The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
David W. Ball - One of the best experts on this subject based on the ideXlab platform.
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Calculated thermochemistry of aminonitroacetylene: a new high-energy material?
The journal of physical chemistry. A, 2009Co-Authors: Kelly Y. Mathews, David W. BallAbstract:As part of an increased interest in amino- and nitro-substituted high-energy-density materials (as exemplified by FOX-7, 1,1-diamino-2,2-dinitroethylene), here we present calculated properties of aminonitroacetylene, NH2−C≡C−NO2. Our results indicate that while the Specific Enthalpy of combustion is less than that of acetylene, its Specific Enthalpy of decomposition is greater than that of TNT, and its predicted density is large enough to predict substantial high-energy-density properties for this substance.
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G2, G3, and complete basis set calculations of the thermodynamic properties of cis- and trans-triazene
Journal of Molecular Modeling, 2008Co-Authors: Ryan M. Richard, David W. BallAbstract:Following our recent study on triazane, we present a follow-up study on the thermodynamic properties of triazane’s unsaturated analog, triazene. We predict optimized structural parameters, vibrational frequencies, enthalpies of formation, enthalpies of combustion, Specific enthalpies of combustion, and proton affinities. Our results indicate that the cis form of triazene has a Specific Enthalpy of combustion of −15.2 kJ g^−1 and the trans form has a Specific Enthalpy of combustion of −14.7 kJ g^−1. Figure Structures of cis- and trans-triazane, N_3H_3
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G2, G3, and complete basis set calculations of the thermodynamic properties of cis- and trans-triazene.
Journal of molecular modeling, 2007Co-Authors: Ryan M. Richard, David W. BallAbstract:Following our recent study on triazane, we present a follow-up study on the thermodynamic properties of triazane’s unsaturated analog, triazene. We predict optimized structural parameters, vibrational frequencies, enthalpies of formation, enthalpies of combustion, Specific enthalpies of combustion, and proton affinities. Our results indicate that the cis form of triazene has a Specific Enthalpy of combustion of −15.2 kJ g−1 and the trans form has a Specific Enthalpy of combustion of −14.7 kJ g−1.
Stefanos Fasoulas - One of the best experts on this subject based on the ideXlab platform.
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Measurement of the aerothermodynamic state in a high Enthalpy plasma wind-tunnel flow
Journal of Quantitative Spectroscopy and Radiative Transfer, 2017Co-Authors: Tobias Hermann, Stefan Löhle, Fabian Zander, Stefanos FasoulasAbstract:Abstract This paper presents spatially resolved measurements of absolute particle densities of N 2 , N 2 + , N, O, N + , O + , e − and excitation temperatures of electronic, rotational and vibrational modes of an air plasma free stream. All results are based on optical emission spectroscopy data. The measured parameters are combined to determine the local mass–Specific Enthalpy of the free stream. The analysis of the radiative transport, relative and absolute intensities, and spectral shape is used to determine various thermochemical parameters. The model uncertainty of each analysis method is assessed. The plasma flow is shown to be close to equilibrium. The strongest deviations from equilibrium occur for N, N + and N 2 + number densities in the free stream. Additional measurements of the local mass-Specific Enthalpy are conducted using a mass injection probe as well as a heat flux and total pressure probe. The agreement between all methods of Enthalpy determination is good.
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Local Mass-Specific Enthalpy Measurements with a New Mass Injection Probe
Journal of Thermophysics and Heat Transfer, 2016Co-Authors: Stefan Löhle, Andreas Steinbeck, Stefanos FasoulasAbstract:The results of local measurements of the mass-Specific Enthalpy in a high-Enthalpy oxygen plasma flow are presented. The sensor measures Enthalpy based on stagnation point heat flux measurements and its reduction by mass addition into the boundary layer. The efficiency of this boundary-layer cooling depends on the freestream Enthalpy. Thus, an analysis of this heat flux reduction is a measure for Enthalpy. The Enthalpy probe is described and theoretically analyzed, and measured data are compared to locally resolved Enthalpy measurements from optical diagnostic measurements. For the pure oxygen plasma flow, a simplified theoretical model neglecting chemical reactions and diffusion fits comparably well to the measurements based on optical diagnostics. The mass-Specific Enthalpy at the corresponding plasma condition applying optical diagnostics is h=27.47 MJ/kg, and the probe measures h=27.64 MJ/kg.
