【作者】

Martin Weinrotter，Inigo Oregui，Leire Alonso

【摘要】

论文已在中国上海举行的2013年CIMAC大会上发表，论文的版权归CIMAC所有。For modern, high efficiency stationary, lean burn natural gas engines there are differ-ent drivers for an improvement of the ignition system: Higher brake mean effective pressure (bmep)=>higher turbulences to maintain short combustion durations=>higher performance requirements of ignition systems. Improvement the combustion stability (COVbmep coefficient of variation of the bmep) or extension of the lean limit. Extension of the spark plug lifetime. Robust and reliable starting of the engine. On three different DR GUASCOR natural gas engines 3 different ignition systems with open chamber spark plugs(OCSP)J-type and pre-chamber spark plugs(PCSP) have been tested: HGM240:8 line; displacement 24 dm3; bore 152 mm; stroke 165 mm; 1800rpm;520kW;17,4 bar bmep; Lambda about 1,7; Miller cycle; PCSP SFGLD560:16 V; displacement 56,3 dm3; bore 160 mm; stroke 175 mm;1500rpm;985kW;14 bar bmep; lambda about 1,6; Otto cycle; OCSP HGM560:16 V; displacement 56,3 dm3; bore160 mm; stroke 175 mm;1500 rpm;1240kW;17,6 bar bmep; lambda about 17,6; Miller cycle; PCSP Three different ignition systems have been used: lgnition system 1: single pulse capacitive discharge system, max.125 mJ, no control of the discharge characteristic lgnition system 2: pulsed, modulated, capacitive discharge system, max.500 mJ, control of the energy and spark duration possible in a rectangular shape possible lgnition system 3: pulsed, modulated, capacitive discharge system, max.700 mJ, complete control of the discharge characteristic possible (energy, spark duration and shape of the energy release) During the last years different PCSP-designs have been developed together with suppliers and tested on DR GUASCOR engines. For this publication a non-optimized version and an optimized PCSP are presented with different electrode gaps.1) HGM240: With the not optimized PCSP one result was that with higher ignition energy the lean limit could be extended clearly from 270 mg/Nm3 NO, with ignition system 1 to 180mg/Nm3 or even to 120 mg/Nm3 NOx with increasing ignition energy with ignition system 2. The lean limit could be reached with ignition system 3-from120mg/Nm3 NOx with ignition system 2 to 70 mg/Nm3 NOx with ignition system 3 with optimized discharge characteristics (with max.4,5% COV bmep). If the discharge characteristic of ignition system 3 was not optimized, about the same performance as with ignition system 2 with 270 mJ could be observed. With the optimized PCSP no difference between the ignition system 2 and 3(also with optimized discharge characteristic) was seen but both ignition systems had aclear advantage to ignition system 1. One explanation is the difference in flow velocity in the electrode gap for the 2 different PCSP geometries. With increasing flow velocity a controlled shape of the discharge characteristic is needed so that the spark doesn't collapse. With the optimized PCSP a very low improvement with the optimized discharge characteristic could be observed. With the optimized PCSP, no improvement of the COV bmep could be observed. The COV bmep could only be improved with the ignition system3 together with the not optimized PCSP-at 150 mg/Nm3 NOx from 3,5% down to 2,5%. PCSP with different gaps have been tested and starting was possible with increasing ignition energy together with decreasing electrode gap. No definitive influence of the spark duration, spark current or discharge shape could be found.2) SFGLD560: No difference in the lean limit or COV bmep could be observed. The main reason for this could be that with the J-type SP the flame quenching is much lower than in the used PCSP and so less ignition energy is needed. Another reason is the lower lambda with which the SFGLD560 is operated in comparison to the HGM240 and so the needed ignition energy is lower. An extensive comparison of different ignition systems on different DR GUASCOR engines has been conducted and the advantages/disadvantages of the different

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

1

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