nfirst piston ring and gap of the second piston ring, piston rings� axial clearance,\nintake valve debit coefficient) gas leakage from the combustion chamber\nthrough the piston rings� area was investigated. This influence was studied by\nmaking an initial forming operation over gas leakage in the analyzed area....
A modified regression rate formula for the uppermost stage of CAMUI-type hybrid rocket motor is proposed in this study.\nAssuming a quasi-steady, one-dimensional, an energy balance against a control volume near the fuel surface is considered.\nAccordingly, the regression rate formula which can calculate the local regression rate by the quenching distance between the\nflame and the regression surface is derived. An experimental setup which simulates the combustion phenomenon involved in\nthe uppermost stage of a CAMUI-type hybrid rocket motor was constructed and the burning tests with various flow velocities and\nimpinging distances were performed. A PMMA slab of 20mm height, 60mm width, and 20mm thickness was chosen as a sample\nspecimen and pure oxygen and O2/N2 mixture (50/50 vol.%) were employed as the oxidizers. The time-averaged regression rate\nalong the fuel surface was measured by a laser displacement sensor. The quenching distance during the combustion event was also\nidentified from the observation.The comparison between the purely experimental and calculated values showed good agreement,\nalthough a large systematic error was expected due to the difficulty in accurately identifying the quenching distance....
When a fire occurs in a tunnel in the absence of sufficient air supply, large quantities of smoke are generated, filling the vehicles\nand any space available around them. Hot gases and smoke produced by fire form layers flowing towards extremities of the tunnel\nwhich may interfere with person�s evacuation and firefighter�s intervention. This paper carries out a numerical simulation of an\nunexpected fire occurring in a one-way tunnel in order to investigate for the critical velocity of the ventilation airflow; this one is\ndefined as the minimum velocity able to maintain the combustion products in the downstream side of tunnel. The computation\nis performed successively with two types of fuels representing a large and a small heat release rate, owing to an open source CFD\ncode called ISIS, which is specific to fires in confined and nonconfined environments. It is indicated that, after several computations\nof full-scale fires of 43.103 and 19.103 kJ/kg as heat release rate, the velocities satisfying the criterion of healthy environment in the\nupstream side of the tunnel are 1.34m/s and 1.12 m/s, respectively....
Recent advances in gas turbine combustor design are aimed at achieving low exhaust\nemissions, hence modern aircraft jet engines are designed with lean-burn combustion systems.\nIn the present work, we report an experimental study on lean combustion in a liquid fuel burner,\noperated under a non-premixed (single point injection) regime that mimics the combustion in a\nmodern aircraft engine. The flame behavior was investigated in proximity of the blow-out limit by an\nintensified high rate Charge-Coupled Device (CCD) camera equipped with different optical filters to\nselectively record single species chemiluminescence emissions (e.g., OH*, CH*). Analogous filters\nwere also used in combination with photomultiplier (PMT) tubes. Furthermore this work investigates\nwell-mixed lean low NOx combustion where mixing is good and generation of solid carbon particulate\nemissions should be very low. An analysis of pollutants such as fine particles and gaseous emissions\nwas also performed. Particle number concentrations and size distributions were measured at the\nexhaust of the combustion chamber by two different particle size measuring instruments: a scanning\nmobility particle sizer (SMPS) and an Electrical Low Pressure Impactor (ELPI). NOx concentration\nmeasurements were performed by using a cross-flow modulation chemiluminescence detection\nsystem; CO concentration emissions were acquired with a Cross-flow modulation Non-dispersive\ninfrared (NDIR) absorption method. All the measurements were completed by diagnostics of the\nfundamental combustor parameters. The results herein presented show that at very-lean conditions\nthe emissions of both particulate matter and CO was found to increase most likely due to the\noccurrence of flame instabilities while the NOx were observed to reduc...
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