Ignition Combustion Research Articles

Experimental Investigation on Performance and Emission Characteristics of Diesel Lean Burn HCCI Engines

The purpose of this study is to analyse the effect of premixed diesel fumigation on the performance and emission characteristics of Homogeneous Charge Combustion Ignition (HCCI) engine and to optimize the diesel fumigation temperature. An experimental investigation was carried out on a single cylinder, four stroke, water cooled, port injected Kirloskar SVI engine. An electric air heater is fixed at the suction pipe. During the experimental study, the diesel fuel was premixed by port injector and get vaporized or fumigated by heated suction air. After the process of heating and premixing, the diesel has changed its phase and mixed with the air in the form of partially homogenous mixture. During the test, the engine was operated at different diesel fumigation temperature of 100 C, 110 C, 120 C, 130 C, 140 C and 150 C to assess the performance and emissions characteristics of the engine. It is observed that the diesel fumigation has made the huge impact on NOx and smoke formation. The emission of NOx and smoke were decreased simultaneously about 10% and 16% compared to the compression ignition engine. Moreover, this engine has produced high amount of CO and HC emissions at low fumigation temperature and also reduced the high fumigation temperature. The suction air temperatures of 120ï‚°C and 130ï‚°C operated under HCCI engine were found to produce lesser NOx and smoke emissions. Moreover, the engine fuel consumption was increased due to the low volumetric efficiency and also slightly affected the brake thermal efficiency.

Improvement of combustion and emission characteristics of a diesel engine working with diesel/jojoba oil blends and butanol additive

The main concerns of exploiting Jojoba oil in CI engines is that it has a high viscosity, low volatility, and high NOx formation. Therefore, this article purposes in endeavoring to improve the combustion and emission parameters of a CI engine working with diesel-jojoba oil blends and n-butanol additives under various engine loads. A 10% by volume of n-butanol is combined with 5%, 10%, 15%, 20%, 25, 30 and 35% of jojoba oil, and they are designated as DBJ5, DBJ10, DBJ15, DBJ20, DBJ25, DBJ30, and DBJ35, respectively. The experiments are divided into two steps, firstly, the viscosity of the fuel mixture is measured according to ASTM standards, and it is compared to ASTM D6751– 12 standers limits. Secondly, the jojoba oil with volume fraction up to 15% is tested in a CI engine to evaluate the combustion and emission developments. The results indicate that the addition of n-butanol with diesel-jojoba oil lowers the mixture viscosities by up to 85% compared to pure raw jojoba oil. The findings display that there is an increase in pmax. and HRR for DBJ5, DBJ10, and DBJ15 blends compared to pure diesel fuel, whereas the combustion duration and ignition delay are slightly reduced. The brake specific fuel consumption is enlarged. The NOx, CO, and UHC formations are reduced by 50%, 30%, and 40% respectively for diesel-jojoba oil-n-butanol mixtures. It can be deduced that combining high fractions of jojoba oil with n-butanol (DBJ15) have the feasible to accomplish low emission formations in the interim having high thermal efficiency level.

Experimental investigation of the ignition process in a separated dual-swirl spray flame

Centrally staged lean premixed pre-evaporation combustion technology has been used in aero engines for its capability in effectively reducing NOx emissions while still providing stable flames. Previous work has shown the “ignition delay” phenomenon in the forced ignition process, revealing that the burner ignition process is complex and needs further exploration. In this work, the spark ignition and flame kernel propagation in a centrally staged optical model combustor are experimentally investigated to further illustrate the interaction between random kernel motion and flow statistics from the perspective of timescales and kernel propagations. Stochasticity involved in each individual phases of the whole ignition is obtained via repeated high-speed imaging tests. Timescales of the successful ignition processes are analyzed in a statistical method, revealing the time randomness of ignition phases. Spatial probability of the flame kernel propagation in turbulent sprays is calculated and analyzed with the combination of time-averaged flow and spray distribution. The flame projected area evolutions show that the burner ignition phase can be further divided into three phases: flame propagation, flame residence and flame growth. Three modes of ignition failure are identified during the burner ignition phase. The flame residence phase features a special period of spark ignition with low light emissions from the highly wrinkled flame kernel in the center, which is the “ignition delay” before the growth of flame. Timescales of ignition stages involve stochasticity and the flame growth phase has a higher proportion in the whole process. Statistical analysis of the flame kernel spatial position shows that in turbulent spray the flame kernel has a greater probability of propagating to the region with low axial velocity, low shear strain rate, and appropriate spray concentration.

