• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.16 no.2
• /
• pp.1-6
• /
• 2020

This work experimentally explored the influence of nano-fouling on CHF, flow boiling heat transfer coefficient, contact angle, and surface roughness. In this study, the flow velocity conditions are established at 0.5, 1.0, and 1.5 m/s. Also, the nanoparticles of oxidized MWCNT were deposited on a heat transfer surface for 0, 120, 180, and 240 sec. As the results, it was found that CHF and superheated temperature were increased in case of nano fouling on the heat transfer surface in oxidized MWCNT fluid. Also, the contact angle and surface roughness decreased when flow velocity and nano coating increased.

• Journal of Advanced Marine Engineering and Technology
• /
• v.29 no.7
• /
• pp.729-735
• /
• 2005

This paper has dealt with the characteristics of mass and heat transfer of vertical flat plate with free convection. The theory of similarity transformations applied to the momentum and energy equations for free convection. To derive the similarity equation of mass transfer. the equation for conservation of species was added to the continuity. momentum and energy equations. The momentum, energy and species equations set numerically to obtain the velocity, temperature and mass fraction of species as dimensionless. For cases where momentum transport dominates, the thermal boundary layers are shorter than the momentum boundary layer. The relationships between momentum, energy and species were clarified from this study.

• Nuclear Engineering and Technology
• /
• v.30 no.1
• /
• pp.26-39
• /
• 1998

The containment pressure and temperature transient analysis computer code CONTEMPT4/MOD5 is modified to incorporate the passive containment cooling models. The correlations are selected from the existing experimental heat transfer correlations to model the natural and mixed convection in annular space between the containment shell and the shield building. The evaporative heat transfer of the water film on the outer shell of the containment is modeled using the correlations derived from the analogy between the heat and mass transfer. The modified code is applied to the Ap600 containment transient analysis for the model verification and the results are compared to the results of GOTHIC calculation done by Westinghouse. Also, d series of parametric sensitivity studies of heat transfer correlations, water film ratio and delay time of the wet cooling on the containment peak pressure and temperature following LOCA are performed for the containment of 1000MWe passive plant, KP1000.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.8
• /
• pp.2599-2606
• /
• 2011

The fluorescence of ethidium bound to DNA, poly[d(A-T)$_2$], and poly[d(G-C)$_2$] at a [ethidium]/[DNA] ratio of 0.005 was quenched by porphyrins when both ethidium and the porphyrins simultaneously bound to the same polynucleotide. The quenching was tested using the "inner sphere" and the "Forster resonance energy transfer" (FRET) models, with the latter found to contribute, at least in part, to the quenching. Meso-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP) exhibited a higher quenching and FRET efficiency than cis-bis(N-methylpyridinium-4-yl)porphyrin (BMPyP) for all of the tested DNA and polynucleotides, demonstrating that energy transfer efficiency is affected by the number of positive charges of porphyrins.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.3
• /
• pp.664-675
• /
• 1990

In this study, the performance test and heat transfer experiment for a 4 cylinder and 4-cycle turbocharged gasoline engine were carried out in order to measure the heat transfer coefficient at the inner wall of the combustion chamber. From the result of heat transfer experiment, the energy balance of the fuel energy and the overall efficiency of the turbocharger were calculated, The variation of them was investigated as well with the engine operation conditions.

• The Bulletin of The Korean Astronomical Society
• /
• v.43 no.2
• /
• pp.52.2-52.2
• /
• 2018

The shape of a galaxy's spectral energy distribution ranging from ultraviolet (UV) to infrared (IR) wavelengths provides crucial information about the underlying stellar populations, metal contents, and star-formation history. Therefore, analysis of the SED is the main means through which astronomers study distant galaxies. However, interstellar dust absorbs and scatters UV and optical light, re-emitting the absorbed energy in the mid-IR and Far-IR. I present the updated 3D Monte-Carlo radaitive transfer code MoCafe to compute the radiative transfer of stellar, dust emission through a dusty medium. The code calculates the emission expected from dust not only in pure thermal equilibrium state but also in non-thermal equilibrium state. The stochastic heating of very small dust grains and/or PAHs is calculated by solving the transition probability matrix equation between different vibrational, internal energy states. The calculation of stochastic heating is computationally expensive. A pilot study of radiative transfer models of SEDs in clumpy (turbulent), galactic environments, which has been successfully used to understand the Calzetti attenuation curves in Seon & Draine (2016), is also presented.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.5
• /
• pp.1561-1565
• /
• 2012

The structures of the four lowest alanine conformers, along with their radical cations and the effect of ionization on the intramolecular proton transfer process, are studied using the density functional theory and MP2 method. The energy order of the radical cations of alanine differs from that of the corresponding neutral conformers due to changes in the basicity of the $NH_2$ group upon ionization. Ionization favors the intramolecular proton transfer process, leading to a proton-transferred radical-cation structure, [$NH_3{^+}-CHCH_3-COO{\bullet}$], which contrasts with the fact that a proton-transferred zwitterionic conformer is not stable for a neutral alanine in the gas phase. The energy barrier during the proton transfer process is calculated to be about 6 kcal/mol.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.2319-2324
• /
• 2003

This paper addresses the optimal design of dividing wall distillation column which is rapidly applied in a variety of chemical processes over recent several years because of its high energy saving efficiency. A general dividing wall column model which can cope with the heat transfer through the dividing wall is developed using rigorous computer simulation. Based on the simulation model, the effects of the internal recycle flow distribution around the dividing wall and the heat transfer across the dividing wall on overall system performance are investigated. An improved method is suggested to utilize the heat transfer through the wall to optimal column design. The suggested method is compared with the existing method via. simulation study and shows more improved energy saving result. Several control strategies for the divided wall column are tested and the optimal control strategy is propose

• Solar Energy
• /
• v.9 no.3
• /
• pp.64-72
• /
• 1989

In this study, the computer simulation for the heat transfer in pulse combustion water heater is performed. The attention is focused to the effects of the installation of corebuster in the flue tube on heat transfer. The energy equations are established for both wall and gas side in the combustion chamber, flue way, exhaust chamber and muffler, and the numerical calculation is executed. Zone method takes longer computer calculation time compared with semi-zone method. Semi-zone method is chosen for numerical calculation. As a result of this study, it is found that the installation of the core buster in flue tube increases total heat transfer. It is also found that the total heat transfer is increased with the increasing of the ratio of the cross section area of corebuster to that of the flue tube. However, the heat transfer effect is negligible for the area ratio above 0.5.

• 한국태양에너지학회:학술대회논문집
• /
• 2009.04a
• /
• pp.155-161
• /
• 2009

Desiccant systems have been proposed as energy saving alternatives to vapor compression air conditioning for handling the latent load. Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration. The liquid desiccants contact the gas inside the packed column and the heat transfer and mass transfer will occur. This proposal is try study the mass transfer and heat transfer inside the packed column of dehumidifier and regenerator systems. And later on, the rates of dehumidification and regeneration that were affected by desiccant flow rates, air temperature and humidity, and desiccant temperature and all that variation will influence the performance of the systems.