Glow Plug Research Articles

Effect of ceramic coating on the performance, emission, and combustion characteristics of ethanol DI diesel engine

Ethanol and vegetable oils played an important role for more than 70 years in many countries all over the world. Since 19th century, ethanol has been used as fuel for Compression Ignition (CI) engines. By fermenting and distilling the biomasses, ethanol can be obtained and hence it can be considered as a renewable fuel. One way of increasing the efficiency of the ethanol fuel CI engine is to use it as a Low Heat Rejection Engine (LHR). In LHR engine, the thermal efficiency of the CI engine can be increased by reducing the heat loss to the surroundings through coolant and exhaust gas. The heat can be transferred from the combustion chamber to the piston, cylinder wall and finally to the cooling water. The heat transfer can be minimized by insulating the piston and cylinder wall and coating the piston and the cylinder wall with ceramics, which can withstand high thermal stresses. The coating materials have low thermal conductivity, thus reducing the heat flux into the piston and thus the heat transfer to the coolant is reduced. In the present work, Zirconia is used for coating the engine components for lower thermal conductivity. It is concluded that sole ethanol as fuel with glow plug show a reduction in exhaust emissions with reduced efficiency compared with conventional CI engine operated with diesel fuel. But it was observed that, there is a slight increase in thermal efficiency of the engine with the retarded injection timing. Converting a conventional engine to low heat rejection diesel engine further increases the thermal efficiency and reduces the carbon monoxide and unburned hydrocarbon emissions drastically, whereas oxides of nitrogen emission are increased because of higher combustion temperature.

Effect of hydrogen addition on the operating characteristics of a free piston linear engine

A free piston linear engine (FPLE) with glow plug ignition was designed and manufactured. This paper investigated effects of hydrogen addition on the FPLE performance and emission characteristics. Experimental results showed that the FPLE can be started manually and then steady FPLE operating state is achieved. Compared with the crankshaft model engine, the FPLE has a greater speed around the top dead centre. The peak acceleration of the FPLE (4100 m/s2) is more than three times greater than that of the crankshaft model engine. Results also showed that the FPLE performance including the indicated power, indicated thermal efficiency and indicated mean effective pressure improves remarkably with hydrogen addition. The optimal FPLE performance is achieved when the hydrogen volume fraction is 4%. However, the engine performance cannot be further improved when the hydrogen volume fraction continues to increase due to the occurrence of over-advanced combustion phasing. Moreover, the FPLE operating range is significantly broaden and the operating stability is improved with hydrogen addition since the fast burning speed and wide flammability of hydrogen. Besides, the heat release rate, in-cylinder peak pressure and pressure rise rate are also obviously enhanced. The high-speed flame images showed the flame color becomes lighter and the yellow area is smaller compared with that of pure methane condition, indicating that the hydrogen addition to the fuel contributes to burn completely and reduce the soot formation.

Experimental investigation on ignition and combustion characteristics of n-butane/air mixtures by glow plug in miniature chamber

The aim of this work is to understand the ignition and combustion behaviors of n-butane/air mixtures under glow plug ignition in the start-up condition of miniature IC engines. We utilized a centimeter-scale constant-volume chamber setup to investigate the effects of glow plug heating power, equivalence ratio, and initial pressure on the characteristics of ignition and flame propagation of n-butane/air mixtures. Results indicated that the ignition time and ignition temperature decrease as the heating power increases and the flame propagation time is weakly sensitive to that. Increasing the initial pressure can reduce the ignition time, decrease the ignition temperature and slow flame propagation; except for the flammable limit, the ignition time and ignition temperature increase as the equivalence ratio increases, in addition, the flame propagation is fastest at φ = 1.2. Furthermore, an obvious two-stage combustion phenomenon was observed under fuel-rich flame propagation conditions. Overall, the order of influencing factors on the ignition characteristics shows heating power > initial pressure > equivalence ratio, and that on the flame propagation characteristics shows equivalence ratio > initial pressure > heating power in present experimental conditions.

Failure analysis of diesel engine glow plugs

The implementation of start-stop technology in modern cars requires improvements of several elements of the internal combustion engine start-up system. In the present study, we have been focused on the failure phenomena of diesel engines glow plugs and attempts to extend their lifespan. The investigation revealed that the most sensitive element of the glow plug is a heating coil made of FeCrAl (Kanthal AF®) wire. Despite excellent anti-oxidation properties of these alloys, provided by the formation of a protective alumina scale on the alloy surface, the oxidation resistance is limited when exposed to thermal cycling up to 1050 °C. The reason is cracking and constant re-formation of the alumina protective scale and consequent consumption of the aluminium in the subsurface area of the wire. To prevent premature failure of heating coils, powder pack aluminization was implemented to increase the aluminium content in the subsurface of the alloy and thus the possibility of easier re-formation of the protective alumina scale. Phenomena that lead to failure of the glow plug were studied by X-ray computerized tomography (CT), optical microscopy (OM), scanning electron microscopy (SEM-EDXS), and microhardness measurements (HV). Comparison between aluminized and untreated samples is outlined and microstructural changes during thermal cycling and isothermal annealing discussed.

