• Korean Chemical Engineering Research
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• v.53 no.6
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• pp.770-775
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• 2015

Adsorption of Congo Red (CR) from dye-containing effluents using modified bentonite (MB) has been investigated here. Isothermal studies were conducted to ascertain maximum adsorption capacity of the adsorbent. MB exhibited superior adsorption capacity compared to other low-cost adsorbents. Experimental data fitted the Langmuir isotherm better, indicating monolayer coverage of CR on MB. The feasibility of the process was measured in terms of separation factor $R_L$. The values of Gibbs free energy, entropy and enthalpy were calculated from the thermodynamics of the process. Adsorption was feasible and spontaneous, being endothermic. Analytical techniques including SEM, EDS, FTIR and XRD were applied to characterize MB and also to provide conclusive proof of the accumulation of CR on to MB.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.743-748
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• 2013

The temperature dependence of the partition coefficients of a neuropeptide, substance P (SP), in isotropic acidic bicelles was investigated by using a pulsed field gradient nuclear magnetic resonance diffusion technique. The addition of negatively charged dimyristoylphosphatidylserine to the neutral bicelle changed the SP partitioning a little, which implies that the hydrophobic interaction between the hydrophobic residues of SP and the acyl chains of lipid molecules is the major interaction while the electrostatic interaction is minor in SP binding in a lipid membrane. From the temperature dependence of the partition coefficients, thermodynamic functions were calculated. The partitioning of SP into the acidic bicelles is enthalpy-driven, as it is for small unilamellar vesicles and dodecylphosphocholine micelles, while peptide partitioning into a large unilamellar vesicle is entropy-driven. This may mean that the size of lipid membranes is a more important factor for peptide binding than the surface curvature and surface charge density.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1605-1612
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• 2002

Thermodynamic performance analysis has been carried out for a hybrid electric power generation system combining a gas turbine and a solid oxide fuel cell and operating at over-atmospheric pressure. Performance characteristics with respect to main design parameters such as maximum temperature and pressure ratio are examined in detail. Effects of other important design parameters are investigated including fuel cell internal parameters such as fuel utilization factor, steam/carbon ratio and current density, and system parameters such as recuperator efficiency and compressor inlet temperature.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.141-147
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• 2011

A two-phase numerical model for plate-fin heat exchangers with plain fins and wave fins is studied incorporating the thermodynamic properties and the characteristics of fluid flow. The numerical simulations for the two fins in cryogenic conditions are earned out by employing a homogenous two-phase flow model with the CFD code ANSYS CFX. The heat transfer coefficients and the friction factor for nitrogen saturated vapor condensation process inside two types of plate fin heat exchanger are evaluated including the effects of saturation temperature (pressure), mass flow rate and inlet vapor quantity. The convective heat transfer coefficients and friction factors will be used for design of plate-fin type heat exchangers operating under cryogenic conditions.

• Korean Journal of Materials Research
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• v.16 no.1
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• pp.50-57
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• 2006

Phase mixtures of Titanium boride, nitride, and carbide powder were produced by the reduction of a mixture of titanium and boron oxides with carbon via a gas-solid phase reaction. Boron oxides produce a vapour phase or decompose to a metal sub-oxide gaseous species when reduced at elevated temperature. The mechanism of BO sub-oxide gas formation from $B_2O_3$ and its subsequent reduction to titanium diboride for the production of uniform size hexagonal platelets is explained. These gaseous phases are critical for the formation of boride, nitride and carbide ceramics. For the production of ceramic phase composite microstructures, the nitrogen partial pressure was the most critical factor. Some calculated equilibrium phase fields has been verified experimentally. The theoretical approach therefore identifies conditions for the formation of phase mixtures. The thermodynamic and kinetic factors that govern the phase constituents are also discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.11
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• pp.1079-1088
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• 2001

A dynamic simulation model was developed to analyse the transient characteristics of a multi-inverter heat pump. The programs included a basic air conditioning system such as a evaporator, condenser, compressor, linear electronic expansion valve (LEV) and by-pass circuit. The theoretical model was derived from mass conservation and energy conservation equations to predict the performance of the multi-inverter heat pump at various operating conditions. Calculated results were compared with the values obtained from the experiments at different operation frequencies of compressor, area of the LEV and configuration of indoor units operation. The results of the simulation model showed a good agreement with the experimental ones, so that the model could be used as an efficient tool for thermodynamic design and control factor design of air-conditioners.

