Showing papers by "Jyeshtharaj B. Joshi published in 2015"
TL;DR: In this article, the authors show that integrating solar thermal systems into power plants can be done with minimal modifications, and that such a strategy is more economic than installing carbon-capture and compression equipment to reduce greenhouse-gas emissions.
Abstract: Integrating solar thermal systems into power plants can be done with minimal modifications. Statistical analysis shows that such a strategy is more economic than installing carbon-capture and compression equipment to reduce greenhouse-gas emissions.
64 citations
TL;DR: In this paper, the hydrogen absorption properties of multiwalled carbon nano-tubes (MWCNTs) doped with Pd nanoparticles by the conventional wet impregnation method and the polyol method were investigated.
61 citations
TL;DR: This work focuses on synthesizing recent advances in computational and experimental techniques that will enable future designs of multiphase reactors in a more rational manner by exploring a large design space with high-fidelity models (computational fluid dynamics and computational chemistry models) that are validated withhigh-f fidelity measurements (tomography and other detailed spatial measurements) to provide a high degree of rigor.
Abstract: Multiphase reactors are very common in chemical industry, and numerous review articles exist that are focused on types of reactors, such as bubble columns, trickle beds, fluid catalytic beds, etc. Currently, there is a high degree of empiricism in the design process of such reactors owing to the complexity of coupled flow and reaction mechanisms. Hence, we focus on synthesizing recent advances in computational and experimental techniques that will enable future designs of such reactors in a more rational manner by exploring a large design space with high-fidelity models (computational fluid dynamics and computational chemistry models) that are validated with high-fidelity measurements (tomography and other detailed spatial measurements) to provide a high degree of rigor. Understanding the spatial distributions of dispersed phases and their interaction during scale up are key challenges that were traditionally addressed through pilot scale experiments, but now can be addressed through advanced modeling.
57 citations
TL;DR: In this article, a 3D computational fluid dynamics model was developed using multiphase volume of fluid (VOF) method combined with the dynamic meshing technique to capture the details of collision physics especially the movement of three phase contact line (TPCL) on the particle surface.
43 citations
TL;DR: Oleyl amine stabilised Pd nanoparticles have been prepared by reverse micro-emulsion method and supported on multi walled CNTs in this article, where it is inferred that the PD nanoparticles interact with CNT support to form sp3 carbon species, which get effectively dispersed on the CNT.
Abstract: Oleyl amine stabilised Pd nanoparticles have been prepared by reverse micro-emulsion method and supported on multi walled CNTs. TEM studies have confirmed that Pd nanoparticles, having sizes in the range of 3–5 nm, are well dispersed on the CNTs. Based on 13C MAS NMR and TG-DTA studies it is inferred that the Pd nanoparticles interact with CNT support to form sp3 carbon species, which get effectively dispersed on the CNTs. Such finely dispersed Pd nanoparticles facilitate the spillover of hydrogen to the CNT support and improve the hydrogen storage capacity.
31 citations
TL;DR: In this paper, the authors compared the performance of the standard k-e, RSM and large eddy simulation (LES) turbulence models and provided a clear insight into each modeling assumption.
30 citations
TL;DR: In this paper, the authors used particle image velocimetry (PIV) to obtain the 2D instantaneous velocity field in a homogeneous near isotropic turbulence field using four different methods, namely: (1) dimensional analysis, (2) velocity gradient, (3) structure function, and (4) energy spectrum.
30 citations
TL;DR: In this paper, a particle dynamics simulation of S + D granular systems in various irregular shaped tumblers in the rolling regime (10−4 4 ) is presented. But the simulation is restricted to the case where size and density drive segregation simultaneously.
26 citations
TL;DR: In this article, the authors investigated the 3D natural circulation phenomenon in the gravity-driven water pool (GDWP) in order to reduce the thermal stratification phenomenon by optimizing the distribution and position of heat exchangers.
23 citations
TL;DR: In this paper, two different vaporization mechanisms of feedstock, namely homogeneous mode and heterogeneous mode, were studied to predict the vaporization time of the feed droplets typically expected in FCC feed vaporization zone.
Abstract: Vaporization of atomized feedstock is one of the critical processes in fluid catalytic cracking (FCC) risers; which is more often ignored in most of the FCC riser modelling studies. In this study, two different vaporization mechanisms of feedstock namely homogeneous mode and heterogeneous mode were studied. Different homogeneous models duly validated for various pure component droplets were applied to predict the vaporization time of the feed droplets typically expected in FCC feed vaporization zone. A new physical model for heterogeneous vaporization considering droplet–particle collision mechanics was also developed in the present study which compared well with the other existing heterogeneous modelling approaches. Comparison of the two vaporization modes indicates that under typical operating conditions of FCC riser, vaporization time of feed droplets predicted by heterogeneous mode is always lower than the homogeneous mode at least by an order of magnitude due to significant increase in heat transfer coefficient which accounts for droplet-particle contact. It is expected that actual vaporization time of feed droplets in an industrial FCC riser should lie in the range predicted by these two vaporization mechanisms which actually set the two limiting modes of vaporization. Obtained results predicted by the models could be used to aid design of the FCC feed vaporization zone.
