کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6468385 1423564 2016 17 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Combustion stability and hetero-/homogeneous chemistry interactions for fuel-lean hydrogen/air mixtures in platinum-coated microchannels
ترجمه فارسی عنوان
پایداری احتراق و تعاملات شیمیایی هتروژن / همگن برای مخلوط های هیدروژن و هوا در مخلوط سوختی در میکرو کانال های پلاتین پوشش داده شده
کلمات کلیدی
احتراق هترو و همگن هیدروژن بر روی پلاتین، محدودیت های پایداری احتراق هیدروژن میکروسکوپ، شیمی تجزیه و تحلیل جامد و فاز گاز، انقراض، وابستگی فشار محدودیت های پایداری،
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
چکیده انگلیسی

The hetero-/homogeneous combustion and stability limits of fuel-lean hydrogen/air mixtures (equivalence ratio φ = 0.40) were investigated numerically in a platinum-coated planar microchannel with a length of 10 mm and a height of 1 mm. A two-dimensional numerical model was used for both the gas and the solid, which included elementary heterogeneous and homogeneous reaction mechanisms, detailed transport, heat conduction in the solid, surface radiation heat transfer, and external losses via a heat transfer coefficient h. Pressures of 1 and 5 bar and solid thermal conductivities ks = 1 and 16 Wm-1K−1 were analyzed, while stability maps were constructed in terms of the critical extinction heat transfer coefficient hcr versus inlet velocity UIN (or mass throughput). For a given solid thermal conductivity, there existed a crossover mass throughput above (below) which the stability envelope was broader at 5 bar (1 bar). Simulations with a surface perfectly stirred reactor (SPSR) model qualitatively reproduced the crossover points, which originated from a shift in the pressure dependence of the catalytic reactivity of hydrogen. For the low solid thermal conductivity ks = 1 Wm-1K−1, a non-monotonic dependence of the stability limits on the mass throughput was shown, with local minima created below the crossover point. The stability limits of hydrogen were solely determined by catalytic chemistry, as it sustained combustion at temperatures down to 320-380 K, at which gas-phase chemistry was frozen. Away from the critical extinction points, both catalytic and gas-phase reaction pathways were controlling. The diffusional imbalance of hydrogen, which led to catalytically-induced superadiabatic surface temperatures, and the suppression of the surface superadiabaticity by gaseous chemistry resulted in rich combustion phenomena, such as increasing peak wall temperatures with increasing heat transfer coefficients h. Critical extinction heat transfer coefficients for hydrogen were three to four orders of magnitude higher than those reported for methane and propane fuels in a similar channel geometry.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Combustion and Flame - Volume 173, November 2016, Pages 370-386
نویسندگان
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