• Bulletin of the Korean Chemical Society
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• v.18 no.5
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• pp.478-484
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• 1997

In a recent paper[Bull. Kor. Chem. Soc. 17, 735 (1996)] we reported results of molecular dynamic (MD) simulations for the thermodynamic and structural properties of liquid n-alkanes, from n-butane to n-heptadecane, using three different models. Two of the three classes of models are collapsed atomic models while the third class is an atomistically detailed model. In the present paper we present results of MD simulations for the dynamic properties of liquid n-alkanes using the same models. The agreement of two self-diffusion coefficients of liquid n-alkanes calculated from the mean square displacements (MSD) via the Einstein equation and the velocity auto-correlation (VAC) functions via the Green-Kubo relation is excellent. The viscosities of n-butane to n-nonane calculated from the stress auto-correlation (SAC) functions and the thermal conductivities of n-pentane to n-decane calculated from the heat-flux auto-correlation (HFAC) functions via the Green-Kubo relations are smaller than the experimental values by approximately a factor of 2 and 4, respectively.

• Progress in Superconductivity and Cryogenics
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• v.8 no.4
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• pp.34-38
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• 2006

Cycle analysis was performed in order to find the optimum design point of the LNG Boil-off gas re-liquefaction system. Thermodynamic analysis revealed the system could be defined by three state variables. Thus the system performance could be described by the three cold endpoint temperatures of the three-pass heat exchanger. This enabled us to investigate the cycle performance in terms of the heat exchanger parameters. To get access to the cycle states of higher system performances, larger heat exchangers were found necessary. Also the thermal pinch in cryogenic heat exchangers was found to act as a limiting factor to the system performance.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1839-1844
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• 2012

We have investigated binding between wild-type and mutant Heat Shock Factor (HSF) DNA binding domains (DBDs) with 17-bp HSE containing a central 5'-NGAAN-3' element by equilibrium analytical ultracentrifugation using multi-wavelength technique. Our results indicate that R102 plays critical role in HSE recognition and the interactions are characterized by substantial negative changes of enthalpy (${\Delta}H^0_{\theta}=-9.90{\pm}1.13kcal\;mol^{-1}$) and entropy (${\Delta}S^0_{\theta}=-12.46{\pm}3.77cal\;mol^{-1}K^{-1}$) with free energy change, ${\Delta}G^0_{\theta}$ of $-6.15{\pm}0.03kcal\;mol^{-1}$. N105 plays minor role in the HSE interactions with ${\Delta}H^0_{\theta}$ of $-2.54{\pm}1.65kcal\;mol^{-1}$, ${\Delta}S^0_{\theta}$ of $19.28{\pm}5.50cal\;mol^{-1}K^{-1}$ and ${\Delta}G^0_{\theta}$ of $-8.35{\pm}0.05kcal\;mol^{-1}$, which are similar to those observed for wild-type DBD:HSE interactions (${\Delta}H^0_{\theta}=-3.31{\pm}1.86kcal\;mol^{-1}$, ${\Delta}S^0_{\theta}=17.38{\pm}6.20cal\;mol^{-1}K^{-1}$ and ${\Delta}G^0_{\theta}=-8.55{\pm}0.06kcal\;mol^{-1}$) indicating higher entropy contribution for both wild-type and N105A DBD bindings to the HSE.

• Fire Science and Engineering
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• v.17 no.2
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• pp.43-49
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• 2003

For the inert gases of Ar, $N_2$and $CO_2$, the empirical equations of the gas mixture were correlated in terms of saturated pressure, density and viscosity. They were obtained by regression analysis based on the mixing rule. The empirical equation of saturated pressure was assumed as the first order function of temperature. The empirical form of density was expressed as compressibility factor and saturated pressure while the empirical equation of viscosity was formulated as a power function of temperature. This empirical equations of the physical properties were obtained in the composition of Ar, $N_2$and $CO_2$, 40/50/10(mol. %).