There have been several studies focused on improving the efficiency of internal combustion engines using various techniques such as better design, better materials, and regenerative technologies. Recently, in 2016, Toyota reported 40% gas engine efficiency with their Prius model; however, there remains a lot more room for improvement towards the theoretical maximum value of 73% using the Carnot theorem. In this research, we present a freshly designed valvetrain that has the potential to improve the efficiency of a known conventional valve designed engine. The goal of this research was to prove the feasibility and significance of the new valve design. This research developed a simulation model of the new valve design and produced its physical property data. The data of the new design were compared to the conventional poppet valve design with respect to several parameters to discuss its working principle and advantages over the conventional valve mechanism. Modeling was performed using Python programming to predict the valve-opening mechanism. The design of experiments was setup to control and tune different parameters accordingly within the reasonable range of engine speed, viz., 1000–6000 rpm to simulate various working conditions. The maximum opening area for the rotary valve is calculated to be 0.795 sq.in which is smaller than the poppet valve’s area of 1.315 sq.in. However, under an example of 2900 rpm, the rotary valve was able to remain fully opened with constant efficiency of about 54% from 40 to 160 degrees of the crankshaft angle. While the poppet valve can achieve 88% efficiency at 90 degrees of the crankshaft angle and the efficiency significantly drops on either side of the maxima, the authors believe that this research would help explore improvements in the performance of a combustion cycle due to the novel rotary valve design that is investigated in this paper.

The article contains a comparative analysis of two types of burners used in different methods of fuel-air mixture preparation: (1) vortex mixing and (2) mixing with transverse jets. The analysis was carried out in order to determine which one of the two burning devices is more efficient and has better environmental performance. In device no. 1, conditions for the fuel-air mixture formation are created by vortex turbulence. The basic principle lying at the core of this design is a vortex flow inside, which provokes a more intense mixing of fuel and air. Moreover, preliminary physical and thermal treatment of the fuel-air mixture has a positive effect on its environmental performance. In contrast, in device no. 2 based on transverse jets’ active mixture formation is achieved through collision of air and fuel flows at an angle close to 90°. The research was based on an experiment carried out with the use of a laboratory firing stand. Flue gas samples were analyzed in order to compare the main harmful air emission indicators with TESTO 350-XL gas analyzer. A propane-butane mixture of 60% C3H8 (propane) and 40% C4H10 (butane) was used as the main fuel. Some indicators were determined after the experiment: measurement units conversion from “ppm” to “mg/m3,” excess air ratio α and equivalence ratio φ, flue gas concentrations recalculation taking oxygen into account, fuel calorific value, and heat release rate. The analysis results are as follows: (i) the swirl burner shows better performance in terms of nitrogen oxides (NOx) emissions; there is a 1.75-fold difference in total NOx emissions compared to the cross jet burner; (ii) the burner on transverse jets is 10 times more efficient than the swirl burner in terms of carbon monoxide (CO) emissions.

This study characterized uranium metal dust cloud combustion using absorption spectroscopy, imaging, and broadband emission measurements. Other metals were similarly combusted to establish correlations between results from this study and those found in the literature. It was determined that the burn temperature of uranium was limited to the volatilization temperature of uranium dioxide. Combustion behavior was similar to that of other refractory metals in terms of burn time and the observation of exploding particle behavior.

Gallus domesticus is one of the world’s most consumed animals, with a significant presence in all parts of the planet. Chicken oil appears to be a credible raw material in the context of alternative energy research. This study focuses on a literature review to highlight the chicken’s energy potential and the application of energy recovery from local slaughterhouse-based Gallus gallus domesticus greasy residues and it is proposed to make biodiesel from the fatty residues of Gallus gallus domesticus. The transesterification reaction takes place at 60°C. Methanol is used in a 1 : 6 oil-to-alcohol mass ratio. Catalysis is carried out with 1% (m/m) potassium hydroxide (KOH). The accepted reaction time under light agitation is 120 minutes. The reaction yield is estimated to be 85.6%, and the biodiesel produced is characterized. The postcharacterization values are consistent with the EN14214 biodiesel standard. Gas chromatography coupled with mass spectrometry reveals the intrinsic composition of the acids derived from the developed biodiesel methyl esters. The latter reveals a predominance of oleic acids with a value of 29.47% and palmitic acids with a value of 29.21%. The viscosity of greasy residues appeared to be relatively high at 69.32 mm/s. The low calorific value is 38775.363 KJ/Kg and the cetane index is 50. It has been observed that, for 1000 g of fat waste, it is possible to extract by cooking 507.807 g of oil, or an extraction yield of 51%. Fatty chicken residues from tropical market areas can be used as a raw material for biofuel development.

