Natural gas is a clean, environmentally friendly, new, and efficient energy source. Due to its lower pollutant emissions, it is gradually being adopted to replace traditional fossil energy in the architectural ceramics industry. For industrial production, the air disc at the outlet of the swirl burner is crucial for ensuring the burner’s adequate combustion. In the present study, the structure of the existing swirl burner used in the architectural ceramics industry was improved and optimized, and a three‐dimensional CFD numerical simulation was conducted. The results show that as the blade angle increases, combustion stability is enhanced, with a slight increase in flame length. Meanwhile, when the blade angle is 25°, the emissions of CO and NO gradually decrease, and combustion efficiency is improved. As the swirler thickness increases, the high‐temperature zones expand, and CO and NO emissions are reduced. Specifically, when the swirler thickness is 14 mm, CO and NO emissions are significantly decreased; compared with those at 8 mm, NO emissions are reduced by 72.73%. This work provides a reference for the application of hydrogen‐blended natural gas in swirl burners.
Natural gas is a clean, environmentally friendly, new, and efficient energy source. Due to its lower pollutant emissions, it is gradually being adopted to replace traditional fossil energy in the architectural ceramics industry. For industrial production, the air disc at the outlet of the swirl burner is crucial for ensuring the burner's adequate combustion. In the present study, the structure of the existing swirl burner used in the architectural ceramics industry was improved and optimized, and a three-dimensional CFD numerical simulation was conducted. The results show that as the blade angle increases, combustion stability is enhanced, with a slight increase in flame length. Meanwhile, when the blade angle is 25 degrees, the emissions of CO and NO gradually decrease, and combustion efficiency is improved. As the swirler thickness increases, the high-temperature zones expand, and CO and NO emissions are reduced. Specifically, when the swirler thickness is 14 mm, CO and NO emissions are significantly decreased; compared with those at 8 mm, NO emissions are reduced by 72.73%. This work provides a reference for the application of hydrogen-blended natural gas in swirl burners.
This paper presents a comparative study between natural and mechanical smoke extraction during fire in a high-rise building. Experiments were conducted in a small scale F + 1 building with dimensions 1.23 x 1.23 x 2.0 m. A stair-well of dimensions 0.22 x 0.22 m allowed the passage between the first floor and the second floor. This experimental device was operated under two configurations. Configuration 1 which studied the natural extraction of smoke through the window of Floor 1, and Configuration 2 which focused on the mechanical evacuation of smoke owing to an extractor located on the main side at 1.95 m above the floor. Fire tests were performed in both configurations with a constant fire source. Results reveal that the temperature variation over time shows a maximum smoke temperature of 145 degrees C in Configuration 1 compared to 85 degrees C in Configuration 2. Furthermore, at time t = 400 s, temperature reaches 90 degrees C in Configuration 1 compared to 64 degrees C in Configuration 2. All these results highlight the role of mechanical extraction in improving the evacuation of smoke and hot gases. This process facilitates both occupant evacuation and emergency response as part of a fire safety strategy.
Compressed natural gas (CNG) is one of the most potential alternative fuels for internal combustion engines (ICEs). Investigation of injection strategies is crucial to improve CNG engine performance and extend flammability limit, especially for direct-port combined injection (DI-PI) CNG engine. In this study, engine performance characteristics of a DI-PI CNG engine are predicted and optimized using machine learning techniques. The engine performance data are collected from an experimental single-cylinder CNG engine with combined direct-port injection systems. The performance parameters (BTE, VE, BSFC, and EGT) are predicted using different machine learning algorithms including ANN, LSTM, LR, PR, RFR, and SVR. All predicted models show great performance in fitting the predicted values to experimental results within an error range of 10%. The prediction R-squared values are achieved higher than 0.90 for all performance parameters in most cases. PR, ANN, and RFR models exhibit great accuracy for BTE prediction; ANN and LSTM models show better accuracy for VE prediction; PR shows the best prediction performance for BSFC, while RFR shows greatest accuracy for EGT prediction, with R-squared scores higher than 0.99. Furthermore, the response surface methodology (RSM) is applied to analyze and optimize the output response of BTE, VE, BSFC, and EGT. The optimization R-squared values are achieved as 0.9735, 0.9853, 0.9376, and 0.8993 for BTE, VE, BSFC, and EGT, respectively. The optimum conditions are found at 80.16 L per minute (LPM) of injected fuel, 0.91 of DI/PI ratio, and 98.12 (Nm) of engine torque. The optimum performance characteristics are obtained as 32.10 (%), 82.79 (%), 246.2274 (g/kWh), and 352.50 (degrees C) for BTE, VE, BSFC, and EGT, respectively. The developed models are beneficial for predicting and optimizing the performance of DI-PI CNG engine and have potential for further development of CNG engine.
