• Transactions of the Korean Society of Automotive Engineers
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• 제14권6호
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• pp.43-49
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• 2006

Optimizing in-cylinder flow such as tumble or swirl is one of the key factors to develop better internal combustion engines. Especially, the tumble, which is more dominant flow in current high performance gasoline engines, has significant effects on the fuel consumptions and exhaust emissions under part load conditions. The first step for the tumble optimization is to find an accurate but cost-effective way to measure the tumble ratio. From this point of view, tumble ratios from three different measuring methods were compared and correlated in this research. Steady flow rig, water rig, and PIV were utilized for that purpose. Engine dynamometer test was also performed to find out the effect of the tumble. The results show that the tumble ratios from those methods are well correlated and that the steady flow rig is the effective method to measure the tumble despite its limitations.

• Transactions of the Korean hydrogen and new energy society
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• 제16권2호
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• pp.191-198
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• 2005

Adding hydrogen gas in natural gas leads to stable combustion in internal combustion engine and its performances rely on compression ratio. To analyze the effects of compression ratio and rate of hydrogen addition on the engine performance, the characteristics of overall engine performance including emission were investigated by using the medium duty natural gas fueled engine. As results, it was found that compression ratio occurred knock was nearby compression ratio, $\varepsilon$=14 for the case that hydrogen was enriched in the natural gas fueled engine. But slight knock was occurred at $\varepsilon$=14.7 in the case of neat natural gas. Also HC and $CO_2$ were reduced around 80% and 20% respectively when the rate of hydrogen addition was increased to 50% and compression ratio from $\varepsilon$=13 to $\varepsilon$=14.7.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제37권3호
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• pp.243-248
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• 2013

Internal combustion engines typically expel 30%-40% of the energy supplied by fuel to the environment through their exhaust system. Therefore, further significant improvements in the thermal efficiency of IC engines are possible by recovering the waste heat from the engine exhaust gas. With this fact in mind, a numerical simulation was carried out to investigate the potential of using thermoelectric generation with an internal combustion engine for waste heat recovery. Physical parameters such as the exhaust temperature and mass flow rate were evaluated in the exhaust system, and the optimum location for inserting a thermoelectric generator (TEG) into the system was determined. The TEG will be located in the exhaust system and will use the energy flow between the warmer exhaust gas and the external environment. The optimum position of the temperature distribution and the TEG performance were predicted through numerical analysis. The experimental results obtained showed that the power output significantly increases with the temperature difference between the cold and hot sides of the TEG.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제47권4호
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• pp.300-308
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• 2019

For drones to be used for industrial or agricultural applications, it is necessary to increase the payload and endurance. Currently, the payload and endurance are limited by the battery technology for electric powered drones. In addition, charging or replacing the batteries may not be a practical solution at the field that requires near continuous operation. In this paper, a procedure to optimize the power system of an electric hybrid drone that consists of an internal combustion engine, a generator, a battery, and electric motors is presented. The example drone for crop dusting is sized for easy transportation with a maximum takeoff weight of 200 kg. The two main rotors that are mechanically connected to the internal combustion engine provides most of the lift. The drone is controled by four electric motors that are driven by the generator. By analyzing the flow of the energy, a methodology to select the optimum propeller and motor among the commercially available models is described. Then, a procedure of finding the optimum operational condition along with the proper gear reduction ratios for the internal combustion engine based on the test data is presented.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 춘계 학술대회논문집
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• pp.121-127
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• 2002

The transient flow fields in direct injection engine was analyzed by using the STAR-CD CFD code during the intake/compression processes. The grids are generated by using the IC3M. The CFD results were compared with experimental data. The results showed that the used techniques were well suited for the flow analyses on any internal combustion engines.

• Journal of the Korean Professional Engineers Association
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• 제44권4호
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• pp.39-43
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• 2011

To cope with recent high gas prices and global warming phenomenon, the latest gasoline engine technologies are focusing on direction injection, downsizing by turbo charging, variable compression ratio, controlled auto Ignition to enhance fuel efficiency and satisfy emission regulations. The variable valve train technology will be a basement for these innovative technologies in internal combustion engines and is supposed to play a key role to improve low thermal efficiency and pumping loss in gasoline engine caused by low compression ratio and throttled operation respectively.

