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The issue of maintaining low-gradient combustion in the conditions of high heat extraction has been investigated numerically in this work. The analyses include the application of a convective boundary condition at the wall (with estimated boiling heat transfer coefficient); analysis of the Internal Recirculation Device's impact on combustion products and heat transfer under low-gradient conditions; and comparison of both traditional and low-gradient combustion modes. It was shown that the Internal Recirculation Device material and geometry has a significant impact on the nitrogen oxide (NO x ) formation mechanism, as NO 2 emission becomes predominant and can rise up to several hundreds ppm. What is more, along with decrease in thermal resistance of the IRD, CO emissions also increase rapidly, even achieving over 2000 ppm. Additionally, the convective heat transfer rate decreased by about 25% after switching from traditional to low-gradient combustion, whereas the radiative mechanism increased by ≈40% compared to traditional mode. It should also be mentioned that the low-gradient combustion applied in this work achieved approximately 10% higher efficiency than conventional combustion. [ABSTRACT FROM AUTHOR]

This paper deals with the numerical simulation of a pilot-scale axial cyclone separator. The main purpose of this paper is to develop a numerical model that is able to foresee the cyclone separator cut-off point. This is crucial in blast furnace gas installation to capture large particles containing carbon and iron, while allowing smaller particles such as zinc and lead to pass through. The cut-off point must be designed to give a sufficiently high zinc and lead content in the sludge created after the second cleaning stage. This allows the sludge to become a commercial product. To design this cut-off point, an investigation of the influence of inlet gas velocity, temperature, and the angle of guiding vanes at the inlet was done. The developed CFD model was validated against experimental data on the fractional efficiency of the cyclone separator. The results were in good agreement with the experimental data for all parameters tested. The behavior of the particles inside the cyclone was also physically correct. [ABSTRACT FROM AUTHOR]

Combi-steamer condensation hoods are widely used in modern gastronomy. They condense steam produced by the combi-steamer and also filter solid particles, moisture, grease and smells. All these factors negatively affect the staff and dishes, so efficient work of the condensation hoods becomes important. A mathematical and experimental analysis of such a device is described in this paper. First a measurement methodology was designed and measurements of air humidity, temperature and mass flow rates were performed. The measurement procedure concerned dedicated a steam generator and combi-steamer. Next a mathematical model was developed. It was based on mass and energy balances of the condensation hood. The condensate flow rate turned out to be insufficient to fulfill the energy balance while measured directly. Hence, it was calculated from heater's power of the steam generator and the balance model was validated. The combisteamer had an unknown output, so the condensate flow rate was provided by the balance model after its validation. A preliminary diagnosis of the device was carried out as well. [ABSTRACT FROM AUTHOR]