• Journal of Energy Engineering
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• v.18 no.4
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• pp.239-246
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• 2009

A fundamental investigation has been conducted on the combustion of single particle of a sub-bituminous coal char burning at different temperatures and residence times. The lab-scale test setup consisted of a drop tube furnace where gas temperatures varied from $900^{\circ}C$ to $1400^{\circ}C$. A calibrated two color pyrometer, mounted on the top of the furnace, provided temperature profiles of luminous particle during a char oxidation. An amount of char mass reacted during the reaction is measured with thermogravimetry analyzer by using an ash tracer method. As a result, mass and area reactivity as well as reaction rate coefficients are determined for the char burning at atmospheric pressure condition.

• Fire Science and Engineering
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• v.14 no.3
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• pp.6-12
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• 2000

This paper describes the smoke movement of a fire field model based on a self-developed SMEP(Smoke Movement Estimating Program) code to the simulation of fire induced flows in the two types of compartment space containing the radiation effect under smoke movement in room fire. The SMEP using PISO algorithm solves conservation equations for mass, momentum, energy and species, together with those for the modified k-$\varepsilon $ turbulence model with buoyancy term. Also it solves the radiation equation using the discrete ordinates method. The result of the calculated smoke temperature containing radiation effect has shown reasonable agreement compared with the experimental data. On the other hand, a difference of a lot was found between the temperature predicted by the SMEP with only convection effect and obtained by the experimental result. This seems to come from the radiation effect of $H_2$O and $CO_2$ gas under smoke productions. Thus, the consideration of the radiation effect under smoke in fire may be necessary in order to produce more realistic result.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.86-92
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• 2017

A process, which converts carbon dioxide contained in the flue gas of coal-fired power plants to sodium bicarbonate, was studied experimentally and numerically. In this process, the carbon dioxide reacts with sodium hydroxide which is produced through saline water electrolysis. A bench scale reactor system was prepared for experiments of this process and numerical process modeling was performed for the bench scale reactor system. Comparing the process modeling results with the experimental data, responsibility of the process modeling was confirmed. Using this model, commercial scale process was simulated. Mass and energy balance of this process were calculated. Temperature profile in the reactor and carbon dioxide removal rate were obtained.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2007-2009
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• 1999

In this paper, discharge domain of wire-cylindrical plasma reactor was separated from a gas flow duct to avoid unstable discharge by aerosol particle deposited on discharge electrode and grounded electrode. The NOx, SOx removal was experimentally investigated by a reaction induced to ammonium nitrate, ammonium sulfate using a low price of aqueous NaOH solution and a small quantity of ammonia. Volume percentage of aqueous NaOH solution used was 20% and $N_2$ flow rate was 2.5[$\ell$/min] for bubbling aqueous NaOH solution. Ammonia gas(14.82%) balanced by argon was diluted by air and was introduced to a main simulated flue gas duct through $NH_3$ injection system which was in downstream of reactor. The $NH_3$ molecular ratio[MR] was determined based on $NH_3$ to [NO+$SO_2$]. MR is 1.5. The NOx removal rates increased in the order of DC, AC and pulse, but SOx removal rates was not significantly effected by source of electricity. The NOx removal rate slightly decreased with increasing initial concentration but SOx removal rate was not significantly effect by initial concentration, and NOx, SOx removal rates decreased with increasing gas flow rate.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.289-296
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• 2004

The present study has been performed to investigate the influences of rectangular fins on heat transfer in an impingement/effusion cooling system with crossflow. To simulate the impingement/effusion cooling system with initial crossflow, two perforated plates are placed in parallel and staggered arrangements with a gap distance of 2 times of the hole diameter. The crossflow passes between the plates, and various rectangular fins are installed on the plates. Reynolds number based on the hole diameter is fixed to 10,000 and the flow rate of crossflow is changed from 0.5 to 1.5 times of that of the impinging jet. A naphthalene sublimation method is used to obtain the heat/mass transfer coefficients on the effusion plate. Also to analyze the flow characteristics, a numerical calculation is performed. When rectangular fins are installed, the flow and heat transfer pattern is changed greatly from case without fins. In the injection hole region, the jet impinges on effusion plate without deflection and wall jet spreads symmetrically. In the effusion region, the crossflow accelerates due to the decrease of cross-sectional area in the channel. Local heat/mass transfer coefficients are enhanced significantly compared to case without fins. As the blowing ratio increases, the effect of fins against the crossflow becomes more significant and then the higher average heat/mass transfer coefficients are obtained than the case without fins.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.76-82
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• 2016

