Determination of the Temperature-Dependent Thermal Material Properties in the Cooling Process of Steel Plates

Accelerated cooling (ACC) is a key technology in producing thermomechanically controlled processed (TMCP) steel plates. In a TMCP process, hot plates are subjected to a strong cooling resulting in a complex microstructure leading to increased strength and fracture toughness. The microstructure, residual stresses, and flatness deformations are strongly affected by the temperature evolution during the cooling process. Therefore, the full control (quantification) of the temperature evolution is essential regarding plate design and processing. It can only be achieved by a thermophysical characterization of the material and the cooling system. In this paper, the focus is on the thermophysical characterization of the material properties which govern the heat conduction behavior inside of the plates. Mathematically, this work considers a specific inverse heat conduction problem (IHCP) utilizing inner temperature measurements. The temperature evolution of a heated steel plate passing through the cooling device is modeled by a 1D nonlinear partial differential equation with temperature-dependent material parameters which describe the characteristics of the underlying material. Usually, the material parameters considered in IHCPs are often defined as functions of the space and/or time variables only. Since the measured data (the effect) and the unknown material properties (the cause) depend on temperature, the cause-to-effect relationship cannot be decoupled. Hence, the parameter-to-solution operator can only be defined implicitly. By proposing a parametrization approach via piecewise interpolation, this problem can be resolved. Lastly, using simulated measurement data, the presentation of the numerical procedure shows the ability to identify the material parameters (up to some canonical ambiguity) without any a priori information.

Synthesis and Characterization of Novel Ternary Hybrid Nanoparticles as Thermal Additives in H2O

The performance of water as a heat transfer medium in numerous applications is limited by its effective thermal conductivity. In order to improve the thermal conductivity of water, herein we report the development and thermophysical characterization of a novel metal-metaloxide-carbon based ternary hybrid nanoparticles (THNp), GO-TiO2-Ag and the rGO-TiO2-Ag. The results indicate that the graphene oxide and reduced graphene oxide based ternary hybrid nanoparticles dispersed in water enhance its thermal conductivity by 66% and 83%, respectively, even at very low concentrations. Mechanisms contributing to this significant enhancement are discussed. The experimental thermal conductivity is plotted against the existing empirical hybrid thermal conductivity correlations. We found that those correlations are not suitable for the metal-metaloxide-carbon combinations, calling for the developing a new thermal conductivity models. The rheological measurements of the nanofluids display non-Newtonian behavior, and the viscosity reduces with the increase in temperature. Such behavior is possibly due to the non-uniform shapes of the ternary hybrid nanoparticles.

Synthesis and Characterization of Novel Ternary Hybrid Nanoparticles as Thermal Additives in H2O

The performance of water as a heat transfer medium in numerous applications is limited by its effective thermal conductivity. In order to improve the thermal conductivity of water, herein we report the development and thermophysical characterization of a novel metal-metaloxide-carbon based ternary hybrid nanoparticles (THNp), GO-TiO2-Ag and the rGO-TiO2-Ag. The results indicate that the graphene oxide and reduced graphene oxide based ternary hybrid nanoparticles dispersed in water enhance its thermal conductivity by 66% and 83%, respectively, even at very low concentrations. Mechanisms contributing to this significant enhancement are discussed. The experimental thermal conductivity is plotted against the existing empirical hybrid thermal conductivity correlations. We found that those correlations are not suitable for the metal-metaloxide-carbon combinations, calling for the developing a new thermal conductivity models. The rheological measurements of the nanofluids display non-Newtonian behavior, and the viscosity reduces with the increase in temperature. Such behavior is possibly due to the non-uniform shapes of the ternary hybrid nanoparticles.

Characterization in expected working environments of recyclable fire-resistant materials

This study focuses on the development of multi-material solutions for fire-resistant structural materials for transport and thermal insulation in the construction field. Special attention was paid to combining recyclable and bio-mass derived raw materials without interfering with an easy end-of-life separation, recycling and reuse. Fire-resistant biomass derived resins were associated with basalt derived Mineral Fibres (BDMF) in the form of prepregs, which were studied as semi-finished materials. Fire-resistance was obtained by associating these prepregs with thin gres tiles in the case of fire-resistant thermal insulating facades and with aluminum layers (giving origin to Fibre Metal Laminates-FML) in the case of structural components for transport applications. Thermophysical characterization of the solutions was carried out to assess both thermal conductivity and thermal diffusivity. Fire resistance tests were performed on FML to determine the number of Al layers needed to ensure fire resistance. Results suggest that fire resistance depends primarily on the number of Al layers, rather than on their thickness. Accelerated ageing tests (salty mist and freeze-thaw) were executed to predict durability in the expected working conditions. Results suggest a durability issue in FML with preceramic interface in salty environments.