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AN ACCURATE AND EFFICIENT CALCULATION OF HIGH ENTHALPY FLOWS USING A HIGH ORDER NEW LIMITING PROCESS
SUNGJUN NOH,KYUNG ROCK LEE,JUNG HO PARK,KYU HONG KIM 한국산업응용수학회 2011 Journal of the Korean Society for Industrial and A Vol.15 No.1
Calculation of accurate wall heat flux for high enthalpy flows requires a dense grid system, which leads to significantly large computational time. A high-order scheme can improve the efficiency of calculation because wall heat flux can be obtained accurately even with a relatively coarse grid system. However, conventional high order schemes have some drawbacks such as oscillations near a discontinuity and instability in multi-dimensional problem. To resolve these problems, enhanced Multi-dimensional Limiting Process(e-MLP) was applied as a high-order scheme. It could provide robust and accurate solutions with high order accuracy in calculation of high enthalpy flows within a short time. We could confirm the efficiency of the high order e-MLP scheme through grid convergence tests with different grid densities in a hypersonic blunt nose problem.
Development of Pd–Cu/Hematite Catalyst for Selective Nitrate Reduction
Jung, Sungyoon,Bae, Sungjun,Lee, Woojin American Chemical Society 2014 Environmental science & technology Vol.48 No.16
<P>A new hematite-supported Pd–Cu bimetallic catalyst (Pd–Cu/hematite) was developed in order to actively and selectively reduce nitrate (NO<SUB>3</SUB><SUP>–</SUP>) to nitrogen gas (N<SUB>2</SUB>). Four different iron-bearing soil minerals (hematite (H), goethite (G), maghemite (M), and lepidocrocite (L)) were transformed to hematite by calcination and used for synthesis of different Pd–Cu/hematite-H, G, M, and L catalysts. Their characteristics were identified using X-ray diffraction (XRD), specific surface area (BET), temperature programed reduction (TPR), transmission electron microscopy with energy dispersive X-ray (TEM-EDX), H<SUB>2</SUB> pulse chemisorption, zeta-potential, and X-ray photoelectron spectroscopy (XPS). Pd–Cu/hematite-H exhibited the highest NO<SUB>3</SUB><SUP>–</SUP> removal (96.4%) after 90 min, while a lower removal (90.9, 51.1, and 30.5%) was observed in Pd–Cu/hematite-G, M, and L, respectively. The results of TEM-EDX, and TPR analysis revealed that Pd–Cu/hematite-H possessed the closest contact distance between the Cu and Pd sites on the hematite surface among the different Pd–Cu/hematite catalysts. The high removal can be also attributed to the highly active metallic sites on its positively charged surface. The XPS analysis demonstrated that the amount of hydrogen molecules can have a pivotal function on NO<SUB>3</SUB><SUP>–</SUP> removal and a ratio of nitrogen to hydrogen molecule (N:H) on the Pd sites can critically determine N<SUB>2</SUB> selectivity.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/esthag/2014/esthag.2014.48.issue-16/es502263p/production/images/medium/es-2014-02263p_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/es502263p'>ACS Electronic Supporting Info</A></P>