120kW급 IGBT 인버터의 열 응답 특성 실시간 모델

임석연,차강일,유상석 한국수소및신에너지학회 2015 한국수소 및 신에너지학회논문집 Vol.26 No.2

As the power electronics system increases the frequency, the power loss and thermal management are paid more attention. This research presents a real time model of dissipation power with junction temperature response for 120kw IGBT inverter which is applied to the thermal management of high power IGBT inverter. Since the computational time is critical for real time simulation, look-up tables of IGBT module characteristic curve are implemented. The power loss from IGBT provides a clue to calculate the temperature of each module of IGBT. In this study, temperature of each layer in IGBT is predicted by lumped capacitance analysis of layers with convective heat transfer. The power loss and temperature of layers in IGBT is then communicated due to mutual dependence. In the dynamic model, PWM pulses are employed to calculation real time IGBT and diode power loss. Under Matlab/Simulink® environment, the dynamic model is validated with experiment. Results showed that the dynamic response of power loss is closely coupled with effective thermal management. The convective heat transfer is enough to achieve proper thermal management under guideline temperature

볼텍스 튜브의 노즐 형상에 따른 토출유량 및 온도분리 특성 연구

임석연 한국기계기술학회 2018 한국기계기술학회지 Vol.20 No.5

Vortex tubes are simple tubes that can separate hot and cold air from compressed air without any internal device configuration and are used in many industries. If the vortex tube with these advantages is applied to an air conditioning system, it will be free from the use of refrigerant. In this study, basic study on discharge flow rate and temperature separation characteristics was carried out by varying the number of generator nozzle hole in various shapes of the vortex tube according to the inlet pressure of the vortex tube. Experimental results show that as the number of nozzles increases, the discharge flow rate tends to decrease and the temperature separation characteristics were excellent in the number of nozzles 6∼7.

EXPERIMENTAL STUDY OF THE PHYSICAL AND CHEMICAL CHARACTERISTICS OF BIODIESEL BLENDED FUEL USING ULTRASONIC ENERGY IRRADIATION

임석연,Y. S. SONG,J. I. RYU 한국자동차공학회 2008 International journal of automotive technology Vol.9 No.3

The purpose of this study is to understand the physical and chemical characteristics of biodiesel blended fuel reformed by ultrasonic energy irradiation. To do this, a mixture of commercial diesel fuel and biodiesel was compared and analyzed according to whether or not ultrasonic energy irradiation was performed and the duration of irradiation. The results of the experiments indicate that when ultrasonic energy irradiation was performed on biodiesel blended fuel, its viscosity decreased by 3−7%. In the case of BD20, when ultrasonic energy irradiation was performed, its Sauter mean diameter (SMD) dropped by 12% on average. As the irradiation duration increased, the volume ratio of olefins increased up to a maximum of 2.7%, and the higher heating value increased to a maximum of 5.8%. On the contrary, the ratio of aromatics decreased by a maximum of 2.7%, and BI decreased by a maximum of 7%.

ULTRASONIC-ASSISTED MEASUREMENT AND EFFECT OF NATURAL METHANE GAS

임석연 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.1

This work is an experimental research to investigate the gas fuel (CH4) characteristics necessary for natural gas vehicles based on ultrasonic-assisted measurement using two different ultrasonic sensors. This paper offers the technical methods including energy transfer process, ultrasonic propagation, sensitivity, amplitude signal, and relationship of CH4 density and ultrasonic signal. The experiment is composed of a constant volume chamber (CVC), two different sensors (AUS and HSUS), and gas fuel (methane). The experimental conditions are set by 1 ~ 4 bar of initial pressure, 7 Hz of pulse rate, 53.7 kHz of resonant frequency, and 0.45 ~ 0.85 m of measurement distance in natural gas space. As a result, HSUS is measured by 0.92 V of the height, 4 cm of main width, 12.7 cm of full width, and 42.8º of slope angle. The important thing is to highly increase the height and slope angle of HSUS model comparing with AUS model. Consequently, this experiment is shown that ultrasonic signal is gradually diminished as distances increases, the amplitude is improved as initial pressure increases, and ultrasonic sensor capable of transferring longitudinal wave is significantly affected by distance difference in CH4 gas space.

