Papers by Keyword: Thermodynamic Simulation

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Authors: Y.A. Alduqri, Md Nor Musa, Z.A.B. Ahmad
Abstract: This paper introduces a novel two-sleeve rotary compressor (TSRC) concept. The compressor mechanism is basically that of a rotary motion whereby the novelty lies in the usage of two rotating sleeves and a secured vane that has one end fixed to an outer sleeve and the other end to a rotor, respectively. The paper introduces the working principle and thermodynamic model of the TSRC compressor. The swept volume, the delivered pressure, the work and the power of the TSRC are formulated and analyzed. The compressor configuration and thermodynamic analysis are based on the 174 cm3.rev-1 swept volume with R134a as the compressed gas. The thermodynamic analysis reveals that the TSRC will perform well as refrigerant compressor and can be reliably adopted for refrigeration and air-conditioning applications.
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Authors: Johanne Laigo, Franck Tancret, René Le Gall, Jader Furtado
Abstract: Heat-resistant steels of HP series (Fe-25Cr-35Ni) are used as reformer tubes in petrochemical industries. Their composition includes Nb and Ti as strong carbide formers. In the ascast condition, alloys exhibit an austenite matrix with intergranular MC, M23C6 and/or M7C3 eutectic carbides. During exposure at high temperature, phase transformations occur: chromium carbides of M7C3 type transform into the more stable M23C6 type, intragranular M23C6 carbides precipitate, and a silicide, the G-phase (Ni16Nb6Si7), forms due to the instability of MC carbides (NbC). Thermodynamic simulation is of great help for understanding precipitate formation and transformations. Thermo-Calc and Dictra are used to simulate the precipitation of carbides in the austenite matrix during service. However, from an experimental point of view, M23C6 and M7C3 are not easy to distinguish in bulk alloys. Indeed, backscattered scanning electron microscopy does not bring any contrast between the two phases, and energy dispersive spectroscopy (EDS) analysis does not lead to carbon content and consequently to the distinction between M23C6 and M7C3. With transmission electron microscopy (TEM), sample preparation is difficult and the observed area is extremely small. In the present work, HP alloys are investigated by electron backscatter diffraction (EBSD) coupled to EDS. Carbides are identified on the basis of crystal structure, in the bulk, within their microstructural context, and the experimental procedure is both simpler and cheaper than TEM. Precipitates (M23C6, M7C3) could be identified by orientation mapping and single spot analysis.
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Authors: Se Weon Choi, Young Chan Kim, Chang Seog Kang, Jae Min Jung, Sung Kil Hong
Abstract: The effects of Mn and Ca contents on the microstructure and mechanical properties in Al-Mg alloy were investigated. The results showed that mechanical properties of Al-4.5wt.%Mg were increased as Mn content was raised from 0.1 to 0.5wt.%. Thermodynamic analysis and FE-SEM observation showed that Al15(Fe,Mn)3Si2 phase began to form as Mn content exceeded 0.3wt.%. The case of Ca addition, the tensile strength and elongation of Al-4.5wt.%Mg were decreased as Ca content was increased from 0 to 3wt.%. The maximum solubility of Ca for Al is very lower to 0.074wt.%, the most of Ca precipitated in the form of Al2Ca phase which is very brittle and the increase of Ca content was reduced the mechanical properties.
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Authors: Anderson Dias, Virgínia S.T. Ciminelli
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Authors: Jing Yu, Xiong Zhu Bu, Xiao Gang Chu
Abstract: In the field of aerospace, the Gardon heat flux sensor is not allowed water-cooling device, so the sensor sensitivity would be greatly affected by the temperature rise of the heat sink. To deal with this problem, a high-temperature, high-precision heat flux sensor is designed based on the metal thermo-electric effect and the principle of thermal conduction. First of all, the measuring principle of the Gardon heat flux sensor is expounded. Then the heating process of the copper heat sink is derived. In order to slowdown the temperature of the heat sink, kinds of adiabatic measures are taken. Thermodynamic simulation for the designed sensor is performed by the ANSYS finite element simulation software. Finally, experiments have been carried out to test the performance of the sensor. The experimental results show that the sensitivity of the sensor with adiabatic measures did not decline within 1000s, and its linearity is 1.38%. So the sensor is able to meet applications in the aerospace field.
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Authors: Jian Zhuang, Wei Hu, Da Ming Wu, Ya Jun Zhang, Zhong Li Zhao, Shui Xing Liu
Abstract: With successful development of LED lamps, the dissipation of LED lamps has become the core problem. If the heat produced during the work cant be loss in time, the high temperature of the lamps will affect their service lives or even damage the LED permanently. In this paper, based on the principle of finite element method, using thermal simulation software, the effect of the geometric characteristics micro-structure of the heat exchanger combining polymer micro-scale fins and metal base on the heat transfer characteristics was simulated. The impact of the fin width, wing fin pitch, fin height and thickness of the substrate on the tablet microstructure heat transfer characteristics was analyzed. The results provide some technical reference for the design and application of the micro heat exchanger.
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Authors: Christophe Jacquier, Gabriel Ferro, François Cauwet, Yves Monteil
307
Authors: L. Sánchez, F.J. Bolívar, M.P. Hierro, F.J. Pérez
Abstract: In this work, iron aluminide coatings were developed by Chemical Vapor Deposition in Fluidized Bed Reactor (CVD-FBR) on ferritic-martensitic steels. Small additions of zirconium powder were introduced in the fluidized bed; as a consequence, the obtained coatings are thicker than that without zirconium additions. When Zr powders are added in the fluidized bed, the deposition atmosphere drastically changes, leading to increase the deposition rate. Thermodynamic calculations were carried out to simulate the modifications in the CVD atmosphere in the Al/Zr deposition system in comparison to the single aluminization. In order to optimize the conditions of the deposition, parameters such as temperature and concentration of zirconium introduced into the bed were evaluated and compared with the results obtained for the single aluminum deposition.
293
Authors: Y.A. Alduqri, Md Nor Musa
Abstract: A novel four-chamber rotary compressor (FCRC) is being developed for a refrigerator and an air-conditioning system. The novelty lies in the usage of three rotating sleeves and two oppositely installed vanes each has one end fixed to an outer sleeve and the other end to a rotor, respectively. In this paper, the swept volume, the delivered pressure, the work and the power of the FCRC are formulated and analyzed. The compressor configuration and thermodynamic analysis are based on the 174 cc swept volume with R134a as the compressed gas. Considering the encouraging results, added by design simplicity of mainly cylindrical shaped components, the proposed FCRC is reckoned to be very suitable to be used for air-conditioning and refrigeration applications.
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Authors: Sheng Yao Gao, De Shi Wang, Qi Zheng Zhou
Abstract: To control the inertial forces and moments, the new type of the reciprocating cam engine with counter-position placement has been invented. Such a thermodynamic model based on the kinematic and dynamic analysis is developed and the engine performance is simulated. Under the same structural design parameters, the counter-position placement cam engine would have the inadequate work due to the increase of throttle loss. Then effects of the gas distributions to the dynamic performance of the engine are researched. Six variables are selected to optimize maximum average indicated power and the minimum indicated specific consumption with the method of discrete variable gridding. The results indicate that: (a) The new engine structure design can present advantage of excitation forces balance. (b) The structural design parameters and the thermal efficiency of the engine should be optimized especially those of the valve actuating mechanism to achieved desired power. (c) The parameters optimized of valve train can conform to the requirements of speed and economy, and it is feasible and reasonable to put forward the scheme of cam engine with the counter-position placement.
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