• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.153-159
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• 2010

In order to see the flame behavior in the annular reverse gas turbine combustor, sector combustion test was performed. Ignition test by using torch ignition system was carried out at the various combustor inlet velocity and air fuel ratio. Also, flame blow out limit was measured by changing fuel flow rate with constant air mass flow rate. In the test results, stable ignition is possible at air excess ratio of 6 and this limit is gradually increased with combustor inlet velocity. The minimum blow out limit is about 4 at 40 m/s of combustor inlet velocity. This blow out limit is also increased up to about 10 with increasing combustor inlet velocity. Test result shows that lean blow out limits are increased with air velocity. The highest blow out limit was found at the combustor inlet velocity of 65m/s.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.181-189
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• 2017

This paper describes experimental results on combustion characteristics with hydrogen contents of synthetic natural gas (SNG) in low swirl combustor. To investigate the effect of hydrogen contents for premixed SNG flame, stability map, CH chemiluminescence images, flame spectrum analysis and emission performances were measured. In the results, as the hydrogen content was increased, the lean flammable limit was expanded and the flame length was decreased. The hydrogen contents affected the flame liftoff height, and it has different tendency according to the equivalence ratio and flame shape. The change of height and length of flame according to hydrogen contents is caused by the fast burning velocity of hydrogen, which can be confirmed by GRI 3.0 reaction mechanism in PREMIX code. The intensity of $OH^*$, $CH^*$ and $C_2^*$ was confirmed by spectrum analysis of flame. As a result, the $CH^*$ intensity was not significantly different according to hydrogen content. The increase of hydrogen contents influenced positively CO and NOx emission performances.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.1
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• pp.359-368
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• 1996

For fuel economy and pollutant reduction, the interests in lean burn has increased recently. The purpose of this research is to develop a High Frequency Ignition System (HIS) that can make powerful ignition. We studied relations between performance of HIS and probability of inflammation under various ignition conditions. It is concluded that the portion of capacitance energy to the total energy is comparatively larger and that the optimum spark interval and spark duration are dependent upon conditions of Constant Volume Combustion Chamber.

• Journal of the Korean Institute of Gas
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• v.17 no.1
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• pp.7-12
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• 2013

As emission regulation for vehicle has been reinforced, many researches carried out for HCNG(hydrogen-natural gas blends) fuel to the conventional compressed natural gas (CNG) engine. However, abnormal combustion such as backfire, pre-ignition or knocking can be caused due to high combustion speed of hydrogen and it can result in over heating of engine or reduction of thermal efficiency and power output. In the present study, improvement of combustion performance was observed with HCNG fuel since it can extend a flammability limit. Knocking characteristics for CNG and HCNG fuel were investigated. Feasibility of HCNG fuel was evaluated by checking the knock margin according to excess air ratio. The operation of engine with HCNG was stable at minimum advance for best torque(MBT) spark timing and knock phenomena were not detected. However, it is necessary to prepare higher knock tendency since possibility of knock is higher with HCNG fuel.

• Journal of Power System Engineering
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• v.12 no.4
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• pp.5-11
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• 2008

The RI gasoline engine haying a sub-chamber had a high cycle variation due to the difficulty of the residual gas scavenge in the sub-chamber. To solve this problem and improve the combustion performance of RI engine, we devised a method to inject directly CNG fuel into the sub-chamber. A DI diesel engine of single cylinder was converted into a RI-CNG engine and an electronic control unit for the engine was manufactured. In this study, the combustion characteristics of the RI-CNG engine were investigated with the injection timings and air excess ratios at the load conditions of 50% throttle open rate and 1700rpm. As the results from this study, the RI-CNG engine worked reliably under the condition of the ignitable lean limit of $\lambda=1.7$ by showing the $COV_{imep}$ below about 5%. And the highest thermal efficiency could be obtained in the injection timing that produced the high imep and the low $COV_{imep}$ at the same time. The CO emission concentration indicated very low values and the THC and $NO_x$ showed an opposite pattern. With a view to improving the thermal efficiency and reducing the harmful emissions, the proper control region of the ignition timing and the mixture ratio were nearly ATDC $20^{\circ}\sim50^{\circ}$ and $\lambda=1.4$ respectively.

• Journal of ILASS-Korea
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• v.10 no.2
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• pp.1-9
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• 2005

An experimental study was carried out to obtain the fundamental data about the effects of radical ignition on premixture combustion. A CVC(constant volume combustor) divided into the sub-chamber and the main chamber was used. Numerous narrow passage holes are arranged between the main chamber and the sub-chamber. The products including radicals generated by spark ignition in tile sub-chamber derives the simultaneous multi-point ignition in the main chamber. We have examined the effects of the sub-chamber volume, the diameter and number of passage holes, and the equivalence $ratio({\Phi})$ on the combustion characteristics by means of burning pressure measurement and flame visualization. In a CVC, the overall burning time including the ignition delay became very short and the maximum burning pressure was slightly increased by the radical ignition(RI) method in comparison with those by the conventional spark ignition(SI) method. Combustible lean limit by RI method is extended by ${\Phi}=0.25$ compared with that by SI method. Also, In cases of charging the number and the diameter for the fixed total cross section of the passage holes, combustion period increased significantly at a sub-chamber with a single hole, but those of the other conditions had almost a similar tendency in the sub-chamber with 4 or more holes. regardless of equivalence ratio. Therefore, it was Proved that a critical cross section exists with the number of passage holes.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.60-69
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• 2013

An optimum configuration of the hybrid/dual swirl jet combustor for a micro-gas turbine was investigated experimentally. Location of pilot nozzle, angle and direction of swirler vane were varied systematically as main parameters under the conditions of constant thermal load. The results showed that the variation in locations of inner fuel nozzle and pilot burner resulted in significant change in flame shape and swirl intensity due to the changes in recirculating flow pattern and minimum flow area near burner exit, in particular, with the significant reduction of CO emission near lean-flammability limit. In addition, it was observed that the co-swirl configuration produced less CO and NOx emissions compared to the counter-swirl configuration.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.251-257
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• 2012

This work presents an experimental investigation of NOx emissions according to inlet air temperature (550-660 K), stoichiometric air ratio (${\lambda}$, 1.4-2.1), and elevated pressure (2-5 bar) in a High Press Combustor (HPC) equipped with a double cone burner, which was designed by Pusan Clean Coal Center (PC3). The exhaust-gas temperature and NOx emissions were measured at the end of the combustion chamber. The NOx emissions generally decreased as a function of increasing ${\lambda}$. On the other hand, NOx emissions were influenced by ${\lambda}$, inlet air temperature and pressure of the combustion chamber. In particular, when the inlet air temperature increased, the flammability limit was extended to leaner conditions. As a result, a higher adiabatic temperature and lower NOx emissions could be achieved under these operation conditions. The NOx emissions that were governed by thermal NOx were greatly increased under elevated pressures, and slightly increased at sufficiently low fuel concentrations (${\lambda}$ >1.8).

• Journal of the Korean Institute of Gas
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• v.13 no.4
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• pp.46-52
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• 2009

Hydrogen can extend the lean misfire limit to a large extent when it is mixed with conventional fuels for an internal combustion engine. This study is about fuel reforming to produce hydrogen enriched gas as a fuel for engine. Especially gasoline, which consists of numerous hydrocarbon fuels, considered as source of reformed gas. Various hydrocarbons, including commercial fuel were reformed and potentialities of reformed gas on vehicles were accessed. The reforming efficiency and hydrogen yield were observed. Maximum hydrogen yield were found with different gas hourly space velocity(GHSV) and O2/C ratio of reforming conditions.