Prechamber Spark Plug Research Articles

Investigation on the lean-combustion characteristics of non-uniform orifice pre-chamber spark plug in low engine speed working conditions compared with high energy spark ignition

For a long time, pre-chamber jet ignition has been an effective method to achieve stable lean-combustion of the engine. However, due to the lack of an additional fuel injector, the passive pre-chamber easily leads to unstable combustion and even misfires during the engine’s low-speed working conditions. This study used simulation and optical single-cylinder engine visualization experiments to investigate the ignition and combustion performance of the pre-chamber spark plug (PCSP) ignition system and different orientations of the scavenging jet nozzle in the cylinder. The results indicate that the PCSP at low speed (1200 r/min) can improve the lean-combustion load performance by up to 6.7% compared with traditional high-energy spark ignition but cannot significantly improve the lean combustion limit and stability. In addition, under each λ condition, the scavenging jet nozzle face toward one of the intake valves (IV2) is most advantageous. The effect of lean combustion on reducing NO began to manifest after λ > 1.3 and achieved the best at 1.6. This kind of jet ignition pre-chamber provides a more stable ignition solution than high-energy spark ignition for low speed and medium/low load aspects.

Experimental Study of the Performance of Turbo-Charged Gasoline Direct-Injection Engine Based on Different Pre-Chamber Structures

In this paper, in order to improve the fuel economy of the actual application of the engine under multi-operating conditions, an experimental study is carried out on a turbo-charged direct-injection engine based on different pre-chamber structures. The engine used for the study is a four-cylinder turbo-charged direct-injection gasoline engine with different structures of pre-chamber spark plugs. The operating conditions in this study include load characteristics at 2000 r/min and characteristic loads at different speeds, including 3000 r/min, 3200 r/min, and 3600 r/min. With stable BMEP or fully open throttle and pedal, the experiment was conducted by the spark angle scanning method to collect data of engine power, economy, and emission under each condition. It was found that the pre-chamber structure has a direct effect on engine performance, with a clear load demarcation line for its effect. Under the WOT condition, the power of pre-chamber ignition is 1.6% higher than that of conventional spark plugs; at the low load of 2 bar, the economy of pre-chamber ignition is degraded by 6%; at the medium load of 8 bar, the economy of the two is comparable; at the large load of 16 bar, the fuel economy proves advantageous. Compared with conventional spark plugs, the pre-chamber spark angle can be advanced by 2~3 °CA, and the pre-chamber ignition with separate ground electrodes is highly reliable. The emission levels of the pre-chamber spark plugs and conventional spark plugs are comparable at all loads.

Optical and Thermodynamic Investigations of a Methane- and Hydrogen-Blend-Fueled Large-Bore Engine Using a Fisheye Optical System

The following paper presents thermodynamic and optical investigations of hydrogen-enriched methane combustion, showing the potential of a hydrogen admixture as a means to decarbonize stationary power generation. The optical investigations are carried out through a fisheye optical system directly mounted into the combustion chamber, replacing one exhaust valve. All of the tests were carried out with constant fuel energy producing 16 bar indicated mean effective pressure. The engine under investigation is a port-fueled 4.8 L single-cylinder large-bore research engine. The test series compared the differences between a conventional spark plug and an unscavenged pre-chamber spark plug as an ignition system. The fuel blends under investigation are 5 and 10%V hydrogen mixed with methane and pure natural gas acting as a reference fuel. The thermodynamic results show a beneficial influence of the hydrogen admixture on both ignition systems and for all variations concerning the lean running limit, combustion stability and indicated efficiency, with the most significant influence being visible for the tests using conventional spark plugs. With the unscavenged pre-chamber spark plug and the combustion of the 10%V hydrogen admixture, an increase in the indicated efficiency of 0.8% compared to NG is achievable. The natural chemiluminescence intensity traces were observed to be predominantly influenced by the air–fuel equivalence ratio. This results in a 20% higher intensity for the unscavenged pre-chamber spark plug for the combustion of 10%V hydrogen compared to the conventional spark plug. This is also visible in the evaluations of the flame color derived from the dewarped combustion image series. The investigation of the torch flames also shows a difference in the air–fuel equivalence ratio but not between the different fuels. The results encourage the development of hydrogen-based fuels and the potential to store surplus sustainable energy in the form of hydrogen in existing gas grids.

Hybrid powertrains with dedicated internal combustion engines are the perfect basis for future global mobility demands

