• Title, Summary, Keyword: Free-piston hydrogen fueled engine

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A Study on the Backfire and Abnormal Combustion in the Free-piston Hydrogen Fueled Engine (프리피스톤 수소기관의 역화 및 이상연소에 관한 연구)

  • Kim, K.M.;Park, S.W.;Lee, J.H.;Noh, K.C.;Lee, J.T.;Lee, Y.K.
    • Transactions of the Korean hydrogen and new energy society
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    • v.17 no.1
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    • pp.1-7
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    • 2006
  • The free-piston hydrogen fueled engine is estimated as the next generation power system which can obtain high efficiency and low emission, simultaneously. In order to develop the free-piston hydrogen fueled engine, it is necessary to stable the combustion. The engine combustion, backfire and knock phenomenons were studied by using RICEM for researching combustion characteristics of free-piston engine. As the results, backfire occurrence was not observed in the free-piston engine under limited experimental condition. And knocking occurred in case of higher cylinder wall temperature.

A Basic Study on the Dynamic Characteristics of Free-Piston Hydrogen Fueled Engine (프리-피스톤 수소기관의 동적 운전특성에 관한 기초연구)

  • Kim, Y.Y.;Lee, Jong T.
    • Transactions of the Korean hydrogen and new energy society
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    • v.14 no.4
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    • pp.283-290
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    • 2003
  • To clarify the cause of backfire occurrence and realize a hydrogen fueled engine linear alternator system, dynamic characteristics of a free-piston hydrogen engine were analyzed and compared with those of conventional reciprocating engines. It was found that the mean velocity and acceleration of a free-piston engine were higher than those of reciprocating engines. Piston displacement and compression ratio were varied with the change of the fuel mass flow rate. Therefore, the operational stability and controllability were the most important thinks of the development of a free-piston hydrogen engine.

The Characteristics of Backfire for 2 stroke Free-Piston Hydrogen Fueled Engine with Uni-flow Scavenging (Uni-flow 소기방식 2행정 프리피스톤 수소기관의 스트로크변화에 따른 역화 특성)

  • Cho, Kwan-Yeon;Cho, Hyung-Wook;Lee, Jong-Tae
    • Transactions of the Korean hydrogen and new energy society
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    • v.20 no.5
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    • pp.371-377
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    • 2009
  • Backfire characteristics for hydrogen fueled free piston engine with uni-flow scavenging is investigated with different stroke, exhaust vlave openning timing and fuel-air equivalence ratio by using RICEM (Rapid Intake Compression Expansion Machine) for combustion research of free piston engine. As results, it is found that backfire can be occurred due to slow combustion of unhomogeneous mixture in the piston crevice volume or/and in the cylinder near piston head. And the more stroke of free piston H2 engine with uni-flow scavenging is short the more opening timing of exhaust valve have to be advanced to control backfire.

An Investigation on Enhencing Thermal Efficiency of a Hydrogen Fueled 2 Stroke Free-piston Engine with Reverse Uni-flow Scavenging (역단류 소기방식을 갖는 2행정 프리피스톤 수소기관의 열효율 향상에 관한 연구)

  • Byun, Chang-Hee;Baek, Dae-Ha;Lee, Jong-Tae
    • Transactions of the Korean hydrogen and new energy society
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    • v.22 no.3
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    • pp.299-304
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    • 2011
  • A hydrogen fueled 2 stroke free-piston engine with reverse uni-flow scavenging have a advantageous structure for the backfire occurrence, but it can reduce thermal efficiency by the circuit-flow to go through a exhaust-port. In this research, varied boost pressure, SVOT and exhaust pressure are used in a 2stroke free-piston engine with hydrogen fueled for studying the possibility of increasing thermal efficiency of free-piston hydrogen engine. As a result, to increase thermal efficiency of free-piston are suitable to supply the mixture after port closed the exhaust rater than to use the scanvenging. And it was increased by the exhaust pressure, to achieve it must be used the lean-mixture at SVOT aBDC $34^{\circ}$.

A Study on the Combustion Stabilization and Performance Improvement in the Free-piston Hydrogen Fueled Engine (프리피스톤 수소기관의 연소안정화 및 성능향상에 관한 연구)

  • Noh, K.C.;Yoon, J.S.;Kim, K.M.;Park, S.W.;Lee, J.T.
    • Transactions of the Korean hydrogen and new energy society
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    • v.17 no.2
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    • pp.227-233
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    • 2006
  • A free-piston hydrogen fueled engine is considered as one of the next power systems which is able to obtain high efficiency and low emission, simultaneously. In this study, in order to ensure the possibility as the next generation power system, the combustion characteristics and the performance of the free-piston hydrogen fueled engine are analyzed by using the linear RICEM for the change of injection pressure and equivalence ratio. As the results, in-cylinder maximum pressure is shown at injection pressure $P_{inj}$=6bar. Backfire phenomenon is not observed under experimental condition and knock occurs over ${\Phi}=0.8$. The thermal efficiency is the highest at injection pressure, $P_{inj}$=6bar and equivalence ratio, ${\Phi}=0.7$, respectively.

