Current Issue : July - September Volume : 2015 Issue Number : 3 Articles : 5 Articles
Natural gas plays an important role as an alternative fuel for gasoline and diesel engines. It has a\npromising future especially with the world crisis in fuel and the lower prices of natural gas compared to\nthe prices of gasoline and diesel fuels. It can be used as a sole fuel in spark ignition engines because it\nhas nearly similar properties as gasoline, but in diesel engines it is used as a main fuel while the diesel\nfuel is injected to the combustion chamber as a pilot fuel to be an ignition source.\nThis paper investigates the performance of a small dual fuel engine where a single cylinder, four stroke\nwater cooled diesel engine is converted to run on a dual fuel of diesel and compressed natural gas (CNG).\nAn exhaust gas recycling system is used to introduce two ratios of EGR (Exhaust gas recirculation) to\nthe engine. Effects of percentage of natural gas content and EGR ratio on engine performance and\nemissions are investigated for different engine loads.\nBased on the obtained experimental results, it can be concluded that the total reduction in engine thermal\nefficiency increases as the ratio of the used natural gas increases. A maximum reduction of about 5 %\nin engine efficiency is recorded when 80% of diesel fuel is replaced by natural gas to deliver the same\nengine power. Also, NOx emissions are decreased while CO is increased with utilization of EGR....
Thepresent work presents the comparative simulation of a diesel engine fuelled on diesel fuel and biodiesel fuel. Twomodels, based\non tabulated chemistry, were implemented for the simulation purpose and results were compared with experimental data obtained\nfrom a single cylinder diesel engine. The first model is a single zone model based on the Krieger and Bormann combustion model\nwhile the second model is a two-zone model based on Olikara and Bormann combustionmodel. It was shown that both models can\npredict well the engine�s in-cylinder pressure as well as its overall performances. The second model showed a better accuracy than\nthe first, while the first model was easier to implement and faster to compute. It was found that the first method was better suited\nfor real time engine control and monitoring while the second one was better suited for engine design and emission prediction....
In order to satisfy the increasing need for security and comfort the active safety systems of the smaller\nvehicles like the motorbikes, scooters, e-bikes and bicycles have an intensively studied research topic\nover the last decade. This paper describes the development of a hydraulic type anti-lock braking\nsystem (ABS) prototype for bicycle applications. Based on vehicle dynamics of bicycles, a mechanical\nmodel has been built and a novel ABS control algorithm was designed. This algorithm is based on a\nnewly developed reference speed calculation method which uses the angular acceleration values of the\nwheels. The proper operation of the algorithm is proved through simulations and based on the results a\nprototype was built. In the prototype system the algorithm was implemented on an external controller\nmodule which involves a Continental-developed motorbike hydraulic electronic control unit. The\nfunctionality of the prototype system has been verified on a test track in several real road surface\nconditions such as dry and wet asphalt, grassy ground and dirt road....
NOx is one of the major toxic emissions that needs to be regulated stringently in both EU and USA\nemission regulations. The engine designer is keen to get an accurate, reliable and cost effective NOx\nmeasurement system. In this paper, the application of the cylinder pressure for predicting the NOx\nemission of compression ignition (CI) engine fuelled with diesel and biodiesel during steady state\noperations is carried out. To address the problem, an experimental work was conducted on four-cylinder,\nturbo-charged, four-stroke and direct-injection CI engine which was fuelled with diesel and biodiesel\nblends. During the experiment, the main parameters consisting of in-cylinder pressure, fuel flow rate,\nair flow rate, and the NOx emission, were measured. The temperature within the cylinder was predicted\nusing the cylinder pressure and air flow rate. Using the temperature values, the NOx emission was\nsimulated in the Zeldovich extended mechanism. The simulation result was then compared with the\nmeasured one for a range of engine operating conditions. The models were shown to produce consistent\nresults with the measured one for a range of engine working speeds and loads....
An automobile disc brake system is used to perform three basic functions, i.e. to reduce speed of a\nvehicle, to maintain its speed when travelling downhill and to completely stop the vehicle. During\nthese braking events, the disc brake may suffer of structural and wear issues. It is quite sometimes that\nthe disc brake components fail structurally and/or having severe wear on the pad. Thus, this paper\naims to examine stress concentration, structural deformation and contact pressure of brake disc and\npads during single braking stop event by employing commercial finite element software, ANSYS.\nThe paper also highlights the effects of using a fixed calliper, different friction coefficients and\ndifferent speeds of the disc on the stress concentration, structural deformation and contact pressure of\nbrake disc and pads, respectively. Results from the investigation could provide a better explanation of\nthe variation in contact pressure distribution and in turn squeal generation. Thus, this study provides\neffective reference for design and engineering application of brake disc and brake pad....
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