Decrease In NOx Emissions Research Articles

Experimental study results of the front-end device with two-tier air burner as part of the gas turbine engine combustion chamber

In recent years, the gas turbine power plant has been increasingly used in various industries in Kazakhstan. The reasons for this are: thermal efficiency, simplicity of the thermal scheme and design, small mass per power unit, high maneuverability, low toxicity, and relatively simple automation of operation. This paper presents the experimental study results of a two-tier air burner as the part of the gas turbine engine combustion chamber at burning liquid fuel. ? new design of a microflame device was developed. Two-tier burner makes possible the combustion process in a number of discrete zones, i.e. microflame combustion. During the experiment, the installation angles of the blades of the external and internal registers, as well as the ratio of the coefficients of excess air in the tiers, were changed. The experimental studies of a two-tier burner confirmed the possibility to increase fuel combustion efficiency, a low degree of temperature field unevenness and to decrease NOx emission.

Optimization for waste coconut and fish oil derived biodiesel with MgO nanoparticle blend: Grey relational analysis, grey wolf optimization, driving training based optimization and election based optimization algorithm

The present work aimed at the practical utility of waste hybrid (coconut + fish oil) oil-derived biodiesel with magnesium oxide (MgO) nanoparticles (NPs) fuelled to diesel engines. Central composite design (CCD) experimental matrices with different sets of variables (blend type: 10–40 % vol. of biodiesel; MgO NPs: 60–180 ppm; engine speed: 1000–2000 rpm; engine load: 40–100 %) were used to examine the engine performance (brake specific fuel consumption: BSFC; and brake thermal efficiency: BTE) and emission characteristics (carbon monoxide: CO; unburnt hydrocarbon: UHC; nitrous oxide: NOx). The MgO NPs are characterized by using an X-ray diffractometer: XRD, scanning electron microscope: SEM and transmission electron microscope: TEM and confirm the compositions and the crystallite particle size equal to 132 nm. The models developed for each output showed a better value of coefficient of determination (R2) equal to 0.9843 for BSFC, 0.9859 for BTE, 0.9772 for CO, 0.9777 for NOx, and 0.9368 for UHC. Grey relational analysis (GRA) with quality loss function (QLFs) and principal component analysis (PCA) were used to correlate the multiple responses and transform multiple objective functions to single objective function necessary for optimization. Three population-based search algorithms, such as driving training-based optimization (DTBO) and election-based optimization algorithm (EBOA) and grey wolf optimization (GWO), were applied and evaluated their optimization performances. EBOA, DTBO and GWO determined the same optimal conditions and converged to 1000 iterations with a computational time equal to 2, 5 and 30 s, respectively. The algorithms determined optimal conditions produced better experimental values than GRA-based QLF and PCA with 31.27 % decrease in BSFC, 24.27 % decrease in CO, 4.64 % decrease in HC, 19.82 % decrease in NOx emissions, and 9.82 % decrease in BTE, respectively. MgO NPs addition to biodiesel fuel resulted in better performance and emission characteristics than without MgO NPs.

EGR and Emulsified Fuel Combination Effects on the Combustion, Performance, and NOx Emissions in Marine Diesel Engines

Techniques such as exhaust gas recirculation (EGR) and water-in-fuel emulsions (WFEs) can significantly decrease NOx emissions in diesel engines. As a disadvantage of adopting EGR, the afterburning period lengthens owing to a shortage of oxygen, lowering thermal efficiency. Meanwhile, WFEs can slightly reduce NOx emissions and reduce the afterburning phase without severely compromising thermal efficiency. Therefore, the EGR–WFE combination was modeled utilizing the KIVA-3V code along with GT power and experimental results. The findings indicated that combining EGR with WFEs is an efficient technique to reduce afterburning and enhance thermal efficiency. Under the EGR state, the NO product was evenly lowered. In the WFE, a considerable NO amount was created near the front edge of the combustion flame. Additionally, squish flow from the piston’s up–down movement improved fuel–air mixing, and NO production was increased as a result, particularly at high injection pressure. Using WFEs with EGR at a low oxygen concentration significantly reduced NO emissions while increasing thermal efficiency. For instance, using 16% of the oxygen concentration and a 40% water emulsion, a 94% drop in NO and a 4% improvement in the Indicated Mean Effective Pressure were obtained concurrently. This research proposes using the EGR–WFE combination to minimize NO emissions while maintaining thermal efficiency.

