• Journal of Energy Engineering
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• v.26 no.1
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• pp.23-27
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• 2017

An expander of an organic Rankine cycle is an essential component that significantly influences its entire performance and cycle efficiency. The inlet pressure and temperature of the expander used for the organic Rankine cycle are limited by the expander's mechanical properties and the characteristics of the working fluid. The organic Rankine cycle's output, heat absorption, and efficiency are altered by the inlet pressure and temperature of the expander. In this study, a theoretical comparative analysis was conducted on an organic Rankine cycle's performance changes, which are dependent on the inlet condition of the expander. The working fluid is an R134a refrigerant, and the expander is a positive-displacement type.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.5
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• pp.172-180
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• 2006

This study was to analyze the effect of mixed fuel composition and mass fraction on the characteristics of evaporating diesel spray and combustion under the various ambient conditions. The characteristics of vaporization distribution and combustion were visualized by laser induced fluorescent method and direct photography. The experiments were conducted in the constant volume vessel and rapid compression expansion machine with optical access. Multi-component fuels mixed i-octane, n-dodecane and n-hexadecane were injected the vessel and rapid compression expansion machine with electronically controlled common rail injector. Experimental results show that fuel vapor formed stratified distribution. And vaporization and diffusion are become actively increasing in mass fraction of low boiling point component. Consequently multi-component fuels were expected to control the evaporating behavior according to their suitable mass fraction.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.78-85
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• 2005

The purpose of the study was to establish the design procedure and develop the program for designing regenerative cooling system. To obtain the design parameter necessary for the realization of regenerative cooling system, water-cooled regenerative cooling system was designed from suggested procedure. To compare experimental results with a present method of analytically predicting the heat transfer loads, $250kg_{f}$ experimental LRE with water-cooled regenerative cooling system was investigated. Based on the investigation, the good correction between the predicted and measured data was verified. Developed design program can be used to designing Kerosene- cooled regenerative cooling system. The basic experimental data and correlations obtained in this study for 250kgf experimental LRE with water-cooled regenerative cooling system can be directly applicable to the real LRE.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.7-14
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• 2008

The temperature distribution in a surface of diesel particulate filter(DPF) was measured using an infrared temperature camera. In order to regenerate the DPF, five partitioned electric heaters were used for heating the ceramic filter. The five partitioned heaters were switched on/off with some time interval one the other. The surface temperature distribution in the ceramic filter and electric heaters were measured with varying both the electrical power supply to the heaters and the mass flow rate of the air supply from a blower. The higher mass flow rate in the DPF system enhanced the uniformity in the surface temperature distribution of the ceramic filter due to effective convection heat transfer. The flow in the monolith ceramic structure of the DPF move mainly in the axial direction, which could be identified from the surface temperature of the ceramic filter.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.465-471
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• 2006

Controlled auto-ignition(CAI) combustion, offers the potential to improve fuel economy and reduce emission simultaneously. In this study, CAI-combustion was achieved in a single cylinder gasoline DI engine with modified camshafts in order to restrict the gas exchange process. We investigated the effects of air-fuel ratio, residual EGR rate and injection timing such as early injection and late injection on the attainable CAI combustion region. The effect of injection timings on combustion characteristic such as start of combustion, combustion duration and heat release rate was also investigated. From the result early injection causes the mixture to ignite earlier and burn more quickly due to the exothermic reaction during the recompression and gives rise to good mixing of the fuel/air. On the other hand, late injection extended the operation region more than early injection but the emissions of HC and NOx were more or less increased than early injection.

