• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.47-55
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• 1998

A new ignition system concept was developed to improve ignition performance, accuracy of control and the reliability of the ignition system. The new ignition system has ho호 frequency discharge characteristics with 1.5-2.0 ms discharge duration, in place of the usual solitary longer duration event. We applied the system to a commercial engine to study its influence on the maximum combustion pressure attained during the cycle, when this peak pressure occurred, imep, variation rate of the engine speed and the flammability limit of a lean mixture. In this study, we clarified that the new ignition system had a beneficial effect of the lean mixture flammability limit. Also for a given mixture strength we found that the mew ignition system gave a higher peak cylinder pressure than in the case of the conventional ignition system.

• Journal of the Korean Society of Safety
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• v.19 no.1
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• pp.66-71
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• 2004

This paper describes that the improved effects on the ignition limit are studied by parallel safety components for propane-air 5.25vol.% mixture gas in low voltage inductive circuits. The experimental devices are used in the IEC type spark ignition test apparatus. The improved effects on the ignition limit are respectively obtained as the maximum rising rate of 650%, 1,080% by composing parallel circuits between inductance and safety components (condenser and diode) as compared with disconnecting inductance with the safety components. The more values of inductance the higher improved effects of ignition limit rise. This improving method for the ignition limit is not concerned with the safety components. Diode appears to effect greatly better than condenser. It is considered that the result can be used for not only data for researches and development of intrinsically safe explosion-proof machines which are applied equipment and detectors used in hazardous areas but also for data for its equipment tests.

• Fire Science and Engineering
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• v.18 no.1
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• pp.18-23
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• 2004

This paper describes the minimum ignition limits for propane-air 5.25 Vol.% mixture gases in low voltage inductive circiuts. The improved effects on the ignition limit are studied by parallel safety components(resistors) for propane-air 5.25 Vol.% mixture gas in low voltage inductive circuits. The experimental devices used in this test are the IEC type spark ignition test apparatus. The minimum ignition limits are controlled by the values of current in inductive circuit. Energy supplied from electric source is first accumulated at the inductance, it's extra energy is working as ignition source of the explosive gas. The improved effects on the ignition limit are respectively obtained as the maximum rising rate of 330% by composing parallel circuits between inductance and resistor as compared with disconnecting inductance with the safety components. The more values of inductance increase the higher improved effects of ignition limit rise. The less values of resistor the higher improved effects of ignition limit rise. It is considered that the result can be used for not only data for researches and development of intrinsically safe explosion-proof machines which are applied equipment and detectors used in dangerous areas but also for datum for its equipment tests.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1854-1856
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• 1996

This study describes the minimum ignition limit for LPG-Ai-r mixtures by switching sparks in radio-frequency limits using RF power supply and IEC type ignition spark apparatus. As a result, the minimum ignition limit voltage is increased in proportional to the rate of increasing of frequency in LPG-Air mixed gas. Especially, increment between 10[kHz] and 30[kHz] is typical. It is considered that ignition is caused by one discharge until 10 [kHz] and, beyond 10[kHz] ignition is caused by more than two discharges. The reason is analysed that energy loss is caused by existing pause interval between discharges.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.6
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• pp.183-191
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• 1997

For the improvement of ignitability we need ignition energy and its discharge characteristics which are suitable for a part distribution of the mixture density around the ignition spark plug and the flow characteristics of the mixture in the combustion. Especially, for the solving of the instability of initial ignition and lean ignitability limit in the case of lean-burn combustion, the more powerful ignition energy is required. The conclusions from the observation can be summarized as follows: 1) The ignitability limit for HIS expands wider and the combustion is more stable than for CDI. 2) The combustion duration and ignition timing depend upon the distribution of local mixture density in the vicinity of ignition spark plug.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.92-98
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• 2003

An LPG engine for heavy-duty vehicles has been developed using liquid phase LPG injection (hereafter LPLi) system which has regarded as one of the next generation LPG fuel supply systems. In this wort to investigate the lean bum characteristics of heavy-duty LPLi engine, various injection timing (SOI, start of injection) and double ignition method were tested. The results showed that lean misfire limit of LPLi engine could be extended. by 0.2 $\lambda$ value, using the optimal SOI timing in LPLi system. Double ignition method test was carried out by installing the second spark plug and modified ignition circuit to ignite two spark plugs simultaneously. Double ignition resulted in the stable combustion under ultra lean bum condition, below $\lambda=1.7$, and extension of lean misfire limit compare to ordinary case. Therefore, LPLi engine with optimal SOI and double ignition method could be normally operated at around $\lambda=1.9$ and showed higher engine performance.