Influence of small amount of hydrogen fuel on spark-ignition engine characteristics through H-CNG fuel blend and its comparative study

ABSTRACT An experimental study was performed on single-cylinder, four-stroke, and spark ignition engines to understand the impact of a small quantity of hydrogen fractions in CNG fuel on an engine’s performance and emission characteristics. The two blends of H-CNG in which hydrogen fuel was used were 0.20 kg/hr and 0.25 kg/hr mass flow rate at varying engine rpm. The hydrogen enrichment increases the BTE by 3.54% and 4.94%, for HCNG (0.20 kg/hr) and HCNG (0.25 kg/hr), relative to CNG operation. Similarly, the hydrogen enrichment reduces the BSFC with higher margin due to its increment in calorific value compared to CNG operation. The H-CNG fuel blend has shown severe decrement in HC, CO, CO2, and O2 emissions compared to gasoline and CNG fuel. However, NOx emissions were a concern in CNG-fueled engine. The CNG-fueled engine has produced almost 32% of higher NOx emissions than gasoline. However, adding H2 fuel to CNG decreased NOx emissions and brought it nearly equal to the gasoline-fueled engine emissions at overall engine rpm. Overall, from a future perspective, the H-CNG mode of operation with optimum proportion of Hydrogen-CNG can be considered a suitable fuel blend to control engine emissions without compromising engine performance of conventional SI engines.

Concept of rapid and controllable combustion for high power-density diesel engines

Over recent years, the demand to abate global carbon emissions has attracted significant interest and resulted in more stringent policies and regulations. For diesel engines, the fundamental solution to addressing carbon emissions entails optimizing the thermal efficiency. However, for high power-density marine diesel engines, large amount of injection mass companied with little intake swirl makes further optimization of fuel consumption quite difficult. To address this issue, a concept for rapid and controllable combustion is proposed herein. The concept is a theory-based method to design and optimize the combustion system in a forward direction from theory to control method. The concept of rapid combustion relies on the optimization of the combustion process based on ideal Sabathe-Miller cycle to get the optimal heat release rate. The concept of controllable combustion was conducted by theoretically relating the in-cylinder spray evolution with heat release rate so as to determine the controllable parameters of combustion system. The concept proposed was validated by the computational fluid dynamics simulation as well as a high power-density diesel engine with a cylinder power of 450 kW and displacement of 18.9L which has been optimized by traditional benchmark and design of experiments method. The results showed that, the optimization method suggested is reliable to define the combustion system to achieve thermal efficiency as high as possible under the boundary constrains. Moreover, without excessive requirement for turbocharger capacity and injection system, both the fuel consumption and NOx emission decrease under all tested loads by using the proposed method, when compared to the results of traditional optimization method. For the commonly-used 100 % and 75 % load, the fuel consumption respectively drops from 199.02 to 196.5 and 199.75 to 197.15 g/kWh, and NOx emission is reduced by 22 % and 12.6 %, which is relatively remarkable for high power-density marine diesel engines. Therefore, it offers the advantage of significantly reducing the workload when designing and optimizing the combustion of diesel engines.

Three-way catalyst modeling and fuel switch optimization of a natural gas bi-fuel-powered vehicle

In contemporary societies, improving engine efficiency and emission are critical targets for engine designers due to the increasing overwhelming popularity of electric powertrains. Compressed natural gas (CNG) is one of the alternatives for traditional fuels. Due to considerable HC emission during vehicle’s cold-start, the vehicle is started with gasoline and is switched to CNG fuel after a while. The optimum fuel switching time and its effect on total tailpipe emissions have not been addressed in the literature. Therefore, this study focuses on the detailed kinetic modeling of a three-way catalytic converter of a bi-fuel (gasoline/CNG) powered vehicle. The simulated results are validated with experimental data of the new European driving cycle (NEDC) emissions test. The pre-exponential factor (A), the energy of activation (E), and the exponent of temperature (β) for the 22 reactions of the three-way catalytic converter are calibrated by optimization. A genetic algorithm is implemented to optimize the reaction coefficients in both CNG and gasoline fuel mode. The validated model is also used to optimize the vehicle's tailpipe emissions in CNG operation conditions. The results reveal that NOx catalyst conversion efficiency is acceptable in highway driving conditions for CNG mode, while the CO conversion efficiency is inappropriate under the same conditions. It is found that THC catalyst efficiency in gasoline is better than CNG mode after cold-start due to the low reactivity of methane. Most gasoline tailpipe emissions are emitted during the cold-start, while CNG tailpipe emissions gradually increase after the cold-start. The fuel switch time from gasoline to CNG is optimized to 48 s after the vehicle start. While the NOx emission decreases by 15% at the end of the driving cycle, THC is not changed after optimization. The only THC reduction optimization goal leads to a switch time increase to 149 s after the start of driving.