Deposition growth of Zr-based MOFs on cerium phenylphosphonate lamella towards enhanced thermal stability and fire safety of polycarbonate

The fabrication of engineering plastics combining high efficiency flame retardancy and thermal resistance are essential for practical applications. A novel halogen-free binary hybrid with lamellar and porous structure, Zr-BDC@CeHPP, was created by hydrothermal reaction, thereafter blended with polycarbonate (PC) to improve its thermostability and fire safety. With 2 wt% Zr-BDC@CeHPP, temperatures under peak decomposition rates (Tmax1 and Tmax2) of PC were increased by 28 and 34 °C under oxidizing atmosphere. Time to reach PHRR (t-PHRR) and time to ignition (TTI) and of PC were effectively prolonged to 145 and 18 s, respectively. In comparison with pure PC, the peak of heat release rate (PHRR), total heat release (THR), peak specific extinction area (PSEA) and total smoke release (TSR) of PC composites were reduced by 45%, 20%, 74% and 18%, respectively. Moreover, the flame retardant PC reached V-0 rating in UL-94 vertical burning test. The results indicated that the hybrid was able to fully utilize the advantages of Zr-BDC and CeHPP. In the ignition and middle periods of combustion, Zr-BDC@CeHPP played roles in delaying and suppressing explosive combustion. In severe combustion stage, Zr-BDC@CeHPP could catalyze the char-forming process and serve as a barrier.

Effects of an injector cooling jacket on combustion characteristics of compressed-ignition sprays with a gasoline-hydrogenated catalytic biodiesel blend

The fuel properties in Gasoline Combustion ignition modes (GCI) have been adapted by mixing high reactivity fuels for improving poor combustion stability with pure gasoline. Precise control of the injector tip temperature, as well as the fuel temperature, are considered as the essential boundary conditions to conduct the fundamental investigation on combustion process of GCI spray. Therefore, the impacts of an injector cooling jacket on the spray and combustion developments of a mixture contains 60% gasoline and 40% hydrogenated catalytic biodiesel are studied using a constant volume combustion chamber (CVCC) working under GCI mode. A dummy injector is equipped with a thermocouple to measure the effects of the cooling jacket and ambient temperature on tip temperature. The Schlieren imaging and Diffused Background Illumination Extinction Imaging techniques are employed to visualize the reacting spray development and in-flame soot formation. The results illustrate that the injector tip temperature is well-controlled with aiding of the cooling jacket, which only increases by 35 K with increasing ambient temperature by 250 K. Furthermore, it is found from the optical experiments that the liquid length, ignition delay and lift-off length are enlarged for the cooling mode compared to that of the uncooled one. The cooling jacket also brings in a larger overlapping area between liquid length and flame lift-off length. However, the in-flame soot production for the cooling jacket is increased more than twice compared to that of the uncooled one.

Combustion of a solid fuel material at motion

The present paper proposes a mathematical model for the ignition phenomenon of a non static combustible solid fuel bed under the exposure of a constant incoming heat flux impinging on the solid surface. The thermal behaviors in terms of temperature responses of the solids of thermally thin, thermally thick and thermally moderate (finite-depth) target materials are analytically evaluated. Having established asymptotic relations, analytical estimates for the ignition time and critical heat flux are derived together with further approximations for the full temperature distribution inside the solid material without necessitating any numerical treatment. The explicit findings clearly point that a solid fuel bed layer at motion possesses less ignition time with a lower critical heat flux as compared to a solid material at rest, which may constitute a practical significance in applications involving fire, forest fuel and waste burning ignition, since combustion is initiated rapidly for moving flammable targets.

Effect of Cold Weather on Behaviour of Compression Ignition Engine Performance, Combustion and Emission in Various Preheating Mode

Effect of Cold Weather on Behaviour of Compression Ignition Engine Performance, Combustion and Emission in Various Preheating Mode

Modeling of plasma combustion ignition on an electromagnetic wave driven metasurface

We present a multi-physics model of combustion ignition phenomena in an atmospheric pressure hydrogen-air mixture ignited by a microwave surface plasma discharge. The surface plasma is generated over a resonant metasurface structure that provides sufficient field intensification to break down and sustain a discharge. Specifically, a surface electromagnetic (EM) wave mode known as the spoof surface plasmon polariton (SSPP) is excited to yield a hybrid resonance that results from coupling of cavity and surface EM wave modes. Motivated by the need for a large, volumetric ignition kernel for applications in combustion ignition, we numerically demonstrate the volumetric surface plasma discharge enabled by the use of this particular EM wave mode in a high pressure operating regime. We discuss the transient evolution of a centimeter scale plasma kernel and subsequent ignition kernel formation. High density combustion enhancing radical species (O, H, OH) are produced throughout the bulk plasma, which leads to successful ignition. A parametric study shows that the large size of a plasma kernel is attributed to the shortening of ignition delay.

