Improve Combustion Efficiency Research Articles

Thermal shock triggers microexplosion combustion in graded fuel and oxidizer encapsulation microspheres with improved combustion efficiency

The combustion agglomeration of aluminum (Al) and the long heat and mass transfer distance between Al and oxidizer cause serious two-phase flow loss and slag accumulation in the engine of solid propellants. Here, we present an effective strategy by in-situ encapsulating graded nano-aluminum (nAl) and micron-aluminum (μAl) in ammonium perchlorate (AP) simultaneously by using hydroxymethyl cellulose (HMC) as adhesive and constructing a compact coupling fuel oxidizer complex high-energy microsphere (μAl/nAl@AP/HMC) to enhance the energy release efficiency and combustion efficiency. Compared with physical mixture (PM), the ignition delay time and combustion time of μAl/nAl@AP/HMC microspheres are reduced by 69.58 % and 69.87 %, owing to the decomposition process control of AP through the adsorption and spatial constraint effect on the interface between metal fuels and oxidizer. Furthermore, the nAl embedded in the AP surface forms a hot spot around the μAl to promote the combustion reaction, thereby shortening the cavitation threshold and tensile limit time of μAl and accelerating the occurrence of microexplosion. Microexplosion effect in μAl/nAl@AP/HMC microsphere significantly weakens combustion agglomeration and improves combustion efficiency and energy release efficiency by sharp shrinkage of combustion condensation products, which addresses the challenges on energy output and combustion efficiency in high-density solid propellants.

Ignition and combustion of Al–Mg–Li alloy particles at elevated pressures

Al–Mg–Li ternary alloy particles can be a promising metal additive to replace aluminum in solid propellants to improve combustion efficiency by reducing agglomeration during combustion. In this paper, Al–Mg–Li ternary alloy was prepared and its basic physical and chemical characterization parameters were obtained by SEM-EDS, ICP-AES, and XRD analysis. The ignition and combustion characteristics of single Al–Mg–Li particles under different pressures were investigated by using a self-developed experimental setup. The ignition process and combustion flame structure of Al–Mg–Li particles were significantly affected by the increasing pressure, and the ignition delay and combustion time decreased. The ignition mode was clearly identified: surface ignition (0.1–0.2 MPa) and gas phase ignition (0.4–1.2 MPa). Al–Mg–Li particles showed white-pink flame during combustion, and the characteristic peaks of AlO, MgO, and Li were identified, confirming that the particles performed a gas-phase combustion at pressures above 0.4 MPa. The combustion temperature of Al–Mg–Li particles could exceed 3000 °C when the pressure surpassed 0.6 MPa. The composition of different regions in the condensed combustion products were analyzed. Reaction mechanism was proposed to reveal the addition of elemental Mg and Li could improve the ignition and combustion characteristics of Al, especially at higher ambient pressures.

Experimental investigation of the effect of the electromagnetic field on the stability of the hydrogen enriched methane flame under acoustic enforcement

ABSTRACT The current research has investigated the effects of magnetic fields on molecular structures, especially on flame formation, flame behavior and emission gases. This study particularly examines the phenomenon of combustion instability and emission characteristics of CH4 and CH4/H2 fuels under lean combustion conditions and under external acoustic forcing. Conducted within a combustor utilizing premixing and swirl techniques, experiments strategically generated magnetic fields in specific regions: the burner input, pre-mixer, and fuel supply lines. Trials maintained a constant magnetic field intensity of 3500 gauss, with a thermal output of 3 kW, swirl number of 1, and equivalency ratio of 0.7. Evaluation of acoustic resonance was performed at 95 Hz and 175 Hz frequencies within the combustion chamber. Findings suggest that applying a magnetic field positively impacts the combustion process, reducing instabilities in fuels like CH4 and CH4/H2, especially at a 95 Hz frequency. During pure methane combustion, CO emissions initially measured 4785 ppm but decreased to 4143 ppm under the magnetic field’s influence. Introducing the magnetic field to the pre-mixer increased CO emissions to 4233 ppm, while its application to the fuel line reduced emissions to 4104 ppm. For the CH4/H2 fuel mix, CO emissions decreased from 2638 ppm to 1961 ppm with the magnetic field, indicating improved combustion and reduced pollutant gases, including CO and NOx. This study highlights the potential of magnetic fields to improve combustion efficiency and address environmental concerns.

