• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.324-329
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• 1999

In this work, high pressure binary phase equilibria data of carbon dioxide and isopropyl alcohol were obtained by experiment. A static type experimental apparatus was made to measure temperature, pressure and phase equilibria composition. The experimental apparatus was tested by comparing the measured phase equilibria data of the carbon dioxide-isopropyl alcohol system at $80^{\circ}C$ with those of Rodosz. The binary phase behavior data of carbon dioxide-isopropyl alcohol system were measured in range of 41 to 133 bar and at temperatures of 40, 60, 80, 100 and $120^{\circ}C$. The solubility of isopropyl alcohol increases as the temperatures increases at constant pressure. Also, these carbon dioxide-alcohol solute system have critical-mixture curves that exhibit maxima in pressure at temperatures between the critical temperatures of carbon dioxide and isopropyl alcohol. The experimental data obtained in this study were modeled using the statistical associating fluid theory(SAFT) equation of state. A good fit of the data was obtained with SAFT using two adjustable parameters for the carbon dioxide-isopropyl alcohol system.

• Journal of Drive and Control
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• v.15 no.4
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• pp.1-10
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• 2018

Spool displacement of a direction control valve is the standard signal to measure the bandwidth frequency of the direction control valve. When the spool displacement signal is not available, it is suggested in this study to use the metering hydraulic line as an alternative way to measure - 90 degree phase bandwidth frequency of the hydraulic direction control valve. Dynamics of the hydraulic line is composed of inertia, capacitance, and friction effects. The effect of oil inertia is dominant in common hydraulic line dynamics and the line dynamics is close to a derivative action in a range of high frequency; such as a range of bandwidth frequency of common directional control valves. Phase difference between spool displacement and line load pressure is nearly constant as a valve close to 90 degree. If phase difference is compensated from the phase between valve input and pressure, compensated phase may be almost same as the phase of spool displacement that is a standard signal to measure phase bandwidth frequency of the directional control valve. A series of experiments were conducted to examine the possibility of using line pressure in to measure phase bandwidth frequency of a directional control valve. Phase bandwidth frequency could be measured with relatively high precision based on metering hydraulic line technique and it reveals consistent results even when valve input, oil temperature, and supply pressure change.

• Journal of ILASS-Korea
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• v.21 no.4
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• pp.184-194
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• 2016

Many industrial processes require reliable temperature measurements in harsh environments with high temperature, dust, humidity, and pressure. However, commercially-available conventional temperature measurement devices are not suitable for use in such conditions. This study thus proposes a reliable, durable two-color radiation thermometer (RT) for harsh environments that was developed by selecting the appropriate components, designing a suitable mechanical structure, and compensating environmental factors such as absorption by particles and gases. The two-color RT has a simple, compactly-designed probe with a well-structured data acquisition system combined with efficient LabVIEW-based code. As a result, the RT can measure the temperature in real time, ranging from 300 to $900^{\circ}C$ in extremely harsh environments, such as that above the burden zone of a blast furnace. The error in the temperature measurements taken with the proposed two-color RT compared to that obtained using K-type thermocouple readouts was within 6.1 to $1.4^{\circ}C$ at a temperature range from 200 to $700^{\circ}C$. The effects of absorption by gases including $CO_2$, CO and $H_2O$ and the scattering by fine particles were calculated to find the transmittance of the two wavelength bands of operation through the path between the measured burden surface and the two-color probe. This method is applied to determine the transmittance of the short and long wavelength bands to be 0.31 and 0.51, respectively. Accordingly, the signals that were measured were corrected, and the true burden surface temperature was calculated. The proposed two-color RT and the correction method can be applied to measure temperatures in harsh environments where light-absorbing gases and scattering particles exist and optical components can be contaminated.

• Journal of Veterinary Clinics
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• v.17 no.1
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• pp.138-144
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• 2000