Establishing Thermal Stability in an Optically-Accessible CIDI Engine

<div class="section abstract"><div class="htmlview paragraph">Optically-accessible engines are a key tool for the study of sprays, mixing, and ignition and combustion phenomena in internal combustion (IC) engines. Due to their construction, they are typically operated for limited durations, resulting in significant thermal transients in the in-cylinder surface temperatures and cycle-to-cycle in-cylinder gas temperature. This makes collection of highly repeatable data difficult and can introduce considerable uncertainty in the in-cylinder thermal conditions. In this paper, rigorous analyses of transient in-cylinder boundary conditions and in-cylinder gas temperature were performed in an optically-accessible compression-ignition engine. Piston surface thermometry, in-cylinder pressure measurements, and in-cylinder gas thermometry were employed to determine the engine warmup time required to reach a quasi-steady thermal state for motored operation over a range of intake air temperatures and pressures from 300-420 K and 100-300 kPa, respectively. The effect of fueling on thermal stability was investigated for single-injection mixing-controlled compression-ignition combustion utilizing a range of skip-fire ratios from 5:1 to 50:1 and loads from 0.8 to 10.1 bar gross indicated mean effective pressure. Both optical and metal pistons were studied. A motored warmup time of 300 s was found to be sufficient for the engine to reach a thermally stable condition regardless of piston material or intake condition. Piston temperature was found to increase with load, but the increase was modest for even the highest load studied (~4 K) for 10 injection sets typical of late direct-injection optical engine studies.</div></div>

Modernization of a tractor motor for diesel combustible and methanol

When carrying out research to improve the environmental performance of motors, attention should be paid to reducing the nitrogen oxide content of the effluent gases, since they are the most toxic components among the entire range of polluting chemical compounds contained in exhaust gases, since they are formed in the burning process as a result of chemical reactions atmospheric oxygen and nitrogen. The most effective way of using methanol in internal burning engines is now to feed it directly to the diesel cylinder using a dual combustible supply system, which allows replacing up to 80% of the diesel combustible. The ignition of methanol in this case is due to the supply of a seed portion of diesel combustible. This method, with some changes and additions to the design of the motor, can be implemented on engines already in operation. In this paper, the effect of methanol application on the volumetric content and mass concentration of nitrogen oxides in exhaust gases calculated on the basis of the results of experimental studies of a motor of 2H 10.5 / 12.0 air cooling with a hemispherical burning chamber in a piston using a dual combustible delivery system and injection of diesel combustible (ignition) through a multi-jet nozzle, depending on the change in load.

Highly energetic and flammable metallic glasses

Energetic materials are solids that release a large amount of energy in combustion. The evaluation depends on both combustion heat and ignition temperature. Conventional non-metallic materials have low ignition temperature but small combustion heat, whereas metals have large combustion heat but high ignition temperatures. We show that many metallic glasses, combining the merits of both metals and non-metals, have large combustion heat, approximately twice that of the non-metals, and low ignition temperature that is several hundreds of Kelvin lower than that of the metals. The ease in igniting metallic glass results from the low thermal conductivity of the materials and the storage of energy in their liquid-like atomic structure. Metallic glass ribbons outweigh metallic nanoparticles due to their high production efficiency, low cost and nontoxicity. The findings suggest that metallic glasses are alternative energetic materials.

Study on pyrolysis and combustion characteristics of straw briquette fuel

Biomass is mainly composed of cellulose, hemicellulose and lignin. The content of each component has a great influence on the combustion of biomass. The combustion of biomass starts from its thermal decomposition. The main products of cellulose and hemicellulose are volatile components, while the main products of lignin are coke, and cellulose and hemicellulose are easier to decompose than lignin. Therefore, biomass combustion is a very complex process. In order to improve the quality of straw biomass fuels and pyrolysis with high efficiency, thermogravimetric-differential thermogravimetric (TG-DTG) technology was used to conduct thermogravimetric tests on agricultural straw fuels. The combustion characteristics, ignition characteristics, burnout characteristics and comprehensive combustion characteristics were investigated, and the combustion kinetics parameters were calculated.

