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The continuous advancement in the space industry and in space access has opened the doors to greater global participation and exploration, with numerous nations, institutes and companies now actively engaged in space exploration. This expansion owes much to the progress in commercial space technologies, such as reusable launch vehicles and micro satellites, which have significantly reduced the overall costs associated with space missions, thereby enhancing space accessibility. Nevertheless, to foster further growth, it is necessary to look at further options of making space access more sustainable and cost-effective. For that, it is important to investigate and identify the cost drivers. An example is the use of traditional manufacturing techniques and materials, which come with inherent limitations, notably in terms of design flexibility and performance efficiency. This results in solutions that are not only time-consuming to manufacture but also not the most effective, making it a costly process. To address these challenges, increasing emphasis is being placed on utilising alternative manufacturing methods, such as additive manufacturing technologies combined with high-performance ceramic materials. This aims to reduce the overall number of manufacturing steps for producing a component and to optimise complex and functional parts reducing the overall costs of mass-produced or individually manufactured components, as evident in current studies. The primary objective of this study is to enhance space accessibility through the development, production and optimisation of electrically functional, all-ceramic and multi-material components (heating/ignition elements). For that, the AM technology "CerAM MMJ" in combination with high performance ceramic material are utilised and discussed. Subsequently, these components undergo electrical measurements and tests, and the resulting data is presented and analysed in the following sections. The findings aim to shed light on the current state of the art and whether the additively manufactured, fully ceramic and electrically functional components could represent a more cost-effective alternative to conventionally manufactured components in the future. • Insight into additive manufacturing technology: Multi Material Jetting (CerAM MMJ) • State of art and AM of all-ceramic, and electrical functional components • Electrical characteristics and performance of ceramic heating and ignition elements • Enhancing space-accessibility through enhanced all ceramic, electric functional parts • Utilizing AM for ceramics to optimize production of mission-critical parts • Utilizing high performance ceramic materials [ABSTRACT FROM AUTHOR]

The article discusses the most important facts from the history of the development of miniature aircraft engines and carries out their comparative analysis. Already in the 1930s, the structural system characteristic of model engines was established, which has hardly changed to this day. The following sections compare the various types of engines: two-stroke and four-stroke engines, spark-ignition engines, glow plug engines, engines with a push-pull cylinder arrangement, radial and in-line engines. The comparisons of the parameters and operational indicators of such engines presented in the tables allowed for the assessment of the advantages and disadvantages of individual engines, making several observations and drawing some more general conclusions. [ABSTRACT FROM AUTHOR]

In Diesel Engines, the heat energy obtained from the glow plug increases the engine's ability to start up in cold climatic conditions and significantly reduces emissions of harmful gases leaving the exhaust. In cold climatic conditions, before the start off of diesel vehicles it is necessary to wait for about 10 s the cylinder block heating. This period negatively affects driving comfort. In this study, the mathematical results of the processes to optimize the time required for the glow plug to reach the required temperature have been experimentally proven. A test apparatus was developed to confirm experimentally the theoretical results. Thanks to these improvements concerning the manufacture of the glow plug, the time period to reach 850 ° C has been reduced by approximately 5 s. The proposed design is in accordance with the glow plug present in the market. Currently the whole glow plug must be changed at the end of lifetime, with our improvement only the inner tube resistance can be easily changed involving a cost reduction by about 60%. [ABSTRACT FROM AUTHOR]

Ammonia is a kind of energy carrier of hydrogen, and its use as engine fuel has been studied. However, it requires overcoming shortcomings of low combustion speed. We focus that the laminar combustion velocity of gasoline mixture with an excess air ratio at 2.0 is the same as that of ammonia. The combustion of ammonia was simulated by using gasoline experiments under lean-burn conditions and the experimental engine with the sub-chamber and the glow plug. Through experiments, data such as the optimal ignition angle and NOx emissions during lean combustion are obtained. Based on the above experimental data, authors did the co-combustion experiment of gasoline/ammonia/air. Under the conditions of excess air ratio of 1.1, 1.2, 1.3, maximum ammonia content is 33%NH3, the engine could be operated with less than 10% variation in IMEP. [ABSTRACT FROM AUTHOR]