The release of gas-phase polychlorinated biphenyls (PCBs) as one of the persistent organic pollutants (POPs) is an unfortunate result of combustion, especially from medical waste incinerators. This tends to make incinerators unpopular. The idea of a cheaply available air pollution control device fitted to incinerator chimneys can justify the continued use of incinerators. A gas filter unit, consisting of 3 filter beds with activated charcoal as an adsorbent, was designed, constructed, and fitted onto an existing incinerator at a university hospital in Ghana. Flue gas from the incinerator was sampled before and after the filter beds, using cylindrically-shaped mini-polyurethane foam (mini-PUF) samplers, and the analytes in the samples were then Soxhlet-extracted, purified, and analyzed for certain PCBs using the gas chromatography-mass spectrometer (GC-MS) technique. Twelve of the 14 indicators PCBs analyzed in the smoke samples were present, and 11 of them saw mean reductions ranging from 3.67% to 54.9% by the charcoal filter beds. These were PCB 18, PCB 28, PCB 31, PCB 44, PCB 101, PCB 118, PCB 138, PCB149, PCB 153, PCB 170, and PCB180. The gaseous concentrations of PCBs before filtration ranged from 0.0000788 ng/m3 for PCB 180 to 0.00129 ng/m3 for PCB 153. After the filtration by the charcoal adsorbent, they ranged from 0.00003734 ng/m3 for PCB 170 to 0.00112016 ng/m3 for PCB 153. The highest mean reduction of 54.9% came from the homologue, PCB 180, whilst the homologue with a dioxin-like character (PCB 118) saw a 22.44% reduction. This suggests that dioxins and other dioxin-like compounds are most likely adsorbed by the charcoal adsorbent. This gas filter unit should further be investigated for its effectiveness at removing other dioxin-like PCBs, dioxins, and furanes and for testing the effectiveness of thermophilic bacterial strains that can further metabolize these POPs into less harmful products.

Gasoline engines remain a potential source of atmospheric pollution. Dual fuel combustion was under investigation to cope with exposure to pollutants. Investigations on emission parameters and engine performance for a single-cylinder four-stroke petrol engine are carried out using multicriteria decision-making method (MCDM). Bar charts are constructed for three emission parameters in function of engine temperature and fuel consumption for different blends. Fuels were supplied at different engine running speeds. Parameters recorded during the experimental study were the concentrations of carbon monoxide (CO), hydrogen sulfide (H2S), percentages of lower explosive limit (LEL), and combustion duration. The maximum concentration of CO was 339 ppm at 70°C and 4000 rpm. The maximum concentration of H2S (3 ppm), was recorded at 94°C and 4000 rpm. The maximum percentage of LEL recorded was 3% at the majority of temperature and 4000 rpm. Consumption of 25 Cl of (gasoline + HHO) was recorded during the maximum time (50 min). The experiment showed high emissions of CO that can provoke respiratory disorders and explosive gases, factors of explosion at high speeds (4000 rpm), and low temperature (70°C). H2S emissions are very low (0–3 ppm) independently of the engine speeds and temperature. Blending gasoline with HHO shows a reduction in fuel consumption.