Effect of Cetane-Coupled Pilot Injection Parameters on Diesel Engine Combustion and Emissions.

The effects of cetane number (CN) coupled with pilot injection ratio and pilot injection timing on the combustion and emission characteristics of a four-cylinder diesel engine were investigated. The results showed that as the pilot injection ratio increases, the peak cylinder gas pressure (CGP) increases, and the peak of heat release rate (HRR) increases accordingly; the coupled CN increases, the brake specific fuel consumption (BSFC) decreases, and the brake thermal efficiency (BTE) increases; CO and HC emissions increase; and NO x emissions increase. In addition, the number concentration and total mass of particulate matter (PM) decrease with the increasing pilot injection ratio. Only when the pilot injection ratio reaches 20% does the fuel produce pilot injection heat release. The ignition delay time (ID) and combustion duration (CD) are redefined for the pilot injection heat release operating conditions. With the delay of the pilot injection timing, the peak CGP increases, the coupled CN increases, the BTE increases, the BSFC decreases, CO and HC emissions increase, and NO x emissions decrease. With the delay of the pilot injection timing, the number concentration and total mass of PM decrease. In addition, no pilot injection heat release was generated for any of the five fuels at pilot injection timings from 30°CA BTDC to 45°CA BTDC.

A novel online combustion optimization method for boiler combining dynamic modeling, multi-objective optimization and improved case-based reasoning

A new boiler combustion optimization method for online application is proposed based on data-driven and case-based reasoning principle. First, an improved constrained fuzzy association rule (ICFAR) is proposed to extract the boiler combustion rules from historical combustion data. Second, improved particle swarm optimization-based long short-term memory neutral network (IPSO-LSTM) is utilized to constructed an adaptive dynamic combustion model for boiler to adapt to time-variability of boiler combustion system. Whereafter, an improved multi-objective particle swarm optimization (IMOPSO) is designed to achieve the multi-objective combustion optimization of boiler with the goal of increasing boiler efficiency and decreasing NOx emission simultaneously. Case-based reasoning based on error correction mechanism (CBR_ECM) is applied to realize the boiler online combustion optimization. The effectiveness of proposed online combustion optimization technology for boiler is testified by applying it to an actual combustion process. The results illustrated that it could take less time to gain a series of excellent operating solutions based on proposed online combustion optimization method, the boiler efficiency increased by 0.082 % on average and the NOx emission reduced by 6.491 mg/m3 on average. Therefore, proposed online combustion optimization method for boiler has the ability to achieve the online combustion optimization of boiler.

Effect of Injection Timing and Oxygenate Concentration on Performance and Emission Characteristics of DEE-Ethanol-KOME Biodiesel Fuelled CI Engine

The present work aims to study the effect of variable injection timing on emission and performance of DEE-ethanol-biodiesel blended CI engine and find out the optimum injection timing. The optimum performance BE15DE10 (10% DEE, 15% ethanol and 75% biodiesel by volume) blended fuel is selected for experimental investigation. The DEE-ethanol-biodiesel blends vary the retarding of dynamic injection timing as well as the onset of ignition, which needs an alteration in injection timing. The engine tests are carried out at no load, 25%, 50%, 75% and 100% of full load with 3° and 6° advancement, base injection timing and 3° delayed injection timings. The 6° advancement than base injection timing improved BTE, reduced HC and showed a reduction in smoke by 10.34 %. A sharp decrease in NOx emissions has been observed with 3 delayed injection timing. Overall, the 6° advancement is the optimum injection timing which has improved the overall performance and emissions of the DEE-ethanol-KOME biodiesel fuelled CI engine.

