02465nas a2200241 4500008004100000022001400041245006600055210006500121260006800186300001400254490000700268520169600275653000801971653001401979653001801993653002102011653001702032100002302049700001902072700001502091700002002106856009702126 2008 eng d a0001-154100aFlow pattern in vortex diode: experiments and CFD simulations0 aFlow pattern in vortex diode experiments and CFD simulations a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcMAY a1139-11520 v543 a

Vortex diodes are used as leaky nonreturn valves in applications, where it is desirable to avoid valves with moving parts. Despite their use in practice for several decades, no detailed analysis of the flow inside the vortex diodes is available. A strategy was derived for the CFD simulations of the vortical flow in diodes. A good agreement was seen between pressure drop (Delta P) across the inlet-outlet ports from CFD simulations, and the experimental data for five diode sizes. The simulations showed that in the reverse flow situation tangential velocity was dominant and resulted in conservation of angular momentum in the chamber until it reaches the axial exit port. This vortical motion induced a significant pressure drop (Delta P-r). The axial velocity gradient over the chamber cross-section helps in inducing relaminarization of the flow. In the forward flow mode, the fluid gets distributed radially over the chamber and exits through the tangential port, yielding low Delta P-f. The analysis showed that the performance of a diode is strongly affected by diode geometry, size, aspect ratio, nozzle configuration and Reynolds number. Among different configurations, the nozzles with entry port size equal to diode yielded higher diodicity. Simulations showed that using angle of divergence for diffuser sections of nozzles of the order of 7 degrees exhibited higher diodicity than smaller angles. It was also observed that at higher flow rates significantly higher diodicity was obtained using axial nozzles with larger radius of curvature for expander section. The modeling methodology and results presented will be useful for evolving better designs of vortex diodes.

10aCFD10aDiodicity10apressure drop10arelaminarization10aVortex diode1 aKulkarni, Amol, A.1 aRanade, V., V.1 aRajeev, R.1 aKoganti, S., B. uhttps://library.ncl.res.in/content/flow-pattern-vortex-diode-experiments-and-cfd-simulations01803nas a2200241 4500008004100000022001400041245007400055210006900129260010600198300001400304490000700318520096800325653001701293653001401310653001201324653001801336653001701354100002301371700002201394700001501416700002001431856011001451 2009 eng d a0009-250900aPressure drop across vortex diodes: experiments and design guidelines0 aPressure drop across vortex diodes experiments and design guidel aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAR a1285-12920 v643 a

Vortex diodes are used as leaky non-return valves in applications where it is desirable to avoid valves with moving parts. Despite their use in practice for several decades, no clear guidelines for design and optimization of vortex diodes are available. Detailed experimental study on flow and pressure drop characteristics of vortex diodes was therefore carried out to evolve such guidelines. The study covered a wide range of vortex diodes. The variation of diodicity (ratio of pressure drop for reverse and forward flow for the same flow rate) with respect to diode geometry, diode size (d(c)), aspect ratio (d(c)/h), nozzle configuration and Reynolds number (Re) was studied. The experimental results were critically analyzed to develop a design methodology. The methodology is shown to be useful for obtaining the diode dimensions that would yield the desired diodicity for the required operating flow rate. (c) 2008 Elsevier Ltd. All rights reserved.

10aAspect ratio10aDiodicity10aNozzles10apressure drop10aVortex diode1 aKulkarni, Amol, A.1 aRanade, Vivek, V.1 aRajeev, R.1 aKoganti, S., B. uhttps://library.ncl.res.in/content/pressure-drop-across-vortex-diodes-experiments-and-design-guidelines-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

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

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-001596nas a2200229 4500008004100000022001400041245005800055210005800113260006700171300001400238490000700252520084100259653003901100653001801139653001101157653001701168653001801185100002501203700002401228700002201252856009201274 2015 eng d a0008-403400aHeat transfer and mixing in flow through pinched pipe0 aHeat transfer and mixing in flow through pinched pipe a111 RIVER ST, HOBOKEN 07030-5774, NJ USAbWILEY-BLACKWELLcOCT a1860-18680 v933 a

There is an increasing trend of using tubular reactors either with passive or active augmentation methods for process intensification. A new passive method with pinching of pipe' is proposed and investigated for its performance. In the present work, initially, flow in a pinched pipe was studied experimentally and the same was reproduced numerically. The computational model was then used to investigate influences of key geometrical parameters of pinched pipe configuration on pressure drop, heat transfer, and mixing. The simulated results obtained with the pinched pipe were compared with a straight pipe, and with a commonly-used passive augmentation method (twisted tape inserts). The pinched pipe configuration offers better performance and more flexibility in manipulating heat transfer and mixing in intensified devices.

10acomputational fluid dynamics (CFD)10aheat transfer10amixing10apinched pipe10apressure drop1 aHasabnis, Nilesh, S.1 aTotlani, Kartik, A.1 aRanade, Vivek, V. uhttps://library.ncl.res.in/content/heat-transfer-and-mixing-flow-through-pinched-pipe-001501nas a2200193 4500008004100000245005900041210005900100260019200159520069300351653001701044653002101061653001801082653002601100100003001126700002301156700002201179700001301201856009301214 2015 eng d00aTwo phase flow boiling pressure drop in small channels0 aTwo phase flow boiling pressure drop in small channels aSARA BURGERHARTSTRAAT 25, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbIUTAM, Dept Sci Technol India; Ministry Earth Sciences; CSIR; Natl Sci Fdn, USA; Intel Ansys Fujitsu & TSI IndiacDEC3 a

Two-phase pressure drop, flow instability and boiling regime identifications are an essential step in the design of a variety of plant in the power and process industries. Despite the wide spread applications, significant experimental data on flow boiling in small channel is not available. In the present work, experimental set-up was designed for studying boiling flows in 19 mm ID tube and identifies flow regimes at various mass and heat flux conditions by varying inlet fluid temperature. The steady-state pressure data was collected and flow regimes identified using pressure drop and pressure fluctuations inside the channel. (C) 2015 The Authors. Published by Elsevier B.V.

10aflow boiling10aflow instability10apressure drop10aregime identification1 aSardeshpande, Madhavi, V.1 aShastri, Parikshit1 aRanade, Vivek, V.1 aSahu, KC uhttps://library.ncl.res.in/content/two-phase-flow-boiling-pressure-drop-small-channels-0