Study on HCCI combustion improvement by using dual assisted compression ignition (DACI) on a hydraulic free piston engine fueled with methanol fuel

A dual assisted compression ignition combustion mode is researched on a hydraulic free piston engine. The dual assisted compression ignition combustion mode is realized by combining a glow plug with a spark plug in the ignition system to assist the homogeneous charge compression ignition combustion. The effects of control parameters and operating parameters on dual assisted compression ignition combustion mode are revealed by experiments. It is found that as the compression ratio increases, the combustion characteristics of dual assisted compression ignition change from spark ignition to two-stage heat release. The dual assisted compression ignition combustion has more controllability on the combustion phase and the heat release rate than glow plug assisted compression ignition due to the direct and stable spark ignition. When the temperature of the glow plug is lower, the heat release phase is dominated by the spark plug. With the temperature further increases, the heat release process is mainly controlled by the glow plug. The dual assisted compression ignition combustion has a wider compression ratio range than spark assisted compression ignition to guarantee the high indicated thermal efficiency. The suitable methanol/air equivalence ratio range for dual assisted compression ignition combustion mode is between 0.6 and 0.8.

Исследование пусковых свойств вихрекамерных дизелей средств коллективного спасения экипажей морских судов магнитной обработкой топлива

The paper considers the diesel engines as the hearts of the lifeboat power plants 
 of all types of vessels: sea, river and mixed navigation, according to the International Convention on the Protection of Human Life at Sea - SOLAS. In the Russian Federation there are two types 
 of engines produced for this purpose: 4-9.5/11 (“Kaspiy 30”) with vortex-chamber mixing and 
 4-9.5/11 (“Kaspiy 40”) with a combustion chamber in piston and volume-film mixing. The Kaspiy 40 engine is characterized by good starting properties and does not require additional acceleration of the launch. The Kaspiy 30 engine, due to the design of the combustion chamber, must be equipped with a fuel mixture heating device in the combustion chamber, which must work before the engine reaches a stable mode of operation. This device is glow plugs powered by a rechargeable battery and connected sequentially, so that failure of one plug entails the inoperability of the entire chain. If the rescue operation is necessary, the lifeboat engines must be started on deck without 
 a coolant (sea water) in the cooling system and must work for at least 10 - 15 minutes until the crew gets into the boat and the boat is launched, after which the cooling system will take the sea water. If the glow plug system fails, especially when the ambient temperature is low, the start of the engine in the prescribed time may not take place at all. There has been studied the effect of magnetic treatment of fuel before the launch and during the launch on the activation energy of fuel molecules and their reaction in the combustion without external heat

Hot surface ignition dynamics in premixed hydrogen–air near the lean flammability limit

The dynamics of ignition of premixed hydrogen–air from a hot glow plug were investigated in a combined experimental and numerical study. Surface temperatures during heating and at ignition were obtained from 2-color pyrometry, gas temperatures were measured by high-speed Mach–Zehnder interferometry, and far-field effects were captured by high-speed schlieren imaging. Numerical simulations considered detailed chemical kinetics and differential diffusion effects. In addition to the known cyclic (puffing) combustion phenomenon, singular ignition events (single puff) were observed near the lean flammability limit. Detailed analysis of the results of our numerical simulations reveal the existence of multiple combustion transients within the thermal boundary layer following the initial ignition event and, at late times, sustained chemical reaction within a thermal plume above the glow plug. The results have significant implications for ignition from hot surfaces within near-flammability limit mixtures, at the edge of plumes resulting from accidental release of hydrogen, or within the containments of nuclear power plants during severe accidents.