What caused ozone pollution during the 2022 Shanghai lockdown? Insights from ground and satellite observations

Abstract. Shanghai, one of China's most important economic centres, imposed a citywide lockdown in April and May 2022 to contain a resurgence in cases of the coronavirus disease in 2019. Compared with the 2020 lockdown, the 2022 lockdown occurred in a warm season and lasted much longer, thereby serving as a relevant real-world test of the response of ambient ozone (O3) concentrations to emission reductions in a high-O3 season. In this study, we analysed surface observations of O3 and nitrogen dioxide (NO2) concentrations and satellite-retrieved tropospheric NO2 and formaldehyde (HCHO) column concentrations in the first 5 months of 2022 with comparisons to the year 2021. During the 2-month 2022 lockdown, the maximum daily 8 h average (MDA8) O3 concentrations at 1 or more of the city's 19 sites exceeded China's air quality standard of 160 µg m−3 21 times, with the highest value being 200 µg m−3. The city-average MDA8 O3 concentration increased by 13 % in April–May 2022 year-on-year, despite sharp declines in NO2 surface and column concentrations (both by 49 %) and a 19 % decrease in the HCHO column concentration. These results show that the reductions in O3 precursors and other pollutants during the 2022 lockdown did not prevent ground-level O3 pollution. An analysis of meteorological data indicates that there were only small changes in the meteorological conditions, and there was little transport of O3 from the high-O3 inland regions during the 2022 lockdown, neither of which can account for the increased and high concentrations of O3 that were observed during this period. The mean HCHO/NO2 ratio in April–May increased from 1.11 in 2021 to 1.68 in 2022, and the correlation between surface O3 and NO2 concentrations changed from negative in 2021 to positive in 2022. These results indicate that the high O3 concentrations in 2022 were mainly due to large reductions in the emissions of NOx and that the decrease in the concentrations of volatile organic compounds (VOCs) could not overcome the NO titration effect. During the 2022 lockdown, Shanghai's urban centre remained VOC-sensitive despite drastic reductions in road transportation (73 %–85 %) and industrial activities (∼60 %), whereas its semi-rural areas transitioned from VOC-limited to VOC–NOx-co-limited regimes. Our findings suggest that future emission reductions similar to those that occurred during the lockdown, such as those that will result from electrifying transportation, will not be sufficient to eliminate O3 pollution in urban areas of Shanghai and possibly other VOC-limited metropoles without the imposition of additional VOC controls or more substantial decreases in NOx emissions.

Experimental study of the methane and producer gas blends in an optical spark ignition engine: Combustion characteristics, thermodynamics and emissions

Thermal processes and power generation systems may employ producer gas generated through gasification as an alternative to replace natural gas with lower carbon footprint. However, pure producer gas in engines is associated with a significant power derating that can be mitigated by blending it with other biofuels. This work evaluated the effects of methane and producer gas blends on the performance of a SI engine. The additions of methane were 10%, 25% and 50% on a molar basis. The results demonstrated that adding 25% methane to producer gas is enough to sustain the combustion reaction with good stability and a power derating of 10.8%. The addition of 50% methane to producer gas attains efficiency and combustion characteristics remarkably similar to pure natural gas with a power de-rating of 5.4%. Emissions indicated that carbon monoxide (CO) has decreased with the addition of methane to producer gas from 85 to 3.43 g/kWh, while nitrogen oxides ([Formula: see text]) emissions have increased from 0 to 8.85 g/kWh. In the case of unburned hydrocarbons (UHC), emissions did not considerably change before adding 25% methane to producer gas and stayed constant at approximately 10 g/kWh. Engines designed to run on natural-gas could use this mixture without significant modifications to the combustion chamber while decreasing NOx emissions.

