• Title/Summary/Keyword: CNG

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The Engine Performance and Emission Characteristics of CNG/Diesel Dual-fuel Engine by CNG Mixing Ratio (CNG/Diesel Dual-fuel 엔진의 CNG 혼합율에 따른 엔진성능 및 배출가스 특성에 관한 연구)

  • Choi, Gun-Ho;Lim, Ock-Taeck
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.3
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    • pp.38-43
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    • 2011
  • A CNG/diesel dual-fuel engine uses CNG as the main fuel and injects a small amount of diesel as an ignition priming. This study proposed the modification of the existing diesel engine into a dual-fuel engine that injects diesel with a high pressure by common rail direct injection (CRDI) and by injecting CNG at the intake port for premixing. And experiment was progressed for understanding about effect of CNG mixing ratio. The CNG/diesel dual-fuel engine showed equally satisfactory coordinate torque and power regardless of CNG mixing ratio. The PM emission was low at any CNG mixing ratio because of very small diesel pilot injection. In case of NOx and HC, high CNG mixing ratio showed low NOx and HC emissions at low speed. At medium & high speed, low CNG mixing ratio showed low NOx and HC emissions. Therefore, it would be optimized by controlling CNG mixing ratio.

Suggestion for Safety Improvement of Compressed Natural Gas Vehicle (압축천연가스 자동차의 안전성 향상을 위한 제언)

  • Kim, Young-Seob;Park, Kyo-Shik;Kim, Tae-Ok
    • Journal of the Korean Institute of Gas
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    • v.16 no.4
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    • pp.1-7
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    • 2012
  • Systematic safety research by Korea Government has been made to enhance the safety of CNG (compressed natural gas) vehicles since the burst of compressed cylinder of an urban bus in August 9, 2010. This article summarizes some major activities to ensure the safety of CNG vehicles, which covers review of regulation, safety management system including standard of inspection and certification, and training program of inspectors and car mechanics. Specifically, the followings were reviewed; type of CNG cylinder, location of CNG cylinder, material and type of fuel line and vent line, modification of pipeline connection, installation of gas detector, installation of emergency shutdown valve, installation of protecting cover for cylinder, obligations for CNG vehicle filling station. improving periodical inspection, routine test on gas vehicles, training program for engaged in gas vehicles, and designation of safety manager for CNG bus company. This paper suggests how to improve safety of CNG vehicles as a result of review of above mentioned check items.

Economics Approach on Validity of CNG Bus Promotion Policy (천연가스(CNG)버스 보급정책의 타당성 제고를 위한 연구)

  • Shin, Won Shik
    • Journal of the Korean Institute of Gas
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    • v.22 no.5
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    • pp.114-123
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    • 2018
  • As recognizing the necessity of eco-friendly vehicles in order to reduce air pollution from road sector, Korean government has established and implemented a promotion policy which is encouraging the public transportation companies to purchase CNG buses in replacing diesel buses since 2000s. With CNG bus promotion policy, the number of CNG buses had been increased on the road of metropolitan area and big cities. However, increasing rate of CNG buses had been fluctuated between the decrease and the increase since year 2014. In this study, the impact of fuel cost competitiveness between diesel and CNG on CNG bus increasing volume was testified by simple regression, which was only assumed by precedent research on the CNG promotion policy. And this study suggested the necessity of harmonization among the related policies conducted by related Ministries. Eventually this study should contribute to enhance the validity of CNG bus promotion policy. And it is expected that Korean government should apply the new policy suggestion of this study in the establishment of government's promotion policy on LNG cargo trucks and Zero Emission Vehicles in the future.

Study on Performance and Emission Characteristics of CNG/Diesel Dual-Fuel Engine (CNG/Diesel 이종연료용 엔진의 성능 및 배출가스 특성에 대한 연구)

  • Lim, Ock-Taeck
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.35 no.9
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    • pp.869-874
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    • 2011
  • In a CNG/diesel dual-fuel engine, CNG is used as the main fuel and a small amount of diesel is injected into the cylinder to provide ignition priming. In this study, a remodeling of the existing diesel engine into a CNG/diesel dual-fuel engine is proposed. In this engine, diesel is injected at a high pressure by common rail direct injection (CRDI) and CNG is injected at the intake port for premixing. The CNG/diesel dual-fuel engine had an equally satisfactory coordinate torque and power as the conventional diesel engine. Moreover, the CNG alternation rate is over 89% throughout the operating range of the CNG/diesel dual-fuel engine. PM emission by the dual-fuel engine is 94% lower than that by the diesel engine; however, NOx emission by the dual-fuel engine is higher than that by the diesel engine.

Effects of Pilot Injection Quantity on the Combustion and Emissions Characteristics in a Diesel Engine using Biodiesel-CNG Dual Fuel (바이오디젤-CNG 혼소엔진에서 파일럿 분사량이 연소 및 배기 특성에 미치는 영향)

  • Ryu, Kyunghyun
    • Journal of ILASS-Korea
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    • v.21 no.2
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    • pp.95-103
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    • 2016
  • The effect of pilot injection quantity on the combustion and emissions characteristics of a compression ignition engine with a biodiesel-compressed natural gas (CNG) dual fuel combustion (DFC) system is studied in this work. Biodiesel is used as a pilot injection fuel to ignite the main fuel, CNG of DFC. The pilot injection quantity is controlled to investigate the characteristics of combustion and exhaust emissions in a single cylinder diesel engine. The injection pressure and injection timing of pilot fuel are maintained at approximately 120 MPa and BTDC 17 crank angle, respectively. Results show that the indicated mean effective pressure (IMEP) of biodiesel-CNG DFC mode is similar to that of diesel-CNG DFC mode at all load conditions. Combustion stability of biodiesel-CNG DFC mode decreased with increase of engine load, but no notable trend of cycle-to-cycle variations with increase of pilot injection quantity is discovered. The combustion of biodiesel-CNG begins at a retarded crank angle compared to that of diesel-CNG at low load, but it is advanced at high loads. Smoke and NOx of biodiesel-CNG are simultaneously increased with the increase of pilot fuel quantity. Compared to the diesel-CNG DFC, however, smoke and NOx emissions are slightly reduced over all operating conditions. Biodiesel-CNG DFC yields higher $CO_2$ emissions compared to diesel-CNG DFC over all engine conditions. CO and HC emissions for biodiesel-CNG DFC is decreased with the increase of pilot injection quantity.

