• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.11
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• pp.1578-1584
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• 2002

Combustion stability is one of the most important factors that must be considered in burning of heavy fuel oil, especially low-grade oil. This paper describes the combustion characteristics of petrochemical process by- product in the combustion furnace of heavy fuel oil. Main experimental parameters were combustion load, excess 02, fuel preheating temperature and air/fuel ratio. The capacity of CRF(combustion research facility) used in this study was 1.0 ton/hr and the burner is steam jet type suitable far heavy oil combustion and manufactured by UNIGAS in Italy. The fuel used in this experiment were 0.5 B-C, petrochemical process by-product and 3 kinds of 0.5 B-C/process by-product mixtures. The combustion stability was monitored and exhaust gases such as CO, NOx, SOx and particulates were measured with the excess $O_2$ and combustion load. The main purpose of this study is to clarify whether process by-product can be used as a boiler fuel or not in consideration of flame stability and emission properties.

• Journal of the Korean Ceramic Society
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• v.33 no.1
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• pp.17-24
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• 1996

Pb(Mg1/3Nb2/3)O3 powder with high purity chemical homogeniety and reactivity was prepared by solvent eva-poration of common solution. The common solution was fabricated using a Pb(NO3)2 Mg(NO)3 and NB solution which was prepared by dissolving NbC in H2O2 acquous solution. In precusor powder prepared by solvent evaporation method the synthetic temperature of Pb(Mg1/3 Nb2/3)O3 phase was lowered. And the formation of homogeneous Pb(Mg1/3Nb2/3)O3 phase was enhanced but the formation of pyrochlore phase was reduced. The dielectric constant of PMN ceramics from the synthesized powder was found to increase with both sintering temperature and excess MgO and subsequent analysis of the microstructures confirmed that this was due to an increase in grain size. The grain size dependence is explained as a consequence of low-permittivity grain boundaries.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.3 no.3
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• pp.199-208
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• 1974

The effectiveness with which evaporative cooling can be used in Korea was analysed by making use of weather data of 15cities in a past decade. In ASHRAE comfort chart for a still air atmospheric condition was divided into two dimensional array, 14 zones by effective temperature and 10 zones by relative humidity, and all hours of weather condition in those zones were. computed from every 4 hours weather data in a past decade. From this computation obtained were for 15 cities : 1. average annual total hours above $23^{\circ}C$ ET 2. effective temperatures with $5\%$ excess factor, and 3. ratios of all hours in wet (above $25.6^{\circ}C$ WBT), intermediate $(22^{\circ}C\;to\;25.6^{\circ}C\;WBT)$, and dry $(below\;22^{\circ}C\;WBT)$ area to total hours in whole area on comfort chart beyond $23^{\circ}C$ ET to effective temperature of $5\%$ excess factor. It was shown from this computational result that in Korea evaporative cooling was not effective for building and residential comfort air conditioning but could be useful for comfort air conditioning in industry and industrial air conditioning, depending upon the air stream velocity and the type of application.

• Journal of Power System Engineering
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• v.1 no.1
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• pp.51-60
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• 1997

In this paper, we investigated the heating performance and the basic characteristics required for normal combustion of kerosene fan heater. And also the iso-velocity contours and the iso-temperature contours of hot gas discharged from the exit of kerosene fan heater were analyzed. The experiment was carried out with kerosene fan heater attached to the blow-down-type subsonic wind tunnel with a test section of $240mm{\times}240mm{\times}1200mm$. The purpose of this paper was to obtain the basic data for new design from conventional kerosene fan heater. Consequently it was found that (i) the pressure ratio $P_2/P_1$ had a comparatively constant value of 0.844 according to the increase of the revolution of turbo fan, (ii) the primary excess air ratio had a range of $0.84{\sim}1.11$ during normal combustion, and (iii) the heating performance of kerosene fan heater had a range of $1,494{\sim}3,852kcal/hr$.

• Journal of the Korean Chemical Society
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• v.45 no.3
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• pp.201-207
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• 2001

The dielectric relaxation study for aniline-dimethylsulphoxide (DMSO) and aniline-dim.ethylformamide(DMF) has been carried out using the Time domain reflectometry (TDR) technique, at different temperature and concentrations, in the frequency range of 10 MHz to 10 GHz. The dielectric parameters viz. static permittivity, relaxation time, the Kirkwood correlation factor, excess permittivity, excess inverse relaxation time and thermodynamic parameters have been obtained. The calibration method based on least squares fit method has been used. The dielectric parameters show systematic change with temperature and concentrations.