Effects of Fuel Flow and Airflow Swirl on Thermal Performance of a Miniature-Scale Combustor for Direct Energy Conversion Systems

Micropower generation and micropropulsion are two emerging fields where micro- and miniature-scale combustors are anticipated to play a significant role. Today, there is a growing interest in combustion-based direct energy conversion modules such as thermoelectric and thermophotovoltaic micropower generators. In this study, the effects of swirl addition to fuel flow and airflow on combustor operational envelope, flame blowout limit, combustion efficiency, exhaust gas temperature, mean outer wall temperature, emitter efficiency, and normalized temperature standard deviation of a miniature-scale (mesoscale) combustor are studied under various equivalence ratios. The findings demonstrate that swirling flows improve the flame blowout limit and operational envelope of the combustor; however, this improvement is more significant for airflow swirl. Besides simultaneous swirling flows of fuel and air result in the highest blowout limit. Additionally, it has been shown that swirl addition improves combustion efficiency and causes a significant amount of heat to be generated, which raises the temperature of the exhaust gas, the mean outer wall temperature, and the emitter efficiency. Furthermore, mean outer wall temperature and emitter efficiency have the highest values for simultaneous swirling flows of fuel and air. It is also observed that increasing the fuel flow swirl number generally lessens the normalized temperature standard deviation (NTSD) and consequently improves the combustor wall temperature uniformity, while for the airflow swirl case, a swirler with 30° vane angle for airstream has a lower NTSD than a 45° vane angle swirler. The results obtained in this study provide useful information for designing a combustion-based direct energy conversion module.

Computational Fluid Dynamics of Four Stroke In-Cylinder Charge Behavior at Distinct Valve Lift Opening Clearance in Spark Ignition Reciprocating Internal Combustion Renault Engine

In-cylinder flow dynamics in internal combustion Renault engine is complex, expensive and difficult to compute experimentally. The present study attempts to emulate the in-cylinder charge behaviour at distinct valve lift opening clearance in four stroke spark ignition internal combustion engine using computational fluid dynamics. Considering the complexity of the geometry and in-cylinder fluid motion, governing equations for unsteady, three dimensional, compressible turbulent flow were computed with continuity equations (conservation of mass), Navier-Stokes equations (conservation of momentum) and RNG k-ε turbulence model. Assumed to be an inline spark ignition (SI) operating on a four stroke cycle, the engine was modelled with SolidWorks 2019 version while the in-cylinder charge behaviour was simulated using ANSYS Fluent 14.5. Increase in cylinder temperature enhanced the thermal properties of air-fuel mixture during combustion. Increase in valve lift opening clearance led to more charge quantity being ingested through the intake valve opening into the cylinder, thereby causing increase in temperature of in-cylinder charge as well as significant improvement in the volumetric and mechanical efficiency of the cycle. It was also observed that the rate of heat retention in the cylinder may be optimum at lower valve lift which may be characterised by minor or zero loses, while significantly high cylinder charge temperature may be prone to reduction of the intake charge density. Based on Particle Image Velocimetry (PIV), in-cylinder velocity vectors, vorticity magnitudes and distributions of turbulence kinetic energy (TKE) increased with increasing valve lift opening clearance, thereby, improving combustion efficiency, increasing torque and power output for effective engine performance.

Plasma assisted combustion of different biogas mixtures in low swirl burner

This study explores the impact of plasma driving frequency on diverse biogas compositions, emphasizing flame behaviour by analysing spatial emissions of OH*, C2*, and CH* from plasma-assisted flames. Experimental investigation performed combusting mixtures with 25 % and 60 % CH4 in CO2 under lean combustion conditions with the varying fuel equivalence ratios from 0.71 to 0.83 and plasma discharge frequencies from 60 to 120 kHz resulting in higher energy density.Obtained results indicate that the plasma assistance notably enhances flame stability under lean fuel conditions with increasing frequency from 80 to 120 kHz. The discharge frequency of 60 kHz indicates insufficient energy to enhance combustion of low calorific value mixtures as the flame lift-off height increases approximately by 0.43–1.5 % for the mixture of 25 vol% CH4 in CO2 and by 0.26–7.7 % for the mixture of 60 vol% CH4 in CO2. Changing the plasma frequency from 80 to 120 kHz, the flame position is shifted closer to the burner nozzle for both mixtures and the highest effect is determined at 120 kHz. The flame lift-off height is reduced by 2.43–16.34 % for the mixture with 25 vol% of CH4 and by 3.57–51.28 % for the mixture with 60 % of CH4. The plasma-assisted combustion leads to improved combustion efficiency as CO emissions are reduced from 1550 ppm to 45 ppm for biogas mixture, but in the case of low calorific value gas, the CO emissions increase linearly with the frequency increase even the flame curvature and stability is improved.

