@article { ISI:000251763600057, title = {Hydrodynamics and liquid phase residence time distribution in mesh microreactor}, journal = {Chemical Engineering Science}, volume = {62}, number = {24, SI}, year = {2007}, note = {8th International Conference on Gas-Liquid and Gas-Liquid-Solid Reactor Engineering, Indian Inst Technol Delhi, New Delhi, INDIA, DEC 16-19, 2007}, month = {DEC}, pages = {7484-7493}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, type = {Article}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

This paper is focused on the experimental analysis of residence time distribution and phase hold-up in a mesh microreactor. A microreactor, where a finely weaved mesh is sandwiched between two flat plates with specific inlets for gas and liquid, is proposed. The microvolumes formed upon sandwiching the mesh are totally connected and thus it yields a view of several interconnected microvolumes. This system is easy to build and does not need precision micromachining. A high-speed photographic analysis yielded the phase distribution for different mesh types over a wide range of operating gas and liquid flow rates. The RTD was studied by measuring the liquid phase conductivity at the outlet of the reactor. Channeling prevailed for mesh with smaller open area. The ADEM was used for fitting the tracer curves with tailing ends. The RTD and the image analysis for all the mesh types showed hysteresis when the gas flow rate was maintained constant and the liquid flow rate was gradually increased and then decreased. (c) 2007 Elsevier Ltd. All rights reserved.

}, keywords = {hydrodynamics, hysteresis, image analysis, microreactor, residence time distribution}, issn = {0009-2509}, doi = {10.1016/j.ces.2007.08.063}, author = {Kulkarni, A. A. and Gorasia, A. K. and Ranade, V. V.} } @article { ISI:000342087400004, title = {Discontinuous two step flow synthesis of m-aminoacetophenone}, journal = {Green Processing and Synthesis}, volume = {3}, number = {4}, year = {2014}, month = {AUG}, pages = {279-285}, publisher = {WALTER DE GRUYTER GMBH}, type = {Article}, address = {GENTHINER STRASSE 13, D-10785 BERLIN, GERMANY}, abstract = {

The continuous flow nitration of acetophenone followed by reduction of the meta isomer has been demonstrated using simple tubular reactors. Because of ease of separation of the desired isomer from the first step, both steps are made continuous, but separately. The continuous flow nitration was carried out in a safe manner in a shorter reaction time than the conventional approach. The choice of micromixer was seen to affect the performance of the nitration reaction. The effect of different parameters on the yield of the desired product was studied. The reduction step with sodium sulfide was found to be economical and could be carried out efficiently at 70 degrees C using sodium sulfide in ethanol, using a silicone tube. Both steps were demonstrated for several hours, yielding a sufficiently large quantity (similar to 100 g) of m-aminoacetophenone at lab scale in a single day using simple tubular reactors.

}, keywords = {acetophenone, continuous flow synthesis, microreactor, nitration, reduction}, issn = {2191-9542}, doi = {10.1515/gps-2014-0043}, author = {Tibhe, Jagdish and Sharma, Yachita and Joshi, Ramesh A. and Joshi, Rohini R. and Kulkarni, Amol A.} } @article { ISI:000342501300021, title = {Microfluidic platform for continuous flow synthesis of triangular gold nanoplates}, journal = {Colloids and Surfaces A-Physicochemical and Engineering Aspects}, volume = {443}, year = {2014}, month = {FEB}, pages = {149-155}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A microfluidic platform for the continuous flow synthesis of triangular gold nanoplates with and without surfactants is developed. The temperature profile in the microchannel, residence time and composition have been studied to understand effect of these parameters on the yield of the triangular nanoplates and were optimized for obtaining maximum yield of triangles. The flow synthesis approach has been demonstrated where the Br- ions can be supplied to the reaction mixture either from the surfactant viz. Cetyl trimethylammonium bromide (CTAB) or even from HBr. Apart from the Br- ions, the temperature gradient at the inlet of the continuous flow reactor is one of the key parameter that affects the yield of the triangular nanoplates. Finally we establish that with a right combination of the controlling parameters abetter yield of the Au nanotriangles by flow methods can be achieved even in the absence of surfactant. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {Au nanotriangles, Flow synthesis, microreactor, Nucleation kinetics, Surfactants}, issn = {0927-7757}, doi = {10.1016/j.colsurfa.2013.10.047}, author = {Kumar, D. V. Ravi and Kulkarni, A. A. and Bhagavatula L. V. Prasad} } @article {44193, title = {Pressure equalization approach for flow uniformity in microreactor with parallel channels}, journal = {Chemical Engineering Science}, volume = {176}, year = {2018}, month = {FEB}, pages = {96-106}, type = {Article}, abstract = {

Numbering-up using parallel channels helps to achieve higher processing capacity while retaining the advantages of microreactors. However it may also lead to non-uniformity in flow across all the channels. Here we report the CFD simulations and experimental observations on the extent of uniformity in the flow from an assembly of several parallel channels. In the conventional parallel channel geometry, smaller channel size (\<300 m) as well as higher fluid viscosity is seen to give better flow uniformity. Inequality in pressure distribution at the inlet of a large number of parallel channels is overcome by having two {\textquoteleft}pressure equalization slots{\textquoteright} at an equal distance from inlet and outlets that open in the respective manifolds. Having such an arrangement helped to reduce the standard deviation in the flow by almost 90\% when compared to the conventional geometry. However the modification was seen to increase the extent of back mixing to some extent. (C) 2017 Elsevier Ltd. All rights reserved.

}, keywords = {CFD, Experiments, Flow distribution, microreactor, Numbering-up, Parallel channels}, issn = {0009-2509}, doi = {10.1016/j.ces.2017.10.021}, author = {Madane, Ketan and Kulkarni, Amol A.} }