فهرست مطالب امین جودت

Compared to liquid and solid fuels, natural gas produces much less soot during combustion, and the melting and reaction on the surface of these soot is one of the main factors in the production of radiation in the flame. The use of natural gas as a substitute for liquid fuel in industrial and household burners has caused a decrease in thermal efficiency due to the weak radiation bands of gas fuel, therefore the combustion of natural gas has a lower thermal efficiency compared to liquid and solid fuels. And improving the radiant heat transfer of natural gas flame is one of the main challenges of active researchers in this field. In this research, the ethanol fuel was reduced to micron size by the nebulizer and injected into the flame with turbulent flow and as a result, better mixing, and its effects on the radiant heat transfer of the flame as well as the reduction of NOX pollutant were investigated. The results of the present research show that the injection of 1 percent by weight of ethanol in a nebulized form causes a 1 percent increase in the average temperature of the natural gas flame along the length of the boiler and a 3.5 percent increase in the radiant heat transfer flux, and also the injection of micron ethanol particles causes the production of NOX pollutants to decrease by 12.5 percent.

One of the important characteristics of the flame of liquid and solid fossil fuels, is the flame luminosity and the high radiation heat transfer rate compared to the natural gas flame. The use of gas burners instead of gasoil burners has led to lower thermal efficiency and it poses many problems to industrial manufacturers. In this study, the effect of ion and oil combinations injection with a nebulizer on luminosity, radiative heat transfer and pollutant emission of natural gas diffusion flame is investigated. The experimental results show that the injection of 1% oil combinations, enhance thermal efficiency 2.5% and reduce The temperature of the exhaust gases, production of by 12% and 13% respectively also the injection of 2% oil combinations with 1% water drops, reduce the temperature of the exhaust gases, production of and Carbon monoxide by 6%, 42% and 26% respectively. The experimental results show injection method by the nebulizer can be used as a method in gas burners to increase radiation heat transfer rate and reduce the pollutants of exhaust gases from the chimney

In this experimental study, the condensed water in the evaporator coil was injected using the nebulizer technology into the condenser inlet air and its effect on the performance coefficient was studied. The testing equipment employed in the present study consisted of an air conditioner tunnel with the dimensions of 200×35×35cm, which had the compression refrigeration cycle of 1-ton refrigeration with R404a refrigerant. A data logger with pressure and temperature sensors installed at various points of the unit accurately recorded the measured data. The results indicated that the use of a nebulizer would reduce the compressor outlet pressure and compressor power consumption and also increase the performance coefficient. By increasing the air temperature to the condenser from 21 to 36°C, the use of a nebulizer reduced compressor outlet pressure by more than 27%, decreased compressor power consumption by more than 8%, and increased the performance coefficient more than 64%. The results demonstrate the nebulizer technology could be used on hot days of the year by recycling wastewater from air conditioning systems, as a practical and low-cost method to increase the efficiency of direct expansion air conditioning systems.

In this investigation experimental measurements have been done over a wide range of wave parameters, water temperatures and air velocities for . The measurements were performed over a wide range of on a large heated wave flume equipped with a wind tunnel. The effects of forced, free and mixed convection regimes on the water evaporation rate in surface gravity Waves have been investigated. The experimental results shows that wave motion on the water surface increase the rate of evaporation for all air flow regimes. Also Results reveal the evaporation rate increases with air velocity but increasing of , , has different effects on evaporation rate. For free convection regime evaporation rate increases with, , . For forced and mixed convection regime at medium values of , the leeward air flow structures which form barrier for the vertical transport of vapor, decrease water evaporation rate. Results reveal that the effect of induced turbulence at the wavy interfacial surfaces on the water evaporation increment is more than the effect of interfacial area increment percentage.

This study has mainly focused on derivation of aerodynamic data for an airship in particular conditions especially at high angles of attack. When such data are inserted into a flight simulator as a closed loop, it is vital to make use of special computational means and methods, so that the ability to send and receive flight conditions would be achieved through an “in-the-loop” manner. Therefore, using an open source environment such as OpenFOAM is suggested in this regard. Through this study, the aerodynamic coefficients of the airship are calculated by three different CFD approaches and empirical data collected from wind-tunnel tests while geometrical parameters were set for angles of attack between -10 to 20 degrees. In order to achieve aerodynamic goals, air simulation is of great importance. So, the aerodynamic results are compared based on the three methods of calculating fluid "computing" in the loop, the wind tunnel test and the analytical method of the geometric parameters of the ship's aircraft. In this study, the stability of the aircraft, the longitudinal and lateral aspects of the aircraft is examined. Also, by examining the ratio of the coefficients of the lift to the drag, based on the angle of attack, the angle of attack that the aircraft has the best performance is determined.