• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.1
• /
• pp.717-724
• /
• 2020

In general, the factors affecting the heat transfer of asphalt pavement are divided into weather factors and pavement materials. Among them, material factors include the thermophysical and surface properties. An experiment was conducted on the thermal-physical factors of asphalt, which are the basis for the pavement failure model. The thermal conductivity, specific heat capacity, thermal diffusivity, and thermal emissivity were evaluated as the thermo-physical properties of asphalt. The specimens (WC-2 & PA-13) used in the experiment were compacted with a Gyratory Compactor. The experimental results of WC-2 and PA-13 showed a thermal conductivity of 1.18W/m·K and 0.9W/m·K, specific heat capacity of 970.8J/kg·K and 960.1J/kg·K, thermal emissivity of 0.9 and 0.91, and thermal diffusivity of 5.15㎡/s and 4.66㎡/s, respectively. Experiments on the heat transfer characteristics (thermo-physical properties) of asphalt pavement that can be used for thermal failure modeling of asphalt were conducted.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.1191-1196
• /
• 2009

The T-s chart of air displays graphically the thermophysical properties, so it is very conveniently used in various thermal systems. In previous study, the software analyzing 31 kinds of values in water system and 32 kinds of values in air-conditioning system were developed. In this study, the software drawing 13 kinds of quantity of state on air properties as ideal gas and analyzing 25 kinds of values in any air system was developed. The 13 kinds of quantity of state on air properties are temperature, pressure, specific volume, specific internal energy, specific enthalpy, specific entropy, specific exergy, exergy ratio, density, isobaric specific heat, isochoric specific heat, ratio of specific heat, and velocity of sound, and the 25 kinds of values including 13 kinds are mass flow rate, volume flow rate, internal energy flow rate, enthalpy flow rate, entropy flow rate, exergy flow rate, heat flow rate, power output, power efficiency, reversible work, lost work, and relative humidity. The developed software can draw any range of chart and analysis any state or process on air system. Also, this supports various document-editing functions such as power point. We wish to this chart is a help to design, analysis, and education in air system field.

• Proceedings of the SAREK Conference
• /
• 2008.11a
• /
• pp.157-164
• /
• 2008

The temperature-entropy diagram of water or vapor displays graphically the thermophysical properties, so it is very conveniently used in various thermal systems. On general T-s chart of water, there are temperature, pressure, quality, specific volume, specific enthalpy, specific entropy. However, various state and process values besides above properties can be plotted on T-s diagram. In this study, we developed the software drawing twenty six kinds of properties, that is temperature, pressure, quality, specific volume, specific internal energy, specific enthalpy, specific entropy, specific exergy, exergy ratio, density, isobaric specific heat, isochoric specific heat, ratio of specific heat, coefficient of viscosity, kinematic coefficient of viscosity, thermal conductivity, prandtl number, ion product, static dielectric constant, isentropic exponent, velocity of sound, joule-thomson coefficient, pressure coefficient, volumetric coefficient of expansion, isentropic compressibility, and isothermal compressibility. Also, this software can analyze and print the system values of mass flow rate, volume flow rate, internal energy flow rate, enthalpy flow rate, entropy flow rate, exergy flow rate, heat flow rate, power output, power efficiency, and reversible work. Additionally, this software support the functions such as MS-Power Point.

• Journal of Powder Materials
• /
• v.27 no.1
• /
• pp.25-30
• /
• 2020

Recently, the amount of heat generated in devices has been increasing due to the miniaturization and high performance of electronic devices. Cu-graphite composites are emerging as a heat sink material, but its capability is limited due to the weak interface bonding between the two materials. To overcome these problems, Cu nanoparticles were deposited on a graphite flake surface by electroless plating to increase the interfacial bonds between Cu and graphite, and then composite materials were consolidated by spark plasma sintering. The Cu content was varied from 20 wt.% to 60 wt.% to investigate the effect of the graphite fraction and microstructure on thermal conductivity of the Cu-graphite composites. The highest thermal conductivity of 692 W m^-1K^-1 was achieved for the composite with 40 wt.% Cu. The measured coefficients of thermal expansion of the composites ranged from 5.36 × 10^-6 to 3.06 × 10^-6K^-1. We anticipate that the Cu-graphite composites have remarkable potential for heat dissipation applications in energy storage and electronics owing to their high thermal conductivity and low thermal expansion coefficient.