Exploring the efficiency and emission characteristics of hydroxy-boosted canola biodiesel in comparison to traditional diesel fuels

In this research, we experimentally examined how incorporating HHO into blends of 20% canola biodiesel with 80% diesel and 40% canola biodiesel with 60% diesel impacts the engine’s performance and its emission traits. Canola oil, widely used in Europe, served as the biodiesel base. The addition of HHO, recognized for its potential to improve combustion efficiency and reduce emissions which were deteriorated by biodiesel addition. The findings revealed decrement on fuel consumption as 5.74% and 4.43% and rise in thermal efficiencies as 3.92% and 3.97% with HHO addition compared to B20 and B40, respectively. Besides that, CO emissions were reduced significantly up to 35.43%, while CO2 emissions decreased moderately up to 14.93% compared to diesel fuel. On the other hand, biodiesel and HHO addition increased NOx emissions as 49.80%. Utilization of biodiesel and HHO in diesel engines offers a straightforward way to reduce emissions and enhance fuel efficiency, addressing environmental issues and promoting sustainable transportation.

The Current State of Hydrogen-Enriched Engine Development

In recent years, with the further strengthening of environmental protection, researchers have paid extensive attention to the hydrogen-enriched engine. hydrogen-enriched mix hydrogen with conventional fuels and are designed to reduce exhaust emissions, improve combustion efficiency and enhance power performance. Proper hydrogen incorporation can reduce carbon emissions and nitrogen oxide emissions, and improve engine power output and combustion efficiency. In this paper, four kinds of hydrogen-enriched engines are introduced comprehensively, and the effects of hydrogen-enriched ratio on combustion and emission performance of engines are analyzed, as well as the effects of different technologies on hydrogen-enriched engines. The research results show that hydrogen-enriched engines have significant advantages in reducing emissions, improving combustion efficiency and enhancing power performance, and become one of the important technologies for the future automotive industry to transition to clean energy.

Preparation and study on combustion performance of AP@ZrH2 core-shell composite energetic materials with high volume energy density

The development of composite energetic material with high volume energy density could increase the range and loading capacity of solid propellants. In this study, a series of core-shell composite energetic materials AP@ZrH2 were fabricated by decorating ZrH2 on the ammonium perchlorate (AP) through a solvent-nonsolvent method. A substantial increase in combustion heat (13373.67 J/g) and maximum burning temperature (1415.33 °C) are detected in composites in contrast to physically mixed sample (10660.46 J/g and 837.22 °C). This is due to the enhancement of the decomposition performance of AP, which provides sufficient oxidation gas atmosphere for combustion of ZrH2. In addition, the delay time (524 ms) and burning time (114 ms) of composites are significantly decreased compared to the physical mixed sample (2145 and 256 ms). The remarkable combustion performance and burning rate could be attributed to reduced mass and heat transfer distances. Finally, the improvement of combustion efficiency in the composites makes the size of the residual particles smaller.

The effect of CH4 addition on high-H2 syngas combustion characteristics under N2/CO2 dilution