Combustion, Ecological, and Energetic Indicators for Mixtures of Hydrotreated Vegetable Oil (HVO) with Duck Fat Applied as Fuel in a Compression Ignition Engine

The aim of the present study was to investigate the effects of the application of hydrotreated vegetable oil (HVO) mixed with pure duck fat (F100) as fuel, replacing the conventional fossil diesel fuel (D100). The tests were performed using a four-stroke direct injection CI engine diesel engine. Six fuel samples were used: D100, HVO100, F100, as well as three HVO–fat mixtures F25, F50, and F75. To further study the main characteristics of fuel combustion, the AVL BOOST software (Burn program) was applied. The results of experimental studies showed that with the addition of pure fat to HVO, the ignition delay phase increased with an increase in the amount of heat released during the premix combustion phase and the pressure and temperature rise in the cylinder increased; however, the mentioned parameters were not higher as compared to diesel fuel. It was found that as the concentration of fat in the HVO–fat mixtures increases, the viscosity and density increases, while LHV was decreased, which thereby increases brake specific fuel consumption and slightly decreases brake thermal efficiency in comparison to diesel fuel. A decrease of CO2, HC, NOx emissions, and smoke was established for all HVO–fat mixtures as compared to diesel fuel at all loads; however; under low loads, CO emissions increased.

The Importance of NOx Control for Peak Ozone Mitigation Based on a Sensitivity Study Using CMAQ‐HDDM‐3D Model During a Typical Episode Over the Yangtze River Delta Region, China

AbstractIn recent years, ground‐level ozone (O3) has been one of the main pollutants hindering air quality compliance in China's large city‐clusters including the Yangtze River Delta (YRD) region. In this work, we utilized the process analysis (PA) and the higher‐order decoupled direct method (HDDM‐3D) tools embedded in the Community Multiscale Air Quality model (CMAQ) to characterize O3 formation and sensitivities to precursors during a typical O3 pollution episode over the YRD region in July 2018. Results indicate that gas‐phase chemistry contributed dominantly to the ground‐level O3 although a significant proportion was chemically produced at the middle and upper boundary layer before reaching the surface via diffusion process. Further analysis of the chemical pathways of O3 and Ox formation provided deep insights into the sensitivities of O3 to its precursors that were consistent with the HDDM results. The first‐order sensitivities of O3 to anthropogenic volatile organic compounds (AVOC) were mainly positive but small, and temporal variations were negligible compared with those to NOx. During the peak O3 time in the afternoon, the first‐ and second‐order sensitivities of O3 to NOx were significantly positive and negative, respectively, suggesting a convex response of O3 to NOx over most areas including Shanghai, Hangzhou, Nanjing and Hefei. These findings further highlighted an accelerated decrease in ground‐level O3 in the afternoon corresponding to continuous decrease of NOx emissions in the afternoon. Therefore, over the YRD region including its metropolises, NOx emission reductions will be more important in reducing the afternoon peak O3 concentration compared with the effect of VOC emission control alone.

Experimental investigation on the stability of turbulent swirling methane/air-O2 flames

This work investigates the combustion characteristics of CH4-air/O2 turbulent swirling flames in a co-axial burner with radial fuel injection. The burner configuration consists of two coaxial tubes with a swirler positioned within the annular space for the oxidizer flow. The central tube delivers the fuel through eight holes placed that are uniformly distributed along the circumference of the inner tube nearby the burner exit. The experiments were carried out in a 25-kW combustion chamber of dimensions 50x50x120 cm3. Stereo Particle Image Velocimetry (SPIV) was used to characterize the different velocity fields, whereas the OH* Chemiluminescence is employed to examine the flame structure and stability. The exhaust gas compositions were measured using multi-gas analyzers. The structure and stability of flames, temperature evolutions, CO2, and pollutant emissions (NOx, CO) were examined under different parameters, such as: oxygen enrichment (21–50 %), global equivalence ratio (0.4–1), swirl number (0.5 and 1.4), injection type of fuel (axial or radial). Experiments were conducted at a constant power of 9.41 kW and variable powers in the range from 9.41 to 22.42 kW. The present results show that the oxygen enrichment decreases the lift-off height and enhances the flame stability using constant flame power. Increasing the swirl number improves the flame stability and produces a better attached flame. At constant flame power and variable oxidizer flow rate, a high oxygen concentration yields lower NOx emissions. For lean combustion with excessive oxygen enrichment over 35 %, retaining the same flame power leads to a significant decrease in NOx emissions. The radial injection of CH4 does not affects the NOx emissions, however, the axial injection is shown to be advantageous in terms of CO emissions in the present studied configurations.