Performance, Emission and Combustion of LPG Diesel Dual Fuel Engine Using Glow Plug

Performance, Emission and Combustion of LPG Diesel Dual Fuel Engine Using Glow Plug

Experimental study on the operating characteristics of a reciprocating free-piston linear engine

A miniature reciprocating free-piston linear engine (FPLE) with glow plug ignition (GPI2) was designed and manufactured. The steady-state operation of the prototype is successfully achieved with and without load. The operating characteristics of the FPLE were investigated using a premixed methane/air mixture. The experimental results showed that the in-cylinder mixture was successfully ignited by the glow plug within five cycles and the FPLE could be successfully started under the single-cylinder self-starting strategy. Based on the comparison of the FPLE operating characteristics in the GPI and spark-ignition (SI3), it is found that the performance and operating stability of the FPLE were significantly improved in the GPI due to the flexible ignition timing. Besides, the effects of key parameters such as glow plug heating power (GPHP4), piston assembly mass and fuel/air flow rate on the performance of the FPLE were studied. The electric power and work conversion efficiency increased first and then decreased with increasing external load, and both of them reached maximum values of 31.6 W and 42.8%, respectively, with an external resistance of 6.3 Ω.

A comprehensive analysis of multiple injection strategies for improving diesel combustion process under cold-start conditions

Cold start in diesel engines is an issue of increasing importance due to its high fuel consumption and emissions. In cold-start operations, improving the combustion process is directly related to improving the thermal efficiency and emissions. In this study, a comprehensive analysis of multiple injection strategies was conducted under cold-start conditions to identify an optimal injection strategy that improves diesel combustion process at various ambient temperatures. The cold-start conditions were reproduced in a constant volume combustion chamber (CVCC). While all of the sprays in a single injection strategy were successfully ignited at 293 K, only the sprays near a glow plug showed combustion reactions at 253 K. The low air and diesel temperature at 253 K inhibited the diesel vaporization, which led to the poor combustion development. Pilot injections were implemented to improve the diesel vaporization at 253 K. The pilot injections had a small amount of heat required to vaporize diesel droplets, which reduced the temperature drop in the combustion chamber. The pilot injections also released small amounts of heat prior to the following main injection, thus aiding the vaporization of the main injection. The triple and quadruple injections improved the combustion process significantly at 253 K. However, the double and triple injections showed superior heat release rate and in-chamber pressure rise at 293 K. Based on the results at 253 K and 293 K, the triple injection strategy were determined to be the optimal injection strategy under cold-start conditions.

Analysis of the efficiency of the in-cylinder catalyst to reduce exhaust emissions during the cold start combustion engine

The article concerns the use of an in-cylinder catalyst that allows reducing the exhaust emissions during diesel engine operation. This is an additional method of exhaust emission reduction – however, the active component is placed inside the combustion chamber – hence much closest to the combustion process. This allows reducing the emissions at the very source (catalyst applied on the glow plugs). Such solutions are necessary because the reduction of exhaust emissions from vehicles is a key aspect of reducing the negative impact of transport on the environment.

A numerical study on the effect of thermal and charge stratification on the HCCI natural gas engine

The applications of homogeneous charge compression ignition (HCCI) engine are still limited due to the absence of a definite means to control ignition timing and narrow the operating region. It was found that thermal stratification and charge stratification strategies bring forward good potential to achieve the staged combustion with reduced pressure-rise rates. In this study, a single cylinder engine and a CFD simulation are applied to investigate the combustion processes in the stratified HCCI engine. To obtain thermal and charge stratification on the combustion chamber, exhaust gas recirculation (EGR), glow plug and simulated reformer gas (RG) of CO–H2 mixture are used. Increasing EGR at constant lambda line decreases the maximum achievable power, while at the constant increasing lambda at each constant EGR decreases the indicated mean effective pressure. EGR expands combustion duration hence smoother and quieter operation is achieved. Increasing reformer gas blend fraction considerably expands the operating region toward the lean side. Advancing combustion timing at constant energy flow and intake temperature stem from using glow plug in the combustion chamber, while with increasing mean in-cylinder temperature, combustion duration is prolonged. Abbreviations: 3D: Three-Dimensional; CAD: Crank angle degree; CI: Compression ignition; EGR: Exhaust gas recirculated; HCCI: Homogenous charge compression ignition; NOx: Nitrogen oxides; PM: Particular matter; PRFs: primary reference fuels; RG: Reformer gas; rpm: Revolution per minute; SI: Spark ignition; TB: Third body; THC: total hydrocarbon; UHC: Unburned hydrocarbon

Experimental and numerical study of the ignition of hydrogen-air mixtures by a localized stationary hot surface