The studies were carried out to investigate the effects of esophageal thermal tube for rewarming in the hypothermia in rabbits. Thiry-one rabbits were continuously cooled with femoral arterio-venous bypass circulation to 25.0${\pm}$0.3$^{\circ}C$(profound hypothermia) of rectal temperature. The experiment was consisted with 3 esophageal thermal tube groups perfused with circulation water at 38${\pm}$1$^{\circ}C$(low, n=12), 42${\pm}$1$^{\circ}C$(medium, n=12), and 45${\pm}$1$^{\circ}C$(high, n=7). Esophageal thermla tube specially constructed double-lumen esophageal tube with circulating warm water at respective htermal grade. With this device, rewarming of the rabbits as follows; High-esophageal thermal tube group(45${\pm}$1$^{\circ}C$)had a more effect on mean arterial pressure(MAP), heart rate(HR), esophageal temperature, and rectal temperature than others groups, but the circulation water at 45$\pm$1$^{\circ}C$ may cause thermal injuries in the esophagus because esophageal temperature increased to 41.1$^{\circ}C$. Medium-esophageal thermal tube group(42${\pm}$1$^{\circ}C$) had a more effect on RR than others groups, but the circulation water at 42${\pm}$1$^{\circ}C$ may also cause thermal injuries in the esophagus if the temperature exceeds 42$^{\circ}C$ for an extended period of time because its esophageal temperature increased to 39.4$^{\circ}C$. Low-esophageal thermal tube group(38${\pm}$1$^{\circ}C$) had a more effect on MAP, RR, and esophageal temperature than others groups. In conclusion, rewarming of the central core in the treatment of profound hypothermia using the esophageal thermal tube perfused with circulation water at 38${\pm}$1$^{\circ}C$ appears to be a ideal alternative safety zone of the temperature of circulation water avoiding thermal injury in esophagus causing by out of order or lower precise thermostat of water bath to that of others groups.

• Tribology and Lubricants
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• v.33 no.5
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• pp.207-213
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• 2017

In sliding bearings, viscous friction due to high shear acting on the bearing surface raises the oil temperature. One of the mechanisms responsible for generating the load-carrying capacity in parallel surfaces is known as the viscosity wedge effect. In this paper, we investigate the effect of film-temperature boundary conditions on the thermohydrodynamic (THD) lubrication of parallel slider bearings. For this purpose, the continuity equation, Navier-Stokes equation, and the energy equation with temperature-viscosity-density relations are numerically analyzed using the commercial computational fluid dynamics (CFD) code FLUENT. Two different film-temperature boundary conditions are adopted to investigate the pressure generation mechanism. The temperature and viscosity distributions in the film thickness and flow directions were obtained, and the factors related to the pressure generation in the equation of motion were examined in detail. It was confirmed that the temperature gradients in the film and flow directions contribute heavily to the thermal wedge effect, due to which parallel slider bearing can not only support a considerable load but also reduce the frictional force, and its effect is significantly changed with the film-temperature boundary conditions. The present results can be used as basic data for THD analysis of surface-textured sliding bearings; however, further studies on various film-temperature boundary conditions are required.

• Korean Journal of Food Science and Technology
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• v.33 no.4
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• pp.444-450
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• 2001

Kochujang, fermented hot pepper paste, was treated with combined high hydrostatic pressure and heat. Viable cell counts and chemical compositions of Kochujang were determined as a function of high pressure processing conditions such as temperature, pressure and time, and during storage for 120 days at $37^{\circ}C$. Viable cell counts were decreased with the increase of temperature, pressure and time. Viable cell counts in the treated Kochujang were decreased up to $0{\sim}3$ log cycle with the temperature of $49{\sim}73^{\circ}C$, $0{\sim}3$ log cycle with the pressure of $380{\sim}680\;MPa$, and $2{\sim}5$ log cycle with the time of $10{\sim}70\;min$, compared with the untreated. pH, titratable acidity, amino nitrogen, reducing sugar and ethanol content in the treated Kochujang were comparable to the untreated regardless of the treatment condition. Hunter L, a and b values in the treated Kochujang were higher than those of the untreated. Viable cell counts were decreased with the increase of the storage period at $37^{\circ}C$. Viable cell counts in Kochujang treated at 380 MPa/30 min were decreased up to 2 log cycle from $1.8{\times}10^6\;to\;1.94{\times}10^4\;CFU/g$ after 120 days of storage, while those at 680 MPa/70 min were not detected after 60 days from the initial stage of $4.00{\times}10^1\;CFU/g$. pH, amino nitrogen and ethanol content were decreased, and titratable acidity were increased significantly as the increase of the storage period. Hunter L, a and b values also decreased significantly. The changes in physicochemical properties of Kochujang treated at 680 MPa/70 min were greater than those at 380 MPa/30 min.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.395-406
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• 2023

The first technological advance to improve the output and efficiency of the latest steam turbines operating in co-generation plants in Korea can be said to be progress in the field of materials that can use high-temperature, high-pressures steam. As a result of design efforts to improve the internal efficiency of steam turbines along with the development of materials, only a few manufacturers of steam turbine have produced high efficiency steam turbines. The internal efficiency of a steam turbine on the steam path operating for a long period of time is gradually lost owing to the limit of mechanical life, and efficiency and output decrease. Therefore, this study aims to develop a model that can analyze the steam flow path performance of HP (High Pressure) and IP (Intermediate Pressure) steam turbine for a co-generation plant using a commercial program and propose a performance calculation method. Owing to the complex performance calculation method of steam turbines, major variables are presented to serve as practically useful references for steam turbine practitioners. In addition, the thermal dynamic analysis(such as heat balance diagram calculation) and the the thermal dynamic calculation required for steam turbine performance calculation and the suitability of the steam turbine performance calculation results were compared with the performance test results.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.492-498
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• 2012

