ABSTRACT

Pyrolysis is one of the most important thermo chemical energy conversion methods for renewable energy sources. In our university few project works has been done on pyrolysis. At first the stainless steel was selected for the construction of pyrolysis system and the palm shell was selected as feed material. Nitrogen gas was used to maintain the inert atmosphere in the reactor where the pyrolysis reaction takes place. The feedstock considered in this study was palm shell as it is available waste material in Bangladesh. Finally more liquid product was found (45% wt, which is maximum) at 550°C for size0.7-0.9cm.

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ABSTRACT

A severe scarcity of energy both in the form of electrical energy and fuel is been uprising day by day along with the deterioration of the major natural resource of Bangladesh, natural gas. This lead to necessities of development on renewable energy rather than conventional sources of energy. It has been a great development in the field of biomass solid wastes. But attention has to be given in the recycling of organic solid wastes as it involves more hazard effects on the environment. Fixed bed pyrolysis system is more attractive among various thermo chemical conversion processes because of its higher conversion capability of solid wastes into liquid fuel. The conversion of organic solid tires wastes, which are found in abundance locally into pyrolytic oil by fixed-bed fire-tube heating reactor, has been taken into account in this study. Solid wastes of different sizes were pyrolized in an internally 30 cm height and 10 cm diameter fixed-bed fire-tube pyrolysis reactor. The reactor was heated by two electric heater coils of 1000Watt capacity each. Nitrogen was used as carrier gas which was preheated in the pre heater by a LP gas burner. The products were oil, char and gas. The parameters varied were temperature and feed size. These parameters were found to influence the product yields significantly. The maximum liquid yields were 65, 60 and 50wt% of motorcycle, bicycle and rickshaw tire wastes respectively all at 475⁰C and for tire feed size of 8cm X 1cm X 1cm.The pyrolytic oil obtained at these optimum process conditions were analyzed for their properties as an alternative fuel and compared with petroleum products. 

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ABSTRACT

The main contents of this thesis includes the design and construction of a natural convection & radiation heat transfer equipment. With this equipment the heat transfer rate from a body by different modes can be found. The emissivity and the heat transfer coefficient of the body can also be determined. The total heat supplied to the element (heating element) is transferred in three modes. Heat transfer by conduction process can easily be measured. If the element  in very low pressure or in a vacuum then the heat transfer by convection process become negligible and the total heat transfer by radiation process can be easily determined. And thus emissivity of the element can be determined. It was assume that the G.I sheet was mild steel. And the pressure vessel was made by G.I sheet. But when the vessel was making vacuum, air pressure squeezed the vessel and the equipment failed. Then it was necessary to analysis the case of failure. Moreover, the analysis of the G.I sheet by universal testing machine, it was seen that the properties (hardness, toughness, stress, etc...) of the sheet was not same the mild steel properties. Then necessary to analyze the case of tangential, compression & buckling where the equipment failed. As a result of analysis, buckling was the main cause of failure. In order to eliminate this failure, the properties of the sheet have to consider first.This work will help the beginner who wants to proceed in this field.

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ABSTRACT

DI diesel engine vehicles are becoming popular because of their friendly behavior to the environment as it emits lower CO₂ . The main cause of it is that it consumes relatively smaller amount of fuel than a gasoline engine vehicle. But this increases both regulated and unregulated emissions like No_x, PM, exhaust odor and others. The regulated emissions are No_x, PM etc and unregulated emissions is the exhaust odor. Most diesel engine researches put their attention to reduce the regulated emissions. The attention of the authors is to reduce the unpleasant exhaust odor of DI diesel engines at idling. Among the various exhaust emission problems of DI diesel engine, odor is still a prominent emission problem. Reduction of exhaust odor can be done mainly in three ways. One of them is to optimize the engine parameters. But researches have been shown that the reduction of odor is not significant. The other is that the use of alternative fuels. Some alternative fuels can reduce the exhaust odor significantly but the cost is much higher than diesel fuel. The one is to use the catalyst system. The catalyst system hence cannot be applied at idling and at low temperature operation. The other is the absorption type system like water-washing system. By EGR, NOx reduces but PM emission increases, with which odorous emission increases. For this reason, EGR and Water- Washing System is used to improve emissions by reducing NOx & odor. Odorous emissions seems to be reduced using EGR, While reading is taken directly. This is due to the reason that EGR reduces the speed of exhaust gas. For this reason, indirect odor assessment is done, from which it is found that odor increases with the increase in EGR. The water washing system can be applied at idling and at low temperature operation. Since the emission of exhaust odor at idling at low temperature operation is higher than any other engine condition, and exhaust gas temperature is much lower at idling and low speed operation, the water washing system can be used. Some previous researches have shown that odor can be reduced greatly by washing the exhaust gas by water. Since there are no proper systems to reduce the exhaust odor at idling, this thesis report focuses on the water washing system. In the water washing system the exhaust was first passed through EGR system and then through water. Also, experiments were performed with EGR only and water washing only. From these experiments, it was found that odor reduced to 1point (a significant odor reduction) by using total setup (combination of EGR and water-washing). But individual components could not able to reduce the odor significantly.    