The composition of biomass gas is complex, in order to promote the more extensive and efficient utilization of low-calorific syngas, it is necessary to master the basic combustion characteristics of low-calorific syngas under different compositions. In this paper, the effects of addition of CH4 (0% – 20%) on the combustion characteristics of laminar flow flame of high-H2 syngas (H2:CO = 3:1) were studied by experiments and numerical simulations under the dilution of N2 and CO2 (40%). The laminar burning velocity (LBV) and Markstein length are obtained by experiments. CHEMKIN-PRO software package was used to compare the prediction results of the four mechanisms with the measured data. Finally, GRI3.0 mechanism was selected as the simulation mechanism in this paper. The experimental results indicate that the LBV of N2 dilution is higher than that of CO2 dilution, and the flame is more stable, with adding CH4, the LBV of syngas mixtures is decreased, and the LBV of rich-fuel mixtures is decreased faster, but the stability of premixed flames of syngas is improved. Numerical simulation shows that the dominant branch chain reaction changes from R99 to R38 after CH4 is added, and the mole fraction of H, O decreases while the mole fraction of OH, CH3 increases. The dilution of CO2 results in a lower concentration of active radicals than N2 because CO2 inhibits the important reaction R99. The GRI 3.0 mechanism was used to simulate the formation of NO: the addition of CH4 promoted the formation of hot NO. The NO production of NNH and N2O intermediate mechanism is decreased, and a new way of N2 and CH reaction to HCN is increased. The dilution of CO2 can reduce NO emission more than that of N2. The insights gained from this study have practical implications in a variety of production applications. For example, optimizing mixture equivalence ratios can improve combustion efficiency, thereby increasing energy efficiency and reducing environmental emissions.

Review[sbnd]Recent developments on applying acoustic waves for efficiency improvements of different thermofluids systems

This review classified recent works using proper acoustic waves to develop more efficient thermofluids systems for different industrial equipment such as swirl combustor, jet in crossflow, gas flare, different types of heat exchangers, cooling mechanism, aircraft wings, and turbine blades. For the swirl combustor, the range of proper excitation Strouhal number and jet pulsation intensity depends on the type of fuel, geometry of burner, swirl number, and central and annular Reynolds numbers. The combined effects of early jet break up, and centrifugal force induced by proper acoustic waves can lead to higher jet spread rate that can induce higher levels of mixing of the fuel and air in swirl combustor, improving combustion efficiency. For the transverse jet, the range of proper excitation Strouhal number and jet pulsation intensity depends on the type of fuel, geometry, and angle and direction of the burner, and jet and cross flow Reynolds numbers. Proper acoustic excitation can force the transverse jet flow to synchronized shear layer vortices. This phenomenon can cause the new vortices to appear in the upwind shear layer region of the deflected jet; then the spread, penetration, entrainment, and dispersion of the jet significantly increases, improving combustion efficiency. For the aircraft wing, vertical acoustic excitation significantly improves the lift force when the sound frequency is equal to the period of flow fluctuation in the separated boundary layer. For the heat exchanger, the ultrasonic transducer can be installed on the walls of a heat exchanger with direct contact to the fluid, improving the heat transfer coefficient. The physics of fluids behind the efficiency improvements of all mentioned cases were also clarified. Moreover, the acoustically excited impinging jets with higher cooling efficiency applied in different areas are discussed. Proper acoustic forcing can decrease the rate of unstable frequencies of disturbances related to impinging jets over a short distance. This phenomenon can significantly enhance heat transfer and improve cooling efficiency. This review paper provides insight into how acoustic waves could improve the efficiency of thermofluids systems in a variety of applications. Acoustic excitation could have the potential capability to improve the efficiency of new applications such as wind, gas or steam turbines, some types of industrial chemical mixers with parallel plane jets, aircraft wings or those of unmanned aerial vehicles, more efficient combustion chambers, and less polluting gas flares. However, the feasibility of this concept requires further investigation by the community in the future.

Overview of the use of oxygen sensors in automotive applications

In the process of combustion, the air-fuel ratio is important for control strategies to reduce fuel economy and improve engine performance. Oxygen sensors are key elements in electronic fuel injection systems to indicate the oxygen content and send electrical signals to the electronic control unit. Starting with the first generation of oxygen sensors, which had limited applications, all automotive manufacturers now use wideband sensors to detect oxygen concentration with rapid reaction and linear output characteristics. Also, these new sensors provide accurate information for a wide range of air coefficients (λ = 0.65-2.4), improving combustion efficiency. In this paper, several types of narrowband and wideband sensors were analyzed, measuring the activation temperature for each sensor until a reliable signal was obtained.