A Review on New Technology in Internal Combustion Engine- HCCI engine

In present study a concise literature review on Homogeneous Charge Compression Ignition (HCCI) engine have been performed by taking the many practical problem which are hurdle for implementation of this concept. HCCI combustion is also termed as Low Temperature Combustion (LTC) technology because of its prospective to attain high efficiency and low Nox and particulate matter emission. The typical quality of HCCI technique is the need of preparation of homogeneous mixture early at combustion. Combustion processes in HCCI engine were controlled by chemical kinetics and proper mixing of fuel. Numerous researchers are working towards the challenges and solution for commercialization of this engine. Present review covers the elementary feature for the evaluation of HCCI engine, its working principle and challenges for practical implementation. This study elaborates the prospective solution and future growth in HCCI engine. The most critical challenges for HCCI engine is controlling method for direct ignition of combustion. Therefore in HCCI combustion engine implementation of this problem is way for practical availability of this concept.

Arc Discharge–Induced Ignition of Combustibles Placed on a Damaged AC Power Supply Cord

One of the major causes of unintentional electrical fires is short circuit of an electrically and/or mechanically damaged alternating power supply cord. Detecting of such an event and interrupting the power supply may be beyond the capability of a conventional electro-mechanical circuit breaker. A lot of research papers have been published related to arc fault of wiring and its detection method. Furthermore, arc fault circuit interrupters have been put into practical use. The objective of the present paper is to understand fault of damaged power supply cord under two selected situations observed in practical use or considered suitable to understand fire ignition. Using two kinds of samples similar to but different from samples prescribed in UL1699 standard, the ignition mechanism of combustibles is discussed based on the results of laboratory experiments. The findings herein underscore the important role of the arc in the ignition of combustibles that are placed on the damaged part of a power supply cord, which is normally followed by a short circuit of broken element conductors or breakage of intact element conductors. Moreover, a possible arc detection feature in the two situations is discussed based on a distorted voltage waveform.

Performance and emission test on diesel engine using Prosopis juliflora seed oil

ABSTRACT The current crisis of fossil fuels along with the increasing cost of fossil fuels, the growing population of vehicles and emissions from these fuels are made to a search of substitute fuels for the combustion ignition engines. The best alternative for diesel is considered to be biodiesel because of its distinctive properties such as a crucial reduction in greenhouse gas emissions, non-sulphur emissions, non-particulate matter pollutants, low toxicity, and biodegradability. The fuels, the Prosopis juliflora biodiesel blended with diesel were identified and tested in this research work. The biodiesel is produced by transesterification of Prosopis juliflora seed oil with methanol in the presence of either alkaline or strong acid catalysts. The various properties of their blends are calculated and compared with those of diesel. This investigation evaluates thermal efficiency, fuel consumption, and emission characteristics of Prosopis juliflora blends in a diesel engine, and the results are compared with neat diesel.

Experimental Research on the Properties of Secondary Raw Materials Resulting from the Recycling of Tyres

The paper deals with the research on the properties of secondary raw materials resulting from the recycling of used tyres and their potential utilization for the production of construction insulations. Evaluation of the possibilities of utilization and a complex analysis has been executed on the basis of the defined basic physical, thermal-insulating and fire properties of the raw textile fibres examined. The results of the research on the material examined indicate possible exploitation of this potential material for the construction of environmentally-friendly objects. Thermal insulating parameters have been determined by the value of thermal conductivity coefficient λ. For measuring of thermal conductivity coefficient of fibres has been used the special laboratory device – the Cooling Box. Physical properties have been determined by microscopic examination and by laboratory measuring of fibres length, diameter, pour bulk and compressed bulk densities. Fire characteristics were determined during several fire tests of textile fibres. On the basis of performed fire test has been determined the combustion heat, flash point (FIT) and ignition temperature (SIT).

