• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.564-570
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• 1997

The most important factor for the desalination system is the fresh water production cost dependent upon the possible energy source which should be obtained easily and with low price. Recently in Korea the demand of LNG, as a cheap and clean energy which does not cause an environmental problem, has sharply been increased. In general, LNG is storaged in a tank as a liquid state below -162 'C. When it is serviced, however, the LNG absorbs energy from a heating source and transforms to the gaseous state with high pressure. During this process a huge amount of cold energy accumulated in LNG is wasted. This waste cold energy can be utilized for producing fresh water from sea water using a sea water freezing desalination system. In order to develop a sea water freezing desalination system and to establish its design technique, a qualitative and quantitative data regarding the freezing behavior of sea water is needed in advance. The goal of this study, therefore, are to reveal the freezing mechanism of sea water, to measure the freezing rate, and to investigate the freezing heat-transfer characteristics. The experimental results help to provide a general understanding of the sea water freezing behavior in a Rectangular vessel cooled from below.

• 대한기계학회논문집B
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• 제20권3호
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• pp.1061-1073
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• 1996

Vortex tube is a simple device which splits a compressed gas stream into a cold stream and a hot stream without any chemical reactions. The phenomena of energy separation taking place in a vortex tube has been investigated experimentally. Recently, vortex tube is widely used to local cooler of industrial equipments and air conditioner of special purpose. In this study, experimental study on vortex tube efficiency was performed with various cold end orifices and nozzles type. The experimental results indicate that there is an optimum diameter of cold end orifice and nozzle type for the best cooling performance. The variation of the maximum wall temperature along the vortex tube surface provides useful information about the location of the stagnation point of the flow field at the axis of the vortex tube. The similarity relation for the prediction of the temperature of the cold exit air was obtained.

• 대한기계학회논문집A
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• 제27권7호
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• pp.1076-1086
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• 2003

The effect of a rubber mould on densification behavior of aluminum alloy powder was investigated under cold isostatic compaction. A thickness of rubber mould and friction effect between die wall and rubber mould were also studied. The hyperelastic constitutive equation based on the Ogden strain energy potential was employed to analyze deformation of rubber. The elastoplastic constitutive equation of Shima and Oyane and that of Lee on densification were implemented into a finite element program (ABAQUS) to simulate densification of metal powder for cold isostatic pressing and rubber isostatic pressing. Finite element results were compared with experimental data for densification and deformation of aluminum alloy powder under isostatic compaction.

• 한국수소및신에너지학회논문집
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• 제31권3호
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• pp.322-327
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• 2020

In this work, a study for the reduction of the electric power consumption has been estimated in main air compressors in the air separation unit through cryogenic distillation columns with PRO/II with PROVISION V10.2 at AVEVA company. Both required LNG mass flow rate and cold heat contained in 1 ton of LNG were also predicted using Peng-Robinson equation of state with Twu's new alpha function. Through this work, we concluded that 32.33-48.69% of electric power could be saved by using LNG cold heat.

• 한국수소및신에너지학회논문집
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• 제29권4호
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• pp.357-362
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• 2018

In this study, computer simulation and optimization works have been performed for a refrigeration cycle using ammonia as a refrigerant and also how much power was saved when the liquefied natural gas cold heat is replaced for the refrigeration cycle. PRO/II with PROVISION release 10.0 from Schneider electric company was used, and Peng-Robinson equation of the state model was selected for the modeling of the refrigeration cycle and LNG cold heat utilization process.

• 한국수소및신에너지학회논문집
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• 제14권3호
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• pp.207-216
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• 2003

By using the electrochemical method, the relation between the deformation and the geometrical shape, and the effect of cold work on hydrogen absorption-desorption cycling in palladium were investigated, In order to study this problem, four kinds of the Pd specimens used were plates and bars as cold worked and annealed states. As results, it is found that the deformation of thickness direction in the palladium plates increased whereas other lateral directions decreased. But the palladium bars showed the same deformation ratio in all directions because of uniform distribution of the $\beta$ phase. Grains in the plate specimens were greatly deformed after hydrogenation cycling whereas grains in the bar specimens were pulverized. Also, deterioration of the hydrogen absorption rate of the bar specimen was larger than the plate specimen. And the effect of cold work on hydrogen absorption capacity was relatively small.

• 한국수소및신에너지학회논문집
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• 제30권2호
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• pp.188-192
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• 2019

Comparative studies between single- and two-stage expansion process using LNG cold heat have been performed for a closed Rankine power generation cycle. PRO/II with PROVISION release 10.0 from Schneider Electric Company was used, and the Peng-Robinson equation of state model with Twu's alpha function was selected for the modeling and optimization of the power generation cycle using LNG cold heat. In two-stage power generation cycle, 6.7% more power was obtained compared to that of single-stage power generation cycle through the optimization works.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2002년도 춘계학술발표회 초록집
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• pp.39-39
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• 2002

In order to improve wear and fatigue resistance of the structural materials, especially cold work roller for 304 stainless steel, an eco-super-finishing and surface hardening treatment using ultrasonic vibration energy was developed and applied to the SKD-ll roller. The eco-super-finishing machine was designed and fabricated by DesignMecha Co, by its own technology. It was observed that the surface roughness, hardness and residual stress were changed from $Ra{\;}={\;}O.25\mu\textrm{m}$, Hv=710 and ${\sigma}$={\;}+400{\;}MPa{\;}to{\;}Ra{\;}={\;}0.165\mu\textrm{m}$, Hv = 1200 and ${\sigma}=-610$ MPa after 20 KHz micro-cold forging, which means almost equal to the 300 % improvement of life-time.

• Advances in Energy Research
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• 제3권3호
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• pp.181-194
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• 2015

In this work, an experimental study of the gasification on wood was carried out in downdraft type fixed bed Gasifier attached with 10 kW duel fuel diesel engine. The main objective of the study was to use wood as the biomass fuel for downdraft Gasifier and to evaluate the operating parameter of gasifier unit to predict its performance in terms of gas yield and cold gas efficiency. The influence of different biomass on fuel consumption rate, gas yield and cold gas efficiency was studied. Composition of producer gas was also detected for measuring the lower heating value of producer gas to select the feed stock so that optimum performance in the existing gasifier unit can be achieved. Under the experimental conditions, Lower heating value, of producer gas, cold gas efficiency and gas yields, using wood as a feed stock, are $4.85MJ/m^3$, 46.57% and $0.519m^3/kg$.

• 열처리공학회지
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• 제4권2호
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• pp.1-8
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• 1991

The spheroidization of cold rolled lamellar pearlite in annealing at the temperatures between 600 and $700^{\circ}C$ has been studied by quantitative micrography. It was foud that the spheroidization proceeded as two stageh. The first stage was the stage of relieving the stored energy by cold work, the second was the stage of reducing the interface energy between ferrite and cementite. The spheroidization rate combining the spheroidization rate of each stages is described by the following equation : $$d(1/S)/dt=k_3{\cdot}D/_{(1/s)}\{{\sigma}V/_{(1/s)}+k_4{\cdot}{\exp}(-bt)\}$$ Where, S is the total area of the interface between ferrite and cementite per unit volume, D is the diffusion coefficient, ${\sigma}$ is the boundary energy, V is the volume fraction of the cementite, and $k_3$, $k_4$, b are constants.