Fire occurring in the chaparral behaves as a crown fire, a dual-layer fire that typically ignites in a dead surface fuel layer and transitions to an elevated live crown layer where it continues to spread. In chaparral fuels including chamise, a dominant species in southern California, flame transition to live crown fuels is associated with higher spread rates and greater fire intensity. Despite the relative importance of surface-to-crown transition and crown fire spread, most fire models represent chaparral fire as surface fire, therefore omitting key behavior processes driving this fire system. The purpose of this study was to characterize transition and spread behavior in chaparral fires modeled experimentally as crown fires. We examined heat release rate in the surface and crown fuel layers, time to transition, flame height, and rate of spread in wind-driven and nonwind-driven fires at two crown base heights. Our results showed that wind increased heat release rate, rate of spread, and flame height. A marked increase in heat release rate was observed in wind-driven fires, where adding wind produced an increase from 328 kW to 526 for a crown base height of 0.6 m and from 243 kW to 503 kW for a crown base height of 0.7 m. Further, crown base height served to decrease heat release rate and rate of spread for wind-driven and nonwind-driven fires.

According to the geometry of compartments, quantities of smokes released during fire tend to accumulate at ceiling so as to form a cloud of hot gases. Heat transfer between these hot gases and walls is decisive for the development of fire. An increase in temperature of these gases could lead to dangerous phenomena such as flashovers and backdrafts. Owing to experiments and numerical simulation, the objective of the present paper is to investigate on the influence of natural ventilation on convective heat transfer between hot gases and walls of a room in fire. So, varying the ventilation level, it was firstly about to carry out fire tests in an experimental room. Secondly, study was focused on the numerical simulation of these tests so as to estimate velocity field of burnt gases near walls during fire. Validation of numerical results has been done by confronting simulated results to experimental results. A full-scale extrapolation of results enabled revealing that while the ventilation level in the room changes, the amplitude of convective heat transfer changes according to the regime of fire. It was shown that for the fuel-controlled fire, the convective heat transfer coefficient strongly increases with the ventilation factor, and for the ventilation-controlled fire, convective heat transfer coefficient weakly decreases with the ventilation factor and remains nevertheless close to value   8.75 W ⋅ m − 2 ⋅ K − 1 .

The equivalence ratio ranges were found between 22.77 and 42.93 for the Saudi LPG/air mixture using a traditional Bunsen burner. An operation problem was found with a traditional Bunsen burner for the Saudi LPG/air mixture, especially in a lean mixture. Therefore, a Bunsen burner was successfully modified to overcome the limits of operation with different mixtures of Saudi LPG/air and a stable flame was obtained. The equivalence ratio ranges were found between 0.68 and 1.30 using the modified Bunsen burner. A premixed flame was used for the modified Bunsen burner. A MATLAB algorithm was successfully applied to flame image processing and measurement of laminar burning velocity. The laminar burning velocity was determined to be approximately 35 ± 0.91 cm/s under stoichiometric conditions using the modified Bunsen burner for the Saudi LPG/air mixture. The half-cone angle of the flame was found to be 16.20 ± 0.76°. The minimum flame height was observed to be 21.50 ± 0.22 mm above the Bunsen burner exit.

Lean premixed (LPM) combustion processes are of increased interest to the gas turbine industry due to their reduction in harmful emissions. These processes are susceptible to thermoacoustic instabilities, which are produced when energy added by an in-phase relationship between unsteady heat release and acoustic pressure is greater than energy dissipated by loss mechanisms. To better study these instabilities, quantitative experimental resolution of heat release is necessary, but it presents a significant challenge. Most combustion systems are partially premixed and therefore will have spatially varying equivalence ratios, resulting in spatially variant heat release rates. For laminar premixed flames, optical diagnostics, such as OH chemiluminescence, are proportionally related to heat release. This is not true for turbulent and partially premixed flames, which are common in commercial combustors. Turbulent eddies effect the strain on flame sheets which alter light emission, such that there is no longer a proportional relationship. In this study, phased, averaged, and spatially varying heat release measurements are performed during a self-excited thermoacoustic instability without and with porous inert media (PIM). Previous studies have shown that PIM can passively mitigate thermoacoustic instabilities, and to the best of the authors’ knowledge, this is the first-time that heat release rates have been quantified for investigating the mechanisms responsible for mitigating instabilities using PIM. Heat release is determined from high-speed PIV and Abel inverted chemiluminescence emission. OH ∗ chemiluminescence is used with a correction factor, computed from a chemical kinetics solver, to calculate heat release. The results and discussion show that along with significant acoustic damping, PIM eliminates the direct path in which heat release regions can be influenced by incoming perturbations, through disruption of the higher energy containing flow structures and improved mixing.

