02092nas a2200229 4500008004100000022001400041245007300055210006900128260006800197300001200265490000700277520133900284653000801623653000901631653001801640653001501658653002401673100001901697700001901716700002901735856009801764 2005 eng d a0001-154100aComputational study of a single-phase flow in packed beds of spheres0 aComputational study of a singlephase flow in packed beds of sphe a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcFEB a365-3780 v513 a

Packed-bed reactors are widely used in petrochemical, fine chemical, and pharmaceutical industries. Detailed knowledge of interstitial flow in the void space of such packed-bed reactors is essential for understanding the heat and mass transfer characteristics. In this paper, fluid flow through the array of spheres was studied using the unit-cell approach, in which different periodically repeating arrangements of particles such as simple cubical, 1-D rhombohedral, 3-D rhombohedral, and face-centered cubical geometries were considered. Single-phase flow through these geometries was simulated using computational fluid dynamics (CFD). The model was first validated by comparing predicted results with published experimental and computational results. The validated model was further used to study the effect of particle arrangement/orientation on velocity distribution and heat transfer characteristics. The simulated results were also used to understand and to quantify, relative contributions of surface drag and form drag in overall resistance to the flow through packed-bed reactors. The model and the results presented here would be useful in elucidating the role of microscopic flow structure on mixing and other transport processes occurring in packed-bed reactors. (C) 2005 American Institute of Chemical Engineers.

10aCFD10adrag10aheat transfer10apacked bed10apacking arrangement1 aGunjal, P., R.1 aRanade, V., V.1 aChaudhari, Raghunath, V. uhttp://library.ncl.res.in/content/computational-study-single-phase-flow-packed-beds-spheres-002163nas a2200241 4500008004100000022001400041245007800055210006900133260006800202300001000270490000700280520138400287653000801671653001601679653001401695653001401709653001601723653000801739100001901747700001901766700002901785856010701814 2005 eng d a0001-154100aDynamics of drop impact on solid surface: experiments and VOF simulations0 aDynamics of drop impact on solid surface experiments and VOF sim a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcJAN a59-780 v513 a

The process of spreading/recoiling of a liquid drop after collision with a flat solid surface was experimentally, and computationally studied to identify the key issues in spreading of a liquid drop oil a solid surface. The long-term objective of this study is to gain an insight in the phenomenon of wetting of solid particles in the trickle-bed reactors. Interaction of a falling liquid drop with a solid surface (impact, spreading, recoiling, and bouncing) was studied using a high-speed digital camera. Experimental data oil dynamics of a drop impact on flat surfaces (glass and Teflon) are reported over a range of Reynolds numbers (550-2500) and Weber numbers (2-20). A computational fluid dynamics (CFD) model, based on the volume of fluid (VOF) approach, was used to simulate drop dynamics on the flat sufaces. The experimental results were compared with the CFD simulations. Simulations showed reasonably good agreement with the experimental data. A VOF-based computational model was able to capture key features of the interaction of a liquid drop with solid surfaces. The CFD simulations provide information about finer details of drop interaction with the solid surface. Information about gas-liquid and liquid-solid drag obtained from VOF simulations would be useful for CFD modeling of trickle-bed reactors. (C) 2004 American Institute of Chemical Engineers.

10aCFD10adrop impact10arecoiling10aspreading10atrickle bed10aVOF1 aGunjal, P., R.1 aRanade, V., V.1 aChaudhari, Raghunath, V. uhttp://library.ncl.res.in/content/dynamics-drop-impact-solid-surface-experiments-and-vof-simulations-001582nas a2200181 4500008004100000022001400041245007200055210006900127260007100196300001400267490000700281520092200288100001901210700001901229700001901248700002901267856010401296 2005 eng d a0888-588500aHydrodynamics of trickle-bed reactors: experiments and CFD modeling0 aHydrodynamics of tricklebed reactors experiments and CFD modelin a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcAUG a6278-62940 v443 a

{Hydrodynamics of trickle-bed reactors involve complex interactions of gas and liquid phases with packed solids. Such complex interactions manifest in different flow regimes occurring in trickle-bed reactors. Knowledge of prevailing flow regime, pressure drop, and liquid holdup is essential for design and performance evaluation of the reactor. Detailed knowledge of fluid dynamics is essential for ``a priory'' predictions as well as for interpretation of available data. In this study, we have used wall pressure fluctuation measurements to identify prevailing flow regime in trickle beds. Experiments were carried out on two scales of columns (of diameter 10 cm and 20 cm) with two sets of particles (3 min and 6 mm diameter spherical particles). Effects of prewetted and unwetted bed conditions on pressure drop and liquid holdup were reported for a range of operating conditions (V-G = 0.22-0.44 kg/m(2)s

1 aGunjal, P., R.1 aKashid, M., N.1 aRanade, V., V.1 aChaudhari, Raghunath, V. uhttp://library.ncl.res.in/content/hydrodynamics-trickle-bed-reactors-experiments-and-cfd-modeling-101139nas a2200133 4500008004100000245003500041210003500076260001800111300001200129520075700141100001900898700001900917856006900936 2016 eng d00aCatalytic reaction engineering0 aCatalytic reaction engineering bElsevier Inc. a263-3143 ahemical reaction engineering has contributed remarkably in bringing laboratory-developed chemistry into commercial practice. Reaction engineering is useful for analysis of reactions, identifying rate-limiting steps, determining overall rates, selection of reactor configuration and design and scale-up of reactors. Reaction engineering also provides useful insights into catalytic cycles and provides clues for improving catalyst systems. It essentially includes all the activities necessary to evolve best possible hardware and operating protocol for the reactor to carry out the desired transformation of raw materials (or reactants) into value-added products. This chapter provides an overview of reaction engineering aspects of catalytic processes.1 aGunjal, P., R.1 aRanade, V., V. uhttp://library.ncl.res.in/content/catalytic-reaction-engineering