Tire pyrolysis oil (TPO) has been recently used as an alternative to conventional fuels for internal combustion (IC) engines in order to satisfy some environmental and economic concerns. The main focus of this review is to shed light on the importance of TPO as an alternative fuel for IC engines. This paper systematically describes the TPO productions, composition, properties, and application methods in IC engines, such as binary blend, ternary blend, dual fuel mode, and spark ignition (SI) mode. The results indicate that blending TPO in diesel fuel deteriorates the engine performance and emissions, which can be improved by adding biofuels or nanoparticles. Dual fuel mode is a promising method to enhance the overall fuel quality and reduce nitrogen oxide (NOx) emissions. TPO blended with alcohols can serve as fuel in SI engines and the ratio of TPO is less than 25 vol.%. The TPO–diesel blend had better performance at each test engine load in terms of energy, exergy, and sustainability when the ratio of TPO is 10 vol.%. In conclusion, it can be said that TPO is an important factor from the viewpoint of both waste management and the protection of fossil fuel resource depletion.
This study focused on the unsteady behavior of fire whirls. A laboratory-scale fire whirl was generated, and temporal variations in flame height were measured from images taken by a high-speed camera and subjected to frequency analysis. The flame height fluctuations of the fire whirl also showed intermittent behavior, such as the puffing of a pool flame. However, the period and amplitude were irregular compared to the pool flame. In addition, the fire whirl exhibited a greater amplitude spectrum at higher frequencies than the pool flame. To investigate the velocity distribution in the horizontal plane, particle image velocimetry (PIV) was employed. The results demonstrated that the mean velocity increased from the outer radial direction toward the inner radial direction, peaked, and decreased. Conversely, the coefficient of velocity variation decreased from the outer to the inner radial direction, exhibited a minimum, and then increased. Finally, the flame was photographed from horizontal and vertical directions under two conditions with different flow velocities from the fan to generate the fire whirl. Image analysis was employed to investigate the relationship between the center position of the flame and the flame height. The results demonstrated that under conditions where the flow velocity from the fan was low, the fire whirl was intermittent and moved following the circular path drawn by the swirling flow, exhibiting unstable behavior. Furthermore, the flame height was lower when the center of the flame was further from the liquid fuel pool.
Although the global focus is shifting towards clean energy to replace coal, an immediate technological transition is not yet feasible due to the widespread prevalence of the existing coal combustion technology. The main objective of the present work is to investigate the characteristics of pulverized coal combustion by using Ansys Fluent. This study describes the fluid flow and combustion reactions in the 2D axisymmetric computational fluid dynamics (CFD) model for the 300 kW cylindrical swirl pulverized coal burner. The study was conducted to analyze the combustion process including the volatilization and char combustion models, while varying the ratio of air inlet velocity, and examining the effect of swirl number on pulverized coal combustion. The numerical modeling results for burner's operating conditions are validated with the steady-state temperature measurement in the burner. The significant outcome of the associated parameters found that the flame in the burner formed a spiral before converging into the flame line in the main combustion chamber. As a result, increasing the primary airflow rate led to a decrease in the axial temperature in the preliminary combustion chamber and decreasing the primary airflow showed the highest temperature in all three cases. While the secondary airflow increases, the swirling flow will be induced inside the chamber, which affects the highest temperature profile in the preliminary combustion chamber. Changing the tertiary airflow rate did not significantly affect the combustion. However, increasing the tertiary airflow rate improved the completeness of combustion. The swirl numbers also influenced the phenomena of combustion, the volatile released, and combustion reactions which could occur more rapidly with a higher swirl number due to a higher concentration of vortex region. Similarly, the highest swirl numbers resulted in the lowest excess O2 at the exit and the least amount of CO formation.
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.
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.
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.
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 .
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.
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.
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 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.