[이슈] 저탄소와 그린카 - 차세대 저탄소 친환경 대중교통 수단의 도입 필요

  • Kim, Yong-Rae
    • Korea Petroleum Association Journal
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    • s.292
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    • pp.24-27
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    • 2014
  • 환경부에서는 1990년대 말경 대기오염 문제를 해결하기 위한 방안으로서 디젤 버스를 CNG 버스로 대체하고자 CNG 탱크 추가 등으로 가격이 비싼 CNG 버스에 대하여 보조금을 지급하고 CNG 충전 인프라를 구축하는 등의 지원정책을 실시하여, 현재 국내에서 운행하는 버스는 일부 소도시를 제외하면 대부분 CNG 버스로 대체되었다. 이러한 CNG 버스 정책으로 인하여 당시만 해도 매연 배출이 심하던 디젤 버스로 인한 공해물질이 줄어들고 대기질이 어느 정도 개선된 효과를 거두었다. 최근들어 환경에 대한 중요 이슈의 개념이 변화하고 있으며 자동차 기술도 새로운 변모를 보여주고 있는 것이 현실이기 때문에 CNG 버스만으로 운영되는 정책이 향후에도 계속 유지가 되어야 할지 다시 한번 생각해보아야 할 필요가 있다.

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Analysis of SSL Communication Process in CNG Crypto Library (CNG 암호 라이브러리에서의 SSL 통신과정 분석)

  • Lee, Kyungroul;Oh, Insu;Lee, Sun-Young;Yim, Kangbin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.42 no.5
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    • pp.1027-1037
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    • 2017
  • By a spread of utilizing environment of the CNG library, it is required to analyze its vulnerability. For this reason, in this paper, we analyzed SSL communication process in CNG library. This study is expected to draw vulnerabilities and security threats and improve security criteria for various applications to fully take advantage of the CNG library.

Analysis on Actual Condition of Usage and Safety Management for CNG Pressure Vessel in Bus (CNG버스 내압용기 사용 및 안전관리 실태 분석)

  • Kim, Eui Soo
    • Journal of the Korean Society of Safety
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    • v.34 no.4
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    • pp.6-14
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    • 2019
  • There are about 38,977 CNG cars and 247 natural gas vehicle charging stations in operation in order to improve the urban air environment. With the introduction of natural gas vehicles, the atmospheric environment, which was the main cause of air pollution in the metropolitan area, was remarkably improved. However, unlike these positive effects, CNG bus accidents, which occurred more than 10 times since 2005, have caused concern among the majority of citizens using public transportation. It is necessary to make a judgment on the feasibility and future direction of CNG pressure vessel safety management that can safeguard the safety of CNG pressure vessel at the time of starting. In this study, we investigates production and use of CNG vessel, the current status of safety management of CNG bus transportation companies & charging stations and then proposes measures to prevent accident recurrence and safety management based on the actual situation investigation and analysis.

Gaseous Fuel Level Measurement of Ultrasonic Wave based on Gauss Algorithm (가우스알고리즘에 의한 초음파의 가스연료레벨 계측)

  • Kim, Hong-Ju;Choi, Doo-Seuk
    • Journal of the Korea Convergence Society
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    • v.9 no.4
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    • pp.161-167
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    • 2018
  • The amount of CNG was measured using a pressure sensor in the case of CNG vehicles. However, the current measurement method causes anxiety to the driver because it is difficult to measure the detailed amount of CNG according to various environmental conditions. This study was performed to measure the amount of CNG in CNG fuel system, and presented the method of measurement by simulating the detection system of CNG. In this experiment, a detection simulator with an ultrasonic sensor in CNG tank of Type-3 was designed, and the reception signal of the ultrasonic sensor was verified by reducing the pressure from 100 bars to 0 bars (increment=5 bars) using compressed air. As a result, the output signal voltage of the ultrasonic sensor decreased as the pressure in the tank decreased, and the it was verified that the shape of the graph was linearity.

An Analysis of a Structure and Implementation of Error-Detection Tool of Cryptography API-Next Generation(CNG) in Microsoft (마이크로소프트의 차세대 암호 라이브러리 구조에 관한 연구 및 오류-검출 도구 구현)

  • Lee, Kyungroul;You, Ilsun;Yim, Kangbin
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.26 no.1
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    • pp.153-168
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    • 2016
  • This paper introduces a structure, features and programming techniques for the CNG(Cryptography API: Next Generation), which is the substitution of the CAPI(Cryptography API) from Microsoft. The CNG allows to optimize a scope of functions and features because it is comprised of independent modules based on plug-in structure. Therefore, the CNG is competitive on development costs and agility to extend. In addition, the CNG supports various functions for the newest cryptographic algorithm, audit, kernel-mode programming with agility and possible to contribute for core cryptography services in a new environment. Therefore, based on these advantageous functions, we analyze the structure of CNG to extend it for the enterprise and the public office. In addition, we implement an error-detection tool for program which utilizes CNG library.