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Rheology of cyclopentane hydrate slurry in a model oil-continuous emulsion
Karanjkar, P. U.,Ahuja, A.,Zylyftari, G.,Lee, J. W.,F. Morris, J. Springer Science + Business Media 2016 Rheologica Acta: an international journal of rheol Vol.55 No.3
<P>Liquid cyclopentane (CP)-based hydrate slurry is prepared at atmospheric pressure from a density-matched water-in-oil emulsion by quenching it to a lower temperature at a fixed shear rate. Viscosity increases by several orders of magnitude and is indicative of hydrate formation on the dispersed water droplets and subsequent agglomeration. A mechanism in which the hairy and porous hydrate growth combined with enhanced agglomeration due to liquid bridges formed by wetted water films leads to the development of a porosity, resulting in greater effective dispersed phase fraction, is proposed. This is supported by experiments performed for water volume fractions ranging from 10 to 45 % at variable shear rates, temperatures, and surfactant (Span 80) concentrations. The observed dependence on the degree of sub-cooling, with lower slurry viscosity obtained at higher sub-cooling, and the possible anti-agglomerant like effect of high Span 80 concentrations, support our proposed mechanism. The hydrate slurries are found to exhibit shear-thinning and a small degree of thixotropy.</P>
Gas Hydrates Phase Equilibria and Formation from High Concentration NaCl Brines up to 200 MPa
Hu, Yue,Makogon, Taras Y.,Karanjkar, Prasad,Lee, Kun-Hong,Lee, Bo Ram,Sum, Amadeu K. American Chemical Society 2017 Journal of chemical and engineering data Vol.62 No.6
<P>Gas hydrate phase equilibrium and kinetics at high NaCl concentrations (near and at saturation in solution) and very high pressures (up to similar to 200 MPa) are investigated to study the interplay of hydrate formation and salt precipitation. Limited experimental data above 80 MPa exist for hydrate phase equilibrium in high salinity systems. This study reveals the unusual formation of gas hydrates under these extreme conditions of high salinity and very high pressure. In particular, the results demonstrate that hydrates can form from saturated salt solutions, and the formation of hydrates and salt precipitation are competing effects. It is determined that hydrates will remain in equilibrium with a saturated salt solution, with the amount of salt precipitation determined by the amount of hydrates formed. These data are essential fundamental data for gas hydrates applications in the oil and gas production flow assurance and seawater desalination.</P>
Hu, Yue,Makogon, Taras Y.,Karanjkar, Prasad,Lee, Kun-Hong,Lee, Bo Ram,Sum, Amadeu K. Elsevier 2018 The Journal of chemical thermodynamics Vol.117 No.-
<P><B>Abstract</B></P> <P>Gas hydrates phase equilibria for structure I and II hydrates with chloride salts (NaCl, CaCl<SUB>2</SUB>, KCl and MgCl<SUB>2</SUB>) were measured at high salt concentrations and up to 200MPa. The measured equilibrium data represent three-phase (Solution – Hydrate – Vapor) or four-phase (Solution – Hydrate – Salt precipitated – Vapor) equilibrium depending on the salt concentration. The hydrate phase boundary with salts was shifted to lower temperatures and higher pressures when the experimental system was below the salt saturation concentration, while the boundaries were unchanged at salt concentrations above saturation, corresponding to quadruple points. The experimental data were compared with hydrate equilibrium predictions calculated by commonly used predictive tools to assess the reliability of these tools for the brines and conditions considered. The comparison demonstrates that predictive tools exhibit large deviation to the measured data, especially at high pressures and high salinity conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Gas hydrates phase equilibria with chloride salts were measured up to 200MPa. </LI> <LI> Predictions deviate from measured data at high salt concentration and high pressure. </LI> <LI> Measured data are valuable to test and improve hydrate predictive tools. </LI> </UL> </P>
Bhat, T. S.,Mali, S. S.,Korade, S. D.,Shaikh, J. S.,Karanjkar, M. M.,Hong, C. K.,Kim, J. H.,Patil, P. S. Springer Science + Business Media 2017 Journal of materials science. Materials in electro Vol.28 No.1