The ignition of hydrogen-air mixtures by a stationary hot glow plug has been experimentally investigated using two-color pyrometry and interferometry. The ignition process was characterized by the surface temperature at ignition, as well as by the location where the initial flame kernel was formed. The experimental results indicate that: (i) the ignition temperature threshold is a function of equivalence ratio; (ii) the ignition location is a function of the rate at which the glow plug is heated because high heating rates favor non-uniform heating. As a result, ignition occurs on the side rather than near the top face of the glow plug. Comparison with two-dimensional numerical simulations exhibits discrepancies in terms of the temperature threshold value and dependence on equivalence ratio. Simulations performed imposing a non-uniform surface temperature show that a temperature difference between the side and the top of the glow plug as low as 12.5 to 25 K resulted in side ignition for hydrogen-air mixtures. The effect of surface chemistry was estimated numerically by imposing a boundary condition of zero species concentration for intermediate species, H and HO2, at the hot surface, which increased the ignition threshold by up to 50 K for an initial H2 concentration of 70%. The present study shows that surface temperature non-uniformity, heterogeneous chemistry and reaction model used, could influence the experimentally reported and numerically predicted ignition threshold as well as the location of ignition.

Performance Enhancement of a Small Two-Stroke Engine Using Nitromethane Blends

Increasing demand for unmanned aerial vehicles (UAVs) calls for a better understanding of its propulsion system. The present study characterizes a small two-stroke glow plug engine for up to 10 kg class of UAVs. To enhance the specific power output of the engine, nitromethane was used as a fuel additive. Understanding the effect of nitromethane concentration on the engine characteristics is the key objective of this present study. An engine test rig has been built to test a small two-stroke engine. The engine was run at various equivalence ratios. Engine characteristics such as thrust, RPM, torque, power, brake-specific fuel consumption (BSFC), and brake thermal efficiency (BTE) have been measured and compared with the base methanol fuelled engine. The results show around a 24% rise in the engine thrust with 40% (by mass) of nitromethane addition to methanol fuel. Energy balance analysis was carried out to show that the increased thrust is due to enhanced combustion efficiency with nitromethane addition. Hence, it is proposed that nitromethane blends can be used in short bursts whenever a large thrust is required by the UAV.

Laminar Burning Speeds of Nitromethane-Gasoline Blends at Elevated Temperatures and Pressures

Nitromethane is extensively used in drag races and in glow plug unmanned aerial vehicle (UAV) engines. However, it has not been analyzed in the combustion literature enough. Nitromethane has a low stoichiometric air–fuel ratio; it can be blended with gasoline and used in larger quantities to enhance the power output of the internal combustion (IC) engines. This could find potential use in burgeoning UAV industry. The present investigation aims at experimentally determining the laminar burning speeds of nitromethane—gasoline blends at different equivalence ratios. Tests were conducted at both ambient conditions and at elevated temperatures and pressures. A constant volume combustion chamber (CVCC) was constructed and instrumented to carry out the investigation. The pressure rise in the chamber due to combustion was acquired and analyzed to determine the laminar burning speeds. The results showed that with an increase in the nitromethane concentration in gasoline, the laminar burning speeds for all the initial conditions also increased. With the rise in initial temperatures, the laminar burning speeds were observed to increase. However, a drop was observed with a rise in the initial pressures for all the blends. The obtained results for pure gasoline were compared with existing literature. A good match was observed. The investigation also aims at providing vital experimental data, which can be used for computational fluid dynamics validation studies later.

Oxidation of n-hexane in the vicinity of the auto-ignition temperature

The present study examines the possibility of inerting flammable mixtures (making the mixtures non-explosive/non-flammable) using a long duration thermal process close to but below the auto-ignition temperature. Experiments were performed in a stainless steel cell and a Pyrex cell. A Mid-IR FTIR spectrometer, a UV–vis spectrometer and several IR laser diodes were employed to monitor the gas-phase composition. Experiments were performed for n-hexane-air mixtures with Φ = 0.67–1.35. The temperature and pressure were T = 420–500 K and P = 37–147 kPa. Experiments were performed over period of up to 7200 s. At temperatures close to 420 K, the chemical activity is characterized by a slow and constant reaction rate. At temperatures close to 500 K, the reaction proceeds in two-phases: 1) rapid production of CO2, CO and carbonyls, identified as hydroperoxy-ketones, followed by 2) a period of slower production of CO2 and H2O and consumption of hydroperoxy-ketones. At the end of the thermal treatment, the possibility of igniting the mixtures using a large hot surface (representative of low-temperature ignition source) and a stationary concentrated hot surface (representative of high-temperature ignition source) was tested. The low-temperature flammability was verified by rapidly increasing the temperature of the test cell wall whereas the high-temperature flammability was verified by turning on a glow plug. The inerting strategy seems effective in preventing the low-temperature ignition but high-temperature ignition was always observed. .