 

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ABSTRACT

The mixed model assembly line has been taken into account. The balanced line has been studied for mixed model production scenario. Published mixed model situation is taken under study. Without proper sequencing for different demand situation line balancing problem study is not complete. To do so sequencing for the balanced mixed model assembly line is done. Simulation technique is widely used to solve the different complex problem in real world situation. So the simulation technique is applied to solve the problem and the simulation package AutoMod is used. The mixed model balanced line case study has been taken from published literature. The proper sequencing for the mixed model assembly line has been found. It is noticed that the completion time shows little higher than in the balanced mixed model assembly line. But it is better result than the original situation. This happened due to simulation as the previous solution has not taken some real world complexity. 

 

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ABSTRACT

The title “Tensile strength Testing Machine for threads” implies the function of the machine. It is a machine used to measure the tensile strength and tenacity of threads. Our project was to design such a machine for small range capacity up to 150 N. Then the task was to construct the designed Machine by using indigenous materials. After the completion of the construction of the desired machine, it was necessary to test its performance. Hence various types of threads were tested by the machine and test results were compared.

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ABSTRACT

The main contents of this project and thesis include the design, construction, determination of fin efficiency, fin effectiveness and heat transfer by using different combination of fins, in practical field of mechanical and electrical engineering there are large number of engines and machines which work on the basis of heat energy transfer and requires cooling of the body. In many applications where water cooling or other means of cooling system may not be applied fin cooling may be the on of the options. Fins are extended surfaces of heat generating body that increase the rate of heat transfer and reject heat from the body to keep it cool for providing its operations efficiently. In this project work rectangular, triangular and inverse parabolic fin were considered. Heat transfer can be studied either by maintaining constant heat flux or constant temperature. This work was carried out at constant temperature to the base plate. This thesis compares the theoretical and experimental values of quality of heat transfer for all shape and position of the fins. It has been observed that the theoretical values are higher than their respective experimental values. The project work was carried out by placing the fin at vertical position.

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ABSTRACT

Diesel engines are a major source of urban air pollution. The engine exhaust gases contain oxides of nitrogen (Nitric oxide, NO and small amount of nitrogen-di-oxide, NO₂-collectively known as NOx), Carbon monoxide (CO) and particulate matter. Among this, NOx is a prominent exhaust emission problem. The heavy duty highway engine manufacturers can achieve substation emission reduction.The procedure for emission control are exhaust gas treatment, engine modification, fuel modification. The prime objective of this thesis is to reduction of emission especially NOx by fuel modification. Here fuel modification system include using aqueous salt solution. The engine was running at 50% constant load at variable speed. By this procedure formation of NOx is reduced, CO is increased, BSFC is reduced, exhaust temperature is reduced  compared to neat diesel and also the efficiency of diesel engine is increased. 

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ABSTRACT

DI diesel engine is better than petrol engine in terms of fuel consumption and CO₂  emission. But diesel engine has higher emissions like NOx, PM and exhaust odor. Among the various exhaust emission problems of DI diesel engine, odor is still a prominent exhaust emission problem. Reduction of exhaust odor can be done mainly in three ways. One of them is to optimize the engine parameters. The other is that the use of alternative fuels. The last one is exhaust gas after treatment. It is also of two types. One is to use the catalyst system. The catalyst system works only at high temperature condition, i.e. when the vehicle is in running condition (under load). The other is the non-catalytic type system like charcoal-absorption system, water-washing system, air-dilution system or others. Water washing system is a good option of odor reduction at idling. Last few years thesis report on odor reduction by water washing system showed that water washing system can reduce exhaust odor around 0.75 points. This thesis report focuses on the temperature and pressure effect of the water washing system. The experiment was performed with 20 liter and 112 liter water washing system in which cold water was used and the odor was reduced about 0.5 points for smaller one and more than 0.75 points for larger one. Some combination of water washing and air dilution systems were also used. It was found that odor was reduced about 1 points with the air dilution system combined with water washing system. It was also found that odor level was reduced about 1.25 points with the use of water washing system first then air dilution system. The combination of water washing system and air dilution system not only reduces odorous component but also reduces other emission components like CO, NOx, etc. It also increases eye irritation time which also indicates reduction in irritating components. It was found that CO, NOx, odor and eye irritation were reduced about 90%, 93%, 1.25 points and 96% respectively with the combination of these two systems. 

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