• Journal of the Korean Solar Energy Society
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• v.27 no.1
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• pp.75-81
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• 2007

Steam reforming of methane using Xe-arc solar simulator was studied for the application of concentrated solar energy into chemical reaction. The reactor, a volumetric absorber, consisted of a porous ceramic foam disk coated with commercial reforming catalyst. Operating temperature was in the range of $450\;-\;550^{\circ}C$ and the excess steam ratio to methane was from 3.0 to 5.0. At the steady-state condition, the conversion of methane Increased with temperature in the range of 15 % - 30 % and the experimentally determined conversion was found to be close to theoretical equilibrium conversion. It was also found that the CO selectivity slightly decreased with excess steam ratio. Finally, the conversion of methane decreased significantly with space velocity of reactants.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.412-415
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• 2017

In this study, the decomposition performance of ammonia dinitramide (ADN) based liquid monopropellant was evaluated by using metal supported alumina bead catalyst. Alumina bead was calcined at $1200^{\circ}C$, and Pt and Cu were impregnated on alumina bead by excess water impregnation using a rotary evaporator. The decomposition temperature ($T_{dec}$) of ADN-based liquid monopropellant was measured in a home-made batch reactor. The decomposition temperature of Cu/$Al_2O_3$ catalyst was lower than that of Pt/$Al_2O_3$ catalyst, and $T_{dec}$ was about $130^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.263-263
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• 2013

This work examines the dynamic properties of ice surfaces in vacuum for the temperature range of 140~180 K, which extends over the onset temperatures for ice sublimation and the phase transition from amorphous to crystallization ice. In particular, the study focuses on the transport processes of excess protons and chloride ions in ice and their segregative behavior to the ice surface. These phenomena were studied by conducting experiments with a relatively thick (~100 BL) ice film constructed with a bottom $H_2O$ layer and an upper $D_2O$ layer, with excess hydronium and chloride ions trapped at the $H_2O$/$D_2O$ interface as they were generated by the ionization of hydrogen chloride. The migration of protons, chloride ions, and water molecules to the ice film surface and their H/D exchange reactions were measured as a function of temperature using the methods of low energy sputtering (LES) and Cs+ reactive ion scattering (RIS). Temperature programmed desorption (TPD) experiments monitored the desorption of water and hydrogen chloride from the surface. Our observations indicated that both hydronium and chloride ions migrated from the interfacial layer to segregate to the surface at high temperature. Hydrogen chloride gas desorbs via recombination reaction of hydronium and chloride ions floating on the surface. Surface segregation of these species is driven by thermodynamic potential gradient present near the ice surface, whereas in the bulk, their transport is facilitated by thermal diffusion process. The finding suggests that chlorine activation reactions of hydrogen chloride for polar stratospheric ice particles occur at the surface of ice within a depth of at most a few molecular layers, rather than in the bulk phase.

• Journal of the Korean Society for Heat Treatment
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• v.5 no.4
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• pp.233-239
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• 1992

A study of the precipitation process of Al-Li binary alloy at low ageing temperature has been carried by electrical resistivity measurement. Two types of G.P.zones were formed during ageing at low temperature. G.P. (1) zone and G.P. (2) zone have been formed primarily at ageing temperature below $60^{\circ}C$ and at ageing temperature range of $80^{\circ}C$ to $100^{\circ}C$, respectively. Therefore the precipitation process of Al-Li binary alloy was as follows; G.P.(1) zone ${\rightarrow}$ G.P.(2) zone ${\rightarrow}{\delta}^{\prime}{\rightarrow}{\delta}$ G.P. (1) zone might be affected by excess vacancies, but G.P. (2) zone might be affected by secondary defects. clusters and Li-vacancy pairs. The activation energy for formation of G.P. (2) zone is 0.87eV. It is lower than that of Al-Cu alloy.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.2
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• pp.215-226
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• 2003

Experimental and numerical studies have been done to examine the effects of excess air ratio and tertiary air swirl number on the formation characteristics of NOx in a pilot scale combustor adopting a multi-air staged burner. In numerical calculation the mathematical models for turbulence, radiation and nitric oxide chemistry were taken into account. The radiative transfer equation was solved using the discrete ordinates method with the weighted sum of gray gases model. In the NOx chemistry model, the chemical reaction rates for thermal and prompt NOx were statistically averaged using a probability density function. The results were validated by comparison with measurements. For the experiment, a 0.2 MW pilot multi-staged air burner has been designed and fabricated. Using the numerical simulation developed here, a variation of thermal and prompt NOx formation was predicted by changing the excess air ratio and tertiary air swirl number. As the excess air ratio increased up to 1.9, the formation of the total as well as thermal NOx at exit increased while the prompt NOx decreased. The formation of thermal NOx was more affected by concentration of $O_2$ and $N_2$ than gas temperature. When the tertiary air swirl number increased, the formation of the total as well as the prompt NOx slightly decreased.