17 citations
Abstract: In this paper, a review is presented on the experimental investigations and the numerical simulations performed to analyze the thermal-hydraulic performance of the air-cooled heat exchangers. The air-cooled heat exchangers mostly consist of the finned-tube bundles. The primary role of the extended surfaces (fins) is to provide more heat transfer area to enhance the rate of heat transfer on the air side. The secondary role of the fins is to generate vortices, which help in enhancing the mixing and the heat transfer coefficient. In this study, the annular and plate fins are considered, the annular fins are further divided into four categories: (1) plane annular fins, (2) serrated fins, (3) crimped spiral fins, (4) perforated fins, and similarly for the plate fins, the fin types are: (1) plain plate fins, (2) wavy plate fins, (3) plate fins with DWP, and (4) slit and strip fins. In Section 4, the performance of the various types of fins is presented with respect to the parameters: (1) Reynolds number, (2) fin pitch, (3) fin height, (4) fin thickness, (5) tube diameter, (6) tube pitch, (7) tube type, (8) number of tube rows, and (9) effect of dehumidifying conditions. In Section 5, the conclusions and the recommendations for the future work have been given.
TL;DR: In this paper, the effect of initial nitric acid concentration and temperature on the dissolution rate of sintered UO2 pellets was investigated and the shrinking core model was used to correlate the experimental results.
TL;DR: In this article, a mathematical model has been developed for the absorption of NOx gases using air and enriched oxygen in packed columns, and three more cases have been considered: (1) decomposition and oxidation kinetics of nitrous acid with a typical concentration of oxygen which is usually employed in nitric acid plants, (2) complete decomposition with enriched oxygen, and (3) complete conversion of Nitrous to Nitric acid by liquid phase Nitrous acid oxidation.
TL;DR: In this paper, a post processing method based on the Go-chess concept was developed to quantify the surface area of aggregate structure, and a correlation for prediction of aggregate external surface area was also proposed as a function of aggregate structural characteristics in terms of fractal dimension and coordination number.
TL;DR: In this article, three dimensional computational fluid dynamics analysis has been performed for the moderator flow and temperature fields inside a vertical calandria vessel of nuclear reactor under normal operating condition using OpenFOAM CFD code.
TL;DR: In this article, an oscillating grid device was used to generate turbulent liquid motion around the particle-bubble aggregate, and the velocity data in an envelope surrounding the bubble was extracted to calculate local, instantaneous values of liquid velocity, turbulent kinetic energy and energy dissipation rate.
TL;DR: In this article, a 3D steady state simulation was performed to study the temperature distributions and flow distribution of moderator inside the Calandria vessel using a three-dimensional CFD code, OpenFoam 2.0.
01 May 2015
TL;DR: The Indian Test Facility for Neutral Beams (INTFN) as mentioned in this paper was designed with the objective to not only test the performance of an ion source but also to characterize the transmission of the neutral beam to a length of 20.66 m and thereby generate adequate database on the quality of the beam that is required for the CXRS diagnostics for measurement of Helium ash content in the fusion plasma.
Abstract: The Indian Test Facility (INTF) for Neutral Beams is designed with the objective to not only test the performance of an ion source but also to characterize the transmission of the Neutral Beam to a length of 20.66 m and thereby generate adequate database on the quality of the beam that is required for the CXRS diagnostics for measurement of Helium ash content in the fusion plasma.
TL;DR: In this article, a real case study has been described which has given substantial benefits in capacity and selectivity of a chemical process, and it has been brought out that the key features of process intensification are: (i) to understand quantitatively all the rate processes such as mass transfer, heat transfer, chemical kinetics, etc.
Abstract: While implementing a new chemical process, an attempt is made to design all the equipment by using best available knowledge together with pilot plant experiments. However, the status of current knowledge is closer to an “art” than the desired state of “science”. Therefore, as the new knowledge gets developed with respect to time, the designs of equipment in operating plants can be improved with incremental cost for modifications. Improvements are possible in capacity, selectivity, purity and safety of the plant. The process of incorporating such improvements is called “Process Intensification”. In the present work, a real case study has been described which has given substantial benefits in capacity and selectivity. It has been brought out that the key features of process intensification are: (i) to understand quantitatively all the rate processes such as mass transfer, heat transfer, chemical kinetics, etc. and (ii) to understand the fluid mechanics and relate fluid mechanical parameters to the r...
01 Jan 2015