• Nuclear Engineering and Technology
• /
• v.53 no.2
• /
• pp.603-610
• /
• 2021

The major drawback of zirconia-based materials, in view of their applications as targets for minor actinide transmutation, is their poor thermal conductivity. The addition of MgO, which has high thermal conductivity, to zirconia-based materials is expected to improve their thermal conductivity. On these grounds, the present study aims at phase characterization and thermophysical property evaluation of neodymium-substituted zirconia (Zr_0.8Nd_0.2O_1.9; using Nd₂O₃ as a surrogate for Am₂O₃) and its composites with MgO. The composite was prepared by a solid-state reaction of Zr_0.8Nd_0.2O_1.9 (synthesized by gel combustion) and commercial MgO powders at 1773 K. Phase characterization was carried out by X-ray diffraction and the microstructural investigation was performed using a scanning electron microscope equipped with energy dispersive spectroscopy. The linear thermal expansion coefficient of Zr_0.8Nd_0.2O_1.9 increases upon composite formation with MgO, which is attributed to a higher thermal expansivity of MgO. Similarly, specific heat also increases with the addition of MgO to Zr_0.8Nd_0.2O_1.9. Thermal conductivity was calculated from measured thermal diffusivity, temperature-dependent density and specific heat values. Thermal conductivity of Zr_0.8Nd_0.2O_1.9-MgO (50 wt%) composite is more than that of typical UO₂ fuel, supporting the potential of Zr_0.8Nd_0.2O_1.9-MgO composites as target materials for minor actinides transmutation.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.5
• /
• pp.673-679
• /
• 2001

The objective of this work is to estimate the temperature dependent thermal properties of the APC-2 composite using a inverse parameter estimation technique. The present inverse method features the estimation of the thermal conductivity and the volumetric heat capacity, which are dependent on the temperature inside the composite. Furthermore, the thermal conductivity is directionally dependent because of the aniosotropy of the composite. An on-line temperature measurement system with a suitable method of heating is built. A composite slab is fabricated using thermoplastic prepreg for the investigation. The corresponding computer code for evaluating the thermal properties inversely using the temperature reading transmitted from the measurement system is developed. The parameterized form is used for the rapid and stable estimation. The modified Newtons method is adopted for the solution technique of the inverse analysis. The estimated results are compared with the measured data from a previous study for the verification.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.453-458
• /
• 2001

Analysis of radiation heating system for producing 60" size PDP panels was carried out using $RADCAD^{TM}$ software. Optimum arrangement of infrared heating elements was found to obtain uniform temperature distribution in PDP panel during heating. Heating capacity of each heater was determined to obtain an appropriate maximum panel temperature. Parametric study to find the effect of design parameters such as the thermophysical and optical properties of glass and cooling system was carried out. As a reference system, about 35 kW heating capacity was chosen to obtain about 800 K maximum panel temperature after 30 minute heating. The maximum temperature difference in panel was below 20 K. The maximum/minimum and its difference in the panel were very sensitive to the variation of the emissivity of glass and cooling block.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.3
• /
• pp.349-356
• /
• 1986

For the extension of application in flash method measuring the thermophysical properties of materials, the heat diffusion equation with the heat transfer loss from front, rear, and circumferential surfaces of two layer cylinderical sample is mathematically analyzed by means of Green's function for axially symmetric pulse heating on the front of samples. The solutions are applied to determine the unknown thermal diffusivity of the two materials and analyzed the measurement error due to heat loss and finite pulse time effects.

• Journal of computational fluids engineering
• /
• v.6 no.1
• /
• pp.47-55
• /
• 2001

The transient laminar reacting flows around fuel droplet have been numerically analyzed. The physical models used in this study can account for the variable thermophysical properties and the chemistry is represent by the one-step global reaction model. The present study is focused on the vaporization and ignition characteristics, flame structure including wake flame, transition flame and envelope flame, and interaction between droplets. Special emphasis is given to the triple flame structure and flame stabilization.

• 한국연소학회:학술대회논문집
• /
• 2004.06a
• /
• pp.89-92
• /
• 2004

This work describes a model development and numerical simulation of detailed combustion mechanisms of RDX/GAP/BTIN propellants. The analysis is based on the conservation equations of mass, energy, and species concentrations for both the condensed and gas phases, and takes into account finite-rate chemical kinetics and variable thermophysical properties. The model has been applied to study the combustion wave structures and burning characteristics of RDX/GAP/BTIN propellants over a broad range of pressures. Reasonably good agreement is achieved between the calculated and measured burning rate at atmospheric pressure. But the model calculation does not result in dark zone experimentally observed.