Coal calorific value is one of the main considerations for using coal as a power plant fuel. In addition, the requirements for indications of slagging and fouling are also important to maintain combustion efficiency. However, coal power plants often experience problems in boiler operations due to the use of certain types of coal, even though they have a relatively high calorific value. This research investigates the effect of coal blending on ash fouling and slagging in an experimental investigation using a drop tube furnace with or without additives. Five different types of coal from different locations have been used in this study. Pulverized low-rank coal samples are burned in a drop tube furnace at 1,175°C with probe temperatures of 550°C and 600°C, corresponding to the combustion chamber of 600 MW power plants, including superheater and reheater areas. The ash particles’ characteristics and material composition were also analyzed using scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) and X-ray diffraction (XRD), respectively. All coal mixture combinations demonstrated potential as a fuel for power plants that use pulverized coal-fired boilers. Because of its capacity to reduce slagging and fouling potentials, combining coal blending with the use of chemical additives yielded the greatest results.

Investigation of combustion temperature through experiments with a wide range of fuels, both solid and liquid, is continuously being conducted by scientists around the world, while the measurement of heat transfer rate can be analyzed when the combustion process occurs. Previous research has generally been conducted using liquefied gas, fossil fuels, and alcohol additives. Specifically, the research in this work investigated the convection heat rate and combustion temperature through the modification of the perforated plate. The experiment was conducted in the fluidized-bed combustor (FBC) fuel chamber using solid waste fuel of oil palm biomass. Measurements were performed at four different points using the HotTemp HT-306 Digital Thermometer. The results of the experiment showed that the convection heat rate in measurement one (M-I) reached 8.258 W/m2 for palm kernel shell (PKS) fuel. Meanwhile, in measurement two (M-II), the convection rate of 7.392 W/m2 was produced by oil palm midrib (OPM) fuel. The highest combustion temperature was recorded with OPM fuel (884°C) at M-I. However, the combustion temperature of the PKS combustion process is higher at 896°C but shows a less good trend than OPM. Overall, the measurement results of the three types of fuel used to modify the perforated plate applied in the FBC fuel chamber are excellent. It can be proven that the fuel is put into the combustion chamber with nothing left.

Compression ignition engine modeling draws great attention due to its high efficiency. However, it is still very difficult to model compression ignition engine due to its complex combustion phenomena. In this work, we perform a theoretical study of steam injection being applied into a single-cylinder four-strokes direct-injection and naturally aspirated compression ignition engine running with diesel and biodiesel fuels in order to improve the performance and reduce NO emissions by using a two-zone thermodynamic combustion model. The results obtained from biodiesel fuel are compared with the ones of diesel fuel in terms of performance, adiabatic flame temperatures, and NO emissions. The steam injection method could decrease NO emissions and improve the engine performances. The results showed that the NO formation characteristics considerably decreased and the performance significantly increased with the steam injection method. The relative errors for computed nitric oxide concentration values of biodiesel fuel and diesel fuel in comparison to the measured ones are 2.8% and 1.6%, respectively. The experimental and theoretical results observed show the highly satisfactory coincidences.