Effects of Varying Equivalence Ratios on the Combustion Efficiency Characteristic of a Dual-Fuel Compression Ignition Engine by Changing Intake Pressures and Exhaust Gas Recirculation Rates

In general, a leaner mixture condition improves combustion efficiency in compression ignition (CI) combustion using diesel. However, in the case of leaner air–fuel mixture conditions, it disturbs flame propagation in spark ignition combustion using gasoline, i.e., low reactivity fuel, causing a decrease in combustion efficiency. Since dual-fuel combustion in a CI engine typically involves the use of high- and low-reactivity fuels together, the differing reactivity conditions in the cylinder become as important as the local equivalence ratio in the cylinder. Thus, there is a need to verify the effect of a leaner mixture condition on combustion efficiency in dual-fuel CI combustion. For this reason, this study experimentally evaluates the effects of varying equivalence ratios on the combustion efficiency of gasoline/diesel dual-fueled CI combustion in a 0.4-L single-cylinder engine under low-speed (1500 rpm) and low-load (total LHV 570 J/str) conditions. To vary the equivalence ratios, intake pressures and exhaust gas recirculation (EGR) rates were, respectively, changed under the part-load condition. The results emphasize that as the equivalence ratio becomes leaner by increasing the intake pressure, combustion efficiency worsens due to the low reactivity properties and certain flame propagation modes of gasoline combustion. On the contrary, increasing the EGR rate did not significantly influence combustion efficiency, but it effectively helped reduce nitrogen oxide (NOx) emissions. Based on these results, it is concluded that optimizing dual-fuel CI combustion to suppress NOx emissions is better achieved using EGR, rather than creating a leaner mixture condition.

Research on Flare Burner for Venting in Gas Transmission Station

With the widespread application of natural gas, the venting of remaining natural gas is an issue that cannot be ignored. Direct venting causes serious environmental pollution, so thermal venting, also known as combustion venting, has become an important way to solve environmental pollution problems. This simulation first established two different types of burners, cluster and array, to quantitatively analyze the flame combustion characteristics. It simulated the distribution patterns of velocity, temperature, and key component concentrations of the two burners under the same number of holes and fuel flow rate. The research results indicate that due to the existence of oblique jet flow in the converging and array types, a reflux zone is formed at the outlet of the diffuser, and natural gas and air are mixed more thoroughly, resulting in a more stable flame. By comparing the burnout rate and combustion failure rate of the two types of burners, it was found that the convergent flame height and residual natural gas content during combustion were the lowest, resulting in better combustion efficiency. On this basis, while ensuring the same flow rate, the number of converging combustion holes was increased, the model parameters were improved, and it was found that the flame height was further reduced. At the same time, while maintaining the combustion removal rate, the burnout rate was improved. The development of the above-mentioned flare burner is of great significance in improving combustion efficiency, reducing flame height, and reducing environmental pollution caused by venting.

Atmospheric CO2 and 14CO2 observations at the northern foot of the Qinling Mountains in China: Temporal characteristics and source quantification

A two-year (March 2021 to February 2023) continuous atmospheric CO2 and a one-year regular atmospheric 14CO2 measurement records were measured at the northern foot of the Qinling Mountains in Xi'an, China, aiming to study the temporal characteristics of atmospheric CO2 and the contributions from the sources of fossil fuel CO2 (CO2ff) and biological CO2 (CO2bio) fluxes. The two-year mean CO2 mole fraction was 442.2 ± 16.3 ppm, with a yearly increase of 4.7 ppm (i.e., 1.1 %) during the two-year observations. Seasonal CO2 mole fractions were the highest in winter (452.1 ± 17.7 ppm) and the lowest in summer (433.5 ± 13.3 ppm), with the monthly CO2 levels peaking in January and troughing in June. Diurnal CO2 levels peaked at dawn (05:00–07:00) in spring, summer and autumn, and at 10:00 in winter. 14C analysis revealed that the excess CO2 (CO2ex, atmospheric CO2 minus background CO2) at this site was mainly from CO2ff emissions (67.0 ± 26.8 %), and CO2ff mole fractions were the highest in winter (20.6 ± 17.7 ppm). Local CO enhancement above the background mole fraction (ΔCO) was significantly (r = 0.74, p < 0.05) positively correlated with CO2ff in a one-year measurement, and ΔCO:CO2ff showed a ratio of 23 ± 6 ppb/ppm during summer and winter sampling days, much lower than previous measurements and suggesting an improvement in combustion efficiency over the last decade. CO2bio mole fractions also peaked in winter (14.2 ± 9.6 ppm), apparently due to biomass combustion and the lower and more stable wintertime atmospheric boundary layer. The negative CO2bio values in summer indicated that terrestrial vegetation of the Qinling Mountains had the potential to uptake atmospheric CO2 during the corresponding sampling days. This site is most sensitive to local emissions from Xi'an and to short distance transportation from the southern Qinling Mountains through the valleys.