In this study, hydrodynamics such as solid circulation rate and voidage in the desulfurizer and the reaction characteristics of Zn-based solid sorbents were investigated using lab-scale high pressure and high temperature desulfurization process. The continuous HGD (Hot Gas Desulfurization) process consist of a fast fluidized bed type desulfurizer (6.2 m tall pipe of 0.015 m i.d), a bubbling fluidized bed type regenerator (1.6 m tall bed of 0.053 m i.d), a loop-seal and the pressure control valves. The solid circulation rate was measured by varying the slide-gate opening positions, the gas velocities and temperatures of the desulfurizer and the voidage in the desulfurizer was derived by the same way. At the same gas velocities and the same opening positions of the slide gate, the solid circulation rate, which was similar at the temperature of $300^{\circ}C$ and $550^{\circ}C$, was low at those temperatures compared with a room temperature. The voidage in the desulfurizer showed a fast fluidized bed type when the opening positions of the slide gate were 10~20% while that showed a turbulent fluidized bed type when those of slide gate were 30~40%. The reaction characteristics of Zn-based solid sorbent were investigated by different desulfurization temperatures at 20 atm in the continuous operation. The $H_2S$ removal efficiency tended to decrease below the desulfurization temperature of $450^{\circ}C$. Thus, the 10 hour continuous operation has been performed at the desulfurization temperature of $500^{\circ}C$ in order to maintain the high $H_2S$ removal efficiency. During 10 hour continuous operation, the $H_2S$ removal efficiency was above 99.99% because the $H_2S$ concentration after desulfurization was not detected at the inlet $H_2S$ concentration of 5,000 ppmv condition using UV analyzers (Radas2) and the detector tube (GASTEC) which lower detection limit is 1 ppmv.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.684-689
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• 2012

Poly(acrylic acid) (PAA) microspheres is one of the widely-used polymeric materials for the bio-field application and the electric materials. For the synthesis of PAA microspheres, the polymerization technique using surfactants is applied. After the synthesis, the purification and separation processes are required for the removal of surfactant. When general organic solvents were used, many problems, such as huge amount of waste solvent, additional separation processes, and the possibility of residual media, were occurred. Thus, High-pressure Soxhlet extraction using liquid $CO_2$ was developed to solve these problems. In this study, High-pressure Soxhlet extraction of the synthesized PAA microspheres using liquid $CO_2$ was conducted for the removal of Monasil PCA which is used for the dispersion polymerization of acrylic acid in compressed liquid Dimethyl ether (DME). The morphology of the extracted PAA particles was checked by field emission scanning electron microscopy (FE-SEM) and the residual concentration of Monasil PCA was analyzed by inductively coupled plasma - Optical Emission Spectrometer (ICP-OES). For studying the effect of the solvent effect, Soxhlet extraction was conducted using n-hexane, liquid DME, and liquid $CO_2$. In case of n-hexane, some extracted PAA microspheres were produced. However, deformation was also occurred due to the high thermal energy of n-hexane vapor. Liquid DME could not remove Monasil PCA. When using liquid $CO_2$, the extracted PAA microspheres which were free for the residual solvent were produced without deformation. For finding the optimum operating condition, high-pressure Soxhlet extraction was conducted for 8 hours with changing the temperature of reboiler and condenser. When the extractor temperature is $19.6{\pm}0.2^{\circ}C$ and the pressure is $51.5{\pm}0.5$ bar, the best removal efficiency was obtained.

• Nuclear Engineering and Technology
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• v.37 no.5
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• pp.457-468
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• 2005

An experimental study on post-CHF heat transfer has been performed with a $3\times3$ rod bundle using a vertical steam-water two-phase flow at low flow conditions. The effects of various parameters on the post-CHF heat transfer are investigated and the reasons for the parametric effects are discussed. As the heat transfer regime changes from CHF to post-CHF, the radial wall temperature distribution is changed depending on the pressure and the mass flux conditions. The superheat of the fluid increases considerably with an increase of the wall temperature (or heat flux) and with a decrease of the mass flux. This implies, indirectly, a strong thermal non-equilibrium at high wall temperature and low mass flux conditions. In order to improve the prediction accuracy of the existing post-CHF correlations, it is necessary to perform more experiments, particularly direct measurement of the vapor superheat, and to modify the correlation by considering a strong thermal non-equilibrium at low flow and low pressure conditions.