Recently, environmental sustainability of the transitional explosives and propellants is an issue of growing importance in energetic materials. For examples, ammonium perchlorate(AP) as an solid propellants oxidizer could create a poisonous gas and atmospheric pollutions, such as HCl. Among the several oxidizers, hydrazinium nitroformate(HNF) is an effective candidate substance for eco-friendly oxidizer, which has high density, pressure index, and less smog generating property during combustion for the thrust control system. This study was controlled the size distribution and shapes through various conditions. Length and diameter ratio(L/D) of crystals has below 1 : 3, and the particle size was two types of $200{\mu}m$ and $50{\mu}m$.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.81-89
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• 2018

In this study, the operating characteristics of a small-scale pulse detonation engine (PDE) were investigated experimentally for application as a small thruster and an igniter. The PDE was constructed using commercial gas tubes with an inner diameter of 4.22 mm. The operating and detonation propagation characteristics of the PDE were investigated over the ranges of equivalence ratios and operating frequencies. Measured detonation speed was close to 10% of the theoretical CJ values at 1 Hz and 5 Hz conditions. However, unstable propagation characteristics were shown at 20 Hz and lean conditions, where the velocity deficit was increased by 20~62%.

• Clean Technology
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• v.14 no.4
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• pp.287-292
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• 2008

In this study, computer simulation works have been performed for the capture process of the $CO_2$ and $H_{2}S$ gases contained in the effluent stream using methanol aqueous solution. In order to increase the solubilities of the $CO_2$ and $H_{2}S$ in the methanol aqueous stream, the operating pressure of the absorber was raised to 30 bar and the feeding temperature of the solvent was lowered to $-20^{\circ}C$ by using refrigeration cycle. NRTL liquid activity coefficient model was used to estimate the liquid phase nonidealities for methanol and water. Soave-Redlich-Kwong equation of state was used for the vapor phase nonidealities. Henry's law option was also used to calculate the solubilities of the supercritical noncondensible gases into the methanol aqueous solvent stream.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.407-416
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• 2007

Fuel spray nozzle has a critical effect on combustion characteristics. Mass flow rate and SMD(sauter mean diameter) were selected as design variables by using the experiment data of various types of duplex fuel nozzles for the swirl atomizers. The sensitivity of each design variable on the mass flow rate and SMD was analyzed and the uniformity of mass flow rate was investigated through the shape optimization of duel-orifice-type swirl atomizers. The design variables that have a little effect on the optimum design were excluded using the DOE(design of experiments) method, which enabled the optimization of sensitive design variables on mass flow rate and limit tolerance. The SMD of the research spray nozzle that was used in this study was found to be most similar to that of the calculation results using the Jasuja's SMD relationship. This study showed the specific characteristics of duel orifice type swirl atomizers and the optimization of these kinds of nozzle. This study provided the optimization design of mass flow rate and its allowable tolerance.

• Fire Science and Engineering
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• v.33 no.5
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• pp.13-18
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• 2019

In this study, the soot formation characteristics of Jet-A1 liquid fuel droplet flames were investigated by measuring the soot concentration under atmospheric conditions similar to the working environment of the Korea Space Launch Vehicle (KSLV) To obtain the desired atmospheric conditions, the oxygen concentration in the combustion chamber was maintained at 30% and the pressure was varied between 0.1 and 0.06 MPa. The full-field light extinction technique was used to measure the concentration of soot particles generated by applying the identical to 2-mm-diameter Jet-A1 fuel droplets. The soot concentration of the Jet-A1 droplet flames was the highest in the nitrogen-substituted atmosphere and the lowest in the carbon dioxide-substituted atmosphere, despite the pressure. the pressure was decreased the measured soot concentrations reduced as a function of Pⁿ.