Numerical study on the effect of oxygen concentration on the piloted ignition of PMMA in reduced pressure atmospheres

PurposeThis study aims to investigate the controlling mechanisms of ambient oxygen and pressure on piloted ignition of solid combustibles under external radiant heating.Design/methodology/approachThe numerical simulation method was used to model the influence of ambient oxygen concentration on the piloted ignition of a thermally irradiated solid sample in reduced pressure atmospheres. The solid phase decomposition and gas phase kinetics were solved simultaneously.FindingsIt was determined that the elevated oxygen atmospheres resulted in a higher flame temperature and a thicker temperature profile over the solid surface. Also, increasing oxygen and reducing pressure had a similar effect in the decrease of the ignition delay time. The shorter ignition time in reduced pressure was mainly because of the decreasing of convective heat losses from the heated solid. As oxygen was reduced, however, ignition occurred later and with a greater mass loss rate because more volatiles of solid fuel at transient ignition were required to sustain a complete reaction under an oxygen-poor condition.Research limitations/implicationsThe results need to be verified with experiments.Practical implicationsThe results could be applied for design and assessment of fire-fighting and fire prevention strategies in reduced pressure atmosphere.Originality/valueThis paper shows the effect mechanism of ambient oxygen and pressure on piloted ignition of solid combustibles.

Adaptive Model Predictive Control of Combustion in Flex-Fuel Heavy Duty Compression-Ignition Engine

Flex-fuel engines can operate on different fuels, from fossil fuel to renewable fuel and their mixture. With the assumption that fuel species is unknown in advance, the mutative fuel properties give rise to an interesting control problem. Since the combustion phasing and ignition delay in the combustion process are intimately coupled, the fuel injection system and air system need to be combined for performance. In this work, an adaptive Model Predictive Control (MPC) approach is proposed to control the combustion process in a multi-cylinder heavy duty compression-ignition (CI) engine. MPC is a suitable design for this multiple inputs/outputs system with actuator constraints, and adaptivity is the solvent for the unknown mutative fuel properties. The combustion timing and ignition delay are extracted from cooled in-cylinder pressure sensors and simultaneously controlled by manipulating injection timings, the intake oxygen concentration, and intake pressure using an exhaust-gas recirculation (EGR) system and a variable-geometry turbocharger (VGT). Diesel, gasoline/n-heptane mixture, and ethanol/n-heptane mixture are used in the experiments. The method is validated in fuel transitions from diesel to gasoline mixture and from gasoline mixture to ethanol mixture.

Experimental analysis of convergent inlet manifold for IC engines

Petroleum product demand is growing day by day, but resources are relatively small. Particularly exhaust emissions from car engines are that in pollution, at the same time everyone is looking for new technology that minimize fuel consumption and high performance with low emissions and environmentally friendly. Such modes of technology are in great demand in the present and in the future. Therefore a convergent inlet manifold is used to check the output and emission characteristics of the engine to address these issues. Convergent inlet manifold technology air is induced with high velocity and full quantity entering the engine cylinder. In Combustion Ignition (CI), engine fuel combustion is often based on the swirling flow of air. The rotating motion of the air will increase by using this sort of funnel. Results characteristics are calculated and contrasted with normal multiplier with convergent manifold. In this paper the output characteristics were compared to an engine with standard intake manifold and convergent type intake manifold. The Engine speed is constant and the load varies from 0 to 7.5 kg. The Specific Fuel Consumption rises with increasing price for all fuels. In convergent funnel, the relationship to regular multiple increasing fuel consumption decreases slightly. Mechanical efficiency shows how well an engine redirects the indicated power into usable fuel. The normal manifold's mechanical efficiency is less than convergent at 3.15%.

Characteristics of Woody Cutting Waste Briquette with Paper Waste Pulp as Binder

The current research aimed to increase the calorific value of woody cutting waste briquette with paper waste pulp as binder. There were three different binder variation used in this study, they are 5 %, 10 %, and 15 %. To create a briquette, a cylindrical iron mold with diameter of 3.5 cm and height of 3 cm and a hydraulic press with 2 t power were applied. The physical characteristics of the combination woody waste briquette and paper waste pulp, such as moisture content, ash content, volatile matter and carbon fix were examined using proximate analysis. The calorific value of briquetted fuel was tested by bomb calorimeter. The combustion test was performed to determine the combustion characteristic of briquettes, for example initial ignition time, temperature distribution, and combustion process duration. The general result shows that the calorific value of briquette stood in the range of 4 876 kCal kg–1 to 4 993 kCal kg–1. The maximum moisture content of briquette was 5.32 %. The longest burning time was 105 min.