• Journal of the Korean institute of surface engineering
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• v.49 no.4
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• pp.368-375
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• 2016

MoN-Cu thin films were prepared to achieve appropriate properties of high hardness and low friction coefficient, which could be applied to automobile engine parts for reducing energy consumption as well as solving wear problems. Composite thin films of MoN-Cu have been deposited by various processes using multiple targets such as Mo and Cu. However, those deposition with multiple targets revealed demerits such as difficulties in exact control of composition and homogeneous deposition. This study is aiming for suggesting an appropriate process to solve those problems. A single alloying target of Mo-Cu (10 at%) was prepared by powder metallurgy methods of mechanical alloying (MA) and spar plasma sintering (SPS). Thin film of MoN-Cu was then deposited by magnetron sputtering using the single alloying target of Mo-Cu (10 at%). Properties of the resulting MoN-Cu thin film were examined and compared to those of MoN-Cu thin films prepared with double targets of Mo and Cu.

• Journal of ILASS-Korea
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• v.26 no.2
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• pp.57-66
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• 2021

The reactivity controlled compression ignition (RCCI) is the technology that provides two different types of fuel to the combustion chamber with the advantage of significantly reducing particulate matter and nitrogen oxides emissions. However, due to the characteristics of lean combustion, combustion efficiency is worsened. The conventional type of pistons for conventional diesel combustion (CDC) has mostly been used in the researches on RCCI. Because the pistons for CDC are optimized to enhance flow and target spray, the pistons are unsuitable for RCCI. In this study, a piston that is suitable for RCCI is designed to improve combustion efficiency. The new piston was designed by considering the factors such as squish geometry, bowl depth, and surface area. The experiment was carried out by fixing the energy supply to 0.9kJ/cycle and 1.5kJ/cycle respectively. The two pistons were quantitatively compared in terms of thermal efficiency and combustion efficiency.

• Design & Manufacturing
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• v.13 no.1
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• pp.19-24
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• 2019

Currently, the world is paying keen attention to the production of renewable energy along with environmental issues, and the share of renewable energy in the world is rising above that of nuclear power. Especially when Korea, which is heavily dependent on foreign countries, needs to reconsider its national competitiveness due to the recent high oil prices, the government's energy policy is to develop and use renewable energy that replaces fossil fuels. In particular, solar energy, the most actively studied and commercialized field of renewable energy, is the main research for solar energy and is commercialized and used. However, the efficiency of solar energy has already reached saturation. Studies are also focusing on increasing the reflectivity of solar energy to increase efficiency. Therefore, this paper proposes a solar collection system that can utilize solar energy rather than solar energy. The proposed solar heat collection system uses solar tracking systems to effectively collect solar energy, particularly those that can be easily produced using single-modular reflectors and have price competitiveness. In addition, temperature measurement experiments with temperature measuring sensors were conducted to ensure reliability in order to verify the results interpreted.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.126-142
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• 2020

This study aims to provide basic design data for a pintle injector and its combustion device through case study on the research and development of combustion devices to which a liquid-liquid pintle injector was applied. From data analysis, it was possible to provide the initial dimension of the combustion chamber and pintle injector based on the engine thrust, and the geometric characteristics of the high-efficiency injector. In addition, the pintle tip heat damage prevention mechanism and materials, face-shutoff pintle injector implementation method, and central propellant selection criteria were summarized. Theses results will be used as basic data for the design criteria of an initial pintle injector combustion device.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.636-641
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• 2021

Using numerical analysis, various factors influencing the performance development of high-pressure pumps for Dimethyl Ether (DME) engines were identified and the impact of each factor was evaluated using Taguchi method. DME fuels are more compressive than diesel fuels and have the lower heat generation, so it is necessary to increase the size of the plunger and speed (RPM) of the pump as well. In addition, it is necessary to change the shape and design of control valve to control the discharge flow and pressure. In this study, various variables affecting the performance and flow rate increase of high-pressure pumps for DME engines are planned using Taguchi method, and the best design method is proposed using correlation of the most important variables. As a result, we were able to provide the design value needed for a six-liter engine and provide optimal conditions. The best combination factors to optimize the flow rate at RPM 2,000 and diameter plunger with 20 mm. The regression equation can also be used to optimize the flow rate; -8, 13+0, 2552 RPM +54, 17 diam. Plunger.