연료 다변화에 따른 용융 탄산염 연료전지 시스템 운전 특성

임석연,성용욱,한재영,유상석 한국수소및신에너지학회 2015 한국수소 및 신에너지학회논문집 Vol.26 No.2

The fuel cells have been investigated in the applications of marine as the high efficient and eco-friendly power generating systems. In this study, modeling of IR Type molten carbonate fuel cell (Internal Reforming Type molten carbonate fuel cell) has been developed to analyze the feasibility of thermal energy utilization. The model is developed under Aspen plus and used for the study of system performances over regarding fuel types. The simulation results show that the efficiency of MCFC system based on NG fuel is the highest. Also, it is also verified that the steam reforming is suitable as pre-reforming for diesel fuel.

COMBUSTION AND EMISSION CHARACTERISTICS OF BD20 REFORMED BY ULTRASONIC ENERGY FOR DIFFERENT INJECTION DELAY AND EGR RATE IN A DIESEL ENGINE

임석연,최두석,류정인 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.2

The purpose of this study is to understand the operational characteristics of a diesel engine that uses BD20 reformed by ultrasonic energy irradiation. In particular we study the effects of tuning injection delay and EGR rate. BD containing about 10% oxygen has attracted attention due to soaring crude oil prices and environmental pollution. This oxygen decreases soot by promoting combustion, but it also increases NOx. To solve this problem, injection timing may be delayed or an EGR system may be applied. These adjustments normally lower engine power and increase exhaust emission but, in using fuel reformed by ultrasonic energy irradiation (which is changed physically and chemically to promote combustion), we may hope to circumvent this problem. To control the duration of the ultrasonic energy irradiation, the capacity of the chamber in an ultrasonic energy fuel supply system was tested at 550cc and 1100cc capacities. As for the results of the experiment, we could identify the optimum EGR rate by investigating the engine performance and the characteristics of exhaust emissions according to the injection timing and the EGR rate while ultrasonically irradiated BD20 was fed to a commercial diesel engine. With UBD20 (at an injection timing of BTDC 16˚), the optimum EGR rate, giving satisfactory engine performance and exhaust emissions characteristics, was in the range of 15~20%. The purpose of this study is to understand the operational characteristics of a diesel engine that uses BD20 reformed by ultrasonic energy irradiation. In particular we study the effects of tuning injection delay and EGR rate. BD containing about 10% oxygen has attracted attention due to soaring crude oil prices and environmental pollution. This oxygen decreases soot by promoting combustion, but it also increases NOx. To solve this problem, injection timing may be delayed or an EGR system may be applied. These adjustments normally lower engine power and increase exhaust emission but, in using fuel reformed by ultrasonic energy irradiation (which is changed physically and chemically to promote combustion), we may hope to circumvent this problem. To control the duration of the ultrasonic energy irradiation, the capacity of the chamber in an ultrasonic energy fuel supply system was tested at 550cc and 1100cc capacities. As for the results of the experiment, we could identify the optimum EGR rate by investigating the engine performance and the characteristics of exhaust emissions according to the injection timing and the EGR rate while ultrasonically irradiated BD20 was fed to a commercial diesel engine. With UBD20 (at an injection timing of BTDC 16˚), the optimum EGR rate, giving satisfactory engine performance and exhaust emissions characteristics, was in the range of 15~20%.

