Evaluation Of Thermal Response Research Articles

Mechanism Identification and Kinetics Analysis of Thermal Degradation for Carbon Fiber/Epoxy Resin.

For carbon fiber epoxy resin used in aerostructure, thermal degradation mechanism and kinetics play an important role in the evaluation of thermal response and combustion characteristics. However, the thermal decomposition process and mechanism are difficult to unify strictly due to the complexity of the components from different suppliers. In the present study, a product of carbon fiber epoxy resin made by AVIC (Aviation Industry Corporation of China) composite corporation is examined to identify its thermal degradation mechanism and pyrolysis products by measurements, including simultaneous thermal analysis, Fourier transform infrared spectroscopy and mass spectrometry, establish the kinetic model by Kissinger/Friedman/Ozawa/Coats-Redfern methods. The results show thermal degradation occurs in three steps under the inert atmosphere, but in four steps under air atmosphere, respectively. The first two steps in both environments are almost the same, including drying, carbon dioxide escape and decomposition of the epoxy resin. In the third step of inert atmosphere, phenol is formed, methane decreases, carbon monoxide basically disappears and carbon dioxide production increases. However, in air, thermal oxidation of the carbonaceous residues and intermolecular carbonization are observed. Furthermore, thermal degradation reaction mechanism submits to the F4 model. These results provide fundamental and comprehensive support for the application of carbon fiber epoxy resin in aircraft industry.

Kinetics and thermodynamical evaluation of electrode material of discarded lithium-ion batteries and its impact on recycling

The investigation of decomposition thermodynamics and kinetics of active electrode materials is an important tool in the development of recycling techniques for discarded lithium-ion batteries. The knowledge of thermal decomposition kinetics and thermodynamics aids the understanding and improving thermal response and can provide guidelines for the design of the thermal recycling process. Evaluation of thermal response, kinetics parameter, and thermodynamic parameters, which include activation energy, change in Gibbs free energy (ΔG), change in enthalpy (ΔH), change in entropy (ΔS) were carried out using isoconversional kinetic methods employing thermogravimetric. Comparative analysis of thermal decomposition kinetics, experimental, and indigenous carbothermal reduction in the single (LiCoO2/C) and the mixed phases cathode (LiCoO2, LiMn2O4, LiNi0.5Mn1.5O4/C) active electrode material was also carried out. The average activation energy for the thermal dissociation of mixed cathode active material is estimated as 187.6 kJ mol−1, and ΔG, ΔH, ΔS are 243 kJ mol−1, 179.9 kJ mol−1, − 0.06 kJ mol−1 K−1, respectively. Thermal dissociation and carbothermal reduction in active electrode material was investigated in 600–1000 °C and found that active electrode material decomposes and reduces above 600 °C. A simple processing comprising reduction followed by water leaching and magnetic separation was used for metallic recovery. The optimum magnetic product of mix phase cathodeactive material comprises Co: 61%, Mn: 19%, Ni: 7%, O: 13%, and lithium was recovered as Li2CO3 with Li extraction ~ 80%.

Evaluation of thermal response on microgel aggregate toward micro gel actuators

Evaluation of thermal response on microgel aggregate toward micro gel actuators

Evaluation of thermal response and performance of PHC energy pile: Field experiments and numerical simulation

This paper presents an experimental and numerical study on evaluation of thermal response and performance of prototype precast-high strength concrete (PHC) energy pile. Short-term field thermal response tests (TRTs) were conducted for the PHC energy piles installed in partially saturated weathered granite soil deposit, in which two types of heat exchangers were considered: W and 3U-shaped heat exchangers. The TRTs were successfully simulated by three-dimensional finite element analyses employing quasi-steady-state convective heat transfer boundary condition. The numerical model was applied to simulate 3-day TRTs, and the simulation results were used for assessing effective thermal conductivity and thermal resistance. Besides, continuous and intermittent operation simulations of the energy piles were performed, and for the results of performance analyses, discussion was made to evaluate energy efficiency of the prototype PHC piles.

Experimental Evaluation of Thermal Response and Condensation Performance of Metal Curtain Walls Subjected to Air Leakage

The condensation resistance of fenestration products is typically determined in standard tests with air leakage eliminated by sealing the cracks and balancing the pressure difference across the test specimen. In reality, however, the fenestration system does experience varying pressure differentials. The infiltration and exfiltration of air can affect the temperature distribution on the fenestration system and, thus, the condensation resistance. In this paper the effect of air leakage on the condensation resistance of a large-scale metal curtain wall subjected to a pressure differential of 150 Pa is studied experimentally. By examining the temperature response profiles and the magnitudes of the temperature variations, likely air leakage paths are identified and the impact of air leakage on condensation resistance is quantified. Since the airtightness of the curtain wall tested is relatively high, the effect of air infiltration is relatively small on the average condensation resistance but is significant locally.

Numerical Analysis of Nonstationary Thermal Response Characteristics for a Fluid-Structure Interaction System

Nonstationary thermal response analysis for a fundamental sodium experiment simulating thermal striping phenomena was carried out using a quasi-direct numerical thermohydraulics simulation code with a third-order upwind scheme for convection terms and a boundary element method code for thermal response evaluation of structures due to random sodium temperature fluctuations developed at Power Reactor and Nuclear Fuel Development Corporation (PNC). Discussions centered on an applicability of the numerical method for the damping effects of the temperature fluctuations in the course of heat transfer to the inside of structures from the fully turbulent region of sodium flows through the comparisons with the experiment. From these comparisons, it was confirmed that the numerical method has a sufficiently high potential in accuracy to predict the damping effects of the temperature fluctuations related to the thermal striping phenomena. Consequently, it is concluded that the numerical prediction by the method developed in this study can replace conventional experimental approaches using 1:1 or other scale model aiming at the simulation of the thermal striping phenomena in actual liquid metal fast breeder reactor (LMFBR) plants. Furthermore, economical improvements in the FBR plants can be carried out based on the discussions of optimization and rationalization of the structural design using the numerical methods.