01938nas a2200229   4500008004100000022001400041245008500055210006900140260009100209300002000300490000600320520108100326653003301407653002501440653001701465653002901482653002001511100002101531700002601552700001901578856011101597       2008                        eng d  a1542-658000aCFD simulation of gas-liquid flows in a reactor stirred by dual rushton turbines0 aCFD simulation of gasliquid flows in a reactor stirred by dual r  a2809 TELEGRAPH AVENUE, STE 202, BERKELEY, CA 94705 USAbBERKELEY ELECTRONIC PRESScJAN  aArticle No. A600 v63 a<p>In the present work, we have simulated gas-liquid flows in a tall stirred reactor equipped with dual Rushton turbines. A two fluid model along with the standard k-epsilon turbulence model and modified drag coefficient, (proposed by Khopkar &amp; Ranade, 2006) accounting for the effect of bulk turbulence, was used to simulate the dispersed gas-liquid flow in a stirred reactor. The multiple reference frames (MRF) approach was used to simulate impeller rotation in a fully baffled reactor. The computational model was mapped on to a commercial solver FLUENT 6.2 (of Fluent Inc. USA). The model was used to simulate three distinct flow regimes in a gas-liquid stirred reactor: L33-VC (lower impeller-upper impeller), S33-VC and VC-VC. The model predictions were compared with the published experimental data of Bombac &amp; Zun (2000). The predicted results show good agreement with the experimental data for all the three flow regimes. The computational model presented in this work would be useful for simulating different flow regimes in a gas-liquid stirred vessel.</p>10acomputational fluid dynamics10adual Rushton turbine10aFlow regimes10agas hold-up distribution10astirred reactor1 aKasat, Gopal, R.1 aPandit, Aniruddha, B.1 aRanade, V., V.  uhttps://library.ncl.res.in/content/cfd-simulation-gas-liquid-flows-reactor-stirred-dual-rushton-turbines-002272nas a2200205   4500008004100000022001400041245008000055210006900135260010200204300001400306490000800320520148800328653003301816653001501849653002101864653001801885100003001903700002201933856011101955       2012                        eng d  a0011-389100aComputational fluid dynamics modelling of solid suspension in stirred tanks0 aComputational fluid dynamics modelling of solid suspension in st  aC V RAMAN AVENUE, SADASHIVANAGAR, P B \#8005, BANGALORE 560 080, INDIAbINDIAN ACAD SCIENCEScJUN  a1539-15510 v1023 a<p>Solid suspension and mixing are crucial in many important processes, including multiphase catalytic reactions, crystallization, precipitation, etc. In recent years, various efforts have been made to numerically simulate solid-liquid flows in stirred vessels using computational fluid dynamics (CFD). In this article, we present a brief account of our group's efforts at developing and using CFD models for simulating solid suspension in stirred tanks. Computational models were developed and evaluated by comparing model predictions with our data as well as published experimental data. A variety of experimental techniques ranging from torque and wall pressure fluctuations to ultrasound velocity profiler were used. Efforts were made to develop appropriate sub-models for capturing influence of the prevailing turbulence and solid volume fraction on effective inter-phase coupling terms. A hysteresis in variation of the height of the cloud of suspended solid with impeller rotational speed was observed. The hysteresis, besides having applications in realizing better suspension at lower effective power consumption, also offers an attractive evaluation test for CFD models. A new way to carry out dynamic settling of solid cloud by sudden impeller stoppage has been developed. The approach, models and results presented here will be useful for extending applications of CFD models for simulating industrial stirred slurry reactors as well as further research in the field.</p>10acomputational fluid dynamics10ahysteresis10asolid suspension10astirred tanks1 aSardeshpande, Madhavi, V.1 aRanade, Vivek, V.  uhttps://library.ncl.res.in/content/computational-fluid-dynamics-modelling-solid-suspension-stirred-tanks-002144nas a2200217   4500008004100000022001400041245005000055210005000105260006700155300001400222490000700236520144400243653003301687653001801720653001801738653001501756100002601771700002301797700002201820856008401842       2013                        eng d  a0001-154100aFlow and heat transfer in serpentine channels0 aFlow and heat transfer in serpentine channels  a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcMAY  a1814-18270 v593 a<p>Serpentine channels are often used in microchannel reactors and heat exchangers. These channels offer better mixing, higher heat and mass-transfer coefficients than straight channels. In the present work, flow and heat transfer experiments were carried out with a serpentine channel plate comprising of 10 units (single unit dimensions: 1 x 1.5 mm(2) in cross section, length 46.28 mm, D-h 1.2 mm) in series. Pressure drop and heat-transfer coefficients were experimentally measured. Flow and heat transfer in the experimental set-up were simulated