The impact of using an in-cylinder catalyst on the exhaust gas emission in real driving conditions tests of a Diesel engine

The article discusses the use of an in-cylinder catalyst, which allows the reduction of harmful exhaust compounds emissions during the internal combustion engine operation. It is a type of exhaust gas aftertreatment system – however, its placement in the combustion chamber – thus as close to the combustion process as possible, allows counteracting the production of pollutants at the source (catalyst applied on glow plugs). This is necessary because the reduction of exhaust emissions from vehicles is a key aspect of reducing the negative environmental impact of transport. The article presents the research results on the in-cylinder catalyst evaluation in dynamic operating conditions – the evaluation was made in road tests using the latest procedures recommended by the European Union. The presented comparative test results concern the road emission of limited vehicle exhaust compounds with the use of standard glow plugs and glow plugs with the catalytic layer applied. The use of an in-cylinder catalyst (on glow plugs) during diverse engine operating conditions results in a few percent reduction in the mass of carbon monoxide, hydrocarbons, carbon dioxide and the number of solid particles. The use of such a solution, technically possible to introduce quickly (replacement of a glow plug) in most vehicles with Diesel engines, would improve the overall ecological properties of internal combustion engines.

Investigation of the effects of exhaust and power loss in dual-fuel six-stroke engine with EGR technology

ABSTRACT In today’s world, the usage of internal combustion engines is inevitable. Particularly the diesel engines find their importance more than the petrol engines due to their operating cost. But diesel engines have their demerits in the area of exhaust and power loss. Necessary steps have to be taken in order to effectively use the fuel available. In this technical presentation, we have discussed about the utilisation of six-stroke engines which run on dual fuel. The six-stroke engine’s principle resembles a double-stage compressor. By this way, effective compression is done and the need for turbocharger is completely neglected. We have also considered cylinder’s position in a six-stroke engine. As the lubrication and cooling system needs special attention in the case of opposing-type cylinders, we have formulated a better and simple arrangement in which same power is produced, eradicating the lubrication problems. Also, the pollution (NOx) emitted by the diesel engines is also taken into account. We found the solution in the form of dual-fuel and exhaust gas recirculation system. The combusting temperature of the diesel engine is above 2000°F and this is the prime reason for NOx emission. So an alternative fuel which can be combusted below the level of diesel should be used. Moreover, the availability and production cost must be taken into consideration. We found ethanol as a better alternative for diesel. The cold starting of the engine is made easier using a glow plug, which is used to preheat the charge coming inside the combustion chamber.

Research on the hot surface ignition of hydrogen-air mixture under different influencing factors

To further reveal the pre-ignition characteristics of hydrogen internal combustion engine, the effect of hot surface characteristic parameters on the ignition characteristics of hydrogen-air mixture was investigated in this research. Based on the prototype of the constant volume combustion bomb with an overhead glow plug, the duration from the heating of the hot surface to the combustion of hydrogen-air mixture, the so-called heating duration, was firstly researched under different fuel-air equivalence ratio, initial temperature, initial pressure, hot surface temperature, and hot surface area, and the influence of each factor on the heating duration was analyzed. The results show that the order of the effect of each factor on the hot surface ignition is as follows: hot surface temperature > initial pressure of hydrogen-air mixture > equivalent ratio > initial temperature of hydrogen-air mixture > hot surface area. The influence of the hot surface characteristic parameters on the heating duration was further analyzed in detail. On this basis, the relationship among the critical ignition temperature, the heating duration and the hot surface area was researched and established. The results show that the heating duration is the only major factor affecting the critical ignition temperature. Finally, the research results were applied to analysis the pre-ignition in hydrogen internal combustion engine.

An integrated diesel fuel processing system with thermal start-up for fuel cells

A diesel fuel processor for high temperature polymer electrolyte fuel cells in the 5 kWe power class was developed and tested. Emphasis was placed on a quick and sustainable start-up. Furthermore, operational conditions were identified that would achieve the desired reformate quality for the fuel cell anode. A thermal start-up strategy using a commercial diesel burner was developed and further optimized, resulting in a hybrid strategy with the help of a glow plug. With this strategy, self-sustaining operation of the fuel processor at full load was achieved in 27 min and the resulting reformate was of sufficient quality to operate the fuel cell in 31 min. The experimental plan includes operation periods of between 4 and 24 h with start/stop/regeneration cycles representing the daily operation of an auxiliary power unit at maximum load. With all fuels used, the target carbon monoxide concentration of 1% at the anode inlet (wet reformate) was achieved. Significant deviations from the design parameters were necessary to demonstrate a stable system performance with desulfurized Jet A-1 and to achieve the target carbon monoxide concentration with premium diesel. These results bring diesel fuel processing for auxiliary power units closer to real application, offering experimentally-validated solutions for start-up and stable operation under realistic conditions with different fuels on a systems level.