<P>Anatase titanium dioxide (TiO2) microspheres were successfully synthesized via a controlled chemical route using carbon spheres as sacrificial templates. The morphology has been controlled by varying the deposition time of carbonaceous (c) spheres from 4 to 16 h with the interval of 4 h, which affect the size of TiO2 spheres. The structural, morphological, optical, compositional and photoelectrochemical properties of the TiO2 thin films were studied. X-ray diffraction (XRD) pattern confirms the formation of anatase TiO2 with the tetragonal crystal structure. Field emission scanning electron microscopy analysis revealed that the synthesized anatase TiO2 microspheres has average diameter of similar to 330-510 nm. The blueshift in optical absorption is observed due to Mie scattering. The indirect optical band gap energy of TiO2 was varied over 3.05-3.16 eV, with the increase in deposition time. The HRTEM and SAED results show the polycrystalline nature of the sample which is in good agreement with the XRD. The anatase TiO2 hollow spheres with mesoporous walls and high specific surface area i.e. 41 m(2) g(-1) was obtained using this simple method. The films were photoelectrochemically active with maximum current density 531 mu A/cm(2) under 100 mW/cm(2) illuminations.</P>
Patil, C.E.,Tarwal, N.L.,Jadhav, P.R.,Shinde, P.S.,Deshmukh, H.P.,Karanjkar, M.M.,Moholkar, A.V.,Gang, M.G.,Kim, J.H.,Patil, P.S. Elsevier 2014 Current Applied Physics Vol.14 No.3
Vanadium pentoxide (V<SUB>2</SUB>O<SUB>5</SUB>) mixed tungsten trioxide (WO<SUB>3</SUB>) thin films have been synthesized by a novel pulsed spray pyrolysis technique (PSPT) on glass and fluorine doped tin oxide (FTO) coated glass substrates at 400 <SUP>o</SUP>C. Aqueous solutions of equimolar vanadium chloride and ammonium tungstate were mixed in volume proportions (5%, 10% and 15%) for the deposition of V<SUB>2</SUB>O<SUB>5</SUB>-WO<SUB>3</SUB> thin films. The structural, morphological, optical and electrochemical properties of V<SUB>2</SUB>O<SUB>5</SUB>-WO<SUB>3</SUB> thin films were investigated by FT-IR, XRD, SEM, cyclic voltammetry, chronoamperometry and chronocoulometry techniques. The results showed that the electrochemical properties of V<SUB>2</SUB>O<SUB>5</SUB> were altered by mixing WO<SUB>3</SUB>. All the films exhibited cathodic electrochromism in lithium containing electrolyte (0.5 M LiClO<SUB>4</SUB> + propylene carbonate (PC)). Maximum coloration efficiency (CE) of about 49 cm<SUP>2</SUP> C<SUP>-1</SUP> was observed for the V<SUB>2</SUB>O<SUB>5</SUB> film mixed with 15% WO<SUB>3</SUB>. The electrochemical stability of the sample was examined and it was found to be stable up to 1000 cycles.
Prevalence of Phytophthora Blight of Pigeonpea in the Deccan Plateau of India
Sharma, M.,Pande, S.,Pathak, M.,Rao, J. Narayana,Kumar, P. Anil,Reddy, D. Madhusudan,Benagi, V.I.,Mahalinga, D.M.,Zhote, K.K.,Karanjkar, P.N.,Eksinghe, B.S. The Korean Society of Plant Pathology 2006 Plant Pathology Journal Vol.22 No.4
Phytophthora blight(PB), caused by Phytophthora drechsleri f. sp. cajani is the third potentially important disease of pigeonpea in the Deccan Plateau(DP) of India after wilt and sterility mosaic. In the rainy-season of 2005, an outbreak of PB was seen throughout DP. To quantify the incidence and spread of the disease, a systematic survey was conducted in the major pigeonpea growing regions of DP during the crop season 2005. Attempts were made to determine the effect of cropping systems on the PB development and identify resistant cultivars, if any, grown by farmers and on research farms. Widespread incidence of PB was recorded on improved, and or local cultivars grown in different intercropping systems. Majority of improved cultivars grown at research farms were found susceptible to PB(>10% disease incidence). Pigeonpea intercropped with groundnut, black gram and coriander had less disease incidence(${\leq}10%$). Three wilt and SM resistant pigeonpea cultivars KPL 96053, ICPL 99044, and ICPL 93179 were found resistant(<10%) to PB as well. However, their resistance to PB needs confirmation under optimum disease development environments.
Prevalence of Phytophthora Blight of Pigeonpea in the Deccan Plateau of India
M. Sharma,S. Pande,M. Pathak,J. Narayana Rao,P. Anil Kumar,D. Madhusudan Reddy,V. I. Benagi,D. M. Mahalinga,K. K. Zhote,P. N. Karanjkar,B. S. Eksinghe 한국식물병리학회 2006 Plant Pathology Journal Vol.22 No.4
drechsleri f. sp. cajani is the third potentially important disease of pigeonpea in the Deccan Plateau (DP) of India after wilt and sterility mosaic. In the rainy-season of 2005, an outbreak of PB was seen throughout DP. To quantify the incidence and spread of the disease, a systematic survey was conducted in the major pigeonpea growing regions of DP during the crop season 2005. Attempts were made to determine the effect of cropping systems on the PB development and identify resistant cultivars, if any, grown by farmers and on research farms. Widespread incidence of PB was recorded on improved, and or local cultivars grown in different intercropping systems. Majority of improved cultivars grown at research farms were found susceptible to PB (>10% disease incidence). Pigeonpea intercropped with groundnut, black gram and coriander had less disease incidence (≤10%). Three wilt and SM resistant pigeonpea cultivars KPL 96053, ICPL 99044, and ICPL 93179 were found resistant (<10%) to PB as well. However, their resistance to PB needs confirmation under optimum disease development environments.