using computational fluid dynamics (CFD) models to understand the mechanisms responsible for performance enhancement. The CFD methodology, thus, developed was applied to understand the effect of various geometrical parameters on heat transfer enhancement. A criterion was defined for evaluation of heat transfer performance (heat transfer per unit pumping power), thus, ensuring due considerations to required pumping power. The effect of geometrical parameters and the corresponding mechanisms contributing for enhancement are discussed briefly. Based on the results, a design map comprising different serpentine channels showing heat transfer enhancement with pumping power was developed for Reynolds number of 200 which will be useful for further work on flow and heat transfer in serpentine channels. (C) 2012 American Institute of Chemical Engineers AIChE J, 59: 1814-1827, 2013</p>10acomputational fluid dynamics10aheat transfer10apressure drop10aserpentine1 aKarale, Chaitanya, M.1 aBhagwat, Sunil, S.1 aRanade, Vivek, V.  uhttps://library.ncl.res.in/content/flow-and-heat-transfer-serpentine-channels-001953nas a2200241   4500008004100000022001400041245011200055210006900167260000800236300001400244490000700258520110100265653003301366653003001399653002601429653001401455653002301469653001701492100002401509700002601533700002301559856012901582       2020                        eng d  a1083-616000aEfficient processing of reactions involving diazonium salts: meerwein arylation in an impinging-jet reactor0 aEfficient processing of reactions involving diazonium salts meer  cSEP  a1658-16640 v243 a<p>This work reports a novel approach for performing high-throughput synthesis of Meerwein arylation in an impingingjet reactor. The multistep reaction was performed in a single reactor via in situ diazonium salt generation followed by Meerwein arylation. The work involves many iterations between experiments and simulations (where we integrate simulating the flow, heat transfer, and reaction simultaneously) for optimization of conditions in an inverted impinging-jet reactor. The effect of design variables viz. catalyst concentration, inlet temperature, and monomer mole ratio on the yield of the desired product was studied in detail, and the simulation results were used to plan the continuous experiments. An infrared camera was used to monitor the transient reactor temperature for steady-state analysis. The lab-scale inverted impinging-jet reactor with over 93% isolated yield can offer a space-time yield of 277.78 tons/m(3)/day. The numbering-up of an inverted impinging-jet reactor can be an effective way for cleaner production of products through typical Meerwein arylation.</p>
10acomputational fluid dynamics10ahigh throughput synthesis10aimpinging-jet reactor10aIR camera10aMeerwein arylation10aNumbering-up1 aShukla, Chinmay, A.1 aAtapalkar, Ranjit, S.1 aKulkarni, Amol, A.  uhttps://library.ncl.res.in/content/efficient-processing-reactions-involving-diazonium-salts-meerwein-arylation-impinging-jet02143nas a2200241   4500008004100000022001400041245010300055210006900158260000800227300001200235490000700247520126500254653003301519653003501552653003001587653002901617100002801646700002301674700002601697700002401723700002301747856013101770       2025                        eng d  a1083-616000aConfined impinging jet reactor for high-throughput continuous flow mononitration of salicylic acid0 aConfined impinging jet reactor for highthroughput continuous flo  cJAN  a479-4890 v293 a<p>
	Novel approach is reported for highly efficient continuous mononitration of salicylic acid using confined impinging jet reactor (CIJR) with a vent. Initially, controlled semibatch reactions are optimized to achieve complete conversion and formation of mononitro products with very high selectivity for 5-nitrosalicylic acid (5-NSA). Further, the combination of computational fluid dynamics simulations and experiments is employed to optimize CIJR design and operating flow conditions, suitable to yield only mononitro products with excellent control over mixing, heat transfer, and liberation of fumes during continuous flow reaction. Detailed analysis of internal flow patterns, rate of heat generation, and concentration distribution inside the CIJR facilitated the optimization of present exothermic reaction in a safe manner. In less than a minute, complete salicylic acid (SA) conversion with good yield and better selectivity for 5-NSA is achieved using the CIJR. Safety and clogging issues are addressed effectively, even at a relatively lower mole ratio (1:5) of SA:acetic acid (AcOH). The present approach is quite scalable using the numbering-up strategy, with advantages viz. nonfouling, high throughput, and the small footprint of CIJR.</p>
10acomputational fluid dynamics10aconfined impinging jet reactor10ahigh-throughput synthesis10asalicylic acid nitration1 aKhan, Muzammilanwar, S.1 aShaikh, Tabrez, R.1 aKulkarni, Sphurti, P.1 aPatil, Abhishek, A.1 aKulkarni, Amol, A.  uhttps://library.ncl.res.in/content/confined-impinging-jet-reactor-high-throughput-continuous-flow-mononitration-salicylic-acid