Showing 4 results for Premixed Combustion
Ali Zargarbashi, Sadegh Tabejamaat, Soroush Sarrafan Sadeghi, Soroush Sheykhbaglou,
Volume 20, Issue 12 (11-2020)
Abstract
In this paper, the experimental study of partially premixed combustion of methane and oxygen in a 5 mm mesoscale quartz reactor with 1 mm wall thickness and 5, 10, and 15 cm lengths. The partially premixed for 25%, 50%, and 75% mixing ratios paid. Experimental results including the factor of affecting flame regimes, formation range, flame dynamics, the outer wall temperature distribution of the reactor had been analyzing and reporting. The above tests were performing in an asymmetrically centered cylinder combustion chamber and a laminar flow regime. In most partial pre-mixing combustion experiments, the oscillation regime, which had an optimal heat distribution throughout the reactor, had been observed. The flame dynamics were more effect by changes in mixing ratio, reactor length, oxygen flow rate, and finally fuel flow rate (equivalence ratio). Also observed that by increasing the reactor length due to the appropriate time for homogenization of the mixture, differences in the flame formation interval were reducing in the different ratios of the pre-mixes.
Mohsen Bashi, Mohsen Ghazikhani,
Volume 22, Issue 2 (1-2022)
Abstract
Numerous studies on using light fuels in compression ignition engines to reduce emission and increase efficiency have been done. The Reactivity Controlled Compression Ignition engines are one of these studies. Nevertheless, using heavy fuels vapor for achieving partially premixed combustion is not investigated. Using diesel fume (to upgrade conventional combustion to premixed combustion) resolves the need for a secondary fuel tank in a car. However, diesel fuel has heavy hydrocarbons and is a high reactivity fuel. So in this study, diesel has evaporated in a tank, and its vapor has injected into the intake air for studying a semi homogeneous combustion. The tests have performed at 2000 rpm (the speed of maximum torque). According to the achieved results, although diesel has heavy hydrocarbons and is a high reactivity fuel, adding diesel fumigation can reduce soot and NOx emissions up to 20% and 50%, respectively. Increasing load reduces the positive impact of adding diesel fumigation on soot and NOx emission reduction. However, the positive impact of adding diesel fumigation continues up to 80% of the full load. Adding diesel fumigation has no impact on cyclic variation and ringing intensity, but increases CO and HC emission. The evaporation of diesel averagely consumes 15% of brake power. Also on average, 5% of diesel evaporation energy can be supplied by recovering heat energy from the exhaust gas (warming up diesel from ambient temperature to the exhaust gas temperature).
Ali Zargarbashi, Soroush Sarrafan Sadeghi, Sadegh Tabejamaat,
Volume 22, Issue 4 (3-2022)
Abstract
An experimental study on the effects of methane-oxygen partially-premixed input flow characteristics in a mesoscale reactor with constant length and geometry was investigated in the present work. For this research, two partially-premixed ratios of 25% and 50% are considered. The reactor is mounted horizontally, made from quartz material and its geometric characteristics are internal diameter: 5 mm, wall thickness: 1 mm, and length: 10 cm. In this research, we have tried to determine the factors affecting flame regimes. The range of flame regimes, flame dynamics, the outer wall temperature distribution of the reactor, frequency, and oscillation of oscillating flames, along with the intensity of the Repetitive Extinction and ReIgnition (RERI) extinguishing sound, were analyzed and reported. This flame's dynamics are more affected by changes in mixing ratio, oxygen volume flow rate, and fuel volume flow rate, causing changes in inlet flow velocity and equivalence ratio, respectively. Examination of the results of acoustic oscillations indicates an increase in oscillating flame velocity with increasing volumetric flow and mixing ratio. Loud extinguishing sound of flames when quenching is caused by converting a portion of the thermal energy of the flame into sound in the flame arrestor and the acoustic vibration waves resulting from the extinguishing of the flame and the difference in gas velocity.
Aref Sohrabi, Seyyed Mahdi Mirsajedi,
Volume 24, Issue 12 (11-2024)
Abstract
This study investigates the combustion of hydrogen-methane mixtures in the annular combustion chamber of a C30 microturbine. The primary objective is to evaluate the impact of premixed methane-hydrogen combustion on pollutant emissions and outlet temperature in an annular combustion chamber. Simulations were performed using a partially premixed combustion model and the k-ε turbulence model, employing the Probability Density Function (PDF) approach for chemical reaction modeling. To ensure a detailed analysis of pollutant emissions, comparisons were conducted at a constant turbine inlet temperature. The results indicate that adding hydrogen to methane increases NOx emissions due to the higher flame temperature compared to pure methane, even at constant turbine inlet temperatures. However, this blend can reduce fuel consumption by up to 35%. Additionally, a fuel mixture of 60% methane and 40% hydrogen results in a 61% reduction in CO2 emissions. The study further revealed that, owing to the premixed nature of the fuel-air mixture, the annular geometry, and the swirling flow pattern within the combustion chamber, a fuel blend containing 30% hydrogen can lower NOx emissions to 16.1 ppm—significantly less than the 46 ppm reported in previous studies. Moreover, increasing the hydrogen fraction in the fuel reduced CO emissions by 16%. These findings demonstrate that annular combustion chambers with premixed flows and hydrogen-methane fuel blends have considerable potential for reducing pollutant emissions and optimizing fuel consumption