Coal reserves at Mui and Taru in Kitui and Kilifi counties in Kenya are estimated to provide over 400 million tons. Being new discoveries, their properties were investigated using the ASTM standards, while the combustion characteristics were studied in a fluidized bed combustor (FBC). Proximate analyses of the Mui1, Mui2, and Taru coal samples were as follows: moisture content 3.75, 5.48, and 3.53%; volatile matter 59.25, 58.05, and 55.10%; ash content 9.25, 11.48, and 24.63%; and fixed carbon 27.80, 25.00, and 16.75%, respectively. Ultimate analysis for Mui1, Mui2, and Taru coal samples is as follows: sulphur wt.% 1.94, 1.89, and 1.07; carbon 65.68, 60.98, and 51.10%; hydrogen 5.97, 5.70, and 5.09%; nitrogen 0.92, 0.94, and 1.00%; and oxygen 11.62, 12.33, and 11.13%, respectively. Temperature–weight loss analysis showed that for Mui and Taru basin coal, devolatilization starts at 200°C and 250°C, and combustion was complete at 750°C and 650°C, respectively. The maximum temperature obtained in FBC was 855°C at 700 mm height, just above the point of fuel feed, while the minimum was 440°C at height of 2230 mm. Maximum pressure drop was 1.02 mbars at 150 mm, while minimum was 0.67 mbars at 700 mm from the base. Gross calorific values were Mui1 coal, 27090 kJ/kg (grade A), Mui2 coal, 25196 kJ/kg (grade B), and the Taru coal, 21016 kJ/kg (grade C). Flue gas analysis for Taru and Mui coal gave hydrogen sulfide as 20 ppm and 6 ppm, maximum carbon monoxide of 2000 ppm at 600°C, and a decrease in oxygen as combustion progressed to a minimum of 15%, followed by an increase to 20.3%, suggesting depletion of coal. Based on the findings, the coal samples were suitable for commercial use.

The cell voltage in alkaline water electrolysis cells remains high despite the fact that water electrolysis is a cleaner and simpler method of hydrogen production. A multiphysical model for the cell voltage of a single cell electrolyzer was realized based on a combination of current-voltage models, simulation of electrolyzers in intermittent operation (SIMELINT), existing experimental data, and data from the experiment conducted in the course of this work. The equipment used NaOH as supporting electrolyte and stainless steel as electrodes. Different electrolyte concentrations, interelectrode gaps, and electrolyte types were applied and the cell voltages recorded. Concentrations of 60 wt% NaOH produced lowest range of cell voltage (1.15–2.67 V); an interelectrode gap of 0.5 cm also presented the lowest cell voltage (1.14–2.71 V). The distilled water from air conditioning led to a minimum cell voltage (1.18–2.78 V). The water from a factory presented the highest flow rate (12.48 × 10−1cm3/min). It was found that the cell voltage of the alkaline electrolyzer was reduced considerably by reducing the interelectrode gap to 0.5 cm and using electrolytes that produce less bubbles. A maximum error of 1.5% was found between the mathematical model and experimental model, indicating that the model is reliable.

Dilution combustion has been widely utilized due to various merits, such as enhanced efficiency, fewer pollutants emissions, and even a promising future in alleviating global warming. Diluents can be introduced through the oxidizer or fuel side to achieve the desired combustion properties, and H2O and CO2 are the most common ones. A comprehensive comparison between the different dilution methods still lacks understanding and optimizes the dilution combustion technologies. This study numerically compared the effects of H2O and CO2 dilution in the oxidizer or fuel stream on counterflow methane diffusion flames, emphasizing NO formation kinetics. Results showed that the impact of different radiation heat transfer models on NO emissions diminishes with increasing the dilution ratio. The calculations of radiation heat transfer were treated in three ways: radiation-neglected, optically thin, and using a nongrey radiation model. When keeping the oxygen content and methane fraction constant, CO2 dilution in the air-side has the most profound influence on NO reduction, and CO2 dilution in the fuel-side has the least. H2O dilution showed a medium impact with a larger degree on air-side than that on fuel-side. To gain a deeper understanding of this effect order, the contributions of different NO formation routes were quantified, and analyses were made based on the diluents’ chemical and thermal effects. It was found that the oxidizer-side dilution and fuel-side dilution affect the NO formation pathway similarly. Still, the influence of H2O dilution on the NO formation pathway differs from that of CO2 dilution.

Backdraft is a complex phenomenon which occurs during cases of confined fires. It appears by a fast deflagration which occurs after the introduction of oxygen into a compartment filled with hot gases rich in unburned combustible vapor. Practically, this situation could occur at the time of intervention of firemen who break the door or when a window breaks under the action of thermal stresses. Based on a strong experimental campaign, the present paper aimed to make a quantitative investigation of the effect of confining on a totally closed fire. With this focus, fire tests were carried out in a completely closed room of dimensions 1.20 m × 1.20 m × 1.02 m, with five sources of fire of different heat release rates. The same fire sources were also tested in a free atmosphere in order to get reference data. After a statistical study of data, a comparative analysis between both results has been done. Its outcome is that confining has a major impact on the quality of combustion and on the fire duration. More precisely, it has been noticed comparatively to fire tests in free atmosphere that confining increases the fire duration by 14.85 percent while it decreases the heat release rate by 21.72 percent.

