The Experts below are selected from a list of 13632 Experts worldwide ranked by ideXlab platform
P K Vijayan - One of the best experts on this subject based on the ideXlab platform.
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experimental and theoretical studies on the natural circulation behavior of molten salt loop
Applied Thermal Engineering, 2016Co-Authors: A Srivastava, Jayaraj Yallappa Kudariyawar, Ananta Borgohain, S S Jana, N K Maheshwari, P K VijayanAbstract:Abstract Molten salts are increasingly getting attention as a coolant and storage medium in solar thermal Power plants and as a liquid fuel, blanket and coolant in High Temperature Reactors (HTR). A Molten Salt Natural Circulation Loop (MSNCL) has been setup for thermal hydraulics, instrument development and material related studies relevant to HTR and solar Power plants. The loop mainly consists of heated section, air heat exchanger, valves, various tanks and argon gas control system. All the components and piping of the loop are made of Inconel 625. Steady state natural circulation experiments at different Power level have been performed in the loop. Transient studies for startup of natural circulation, loss of heat sink, Heater trip and step change in Heater Power have also been carried out. A one dimensional code LeBENC, developed in-house to simulate the natural circulation characteristics in closed loops, has been validated with the experimental data obtained from MSNCL. This paper deals with the description of the loop and experimental studies carried out in the loop. Detailed validation of the LeBENC code with the experimental data has also been discussed in the paper.
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simulation of the unstable oscillatory behavior of single phase natural circulation with repetitive flow reversals in a rectangular loop using the computer code athlet
Nuclear Engineering and Design, 1995Co-Authors: P K Vijayan, H Austregesilo, V TeschendorffAbstract:Abstract Experiments carried out in three rectangular loops differing in diameter showed instability in the loop with the largest diameter. The observed oscillatory behavior involves repetitive flow reversals, the frequency of which is regular (periodic) at low Powers and irregular (chaotic) at high Powers. The flow reversal frequency increases with Heater Power. Due to the flow reversals the Reynolds number vary between +10 000 and −10 000 causing the flow to pass through the laminar and turbulent regime repetitively. Simulation of the oscillatory behavior using the computer code athlet did not show instability with a coarse nodalization. The nodalization was then progressively refined and with a fine nodalization athlet was able to predict the instability behavior and to reproduce all the essential characteristics of the observed oscillatory behavior.
Koichi Kakimoto - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation of the influence of material property of a crucible on interface shape in a unidirectional solidification process
Crystal Growth & Design, 2009Co-Authors: Hiroaki Miyazawa, Lijun Liu, Koichi KakimotoAbstract:We carried out calculations to investigate the influence of thermal conductivity of the wall of a crucible on melt−crystal interface shape using three-dimensional global analyses. It was found that thermal conductivity of the wall of a crucible has significant influence on the melt−crystal interface shape due to modification of the amount of outgoing heat flux through the wall of a crucible. The results indicate that we should control not only Heater Power, growth velocity, and melt flow but also thermophysical properties of the wall of a crucible in order to reduce deformation of the melt−crystal interface.
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numerical analysis of influence of crucible shape on interface shape in a unidirectional solidification process
Journal of Crystal Growth, 2008Co-Authors: Hiroaki Miyazawa, Lijun Liu, Koichi KakimotoAbstract:Abstract We carried out calculations to investigate the melt–crystal (m–c) interface shape with cylindrical and square crucibles and the influence of crucible shape on m–c interface shape using two-dimensional and three-dimensional global analyses. It was found that maximum deformation of the m–c interface occurs near the corner of the square crucible because outgoing heat flux, which has a significant influence on the m–c interface shape, has three-dimensionality. It was also found that shape and dimensions of the crucible have significant influence on the amount of outgoing heat flux. The results indicate that we should control not only Heater Power, growth ratio and melt flow but also shape and dimensions of crucibles in order to reduce deformation of the m–c interface.
M Ravi - One of the best experts on this subject based on the ideXlab platform.
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thermal analysis of electron gun for travelling wave tubes
Applied Surface Science, 2006Co-Authors: K S Bhat, K Sreedevi, M RaviAbstract:Abstract Thermal analysis of a pierce type electron gun using the FEM software ANSYS and its experimental validation are presented in this paper. Thermal analysis of the electron gun structure has been carried out to find out the effect of Heater Power on steady state temperature and warm-up time. The thermal drain of the supporting structure has also been analyzed for different materials. These results were experimentally verified in an electron gun. The experimental results closely match the ANSYS results.
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thermal analysis of electron gun for traveling wave tubes
International Vacuum Electron Sources Conference, 2004Co-Authors: K S Bhata, K Sreedevib, M RaviAbstract:Thermal analysis of a pierce type electron gun using FEM software ANSYS# and its experimental validation are given in this paper. Ultimate temperature reached by the cathode button, at given Heater Power, depends on the heat loss mechanism through the support structure and radiation. Steady state thermal analysis has been carried out for various Heater Powers of the cathode to find out the temperature of the cathode button. Transient thermal analysis of the electron gun structure has been carried out to find the warm up time. These results were verified experimentally in an electron gun assembled in the laboratory. Theoretical and experimental results are closely matching and it validates our model and boundary conditions. Thermal drain of support structure has also been analyzed for different materials.
Lijun Liu - One of the best experts on this subject based on the ideXlab platform.
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numerical investigation of the influence of material property of a crucible on interface shape in a unidirectional solidification process
Crystal Growth & Design, 2009Co-Authors: Hiroaki Miyazawa, Lijun Liu, Koichi KakimotoAbstract:We carried out calculations to investigate the influence of thermal conductivity of the wall of a crucible on melt−crystal interface shape using three-dimensional global analyses. It was found that thermal conductivity of the wall of a crucible has significant influence on the melt−crystal interface shape due to modification of the amount of outgoing heat flux through the wall of a crucible. The results indicate that we should control not only Heater Power, growth velocity, and melt flow but also thermophysical properties of the wall of a crucible in order to reduce deformation of the melt−crystal interface.
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numerical analysis of influence of crucible shape on interface shape in a unidirectional solidification process
Journal of Crystal Growth, 2008Co-Authors: Hiroaki Miyazawa, Lijun Liu, Koichi KakimotoAbstract:Abstract We carried out calculations to investigate the melt–crystal (m–c) interface shape with cylindrical and square crucibles and the influence of crucible shape on m–c interface shape using two-dimensional and three-dimensional global analyses. It was found that maximum deformation of the m–c interface occurs near the corner of the square crucible because outgoing heat flux, which has a significant influence on the m–c interface shape, has three-dimensionality. It was also found that shape and dimensions of the crucible have significant influence on the amount of outgoing heat flux. The results indicate that we should control not only Heater Power, growth ratio and melt flow but also shape and dimensions of crucibles in order to reduce deformation of the m–c interface.
M Piotto - One of the best experts on this subject based on the ideXlab platform.
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a double Heater integrated gas flow sensor with thermal feedback
Sensors and Actuators A-physical, 2005Co-Authors: P Bruschi, A Diligenti, Dino Navarrini, M PiottoAbstract:An integrated thermal sensor for flow rates below 200 sccm, consisting of two central Heaters and two thermopiles, located downstream and upstream with respect to the Heaters, is presented. The sensor, fabricated by post-processing chips produced with a standard microelectronic process, is operated in closed loop configuration through a single operational amplifier, in such a way that the flow-induced temperature difference between the two thermopiles is cancelled by applying a Power mismatch to the two Heaters. The output signal is proportional to the Heater Power unbalance. Static and dynamic electrical characterization of the sensor is performed. The response to nitrogen flow rates has been measured for various gas pressures.