Flameless Combustion as an Alternative for Improving the Efficiency of Thermal Systems: State-of-the-Art Review

The increasing energy demand and polluting emissions have generated a growing number of studies into technologies that can be used to mitigate both problems worldwide. Among the alternatives for improving the efficiency of thermal processes, the flameless combustion regime has been presented as one of the most promising options because it enables high thermal performance by enhancing heat transfer and the combustion process, with the consequent reduction in polluting emissions.

Rendimiento energético de un horno equipado con quemadores regenerativos bajo el régimen de combustión sin llama

El aumento de la eficiencia es una de las principales alternativas para reducir tanto el consumo de combustibles, como la cantidad de contaminantes. En este sentido el régimen de combustión sin llama con quemadores regenerativos se presenta como una tecnología que permite de forma simultánea alcanzar estas características. En el presente estudio se llevó a cabo la evaluación energética de forma experimental de un horno operando a 25 kW en el régimen de combustión sin llama, usando gas natural como combustible.

Estudio teórico, numérico y experimental de la intercambiabilidad del gas natural en Antioquia

Se determinaron los límites operativos de intercambiabilidad con gas natural proveniente de distintas fuentes, de tal manera que no se afecte las propiedades físicas de los equipos de combustión ya instalados y se garantice un flujo de combustible eficiente y seguro. Se estudiaron las mezclas de gas natural recibidas en Antioquia (Colombia) entre 2011-2015.

Study of the flameless combustion mode in presence of thermal load fluctuation

 El presente estudio evaluó numérica y experimentalmente en un horno de 20 kW (a gas natural y con un factor de aireación de 1.2) la estabilidad del régimen de combustión sin llama ante la variación de la carga térmica usando diferentes flujos de aire (43 scfm, 63 scfm y 83 scfm) y una mezcla de Aire-Helio (Aire 82.02 scfm y Helio 7.06 scfm); esta última se utilizó con el fin de evaluar el comportamiento del sistema ante un incremento en el calor especifico del fluido de carga. El estudio se dividió en dos partes, una parte numérica y otra experimental.

Processing Criteria and Experimental Data Quality for a High Compression Ratio Spark Ignition Engine

This article presents the evaluation of some of these methodologies applied to a high compression ratio-spark ignition engine, which was achieved through modification of a commercial Diesel engine. The accuracy on calculation of equivalence ratio from exhaust gas analysis and the start of combustion from mass fraction burned has been tested. The effect of trapped mass on the in-cylinder energy balance was determined.

Laminar burning velocity of natural gas/syngas-air mixture

This study suggests the equimolar mixture of Natural Gas (100% CH4) and Synthesis Gas (40% H2+ 40% CO + 20% CO2) as an alternative to reduce hydrocarbons consumption and reduce pollutant emissions. As a key parameter to characterize this combustible mixture, the laminar burning velocity was studied based on numerical simulations and experimental measurements in flames generated using a contoured slot-type nozzle burner and the Schlieren technique, varying the air-fuel ratio at standard temperature and pressure.

Determination of laminar flame speed of methaneair flames at subatmospheric conditions using the cone method and CH* emission

Experimental measurements of laminar fl ame speed for premixed methane-air fl ames were carried out for different equivalence ratios at subatmospheric conditions, 852 mbar and 298 K. The fl ames were obtained using a rectangular port burner with a water cooler system necessary to maintain the temperature of the mixture constant. An ICCD camera was used to capture chemiluminescence emitted by OH-CH radicals present in the fl ame and thus defi ne the fl ame front.

Numerical calculation of the recirculation factor in flameless furnaces

 This paper performs calculations of the recirculation factor in simulations of a flameless combustion furnace with different percentages of oxygen in air (from 21% to 100% O2 ). Results are compared with Magnussen’s recirculation theory and show that when there are chemical reactions, the recirculation results are overpredicted. An alternative correlation to Magnussen’s theory is proposed, useful in calculating the recirculation factor in flameless furnaces.

Effect of biogas enriched with hydrogen on the operation and performance of a diesel biogaqs dual engine

The effect of hydrogen enrichment was tested for a diesel-biogas dual fuel engine. The operation and performance characteristics, such as thermal efficiency, pollutant emissions and combustion parameters were determined. Experiments have been carried with a stationary compression ignition (CI) engine coupled with a generator in dual mode using a typical biogas composition of 60% vol. CH4 and 40% vol. CO2. For every load engine evaluated, the hydrogen concentration was varied from 5 to 20% H2 v/v.

Numerical analysis of internal recirculation into a radiant tube without internal ignition

This paper presents a numerical analysis using the CFD Fluent (6.3.26 version) program to identify the effects that can be generated when using radiant tubes with internal recirculation of combustion products, but with a pre-combustion chamber. The numerical results are validated with an experimental assembly based on the outlet deviation of gases temperature. These deviations were less than 5 % and are attributed principality to isolation deficiency in the re-radiant surface.