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Measurement of Specific Enthalpy in plasma wind tunnels using a mass injection probe
32nd Thermophysics Conference, 1997Co-Authors: Stefanos Fasoulas, Thomas Stoeckle, Monika Auweter-kurtzAbstract:This article introduces an experimental diagnostic method for the measurement of Specific Enthalpy in low pressure and high Enthalpy devices based on a mass injection probe. First experimental results from measurements in plasma wind tunnel facilities are presented. Different test conditions were investigated in order to determine the characteristics of this new intrusive measurement technique. The obtained results are very important for the assessment of material test conditions as well as for the validation of supporting numerical code systems and theoretical investigations. Nomenclature
Klaus Bauckhage - One of the best experts on this subject based on the ideXlab platform.
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Specific Enthalpy measurement in molten metal spray
Materials Science and Engineering: A, 2002Co-Authors: Marko Buchholz, Volker Uhlenwinkel, Axel Von Freyberg, Klaus BauckhageAbstract:A caloric probe to measure average Specific enthalpies of molten metal droplets in a spray cone of a free fall atomizer was developed. Molten tin was used in this caloric probe to collect the particles of the spray. The results of standard deviation of the consistency measurements were examined comprehensively. The experiments were made with low carbon steel, bearing steel AISI 52100 and copper. The process parameters, gas mass flow rate and melt mass flow rate were varied. The Specific Enthalpy within the spray cone clearly decreased with increasing radial distance from the center of the spray cone and with increasing axial distance to the nozzle. A correlation between median particle diameter and average Specific Enthalpy was clearly observed. Experimental results are compared with data from numerical simulations.
Xinye Chang - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation on aerodynamic characteristics of exhaust passage with consideration of multi-factor components in a supercritical steam turbine
Applied Thermal Engineering, 2019Co-Authors: Xiaoqiang Jiang, Aqiang Lin, Adil Malik, Xinye ChangAbstract:Abstract Heat transfer and vacuum in the condenser are affected by the flow characteristics in the low-pressure steam turbine exhaust passage. In this study, the Eulerian-Eulerian equilibrium two-phase model is applied to investigate the contribution of multi-factor components on aerodynamic performance of twin exhaust passage. Results show that the share of steam phase is reduced in the exhaust passage with consideration of the built-in pipelines. Total-pressure loss in the exhaust hood is about four times of that in the throat. The sensitivity of local loss existing in the exhaust hood on the whole loss is higher than that in the throat. Considering the factors of LSBs and pipelines, both the static-pressure recovery coefficient of 15.44% and effective Specific Enthalpy-drop of 0.145% are the best performance. By evaluating the steam turbine economic, however, static-pressure recovery coefficient and Specific Enthalpy drop are 1.25 times and 0.475 times of that without pipelines, respectively, relative to built-in pipelines. Therefore, a recommendation on the consideration of twin exhaust passage, last stage blades, steam extraction pipelines, low-pressure heater, and wet steam can obtain a representative aerodynamic characteristic.
E. Hahne - One of the best experts on this subject based on the ideXlab platform.
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Thermophysical properties of the composite ceramic-salt system (SiO2 /Na2SO4)
Thermochimica Acta, 1993Co-Authors: W. Notter, Th. Lechner, U. Groß, E. HahneAbstract:Abstract A composite ceramic-salt packed bed configuration is being developed for high-temperature thermal storage. The range of application is industrial waste heat recovery and utilization, off peak utilization reserve and solar thermal power systems application. The thermophysical properties of the hybrid system SiO 2 /Na 2 SO 4 have been investigated in the range from room temperature to temperatures above the melting point of the salt, 884°C. The Na 2 SO 4 fraction in the composite materials was variied between 20 % and 50 %. The following properties were measured: xxx the Specific Enthalpy xxx the coefficient of thermal expansion xxx the thermal diffusivity. The measurement of the thermal expansion was performed with a commercial difference dilatometer; the Specific Enthalpy was measured by drop calorimetry and the thermal diffusivity with a laser flash device. The measured values are correlated to the base properties of the different SiO 2 crystalline modifications. Special attention has been paid to phase change behaviour.