The effects of steam injection on combustion products and thermodynamic properties of diesel fuel, soybean oil-based biodiesel (NBD), and waste cooking oil biodiesel (WCOB) are examined in this study by considering the chemical equilibrium. The model gives equilibrium mole fractions, specific heat of the exhaust mixtures of 10 combustion products, and adiabatic flame temperatures. The results show that the mole fractions of carbon monoxide (CO) and carbon dioxide (CO2) decrease with the steam injection ratios. Nitric oxide (NO) mole fractions decrease with the steam injections ratios for lean mixtures. The specific heat of combustion products increases with the steam injection ratios. The equilibrium combustion products obtained can be used to calculate the nonequilibrium values of NO in the exhaust gases using some existing correlations of NO kinetics.

This research article discloses how a uniquely structured fuel additive can easily be mixed with commercially available diesel fuel to produce an extremely stable nanoemulsion fuel. Even when using an ultralow dose (125 ppm), the additive still creates a large and catalytically active surface area using billions of nanosized water droplets (4 nanometers). No metallic or organometallic compounds were used. When used in heavy duty diesel engines, treated fuel significantly improves vehicle fuel economy. Extensive verification testing was carried out using multiple fleets of heavy duty diesel trucks operating for up to two years under “real-world” driving conditions. Testing used 538 heavy duty trucks and 15 different vehicle fleets. Test vehicles used 475,000 litres of treated fuel and covered a total of 14 million kilometres. Fleet testing was supervised by one of the premier European testing agencies (TNO Quality Services BV). Raw fuel economy data was collected and analyzed by an independent consulting agency andd showed a combined average weighted fuel savings of 9.7%. Diesel engine CO2 emissions are one of the many contributory causes of global warming. Unfortunately, new engine fuel economy technologies can take 10 years to have a 50% impact (typically 5% per year, as older vehicles are slowly replaced with new models). However, using the additive would immediately improve the combustion properties of fuel being used in these vehicles with the potential to reach up to 90% of the entire diesel vehicle population within about 60 days.

This work presents Large Eddy Simulations of the unconfined CORIA Rouen Spray Burner, fed with liquid n-heptane and air. Turbulent combustion modeling is based on the Filtered TAbulated Chemistry model for LES (F-TACLES) formalism, designed to capture the propagation speed of turbulent stratified flames. Initially dedicated to gaseous combustion, the filtered flamelet model is challenged for the first time in a turbulent spray flame configuration. Two meshes are employed. The finest grid, where both flame thickness and wrinkling are resolved, aims to challenge the chemistry tabulation procedure. At the opposite the coarse mesh does not allow full resolution of the flame thickness and exhibits significant unresolved contributions of subgrid scale flame wrinkling. Both LES solutions are extensively compared against experimental data. For both nonreacting and reacting conditions, the flow and spray aerodynamical properties are well captured by the two simulations. More interesting, the LES predicts accurately the flame lift-off height for both fine and coarse grid conditions. It confirms that the modeling methodology is able to capture the filtered turbulent flame propagation speed in a two-phase flow environment and within grid conditions representative of practical applications. Differences, observed for the droplet temperature, seem related to the evaporation model assumptions.

This study investigates the continuous transition from flame-spreading to stabilized combustion near the blow-off limit in opposed forced flow by using expanding solid fuel duct that makes distribution of oxidizer velocity in the axial direction. The stabilized combustion is a diffusion flame that appears in the Axial-Injection End-Burning Hybrid Rocket. The boundary between flame-spreading and stabilized combustion has not been investigated in detail. Polymethyl methacrylate (PMMA) rectangular ducts were used as a fuel, and gaseous oxygen was used as an oxidizer. All firing tests were conducted at atmospheric pressure. The diffusion flame traveled in the opposed-flow field where the oxidizer velocity increases continuously in the upstream direction. The combustion mode changed when oxidizer velocity at the flame tip exceeded a certain value. The oxidizer velocity used in this experiment ranges from 0.6 to 32.8 m/s. Experimental results show that a threshold oxidizer velocity of the transition can be determined. In this study, the threshold velocity was 26.4 m/s.