The Characteristics of Backfire for a Free-Piston Hydrogen Fueled Engine with Reverse Uni-flow Scavenging (Reverse uni-flow 소기방식을 갖는 2행정 프리피스톤 수소기관의 역화 현상에 관한 연구)

  • Byun, Chang-Hee;Choi, Kwan-Yeon;Back, Dae-Ha;Lee, Jong-Tae
    • Transactions of the Korean hydrogen and new energy society
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    • v.21 no.2
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    • pp.98-103
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    • 2010
  • In order to develop two-stroke free-piston hydrogen engine to obtain high thermal efficiency and low emission, backfire occurrence have to be prevented. In this research, backfire characteristics are analyzed as functions of the intake valve opening timing and compression chamber pressure under piston by using RICEM (Rapid Intake Compression Expansion Machine) that has reverse uni-flow scavenging. As the result, reverse uni-flow scavenging is advantage about back fire. but, it exists suitable intake valve opening timing and its timing become known that equivalence ratio 1 retard until the piston rises. Also, To rise chamber pressure of lower piston, this does not cause backfire occurs in equivalent ratio 0.6 observed back fire. Therefore, 2cycle hydrogen fueled free-piston engine is undesirable scavenging compression by compressing the piston.

Flow visualization used PIV of hydrogen fueled free piston engine with uni-flow scavenging (PIV를 이용한 Uni-flow 소기방식 프리피스톤 수소기관의 실린더내 유동가시화)

  • Cho, H.W.;Yoon, J.S.;Lee, J.T.;Lim, H.S.
    • Transactions of the Korean hydrogen and new energy society
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    • v.19 no.3
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    • pp.182-188
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    • 2008
  • In order to improve scavenging performance of free piston hydrogen fueled engine, this study estimate compatibility of uni-flow scavenging. The scavenging flow characteristics in the cylinder is investigated by flow visualization and PIV method. Consequently it has been found that the scavenging performance decreased with abnormal expansion of piston and delay of the exhaust valve opening timing. And the scavenging performance of exhaust valve located center in cylinder head is better than that of exhaust valve located side in cylinder head.

The Research about Free Piston Linear Engine Fueled with Hydrogen using Numerical Analysis (수소를 연료로 사용한 프리피스톤 리니어 엔진의 수치해석에 관한 연구)

  • Nguyen, Ba Hung;Oh, Yong-Il;Lim, Ock-Taeck
    • Transactions of the Korean hydrogen and new energy society
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    • v.23 no.2
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    • pp.162-172
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    • 2012
  • This paper presents a research about free piston linear engine (FPLE) fueled with hydrogen, in which, the numerical models are built to simulate the operation during the full stroke of the engine. Dynamic model, linear alternator model and thermodynamic model are used as the numerical models to predict piston velocity, in-cylinder pressure and electric power of FPLE. The spark timing and air gap length are changed to provide information for the prediction. Beside, the heat transfer problem is also investigated in the paper. The results of research are divided by two parts, including motoring mode and firing mode. The result of motoring mode showed that there is validation between simulation and experiment for volume and pressure in cylinder. For firing mode, by increasing spark timing, the velocity of piston, peak pressure and electric power also increase respectively. Beside, when increasing air gap length, the electric power increases accordingly while the motion of piston is not symmetric. The effect of heat transfer also observed clearly by reducing of the peak pressure, velocity of piston and electric power.

An Analysis on Charateristics of Separate Oiling to Reduce Oil Consumption for a 2 Stroke Free-Piston H2 Engine (오일 소모 저감을 위한 역단류 2행정 프리피스톤 수소기관의 분리 윤활 특성 해석)

  • Byun, Cahng-Hee;Baek, Dae-Ha;Lee, Jong-Tae
    • Transactions of the Korean hydrogen and new energy society
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    • v.22 no.6
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    • pp.794-799
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    • 2011
  • In order to reduce the oil consumption for a 2 stroke free piston hydrogen fueled engine, the behaviors of residual lubricant oil of the cylinder wall surface were visualized and oil mass emitted into exhaust port was measured by using research engine with cross-head and eccentric crankshaft. As the results, it was shown that characteristics of residual lubricant oil such as oil thickness and distribution were remarkably different from a conventional 4 stroke engine. It was also analyzed that these tendencies relied on the configuration and installed position of the exhaust port, piston pin boss and so on.

A Flow Analysis for Improvement of the Loop Scavenging Performance of a Free Piston Linear Power System (프리피스톤 리니어 동력시스템의 루프소기성능 향상을 위한 유동해석)

  • Yoon, Jae-Seong;Cho, Hyoung-Wook;Lee, Jong-Tai;Lee, Yong-Gyun
    • Transactions of the Korean hydrogen and new energy society
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    • v.19 no.2
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    • pp.139-144
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    • 2008
  • The focus of this research is that the scavenging aspect of in-cylinder is visualized by the PIV method and its characteristic is analyzed so that the scavenging performance of the free piston hydrogen fueled engine can improve with loop scavenging. As the results, the piston of convex type shows the best scavenging performance among the presented pistons. In case of the abnormal expansion, the scavenging of area between cylinder head and cylinder wall doesn't operate well.