• Journal of the Korean Society of Combustion
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• v.22 no.2
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• pp.36-41
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• 2017

Aero gas turbine engines must demonstrate their ability to be ignited on ground conditions or relighted in flight. The electric spark ignition is usually used in current aero gas turbine engines. Experiments on ignition characteristics relating to spark igniter penetration depth under atmospheric pressure and temperature conditions were conducted on the model combustor which is scaled in 1/18. Exciter was operated during 2 seconds, and successful ignition phenomena were confirmed by the pressure rising sharply in combustor. In addition, instantaneous ignition images were captured by a high-speed camera. It showed kernel propagation and successful ignition events in the sector model combustor. Ignition test results showed that ignition limit with increase in penetration depth of the igniter plug was wider. When the penetration depth of the igniter plug increased under the same fuel injection pressure condition, successful ignition events were obtained in higher differential pressure conditions between inlet and outlet of the combustor. The results demonstrate that the ratio of the combustible mixture, which is exposed to the high temperature environment around the igniter plug tip, increases. Thereby affect the combustor ignition performance.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.1-6
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• 2014

The more or less homogeneous fuel-air mixture that exists at the end of the compression process is ignited by an electric ignition spark from a spark plug shortly before top dead center. The actual moment of ignition is an optimization parameter; it is adapted to the engine operation so that an optimum combustion process is obtained. Brake mean effective pressure (BMEP) of the spark ignition energy control device (IECD) than conventional spark system at the stoichiometric mixture is increased about 9%. For lean burn engine, the lean limit is extended about 25% by using the IECD. It was considered the stability of combustion by the increase of flame kernel according to the high ignition energy supplies in initial period and discharge energy period lengthen by using the IECD.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.4
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• pp.66-74
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• 1988

The ignition quality of ignition system is influenced by spark energy, discharge pattern of spark energy and spark duration. In this paper, the characteristics of multiple spark ignition system have been investigated for various number of spark and spark interval. The results, which were compared with those obtained with a standard single spark ignition, show that engine output is increased, and lean misfire limit is extended with the multiple spark ignition system. The most effective number of spark at the most effective spark interval that are determined by engine performance test, were 6 times spark at 0.02ms spark interval. For the above condition of spark, engine torque was increased about 20% comparing with conventional ignition system and lean misfire limit was extended to air-fuel ratio 22.5:1. This study researched the rate of heat release and quantity of heat release influenced by a condition of spark on the mass burned in order to investigate the relationship between the rate of mass burned and number of spark times.

• Journal of the Korean Institute of Gas
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• v.1 no.1
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• pp.106-112
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• 1997

This study measured the ignition limits of methane-air, propane-air, ethylene-air, and hydrogen-air mixture gases by discharge spark of D.C. power resistive circuit. The used experimental device is the IEC type spark ignition test apparatus, it consists of explosion chamber and supply -exhaust system of mixture gas. Mixture gases (methane-air, propane-air, ethylene-air, and hydrogen-air) were put into explosion chamber of IEC type spark ignition test apparatus, then it was confirmed whether ignition was made by 3,200 times of discharge spark between tungsten electrode and cadmium electrode. The ignition limits were found by increasing or decreasing the value of current. For the exact experiment, the ignition sensitivity was calibrated before and after the experiment in each condition. The ignition limits were found by changing the value of concentration of each gas-air mixture in D.C. 24 [V] resistive circuit. As the result of experiment, it was found that the minimum ignition limit currents exist at the value of methane-air 8.3 [$Vol\%$], propane-air 5.25[$Vol\%$], ethylene-air 7.8 [$Vol\%$], and hydrogen-air 21[$Vol\%$] mixture gases. For each the minimum ignition concentration of gases, the relationships between voltage and minimum ignition current were found. The results are as follows. - The minimum ignition limits are decreasing in the order of methane, propane, ethylene, and hydrogen. - The value of ignition current is inversely proportional to the value of source voltage. - The minimum ignition limit currents increase sharply at more than 2 [A]. The reason is caused by overheating the electrode.