The paper discusses the application of an in-cylinder catalyst allowing a reduction of the exhaust emissions from a diesel engine. Its placement in the combustion chamber, the area where the process of combustion takes place, allows reducing the emissions (carbon monoxide, hydrocarbons, particulate matter) 'at source'. The paper presents the possibilities of boosting the efficiency of catalysts in diesel engines by extending the time of heating of a glow plug (the catalyst applied on the glow plug). The tests were performed for the following conditions: no heating (marked 0+0), glow plug heating for 60 s after engine start (marked 0+60), glow plug heating prior to engine start for 60 s and glow plug heating for 60 s after engine cold start (marked 60+60). An improvement in the efficiency of oxidation of the exhaust components was observed as the glow plug heating time increased. [ABSTRACT FROM AUTHOR]

Abstract Ignition process, as the initiation of the entire discharge, plays an important role in ablative pulsed plasma thrusters. While spark plug exactly how initiate discharge is achieved is still under review. This study did some experiments with two kinds of propellant surfaces (normal or inclined) and without propellant to explain the ignition process. The experimental results showed: when the thruster discharge without propellant, it is essentially a surface flashover process on ceramics; when the propellant was loaded, the main discharge occurs after the initial conductive path composed of electrons emitted by spark plug forming. This study provides a reference for the high performance pulsed plasma thrusters. [ABSTRACT FROM AUTHOR]

Performance and emissions experiments were conducted on a compression-ignition direct-injected natural gas engine (DING) equipped with a shielded glow plug ignition assist system. Tests were conducted at three different intake pressures (34.5 kPag, 68.9 kPag, 103.4 kPag), and four nominal (targeted) equivalence ratios (0.2, 0.3, 0.4, 0.5). CH 4 , NO x , CO and PM emissions were measured and analyzed, showing that emissions levels are influenced by the DING engine’s combustion modes and intake pressure. Premixed combustion which dominates at low equivalence ratios resulted in higher levels of CH 4 and NO x emissions, while mixing-controlled combustion, which develops at higher equivalence ratios, resulted in elevated CO and PM levels. Higher intake pressure was found to improve all emissions levels. The most significant effect was the reduction of PM and CO emissions due to improved fuel charge mixing and air entrainment that results from a pressure-driven momentum increase of the engine’s air swirl field. Brake specific emissions and fuel consumption were estimated and compared against levels reported in the literature for dual-fuel port-injection, and High-Pressure Direct-Injection (HPDI) natural gas engines. The most significant finding was that the DING engine exhibits lower fuel consumption and PM emissions levels when compared to values reported in the literature for HPDI engines. The PM emissions advantage was attributed to a higher proportion of premixed combustion and the absence of a diesel pilot in DING engine operation. Lastly, PM size distributions were analyzed, showing that the DING engine produces PM that is smaller than PM of a conventional diesel engine, but similar to the PM reported in the literature for HPDI engines. [ABSTRACT FROM AUTHOR]

The effects of a glow plug on the gas temperature distribution prior to ignition in HCCI combustion are investigated. Two custom sleeve adapters were constructed to allow the glow plug access to the gasoline engine in two different locations. The results show that increasing the glow plug voltage causes combustion to advance, which presents a method for controlling the combustion phasing in HCCI. Furthermore, the glow plug is able to broaden the temperature distribution prior to ignition by unevenly heating the charge. This broadening of the temperature distribution decreases the heat release rate in HCCI. Therefore, an actively controlled glow plug could be used for control over the rate of heat release in HCCI, within certain limits. The effect of the glow plug on the temperature distribution is larger when the glow plug is centrally mounted with a longer penetration into the chamber. Additionally, it was found that swirl causes the uneven heating effect of the glow plug to diminish due to enhanced mixing, resulting in a slightly narrower temperature distribution. The combustion efficiency when using the glow plug was slightly improved by reducing the unburned hydrocarbon emissions. The NOx emissions were also reduced somewhat due to the elongation of the heat release causing slightly lower peak temperatures. While much of the results are encouraging, the glow plug has the specific disadvantage of requiring electrical energy, and when counted against the work produced by the engine, the efficiency decreased by 1.4–2.5 percentage points at relatively low loads. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the effects of glow plug assist on a four-cylinder compression ignition (CI) engine fueled with dieseline. Pressure sensor glow plugs (PSG) are utilized to assist low temperature combustion (LTC) at low to medium load range, and the glow plugs are required for fast response and accurate output control. Therefore, a glow plug control unit (GPCU) is developed, and a closed-loop power feedback control algorithm is used. Equipped with PSGs and GPCU, the engine is tested at three speeds under varying loads. As a part of multi-mode combustion for CI engines, glow plug assisted combustion (GA-CI) appears earlier combustion phases and higher peak in-cylinder pressure. GA-CI can effectively reduce cycle-to-cycle variations and misfire is avoided, especially at low load conditions. The nature of the glow plug assisting process is to enhance the in-cylinder temperature and fuel reactivity. Plus, glow plugs also play a role in triggering the auto-ignition of the pre-mixture. With glow plug assist, NOx emissions rise slightly but are still below 0.2 g/kW h, whereas particulate matter (PM) emissions drop sharply and decrease to under 0.02 g/kW h. Since CO emissions and HC emissions decrease as well, the combustion efficiency is significantly enhanced, with the maximum being over 98%. [ABSTRACT FROM AUTHOR]

