توصيفگر ها :
احتراق , پيش مخلوط كننده هوا و سوخت , پايداري شعله , تحليل تجربي , آلاينده CO , مشعل متخلخل استوانه اي , راندمان احتراق , محيط متخلخل
چكيده انگليسي :
The spread of pollutants is one of the effective factors in severe climate changes worldwide, and countries that produce them are constantly striving to reduce their production. Despite the problems that hydrocarbon fuels have and despite the increasing use of solar, hydro, nuclear, wind, and other renewable energies, hydrocarbon fuels still have a special place in the combustion process. The high importance of reducing atmospheric pollutants is fully evident, and in line with reducing the production rate of CO pollutant, a pre-mixer has been designed, analyzed, and constructed in this study to be used in cylindrical porous burners for fuel combustion.
The main objective of this project is to design and construct a pre-mixer for a cylindrical porous industrial burner that mixes fuel (natural gas) and air. The mentioned burner has already been constructed in another master's thesis project and is now available on the combustion chamber device in the thermodynamics laboratory of the Isfahan University of Technology.
The pre-mixer studied in this project is designed to create a completely uniform mixture with efficient fuel and air mixing. In addition to creating a high-quality uniform mixture, the goal was also to reduce the considerable amount of pollutants produced in the porous burner. Achieving such a request is impossible and very difficult in practice, but the goal was to get as close to this state as possible. It should be noted that in the design of this pre-mixer, factors such as safety, weight, aerodynamic resistance, material, appropriate size, etc., have been taken into account.
The project process was carried out in four general stages: design, analysis, construction, and testing. In the first stage, several conceptual designs were presented, and ultimately, after analyzing, reviewing, and comparing the results, one design was selected. Then, UDF coding and analysis of the results obtained from fuel and air injection in the designed component were examined, and finally, after necessary modifications, the selected design was improved for easier construction. After improving the design, the desired component was manufactured and finally installed on the combustion chamber device. In the last stage, the component was tested, and the desired tests were performed on it.
In the conducted tests, the effect of fuel and air mixture homogenization on stability, CO pollutant emission rate, and radiative efficiency in a 150 kW burner were investigated. Then, the values obtained from the burner with, and without this component were compared. All tests were conducted at six different fire rate ranges, and the results showed that after installing the pre-mixture, a higher fire rate was observed under the same experimental conditions. In the study, the difference between the maximum and minimum fire rate values was 463.2 kW/m2, while in previous studies, this difference was only equal to 272.73 kW/m2. Generally speaking, the fire rate has increased by about 40 percent compared to previous tests without the pre-mixer, and a wider range of fire rates and flame variations have been investigated in this project.
The CO pollutant concentration in the combustion products in the previous study was in the range of 100-650 ppm, which decreased to 30-100 ppm after installing the pre-mixer. This is the result of proper fuel and air mixture and more complete combustion of the burner. The reduction in CO pollutant emission is approximately 77 percent compared to the state without the pre-mixer.