A Visual Study on of HCB/Gasoline Dual-Fuel Combustion Strategy and Premix Ratio in a Diesel Engine

Article A Visual Study on of HCB/Gasoline Dual-Fuel Combustion Strategy and Premix Ratio in a Diesel Engine Qian Wang *, Botian Guo, Lixuan Cao, Xu Liu, Yi Jiang, and Jiawei Yao School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China * Correspondence: qwang@ujs.edu.cn Received: 8 November 2023 Accepted: 22 January 2024 Published: 30 January 2024 Abstract: This study investigates the combustion characteristics of hydrogen catalysed biodiesel (HCB) ignited gasoline in an optical engine using the Reactivity Controlled Compression Ignition (RCCI) combustion model. The experiment uses a single injection strategy to determine the optimum injection timing for gasoline ignition by varying the HCB injection timing (-30 to -15° CAATDC) and the ratio of high to low reactivity fuel energy (10% to 30%), to investigate the gasoline premix ratio, and to analyse the flame development characteristics. The results indicate that as the HCB energy ratio increases, the in-cylinder pressure and heat release rate increase significantly, and the in-cylinder combustion temperature improves significantly. As the injection timing is delayed, the combustion phase shifts back, and when the injection timing is close to the upper stop, the in-cylinder combustion pressure and heat release rate increase first increase and then decrease. Based on the results, it can be concluded that optimising the HCB injection timing and energy ratio can effectively control the distribution of the fuel-air mixture in the combustion chamber, thereby improving combustion efficiency and emission performance. By strategically adjusting the injection timing, an ideal balance between fuel stratification and flame propagation can be achieved, which ultimately improves the overall combustion process. The results of this study provide valuable insights for the further development of combustion control strategies and contribute to the development of more efficient and environmentally friendly engine technologies.

Characterization of fuel composite obtained by the mixing of biomass and coal

ABSTRACT This research investigates the potential of biomass-coal blends as an alternative fuel source, focusing on coal from Darra Adam Khel, Cherat, Harnoi, and Daola in the KPK province of Pakistan and Parthenium weed biomass. The study assesses the impact of varying biomass ratios on proximate analysis (net calorific value (NCV), sulfur content, volatile matter, ash content, and moisture content) and calorific values of the composite fuel. Results reveal a linear NCV decline with increasing biomass, affecting high NCV coals less. Daola and Darra coal, starting at 30.43 and 31.32 MJ/kg, decreased to 20.15 MJ/kg and 19.71 MJ/kg with 66% biomass. Sulfur content, notably high in high NCV coals, significantly reduces with biomass; Darra coal decreases from 3.31% to below 1% with 66% biomass. Volatile matter uniformly increases with incremental biomass, enhancing combustibility. Cherat coal, initially at 8% volatile matter, rises to 50% with 66% biomass. Biomass effectively reduces ash content, particularly beneficial for low NCV coals. Harnoi coal, starting with 73% ash content, decreases to 30% with 66% biomass. However, biomass addition raises moisture content due to challenges in removing moisture from Parthenium weed. In summary, these findings optimize biomass-coal blends for enhanced fuel performance, address environmental concerns, and improve combustion efficiency, highlighting their potential as sustainable and eco-friendly energy sources.