• Journal of the Korean Society of Combustion
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• 제18권4호
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• pp.12-20
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• 2013

The ignition delay time is an important factor to understand the combustion characteristics of internal combustion engine. In this study, ignition delay times of cool and thermal flame were observed separately in homogeneous charge compression ignition(HCCI) engine. This study presents numerical investigation of ignition delay time of n-heptane and alcohol(ethanol and n-butanol) binary fuel. The $O_2$ concentration in the mixture was set 9-10% to simulate high exhaust gas recirculation(EGR) rate condition. The numerical study on the ignition delay time was performed using CHEMKIN codes with various blending ratios and EGR rates. The results revealed that the ignition delay time increased with increasing the alcohol fraction in the mixture due to a decrease of oxidation of n-heptane at the low temperature. From the numerical analysis, ethanol needed more radical and higher temperature than n-butanol for oxidation. In addition, thermal ignition delay time is sharply increasing with decreasing $O_2$ fraction, but cool flame ignition delay time changes negligibly for both binary fuels. Also, in high temperature regime, the ignition delay time showed similar tendency with both blends regardless of blending ratio and EGR rate.

• Journal of Mechanical Science and Technology
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• 제17권3호
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• pp.357-369
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• 2003

Electromagnetic valve (EMV) actuation system is a new technology for improving fuel efficiency and at the same time reducing omissions in internal combustion engines. It can provide more flexibility in valve event control compared with conventional variable valve actuation devices. The electromagnetic valve actuator must be designed by taking the operating conditions and engine geometry limits of the internal combustion engine into account. To help develop a simple design method, this paper presents a procedure for determine the basic design parameters and dimensions of the actuator from the relations of the valve dynamics, electromagnetic circuit and thermal loading condition based on the lumped method. To verify the accuracy of the lumped method analysis, experimental study is also carried out on a prototype actuator. It is found that there is a relatively good agreement between the experimental data and the results of the proposed design procedure. Through the whole speed range, the actuator maintains proper performances in valve timing and event control.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제25권4호
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• pp.180-186
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• 2013

An electric vehicle is an environment-friendly automobile which does not emit any tailpipe pollutant. In a conventional vehicle with an internal combustion engine, the internal cabin of the vehicle is usually heated using waste heat from the engine. However, for an electric vehicle, an alternative solution for heating is required because it does not have a combustion engine. Recently, a heat pump system which is widely used for residential heating due to its higher efficiency has been studied for its use as a heating system in electric vehicles. In this study, a heat pump system utilizing air source and waste heat source from electric devices was investigated experimentally. The performance of the heat pump system was measured by varying the mass flow rate ratio. The experimental results show that the heating capacity and COP in the dual heat source heat pump were increased by 20.9% and 8.6%, respectively, from those of the air-source heat pump.

• Journal of Auto-vehicle Safety Association
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• 제13권4호
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• pp.20-25
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• 2021

This paper is the result of a research on hybrid tuning technology developed to improve the actual fuel efficiency and reduce emissions of in-use light-duty diesel trucks. In this study, a hybrid powertrain was constructed by inserting an electric motor between the diesel engine and manual transmission of an internal combustion engine vehicle and installing a battery. To verify the safety, a test was conducted based on the Korean tuning regulations. In particular, since there has been no case of tuning an internal combustion engine vehicle into a hybrid vehicle in Korea, it was necessary to carry out all procedures to receive tuning approval. The approval process consists of a technical review, safety verification test, and application for tuning approval. As a result, the test vehicle was approved for tuning because both the technical review and vehicle test results were suitable. Therefore, this study confirmed the safety of diesel hybrid tuning technology, and laid the foundation for the research and development of technologies to tune into an eco-friendly vehicle as well as the activation of related industries.