Many experiments have been done by authors to study the influence of the natural ventilation through openings on fire behaviour in compartments. It has been revealed that fire will be influenced by the size of existing openings which can be an open window, an open door, or both of them. Concerning the last case, the literature does not give any information about the impact of the arrangement of these openings on the behaviour of fire. The present paper aims then to carry out a comparative study of the disposition of the window compared to the door, on the behaviour of fire in a compartment. To achieve that objective, fire experiments were conducted in a reduced scale room of ​​dimensions 1.20 m × 1.20 m × 1.02 m, which can be modulated into two configurations. The first one named “PFC configuration” is the case where the open door and the open window are in nonopposite walls. The second one named “PFO configuration” is the case where these both openings are in opposite walls. After having performed several fire tests in both configurations using the same amount of diesel fuel as fire source, results revealed that the fuel burns faster in the PFC configuration compared to that in the PFO configuration. This is due to a global mass loss rate of 2.93 × 10−4kg.s−1 against 2.62 × 10−4kg.s−1, respectively. Beyond a difference of 20°C observed on the maximal temperature of burned gases located at ceiling, results also revealed the production of ghosting flames in the PFO configuration.

This study observed the influence of magnetic field orientation on the premixed combustion of vegetable oil. The results show that the magnetic field increased the laminar burning velocity because the spin of electron became more energetic and changes the spin of hydrogen proton from para to ortho. The increase of flame speed became larger on vegetable oil with stronger electric poles. The attraction magnetic field gives the strongest effect against the increase of flame speed and makes flame stability limit wider toward lean equivalence ratio. This is because O2 with the paramagnetic nature is pumped more crossing flame from the south pole (S) to north pole (N) whereas the heat energy carried by H2O from the reaction product with the diamagnetic nature is pumped more crossing flame in the N pole to the S pole. This made the combustion close to Lewis number equal to unity, whereas in the repulsion magnetic poles, S-S, more O2 is pumped into the flame while more heat is pumped out of the flame, and thus, combustion in the flame is leaner and reactions are not optimal. Conversely, at N-N poles, more heat carried by H2O was pumped into the flame while more O2 was pumped out of the flame. As a result, combustion in the flame is richer and the reaction is also not optimal. As a consequence, the velocity of the laminar flame at the repelling poles is lower than that of attracting poles.

This study deals with the development of controlled-ignition technology for high-performance compression ignition alcohol engines. Among the alcohol fuels, we focus on ethanol as it is a promising candidate of alternative fuels replacing petroleum. The objective of this study is to reveal the physical and chemical phenomena in the mixture formation process up to autoignition of an ethanol spray. In our previous numerical study, we showed the mixture formation process for gas oil and ethanol sprays in the form of spatial excess air ratio and temperature distributions inside a spray and their temporal histories from fuel injection. The results showed a good agreement with those of theoretical analysis based on the momentum theory of spray penetration. Calculation was also confirmed as reasonable by comparing to the experimental results. Through the series of our experimental and numerical studies, the reason for poor autoignition quality of an ethanol spray was revealed, that is, difficulty in simultaneous attainments of autoignition-suitable concentration and temperature in the spray mixture formation due to its fuel and thermal properties of smaller stoichiometric air-fuel ratio and much greater heat of evaporation compared to conventional diesel fuels. However, autoignition of an ethanol spray has not been obtained yet in either experiments or numerical analysis. As the next step, we numerically examined several surrounding gas pressure and temperature conditions to make clear the surrounding gas conditions enough to obtain stable autoignition. One of the commercial CFD codes CONVERGE was used in the computational calculation with the considerations of turbulence, atomization, evaporation, and detailed chemical reaction. Required surrounding gas pressure and temperature for stable autoignition with acceptable ignition delay of an ethanol spray and feasibility of the development of high-performance compression ignition alcohol engines are discussed in this paper.