The combustion performance of a cylindrical burner accommodating up to six multiple pairs of opposing methane-air mixtures with a cross-flow of hydrogen was addressed. The cross-flow initially duplicated the stagnation impact and enriched the vortical structures. Aided by the resulting flow strain, the transport of heat and active species from the hydrogen oxidation zone to the methane reaction zones accelerated the combustion across the opposing premixed flames and reduced the peak temperature across the outer diffusion flame. Increasing the cross-flow/opposing jets' velocity ratio to 0.89 merged the two stagnation centers and maximized the shearing stress. By the slight increase in the velocity ratio to 1.07, the H and OH pools provided for methane combustion became closer to the ports such that a hydrogen/methane mass percent of 10.3% extended the stoichiometric blowout velocity from 28.3 to 35.7 m/s. Since the turbulent kinetic energy thus increased to 8.4 m 2 /s 2 , the firing intensity reached values as high as 48.2 MW/m 3. Not only was there a reduction in the residence time for NOx formation, but also the blowout velocity relative gain overrode the relative increase in the NOx formation rates such that the NOx emission index decreased to 17 g/MWhr. By the excessive increase in velocity ratio, the vortical structures shrank such that the NOx exponential increase became dominant above 21 ppm. With fuel-lean mixtures, the hydrogen was partially combusted by the excess air from the opposing flames but the blowout velocity decreased to 13.1 m/s at È ¼ 0.50. The hydrogen flame NOx emissions decreased by providing the excess air at larger jets' diameter/separation ratios, thus reducing the residence times for thermal NOx formation and simultaneously interrupting the prompt NOx formation. At the lean operational limit, tripling the number of opposing jets decreased the hydrogen flame length by 54% such that the NOx emissions decreased by 38.4%.
This study experimentally and numerically investigates a typical HDPE blown film production process cooled via a single-lip air-ring. The processing observations are considered for the proposed subsequent modifications on the air-ring design and the location relative to the die to generate a radial jet, directly impinging on the bubble. Measurements are performed to collect the actual operating parameters to set up the numerical simulations. The radiation heat transfer and the polymer phase change are considered in the numerical simulations. The velocity profile at the air-ring upper-lip is measured via a five-hole Pitot tube to compare with the numerical results. The comparison between the measurements and the numerical results showed that the simulations with the STD [Formula: see text] turbulence model are more accurate with a minimum relative absolute error (RAE) of 1.6%. The numerical results indicate that the peak Heat Transfer Coefficient (HTC) at the impingement point for the modified design with radial jet and longer upper-lip is 29.1% higher than the original design at the same conditions. Besides, increasing the air-ring upper-lip height increased the averaged HTC, which is 13.4% higher than the original design.
With the global population growing (over seven billion), accompanied by escalating economic crises, mismanagement of natural resources, climatic changes, and uncertainties, and increasing poverty and hunger, the world is opposing critical periods of serious challenges. This paper aims to develop an integrated dynamic model for the WEF system for all governances in the State of Kuwait and future demand with and without climate change. Additionally, identifying proper opportunities in the WEF system in Kuwait. The aim is achieved by building an integrated dynamic model and analyzing it via using WEAP and LEAP software. The business as usual scenario concluded that increasing water, energy, and food within the next 17 years for all governorates. Besides that, climate change will also affect increasingly upon the WEF system. The impact is expected to rise, on average between 2 to 4% in the period 2017-2035 with total cumulative demand about 3144 Mm3. By using several interventions, management policies would help the water, energy, and food system to ensure its sustainability. The several interventions, such as reducing per capita consumption, saving devices, population control, and using reverse osmosis technology, will reduce the demand by about 50% by the year 2035.
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