Investigation of the effects of water injection into an SI engine running on M15 methanol fuel on engine performance and exhaust emissions

The use of alternative fuels is an effective method to reduce pollutant emissions from spark-ignition engines. However, the usage of alternative fuels alone will not be adequate comply with strict emission standards. Water injection is one of the measures taken during combustion to achieve the desired emission values. However, deterioration in engine performance, which is not desired, occurs with the measures taken. In this study, a gasoline-methanol blend (85% gasoline + 15% methanol) was used as a fuel in a spark-ignition engine. Water was injected into the intake manifold at different rates to reduce emissions further and improve engine performance in an engine running on M15 fuel. Water was injected into the intake air with an electronic control system with 10, 20, and 30% mass ratios of the engine fuel consumption. As a result of the experimental studies conducted under full load conditions, it was determined that the effective power decreased by 2.5%, and the specific fuel consumption increased by 3.5% compared to the standard condition in the engine fueled with M15. It was revealed that there was a 6% decrease in HC emission at 2200 rpm and a 4% decrease in NOx emissions at 2600 rpm. In comparison to standard engine data, when water injection was applied to the engine, there was a decrease up to 16% in HC emissions and up to 12% in NOx emissions. In comparison to the standard data, an increase of 2.5% in the effective power was observed with 20% water injection in the effective power.

Data-driven based multi-objective combustion optimization covering static and dynamic states

In order to reduce pollutant emissions and improve energy efficiency under the working conditions of static and dynamic states in the coal-fired power plants, data-driven based multi-objective combustion optimization (MOCO), which is around the implementation of air flow adjustment, is proposed to consider NOx emissions and boiler efficiency simultaneously. The strategy of combining kernel extreme learning machine (KELM) model with multi-objective evolutionary algorithm based on decomposition (MOEA/D) is presented to regulate the air distribution mode under static state. The double optimization is proposed to control the air flow under dynamic state. The first optimization is to employ auto-regressive moving-average with exogenous inputs (ARMAX) model and particle swarm optimization algorithm to optimize the parameters of PI controller. The second optimization is to use ARMAX models and tendentious guidance MOEA/D (TG-MOEA/D) to optimize the setpoint of air flow. The experiments showed that the KELM + MOEA/D strategy could further improve the effect of MOCO under static state, and the double optimization had decreased NOx emissions by an average of 12.18 % with keeping the boiler efficiency at a desired level under dynamic state. Moreover, data-driven based MOCO owns a high real-time performance, so that it is suitable for online application.

Computational investigation of ammonia-hydrogen peroxide blends in HCCI engine mode

The potential use of hydrogen peroxide as an ignition promoter to enable the use of ammonia in compression ignition engines is explored in the current study. A simplified numerical HCCI engine model within the Chemkin Pro suite is employed. The numerical investigation reveals that the proposed use of hydrogen peroxide is significantly more advantageous against the more conventional method of preheating the intake charge to achieve ignition, whilst using a glow plug. In particular, the IMEP, power and torque exhibit an increase greater than 65% along with a spectacular decrease of NOx emissions reaching in certain cases a 9-fold decrease. The thermal efficiency exhibits a more moderate, yet non-negligible increase, around 5%. Generally, the incremental increase of hydrogen peroxide leads to the increase of the IMEP, power and torque as well as the maximum temperature and, hence, NOx emissions. These increases are largely linear with the hydrogen peroxide addition. Finally, the introduction of hydrogen peroxide leads to a two-stage ignition process, where the first ignition stage was found to be instrumental to the control of the ignition process, and, therefore, the system’s efficiency. Further research is required to substantiate further the feasibility and the the limitations of the proposed technology which can enable the rapid decarbonization of heavy duty applications, such as marine ships and trucks.