Optical diagnostics in impact of ammonia energy ratio and diesel split ratio on combustion process and flame propagation in an Ammonia-Diesel Dual-Fuel engine

In the context of ammonia-diesel dual-fuel (ADDF) engines, challenges such as ignition difficulties and misfires emerge prominently at elevated ammonia energy ratios. To alleviate these challenges, this study aims to elucidate the effects of ammonia energy ratios (AER) and diesel split ratios (DSR) on the combustion process and flame propagation in an optical ADDF engine configuration. Utilizing optical diagnostics, including flame luminescence and high-speed photography, the study provided insights into combustion boundary conditions specific to ADDF engine operation. The results highlight that an increase in AER to 60 % results in a marked decrease in peak cylinder pressure, peak apparent heat release rate (AHRR), and the in-cylinder pressure rise rate. This is accompanied by a reduction in IMEP from 4.16 bar to 3.24 bar, indicating a decline in combustion efficiency upon greater ammonia addition. Flame luminosity exhibits a shift from a diesel-like blue hue to an ammonia-tinted pale yellow. This change coincides with a significant reduction in soot formation and restrictions in flame area and propagation speed, largely due to ammonia's intrinsically slower burning velocity and its chemical interplay with diesel. Implementing a dual injection approach further accentuates the peak in-cylinder pressure and AHRR, with the second injection playing a crucial role in ignition. Optimizing the DSR to 40 % improves combustion efficiency, attributed to enhanced fuel-oxygen interactions. Conversely, DSR values of 60 % and 80 % pose challenges. A reduction in diesel content in the subsequent injection leads to a leaner blend, subsequently affecting combustion efficiency, as indicated by reduced heat release rate and diminished IMEP. This study emphasizes understanding the ammonia-diesel interaction and the importance of choosing the appropriate DSR to exploit the advantages of ADDF engines.

Flame Deflector Modification for Improved Combustion Efficiency in Domestic Gas Ovens

ABSTRACT This research aimed to examine the effect of port placements in the flame deflector on the combustion efficiency of the grill burner within a domestic gas oven. Six different configurations of the flame deflector were designed for this purpose. Emission tests of the grill burner were carried out at two different pressures for 1 h according to EN30 standard for all types of flame deflectors. The reduction in the C O N content by %11.3 was observed in the flame deflector of No_6 as compared to default deflector. The CFD analysis of the No_6 flame deflector was also carried out to examine the air flow pattern of the flame deflector through the grill burner. Results showed that the air flow from the flame deflector into the grill burner was more uniform than that of the default flame deflector. The temperature, the mass fraction of fuel/air, and CO and CO2 distribution in the grill burner through combustion process were numerically simulated using commercial CFD program, FloEFD. The most appropriate chimney position was recommended based on the distribution of CO2 content. Emission tests and efficiency tests of two different chimney prototypes with different chimney areas (1260 mm2 and 1400 mm2) were tested to evaluate the effect of the chimney area on the combustion quality and combustion efficiency in terms of combustion products and gas consumption. Experimental results showed that reduction in the emission was realized by approximately 50% at both pressures of 17 mbar and 25 mbar when using higher chimney area. However, the gas consumption increased by approximately 0.67%, 1%, and 7% per m3 when the chimney with higher area was used at the burning temperature of 140 K, 180 K, and 220 K, respectively.

Experimental Investigation of Engine Characteristics Fuelled with Emulsified and Nano Emulsified Citrus Limon Seed Biodiesel

The exploration and advancement of alternative fuels serve as catalysts for innovation in energy technologies, fostering economic growth and offering sustainable solutions for transportation and industry. The process of emulsifying lowgrade diesel fuel enhances the atomization and mixing of the fuel with air, resulting in improved combustion efficiency, decreased emissions, and enhanced fuel efficiency. The introduction of nanoparticles into the emulsion results in an increase in the surface area of the fuel droplets, leading to enhanced atomization and improved combustion efficiency. The enhanced dispersion of particles in the air facilitates improved interaction, leading to decreased emissions of nitrogen oxides and particulate matter, contributing to the promotion of environmental sustainability. This study examines the performance and emission characteristics of a single-cylinder diesel engine when biodiesel derived from citrus limon seeds is combined with emulsified citrus limon seed biodiesel and nano-emulsified biodiesel. The nECLB had 2.57–4.2% braking thermal efficiency above the ECLB. Specific fuel consumption was 7.8% to 13.4% lower for the nECLB than the ECLB. The nECLB emitted 8.5% less HC and 21% less CO than the ECLB. When utilising base diesel, nECLB reduced nitrogen oxide and smoke emissions by 50%–65% and 0.5%–1.5%, respectively