In order to still reach the 1.5°C or at least 2°C target, a rapid and significant reduction in the CO2 contribution of all sectors must be achieved. The transport sector in particular has a duty here, as it contributes around 20% to global CO2 emissions and this figure has increased rather than decreased in recent decades as a result of a drastic increase in passenger and freight kilometers.The automotive industry is already making a strong contribution to this through an increasing number of electric vehicles in new vehicle registrations. However, this will not be sufficient, because on the one hand the increase of vehicles in the market is due to several reasons happening not fast enough, and on the other hand the electricity available for the vehicles will not be generated fast enough from fully renewable electricity sources.So as long the supply of regenerative electricity is not sufficient, and as long there are above all many places and applications in the world where a switch to pure electromobility will not be possible in the short and medium term, other highly efficient drive systems will have to be offered in parallel. Highly efficient because only in this way can the valuable energy, from whatever source, be used extremely sparingly.In order to evaluate to what extent hybrid powertrains can contribute to a reduction of the CO2 pollution of the transport sector, this paper deals with the virtual investigation of different hybrid powertrains. In a first step, it is deduced why hybrid powertrains are fundamentally interesting and what potential they have if they are consistently optimized for maximum efficiency. It becomes clear that there is considerable potential in them and that, with consistent further development, they can actually come very close to the future CO2 fleet limits. To achieve this, however, all powertrain components must be optimized. For this reason, a further section presents technologies, such as Pre-Chamber Spark Plugs (PCSP) and technology packages for internal combustion engines that have been optimized specifically for use in hybrid powertrains and achieve Break Thermal Efficiency (BTE) levels of more than 45%.Finally, in the last major chapter, various hybrid topologies are combined with the presented high-efficiency internal combustion engines from chapter 2 and are evaluated in a large simulation study. With the aim to achieve a maximum overall powertrain efficiency under real world driving conditions a combination of a parallel and a serial topology seems most promising.Due to their efficiency and conservation of energy resources, hybrid powertrains have the potential to meet a significant share of future global mobility needs.

Composition of Particulate Matter Emitted from Lean Burn Gas Engine with Pre-chamber Spark-plug Ignition System and Comparing Emissions with Those from Diesel Engines

When investigating the sources of particulate matter (PM) and its reduction methods, it is important to clarify its composition. In this study, PM emitted from a lean burn gas engine with a pre-chamber spark plug ignition system was analyzed by quantifying emission factors of PM components, namely Elemental Carbon (EC), Organic Carbon (OC), sulfate and nitrate, as well as “the other components” . These emission factors were compared with previous results of PM constituents emitted from diesel engines in an attempt to gauge how this gas engine could contribute to reducing PM emissions. At 75% engine load, the percentages of EC, OC, sulfate and nitrate in PM were less than 3%, 70%, less than 1% and 10% respectively with the other components being the remaining 18%. The low proportion of EC was caused by lean fuel conditions inside the gas engine. OC, which accounted for a majority of PM, is thought to have derived from vaporized lubricant oil. A slight amount of sulfur may have originated in either sulfur contents in lubricant oil or odorous components in city gas. At any engine load, the gas engine’s PM emissions were more than 70% lower than those from diesel engines. Two-thirds of reductions in PM emissions came from EC and the remaining one-third were due to a drop in emissions of the other components.

Zero Emission - The Evolution from Natural Gas to Hydrogen Using a Pre-chamber Spark Plug

Zero Emission - The Evolution from Natural Gas to Hydrogen Using a Pre-chamber Spark Plug

The effect of equivalence ratio, temperature and pressure on the combustion characteristics of hydrogen-air pre-mixture with turbulent jet induced by pre-chamber sparkplug

The pre-chamber sparkplug mode can increase the combustion velocity because it can induce the turbulent jet into the cylinder. Higher combustion velocity can increase the brake thermal efficiency and decrease the knock tendency for hydrogen engines. To explore the effect of pre-chamber sparkplug mode on the combustion characteristics of the hydrogen-air mixture, different equivalence ratios, initial pressures and temperatures were selected to study in a constant volume combustion chamber working with pre-chamber sparkplug mode and normal sparkplug mode. The results showed that the pre-chamber sparkplug mode can accelerate the combustion velocity, increase maximum combustion pressure and decrease the combustion duration at all initial conditions. The maximum combustion pressure of pre-chamber sparkplug mode occurred at the equivalence ratio of 1.0 while it occurred at the equivalence ratio of 1.2 with normal sparkplug mode, which means pre-chamber sparkplug mode can increase the higher brake thermal efficiency and power. The combustion intensity of pre-chamber sparkplug mode was bigger than 1 and the biggest value occurred at the equivalence ratio of 0.6. Moreover, the combustion intensity of pre-chamber sparkplug mode was higher with lean equivalence ratios than that of rich equivalence ratios. Increasing the initial pressure can increase maximum combustion pressure and combustion velocity obviously for pre-chamber sparkplug mode, which was different from the normal sparkplug mode. The initial temperatures had little impact on the combustion intensity. These results showed the pre-chamber sparkplug mode was more suitable to be used in the boosting hydrogen engines to improve the performance.

The effect of turbulent jet induced by pre-chamber sparkplug on combustion characteristics of hydrogen-air pre-mixture

Effect of turbulent jet ignition induced by pre-chamber sparkplug (PCSP), a simper version of turbulent jet ignition pre-chamber system without fuel injection, on the air-hydrogen combustion characteristics was conducted based on an optical constant volume chamber under varied equivalence ratio conditions. The dynamic pressure sensor and schlieren system were used to evaluate the heat release and flame propagation characteristics. The results confirm the feasibility of PCSP type turbulent jet. The jet increase the flame propagation speed significantly compared to standard ignition, which shorten ignition delay and combustion duration, advance T50 largely, and increase the maximum combustion pressure slightly. As a result, the combustion intensity is increased largely, especially under lean regime, the combustion intensity index can be as high as 1.7 at certain equivalence ratio. In addition, the PCSP turbulent jet reduces the sensitivity of heat release to variation of equivalence ratio, which is helpful to simplify the combustion controlling strategy. Furthermore, with the enhancement of the flame propagation, the tendency of knocking combustion can be suppressed potentially.