Glow plugs in the automotive industry are based on heating resistors made from FeCrAl alloys, often referred to as Kanthal. Metals and alloys exposed to high temperatures tend to react with the surrounding atmosphere, often resulting in high-temperature corrosion. Some high-temperature alloys use aluminium to form an Al 2 O 3 protective layer in order to improve the oxidation resistance. In the temperature range above 1200 °C, SiO 2 and Al 2 O 3 are the two oxides capable of forming an efficient, protective barrier against further oxidation. The alloy nominally requires more than 4 wt % Al to form a continuous protective layer. In this paper we have investigated the Al 2 O 3 formation and growth on the surface of iron aluminides prepared using different heat-treatment parameters to achieve a continuous protective layer on the surface of the heating resistors. SEM/EDX mapping analyses were performed to confirm the elemental distribution on the cross-section of the resistors heat treated in air or pure oxygen, or in a humid H 2 /Ar atmosphere, for different times and temperatures to achieve a continuous coverage of the oxide layer. The results of different heat treatments and their influences on the oxide growth are compared. [ABSTRACT FROM AUTHOR]

Hot surface ignition is relevant in the context of industrial safety. In the present work, two-dimensional simulations using simplified kinetics of the buoyancy-driven flow and ignition of a slightly leann-hexane–air mixture by a rapidly heated surface (glowplug) are reported. Experimentally, ignition is most often observed to occur at the top of the glowplug; numerical results reproduce this trend and shed light on this behavior. The numerical predictions of the flow field and hot surface temperature at ignition are in quantitative agreement with experiments. The simulations suggest that flow separation plays a crucial role in creating zones where convective losses are minimized and heat diffusion is maximized, resulting in the critical conditions for ignition to take place. [ABSTRACT FROM AUTHOR]

In this work, we present the thermal behavior of a glow plug examined with thermal impedance modeling. The circuit model is based on the analogy of thermal and electrical domains and expresses the glow plug used in diesel engines to preheat the air-diesel fuel mixture. In this study, the circuit design, implementation, and simulation of a glow plug for diesel engines are illustrated. In order to verify this thermal model, 2 different glow plugs are produced. The test results of the glow plugs produced in this study show complete agreement with the simulation results. It is thought that this circuit-based model will provide fast and reliable simulations and will be beneficial in the industry for addressing different glow plug needs. [ABSTRACT FROM AUTHOR]

Development of technologies that allow small, high power density engines such as unmanned aerial vehicles (UAV), unmanned marine vehicles (UMV), and unmanned ground vehicles (UGV) to operate on single logistic fuel such as JP-8 is one of government goals. To advance this goal, a lightweight, compact, and retrofit capable ignition source is critical. Compared to standard spark igniters and noncatalytic glow plugs, the use of catalytic glow plugs will provide benefits of lower required compression ratio, improved igniter life, reduced electrical energy requirements, and overall reduction in system weight and size. Experimental testing demonstrated a significant increase in surface temperature (160+ °C) with impingement of a fuel spray compared to a conventional glow plug with engine testing demonstrating the use of catalyst allows stable engine operation at reduced power requirements. Computational analysis was performed to provide insight into the catalyst behavior. Analytical studies suggested increased stability due to both heat release due to exothermic catalytic reaction and production of reactive species. This technology would allow high power density engines to use heavy fuels, while potentially reducing electric power supply and engine complexity and weight, both of which would allow greater range and/or payload capacity. This paper discusses the feasibility of advanced igniters technology as an enabling component for the use of heavy fuels in small, high power density internal combustion engines. The paper presents and discusses analytical investigation, experimental test results, and durability testing data in an internal combustion engine environment. [ABSTRACT FROM AUTHOR]