• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.2
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• pp.17-26
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• 1993

As fundamental step to find the suitable compression ratio of hydrogen fueled engine, performance and combustion characteristics of that engine were analyzed. Qualitative characteristics of the hydrogen fueled engine were similar to that of the gasoline engine, and it was also found that knock limit compression ratio of the hydrogen fueled engine was higher than that of the gasoline engine.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.3
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• pp.233-241
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• 2002

To achieve hydrogen power system with high performance and stable operation, the COVimep of hydrogen fueled engine with direct injection was evaluated with the change of engine speed, injection timing, air-fuel equivalence ratio and spark timing. And the cause of cycle variation was analyzed by using coefficient of variation in combustion period defined in this study. the results showed that the cycle variation of hydrogen fueled engine is mainly dependent on the early combustion period.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.2
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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 hydrogen and new energy society
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• v.4 no.1
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• pp.1-9
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• 1993

To find performance and knock limit for compression ratio in hydrogen fueled engine, the variable compression ratio hydrogen fueled engine which was able to vary compression ratio during firing was manufactured and estimated. The characteristics of the variable compression ratio hydrogen fueled engine were as follows : 1) compression ratio variation by moving of cylinder head, 2) OHC which can be realized low S/V ratio, short flame propagation distance and unvariable configuration of combustion chamber for compression ratio variation, 3) direct injection of hydrogen gas to restrict back fire.

• Transactions of the Korean hydrogen and new energy society
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• v.7 no.1
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• pp.55-62
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• 1996

As an essential step for development of a duel injection hydrogen fueled engine which can obtain high thermal efficiency and power in overall operating range, performance and BFL(back fire limit) equivalance ratio in hydrogen fueled engine with external mixture are investigated. As the results, BFL equivalence ratio in hydrogen fueled engine with external mixture is approximately 0.7. It is deduced that controls of driving conditions are required in transient stage from external mixture type to inner injection type. And in order to increase thermal efficiency, it is also found that BFL equivalence ratio should be expanded as much as possible.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.1001-1007
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• 2001

Hydrogen fueled engine with dual injection can achieve high power and high efficiency simultaneously. In this study, the suitable compression ratio of hydrogen fueled engine with dual injection were investigated including performance of this engine according to variation of compression ratio. As results, it was found that the suitable compression ratio of that was about CR=11, and torque and thermal efficiency increased by 6% and 7% respectively.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.17 no.3
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• pp.255-262
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• 2006

To develop a hydrogen fueled engine with external mixture which uses in high reliability, low cost and low pressure, the single cylinder research engine with MCVVT(Mechanical Continuous Variable Valve Timing) system is developed and its basic characteristics analyzed. The MCVVT developed has high reliability and the valve timing change is possible in wide range continuously. Though the mechanical loss due to MCVVT system is increased a little, back-fire suppression research for valve overlap period is no difficulty. It's also confirmed that the hydrogen-fueled engine has lower torque and is possible high lean burn. As fuel-air equivalence ratio is high, as thermal efficiency is remarkable increasing.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.1
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• pp.65-73
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• 2002

Because of low flame ion density in hydrogen-air mixture, many residual electric energy could be existed in the ignition system of hydrogen engine, If these residual energy discharged abnormally during intake stroke, it may be the cause of backfire occurrence which is serious problem in development of hydrogen fueled engine but unsolved in spite of many concerned research on it. In this study, the possibility of backfire occurrence by abnormal electric discharge and countermeasure of that were investigated by using the experimental single cylinder hydrogen fueled engine with two types of ignition system. The results show that abnormal electric discharge appeared in low load with low ion density and then results in back fire occurrence, It is also seen that countermeasure method installing larger earth resistance in high tension code is effective to control abnormal electric discharge.

• Transactions of the Korean hydrogen and new energy society
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• v.5 no.2
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• pp.111-119
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• 1994

Analysis of heat loss is needed to achieve the high performance and high efficiency in hydrogen engine. So, cooling losses at each part of the direct injection hydrogen fueled engine were measured to evaluate the behavior and distribution of heat loss. Unsteady instantaneous temperature and heat flux at cylinder head were measured by use of instantaneous temperature prove. And these results were compared with those of gasoline engine.