Development of a Pre-chamber Spark Plug of Gas Engine for Heat Pump Air-conditioner

Development of a Pre-chamber Spark Plug of Gas Engine for Heat Pump Air-conditioner

Activities for high-efficiency small gas engines

Interest in the potential of natural gas is growing, owing to its low CO2 emissions per unit of heat produced, and to the development of techniques for the exploitation of shale gas. Research and development relating to natural gas is also being pursued in view of its potential to increase Japan’s energy security, because deposits are found around the world.Osaka Gas is pursuing the medium-to-long term development of gas engines. Increasing compression ratio, improving combustion under lean combustion conditions, and increasing specific output will be key to improving thermal efficiency. This paper summarizes the results of tests Osaka Gas to date with a view to improving the efficiency of small gas engines.First, tests with downsizing through forced induction were conducted. A naturally aspirated gas engine with a displacement of 3318 cm3 was fitted with a high-efficiency turbocharger, and performance tests were conducted at brake mean effective pressure (BMEP). It was found that thermal efficiency under lean conditions reached 40%, but that NOx emissions exceeded 1500ppm. When exhaust gas recirculation (EGR) was applied with a view to reducing NOx emissions, at the EGR limit (EGR ratio 18%), thermal efficiency was around 39% (NOx 500ppm). With stoichiometric combustion, at the EGR limit, thermal efficiency reached a maximum of 39%.Next, the effectiveness of multi-point ignition, pre-chamber spark plugs and homogeneous charge compression ignition (HCCI) in improving lean/diluted combustion were studied, and each was found to improve stability, extend the lean limit and increase thermal efficiency under lean combustion conditions.Studies were also conducted in relation to the dedicated EGR system proposed by Southwest Research Institute (SwRI) as a means of improving EGR. It was determined that around 9% H2, which has a combustion-promoting effect, was produced under conditions where the equivalence ratio was 1.5.

Investigation of Performance and Emission Characteristics of a Heavy Duty Natural Gas Engine Operated with Pre-Chamber Spark Plug and Dilution with Excess Air and EGR

This article deals with application of turbulent jet ignition technique to heavy duty multi-cylinder natural gas engine for mobile application. Pre-chamber spark plugs are identified as a promising means of achieving turbulent jet ignition as they require minimal engine modification with respect to component packaging in cylinder head and the ignition system. Detailed experiments were performed with a 6 cylinder 9.4 liter turbo-charged engine equipped with multi-point gas injection system to compare performance and emissions characteristics of operation with pre-chamber and conventional spark plug. The results indicate that ignition capability is significantly enhanced as flame development angle and combustion duration are reduced by upto 30 % compared to those with conventional spark plugs at certain operating points. Maximum possible dilution (limited by combustion stability index, Coefficient of Variation (COV) of Gross Indicated Mean Effective Pressure (IMEPg)) with excess air and EGR were investigated experimentally at engine speed of 1500 rpm and 5, 12 and 18 bar IMEPg operating load and results indicate that the lean limit is extended by 0.8-1 Lambda unit and 5-8% EGR rate units. It was also observed that pre-chamber spark plugs cause charge pre-ignition at loads exceeding 10-12 bar IMEPg. To avoid this, the minimum amount of dilution, with excess air and then EGR, which is required to operate above 10 bar IMEPg was estimated experimentally. Finally, to compare performance and emission characteristics of operation with these two ignition techniques, the engine was tested on an ESC-like (European Stationary Cycle) 12 mode cycle. Results indicated marginal reduction in cycle averaged NOx emissions with maximum excess air dilution and about 50% reduction with maximum EGR dilution, whereas CO and HC emissions increased. Other operating characteristics like the flame development angle, combustion duration, brake efficiency etc. are also compared for the tested operating range of the test engine. (Less)

B109 天然ガスエンジン用プレチャンバープラグの開発(OS3 省エネルギー・コジェネ技術),動力エネルギーシステム部門20周年,次の20年への新展開)

As the interest in environmental issues increases, the cogeneration system has recently been attracting much attention. Particularly, the use of gas engines for cogeneration systems with low emission and high thermal efficiency is now expected to become widespread. For improving thermal efficiency, it is necessary to extend the lean limit and accelerate combustion. In this study, attention was focused on "Pre-chamber Spark Plug", which has a pre-chamber at the tip of the standard plug. We studied the effects of using a pre-chamber spark plug for 300kW to 2MW gas engines with a single-cylinder test engine. By the pre-chamber plug, the lean limit was extended and the thermal efficiency was improved.

A Stusy of Pre-chamber Spark Plug for Gas Engine

A Stusy of Pre-chamber Spark Plug for Gas Engine