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.

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%.

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%.

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

초음파 조사 메탄올 혼합 연료의 가솔린 기관 적용 특성 연구

임석연(Seukyeon Im),정영철(Youngchul Jung),최두석(Dooseuk Choi),조성철(Sungchul Cho),류정인(Jeongin Ryu) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

The object of this study is to examine the properties of engine performance and discharged materials. The methanol was mixed with gasoline fuel in common use at the blending ratio 20% and 40%. The reformed methanol blended fuel irradiated by ultrasonic wave was applied to the electric control fuel injection gasoline engine and it was compared and analyzed. The results showed that the engine performance and discharged materials was influenced by the methanol blended ratio.

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.

ASPEN PLUS<SUP>®</SUP>를 이용한 태양열 유기랭킨사이클 열병합 발전시스템의 공동주택 적합도 분석

임석연(Seokyeon Im),김형근(Hyung-Geun Kim),유상석(Sangseok Yu) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.4

본 연구에서는 아파트단지에 적용되는 태양열 급탕 시스템의 에너지 활용도를 높이기 위해 유기랭킨사이클을 적용하여 해석적 연구를 수행하였다. 시스템 해석은 Aspen Plus<SUP>®</SUP> 을 활용하였으며 태양열 집열기는 급탕 온도와 유기랭킨 사이클의 운전 조건을 고려하여 진공관형 집열기를 적용하였다. R134a, R141a, R245fa 등의 냉매를 작동유체로 선정하였으며, 시스템 성능해석을 통하여 R245fa 냉매가 적용가능성이 가장 높게 나타났다. 비가역성 해석과 민감도 해석을 통해 유기랭킨 사이클 시스템의 효율 및 성능 확보를 위해서는 증발기와 터빈에 대한 기술 개발이 매우 중요하다는 것을 밝혀냈으며, 순수 급탕으로만 활용하는 시스템에 전기 생산 설비를 추가하게 되면 약 50%의 추가적인 경제성이 확보됨을 확인하였다. In this study, a solar thermal system is designed to provide hot water and electricity for improvement of solar thermal energy availability in an apartment complex. The electricity is generated with Organic Rankine Cycle (ORC) by the solar thermal energy. R134a, R141b and R245fa are selected for operating fluid of the solar thermal ORC system. ORC with R245fa shows the best performance based on the variation of pressure. The irreversibility of component showed that the technology advance of the evaporator ensures a performance improvement. The sensitivity study results indicate that the turbine performance is most effective way to improve the performance of ORC system. An economic analysis showed that approximately 50% more income could be achieved by a solar thermal ORC system with a hot water supply.

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

임석연(Seokyeon Im),이호길(Hogil Lee),류정인(Jeongin Ryu) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.4

An object of this study is to understand the correlation between the characteristics of an engine performance and combustion characteristics, 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 reformed BD20 by ultrasonic energy irradiation. To control the duration of the ultrasonic energy irradiation, the capacity of an ultrasonic energy fuel supply system was tested with 550cc and 1100cc chambers. As the result of the analysis of the regular BD20 and reformed BD20 by ultrasonic energy irradiation, the BSFC and the Power of the reformed 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 cylinder pressure of reformed 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°.