Effects of EGR combined with DOC on emission characteristics of a two-stage injected Fischer-Tropsch diesel/methanol dual-fuel engine

Fischer-Tropsch (F-T) diesel and methanol are widely regarded as promising clean alternative fuels for engines. The emergence of reactivity controlled compression ignition (RCCI) combustion mode provides new approaches to the application of F-T diesel and methanol in diesel engines, but there is a pressing need to further reduce engine emissions. To this end, a dual-fuel engine test bench was built based on a high-pressure common rail diesel engine with a methanol injection system at the intake manifold combined with a two-stage in-cylinder direct injection (pre-injection + main injection) F-T diesel. The combined effects of methanol substitution ratio (MSR), exhaust gas recirculation (EGR) and diesel oxidation catalyst (DOC) on the combustion and emission characteristics of the dual-fuel engine was investigated at 2000 rpm and 75 % load. The results show that EGR improves the combustion characteristics of the F-T diesel/methanol dual-fuel engine while adding a DOC significantly reduces engine gaseous emissions. However, as the MSR and EGR rate increase, NOx emissions decrease, but other emissions increase. NOx emissions were reduced by 73 % compared to the original engine emissions for an MSR of 30 % and an EGR rate of 15 % without a DOC. When the MSR is 0 %, the DOC promotes the conversion of NO to NO2. While, when the MSR greater than 0, the DOC promotes the conversion of NO2 to NO. When equipped with a DOC, CO, NO, NO2, NOx, MeOH, and HCHO emissions decrease as the EGR rate increases, with the reduction of CO and MeOH emissions being greater than 99.5 % and 93 %, respectively, and the maximum conversion efficiency for HCHO emissions being 82 %. The present study showcases the key challenges as well as advantages in the use of EGR combined with a DOC assisting the application of coal-based alternative fuels in dual-fuel engines.

Exergy, exergoeconomic, and exergoenviroeconomic evaluations of the use of diesel/fusel oil blends in compression ignition engines

In this study, experimentally investigated effects of fuel blends obtained using fusel oil and diesel fuel in different proportions on exhaust emissions and engine performance in a four-stroke, CI engine. The engine experiments contucted of two stages. Firstly, it was attempted to determine the maximum amount of fusel oil that could be added to diesel fuel. The blends obtained to this end were tested in a diesel engine, and it was observed that there was a maximum rate of 37% that would work without any problems. After blending 63% diesel and 37% fusel oil, the test engine does not run if the fusel oil ratio in fuel blends is increased. Afterward, experiments were performed at different engine speeds (1250–3000 rpm) in the full load conditions with the fuel blends created (D100, F5, F10, F20, F30, and F37). Additionally, exergy, energy, and exorgoeconomic analyses were carried out using engine performance and exhaust emission values acquired in experimental studies. It was stated that addition of fusel oil to fuel blends increased fuel consumption. If the engine ran at a speed of 2250 rpm, there was 17% more fuel consumption in F37 fuel than D100 fuel. In fuel blends using fusel oil, NOX, CO2, and soot emissions are lower in comparison with D100 fuel. In this research, it was observed that the addition of fusel oil to diesel exhibited a significant decrease in NOX and CO2 emissions but created a significant increase in particulate matter, CO and HC emissions. A parallel increase occurred in exergy losses in engine due to increase in fusel oil in blends. The highest exergy destruction was calculated as 22 kW in F37 fuel at 3250 rpm. As the ratio of fusel oil in fuel blends increases, the useful power cost and the cost of CO2 released into the atmosphere decrease.

Combustion, performance and emission analysis of propanol addition on safflower oil biodiesel in a diesel engine

Studies on alternative and renewable fuels are maintaining due to the ever-decreasing of petroleum usage and also the environmental pollution that it has created. Alternative fuels, especially renewable fuels are one of the most emphasized issues because renewable energy sources are environmentally friendly, unconsumable and easily degradable in the environment. In this study, biodiesel was obtained from safflower. The biodiesel of safflower oil was mixed with propanol at different ratios and tested as a diesel engine fuel. The effects of both biodiesel and propanol addition on engine performance, combustion parameters and pollutant exhaust emissions have been experimentally tested. The main important point of the presented study is to detect the effects of higher ratios of pure diesel fuel in diesel engines by utilizing the positive sides of a light alcohol, the propanol. The engine performance, specific fuel consumption and emission values of the biodiesel and propanol blended fuels did not show a significant difference compared to the diesel. In the loaded cases, the combustion parameters for all test fuels were obtained in a similar manner. Peak values of HRR in higher engine loads of blend fuels with high propanol were a bit higher. It is seen that there is a decrease in NOx emissions. Safflower biodiesel and propanol mixtures can be used as alternative fuels by adding to diesel fuel in certain amounts.