• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.238-241
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• 2003

In case of liquid rocket using turbopump, the inner pressure of liquid oxygen tank is maintained low, so vaporization of LOX is generally occurred. This vaporization tendency increases as the inlet helium gas temperature is higher. For estimating the amount of helium in the rocket system, the LOX vaporization phenomena should be carefully considered. In this paper, Inner process of LOX tank is analyzed by two phase flow modeling. the vaporization rate and required Helium mass is investigated with varying inlet helium temperature and heat transfer coefficient.

• Journal of Environmental Science International
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• v.21 no.6
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• pp.705-711
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• 2012

Adsorption experiment of carbon dioxide was performed on MCM41 silica with a 30 wt.% EDA(ethylenediamine) loading at different $CO_2$ inlet concentration and various adsorption temperature. The surface characteristics of $CO_2$ capturing agent were carried out using BET analysis, X-ray diffraction and FT-IR. The results of BET showed 781 $m^2/g$ for MCM41 and 464 $m^2/g$ for EDA/MCM41. X-ray diffraction results reveled typical hexagonal pore system. The higher sorption capacity of EDA/MCM41 was about 80 $mg_{CO2}/g_{sorbent}$ with 50% $CO_2$ inlet concentration and 303 K adsorption temperature. The isosteric heat of adsorption in 303-353 K ranged from -25.47 to -28.24 KJ/mole for EDA/MCM41, which indicates $CO_2$-EDA/MCM41 interaction with exothermic adsorption process. Finally, the performance of EDA/MCM41 in 10 consecutive sorption-desorption runs was a stable with only a minor drop in its sorption capacity.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.1
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• pp.50-56
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• 2007

Exhaust manifold is generally subjected to thermal cycle loadings ; at hot condition, large compressive plastic deformations are generated, and at cold condition, tensile stresses are remained in highly deformed critical zones. These phenomena originate from the fact that thermal expansions of the runners are restricted by inlet flange clamped to the cylinder head, because the former is less stiff than the latter and, the temperature of the inlet flange is lower than that of the runners. Since the failure of an exhaust manifold is mainly caused by geometric constraints between the cylinder head and the manifold, the thermal stress can be controlled by geometric factors. The generic geometric factors include the inter distance (2R), the distance from the head to the outlet (L), the tube diameter(d) and the tube thickness (t). This criteria based on elastic analysis up to onset of yield apparently indicate that the pre-stress also reduces the factor; however, high temperature relaxation may reduce this effect at later operation stage.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.354-364
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• 1994

Experiments have carried out to investigate the effects of parameters, such as mass ratio of R141b-to-water, stirrer speed, brine inlet temperature, brine flowrate, and additives, on the performance of the cool storage system using R141b clathrate. The cool storage system in this experiment was composed of storage tank, refrigerator, and heater. The results show that the mass ratio of R141b-to-water, 1 : 3~1 : 3.5 gives the best performance and the stirring speed has optimum point as 600rpm. At this speed impeller Reynolds number is $1.01{\times}10^5$. The lower the inlet brine temperature and the highter the brine flowrate, the better performance. The addition of metal powder turned out to reduce the degree of supercooling. The supercooling reduction was proportional to the amount of the metal power. However when metal powder was added more than 0.1 wt%, there was no additional supercooling reduction. The surfactants shortened the time consumed for cool storage to the half of no surfactant added case.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.30-36
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• 2016

The battery pack which is a main component of E-scooter needs the cooling system because it is the matter of battery safety in spite of the incresing of charge efficiency due to decress the internal resistence in the condition of high temperature. The purpose of this study is to analyse the effects of cooling methods which is the control of air's inlet and outlet operating timing. When each battery had large temperature deviation in the battery pack, the difference of battery's performance and efficiency were appeared. In this study, the cooling performance of battery pack has been improved by changing the operation timing of inlet and outlet fan, it improved the performance and efficiency of battery. The numerical analysis using a commercial code ANSYS CFX version 17.0 were used for the study.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.63-68
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• 2014