초음파 조사 디젤유 적용 커먼레일 디젤기관 특성에 관한 연구

임석연 ( S. Y. Im ),정영철 ( Y. C. Jeong ),조성철 ( S. C. Cho ),류정인 ( J. I. Ryu ) 한국분무공학회 2006 한국액체미립화학회지 Vol.11 No.2

저온 출구의 배압조건에 따른 볼텍스 튜브의 온도분리 특성 연구

임석연(Seokyeon Im) 한국트라이볼로지학회 2016 한국트라이볼로지학회지 (Tribol. Lubr.) Vol.32 No.5

Electric vehicle ownership is expanding for two reasons: its technology features have enhanced fuel economy, and the number of vehicle emissions regulations is increasing. Battery performance has a large influence on the capability of electric vehicles, and even though battery thermal management has been actively researched, specific technological improvements to battery performance are not being presented. For instance, many industrial applications utilize vortex tubes as components for refrigeration machines because of their numerous intrinsic benefits. If electric vehicles incorporate vortex tubes for battery cooling, performance and efficiency advancements are possible. This study uses a counter-flow vortex tube to investigate its temperature separation characteristics, based on the back pressure of the cold air exit and the difference between the inlet and back pressures. The experiment uses a vortex tube with the following parameters: six nozzle holes, a 20 mm inner vortex diameter (D), a 14D tube length, a 0.7D cold exit orifice diameter, and a nozzle area ratio of 0.142. The measurements prove that the temperature difference between the hot air and cold air decreased because of the flow resistance of the hot air and the backflow phenomenon at the cold air exit. The flow resistance causes the temperature difference to decrease, and the back pressure of the cold air exit influences the flow resistance. The results show that the back pressure significantly influences the efficiency of temperature separation.

초음파 에너지 조사 시간과 분사지연에 따른 BD20의 디젤기관 연소특성에 관한 실험 연구

임석연(Seokyeon Im),조성철(Sungchul Jung),정영철(Youngchul Jung),박성영(Sungyoung Park),최두석(Dooseuk Choi),류정인(Jeongin Ryu) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

An object of this study is to understand the correlation between the characteristics of an engine performance and combustion, applying BD20 fuel reformed by ultrasonic energy irradiation to diesel engines. Before conducting the main experiment, an experiment was performed to determine the optimum injection timimg of the fuel used in applying the ultrasonic energy irradiation to BD20. To control the duration of the ultrasonic energy irradiation, the capacity of an ultrasonic energy fuel supply system was tested with 550㏄ and 1100㏄ chambers. As the result of the analysis of the regular BD20 and BD20 to which ultrasonic energy irradiation was applied, the BSFC and the Power of the irradiated BD20 was improved 3% and 6%, respectively compared to those of non-irradiated BD20. When the fuel injection timing was delayed by 5°, the engine power was improved by 3%, and the BSFC was improved by 2%. The maximum combustion pressure of irradiated BD20 was improved by a maximum of 6% in comparison to that of regular BD20, and demonstrated a synergistic effect of 3% by delaying the injection timing 5°.

바이오 디젤 혼합비에 따른 커먼레일 인젝터의 분사 및 내구특성에 관한 실험 연구

임석연 ( Seok Yeon Im ),김태범 ( Tae Bum Kim ),유상석 ( Sang Seok Yu ) 한국분무공학회 2011 한국액체미립화학회지 Vol.16 No.1

An object of this study is to understand the correlation of injection characteristics and injector dimensions according to biodiesel mixture. The Injection characteristics of different types of common-rail injectors are the number of nozzle holes (5~8), jet cone angle (146˚~153˚), hydraulic flow rate (830~900 ml/min) injection quantity and response time. Prior to characteristic experiment, the reference injector has been selected in 6 candidates injectors under the investigation of injected quantity according to the biodiesel mixture so that injector type can be determined. The injector is used for the characteristic experiment which varied the various operating conditions including pressure 23 MPa, 80 MPa, 160MPa, changing in injection duration 0.16 ms~1.2 ms and even mixture ratio. The result shows that the nozzle hole number and cone angle influence the injection quantity much more than nozzle hole diameter at low injection pressure and the nozzle hole diameter at high injection pressure, post injection duration.