JOURNAL OF FACULTY OF ENGINEERING (UNIVERSITY OF TABRIZ)
Year:2003 | Volume:29 | Issue:2 (32) Mechanics|Papers Count:6

A magnesia based refractories were prepared from natural lranian dead burned magnesite with mole ratio of CaO/Si02<1. Different mass-% of CaZrO3 clinker added to dead burned magnesite to investigate the phase transition and sintering behaviour of body. The prepared magnesia refractory samples are fired at 1700°c for 6hr. The effect of calcium zirconate addition up to 12wt% was studied on density, porosity and shrinkage properties. The phase evaluation was studied by XRD technique. Results show that calcium zirconate additions improve sintering behavior of magnesia body. The effect of CaZrDO3 on sintering improvement reduces by increasing the size of clinkers.

Nowadays reduction in fuel consumption and pollutant emissions from direct injection diesel engines are important issues in engine research field. To achieve these reductions, rapid and better fuel air mixing is the most important requirement. For rapid and better fuel air mixing and improvement in diesel engines combustion, air swirl in cylinder and its adaptation with fuel injection is the most important approach. Thus suitable design of combustion chamber geometry is necessary for increasing swirl in intake and during compression stroke in cylinder. In this research, geometry of new combustion chamber in the form of re-entrant combustion chambers has been designed and manufactured and turbocharger and nozzles of injection systems has been used adaptable. The wall impingements of fuel jets depend on jet cone angle, fuel injection timing and engine speed. Thus with an adaptation of these parameters in new combustion chamber, optimum fuel injection angle has been selected. The experimental results show that engine performance is better than baseline engine and engine emission has been reduced. For more NOx reduction other methods for example: reducing compresstion ratio, retard fuel injection and exhaust gas recirculation EGR can be used.

In this paper growth and collapse of a cavitation bubble near a rigid body is studied using BIEM. The behaviour of the cavitation bubble is investigated in both cases of the cavitation bubble located above and below the rigid body. In the case of the cavitation bubble located above the rigid body, the Bjerknes attraction force through the rigid body acts in the opposite direction of the buoyancy forces. Whereas in the case that the cavitation bubble is located below the rigid body, the Bjerknes attraction force acts in the direction of the buoyancy forces. The numerical results of the present study has been compared with the experimental results of Hooton et al. It is shown that the numerical results of the present investigation are in good agreement with the experimental results of Hooton et al.

In this paper it is attempted to reduce of emissions of OM-355 diesel engines such as nitric oxides, carbon monoxide, particulate matters and unburned hydrocarbons simultaneously from Euro 0, European emissions standard level, to Euro 1 without any changing in primary engine design. Mixing of air with fuel before injecting of fuel to the combustion chamber, exhaust gas recirculation, ionization of fuel (prior to injection), using of particulate trap, using of high quality fuel (low sulphur fuel), increasing of fuel injection pressure, correction of fuel injection timing, correction of air-fuel ratio, are combined procedures that have been used in this paper. Finally by using of above mention combined techniques the emissions level of OM-355 diesel engine lie in nearly the "Euro 1" standard. These results are validated and certified by Motor Industry Research Association (MIRA).

In this paper, the fuel pressure regulator for MPFI Paykan 1600cc which is a diaphragm operated valve has been simulated, analyzed and tested. The fuel pressure regulator is usually mounted on the fuel rail to maintain a constant relative pressure (3.5bar) between the fuel injectors and the intake manifold. The valve is first described and analyzed based on its functionality. Then, the mathematical equations of various sections of the valve are presented. After that and based on those equations, the mathematical model of whole valve is derived. This model is solved and analyzed using MATLAB engineering software. To evaluate the model, the simulation results are compared to the experimental results. After validation of the model, the model is used as a reference to evaluate the functionality of the valve at different operating conditions and also sensitivity analysis. In general, discussing about steady state and also transient response of the valve are the main objectives of this paper.

In this research the provide of Cordierite - Mullite bodies that use in ceramic industries specially in sanitary ware and tile factories by slip casting method, is evaluated. At first, the formula has designed from one standard body. Variations in some properties of like, bulk density, porosity, bending strength (MOR and HMOR) and thermal shock resistance at different soaking temperature and soaking time, are measured. Microstructure and analysis of specimens are studied by use of Scaning Electron Microscope (SEM). It observed that distribution of particle size (in slip) must be in a specific range that, material over 500, 100 and 63 (micron) sieves are about 0, 17 and 23.5 percent. The results shows the best condition for formation of cordierite and mullite phases are 1355oC and optimum soaking time is 5 hours.