The numerical analysis of fluid flow in the tube cleaning system is examined. The working flow used in this study is seawater, and the temperature change is not considered as the temperature change of seawater in the tube cleaning system is negligible. Also, the analysis is performed under the assumption of steady state. The screens of complicated morphologies are simplified for the analysis, and only one fourth of the tube cleaning system is modeled as the system has a symmetrical shape. The velocity inlet boundary condition is employed for the seawater inlet, whereas the outflow boundary condition is employed for two seawater outlets. In applying the outflow boundary condition for the system with more than two outlets, the flow rate can be arbitrarily assigned. In the analysis, the finite-volume method based numerical analysis tool, the pressure based solver, the standard k-$\varepsilon$ model are utilized, and the under relaxation factor is modified appropriately. From the analysis, the distribution of velocity vectors, pressure and path lines are obtained, and the physical characteristics of fluid flow in the tube cleaning system is well-examined.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.08a
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• pp.308-312
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• 1999

Developed the model equations which calculate roll force, roll power during hot rolling in real time. The variables which mainly effect on the roll force, roll power are shape factor, reduction, roll diameter, roll velocity, strip inlet temperature, carbon content of strip and strip-roll contact friction coefficient. Among these variables roll diameter, roll velocity, inlet temperature, carbon content and friction coefficient can be excluded in interpolated model equation by introducing equation of die force(F'), power(p') of the frictionless uniform plane strain compression which can be calculated without iteration. At the case of coulomb friction coefficient of 0.3, we evaluated coefficient of polynomial equations of {{{{ { F} over {F' } }}}}, {{{{ { Pf} over {Pd }, { Pd} over {P' } }}}} from the result of finite element analysis using interpolation. It was found that the change of values of {{{{ { F} over {F' }, { P} over {P' } }}}} with the friction coefficient tend to straight line which slope depend only on shape factor. With these properties, developed model equations could be extended to other values of coulomb friction coefficient. To verify developed roll force, roll power model equation we compared the results from these model equation with the results from these model equation with the results from finite element analysis in factory process condition.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.1
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• pp.13-22
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• 2004

This study presents the thermal analyses of a spent fuel dry storage cask under normal and off-normal conditions. The environmental temperature is assumed to be 15 $^{\circ}C$ under the normal condition. The off-normal condition has an environmental temperature of 38 $^{\circ}C$. An additional off-normal condition is considered as a partial blockage of the air inlet ducts. Two of the four air inlet ducts are assumed to be completely blocked. The significant thermal design feature of the storage cask is the air flow path used to remove the decay heat from the spent fuel. Natural circulation of the air inside the cask allows the concrete and fuel cladding temperatures to be maintained below the allowable values. The finite volume computational fluid dynamics code FLUENT was used for the thermal analysis. The maximum temperatures of the fuel rod and concrete overpack were lower than the allowable values under the normal and off-normal conditions.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.29-36
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• 2008

Diesel vehicle is growing in importance in light-duty sector as a way of reducing greenhouse gases due to improved fuel economy. Carbon monoxide, gas-phase hydrocarbon and organic fraction of diesel particulates can be oxidized to harmless products using a diesel warm-up catalyst (WCC). This study investigated the effect of a turbocharger and a baffle on flow fields and temperature distributions in the WCC for Diesel vehicles by a numerical analysis. In the case of the WCC with the turbocharger, velocity vectors and temperatures of inlet of the WCC have the relatively homogeneous distributions by the swirl generated from the turbocharger. Velocity vectors and temperatures of inlet of the WCC with the turbocharger and the baffle have the improved distributions in homogeneity compared with the case of the WCC without the baffle. The homogeneous flow field and the temperature distribution in the WCC may contribute to improve the conversion performance of the catalysts.

• Journal of the Korean Solar Energy Society
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• v.27 no.4
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• pp.35-41
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• 2007

To demonstrate the desalination system, the demo-plant was scheduled to be installed. The system was planned to use solar thermal collector as heat source and PV as electricity source. For the design of the desalination demonstration system, firstly the solar thermal system would be well designed from the result between the supplied heat into the fresh water generator and the fresh water yield. The generator for demonstration system was chosen as the fresh water generator of the single stage and effect with plate-type heat exchanger using low pressure evaporation method. The test facility for the tests to reveal the relationship between the fresh water yield and the supplied heat flow rate was designed and manufactured. The maximum fresh water yield of two fresh water generators applied in this study was designed as 1.5 Ton/day. The parameters relating with the performance of fresh water generator are known as sea water inlet temperature, hot water inlet temperature, and hot water flow rate. Through the experiments, this study firstly showed detail operation characteristics of the generator and designed the solar thermal system for the demonstration system.