NOx Emission Levels Research Articles

Experimental analysis and life cycle assessment of green diesel (HVO) in dual-fuel operation with bioethanol

Renewable fuels have been used for years as an option for supplying energy demand in a sustainable manner. In terms of liquid fuels, hydrotreated vegetable oil (HVO) gained special attention in the last few years due to its good performance in diesel engines, low emissions and renewable aspect. At the same time, bioethanol represents another renewable option for energy supply and has been consolidated in the market for decades. Even though these biofuels are assumed to be environmentally friendly, a complete understanding of their environmental impacts should take into account several indicators, applications and geographical aspects. In this sense, this study presents a detailed Life Cycle Assessment (LCA) regarding the use of petrodiesel, HVO from palm and soybean oil and bioethanol in various operating conditions in a diesel engine, for small-scale electricity generation in stationary applications. Diesel and HVO are used as pilot fuels, while bioethanol was injected in the intake port in various Energy Fraction Ratios (EF), EF = 0%; EF = 28%; EF = 32%; EF = 40%; EF = 44%, in the so-called dual-fuel mode. The results obtained with pure HVO showed reductions in specific levels of NOx, HC, CO and particulate matter (PM) emissions of 30%, 75%, 81% and 55.3%, respectively, and 4.36% efficiency when compared to diesel. The Dual-Fuel application provided a significant reduction in CO2, NOX and PM emissions, but decreased engine efficiency by up to 9.4%. The LCA showed that the palm oil HVO has an environmental performance superior to the soybean HVO and is capable of reducing the Global Warming Potential up to 75%. Palm oil HVO reduces impacts in categories such as Terrestrial Acidification, Ozone Formation and Consumption of non-renewable resources when compared to diesel. The environmental impact of the dual-fuel operation presents a decrease in the levels of Global Warming Potential, Depletion of Fossil Resources and Ozone Formation.

Numerical analysis of injection parameters influence on diesel engine performances and emissions correlated by maximum in-cylinder pressure

The present work deals with a numerical investigation on an experimental single cylinder direct injection Diesel engine. Calculations are carried out with Kiva3v2 code using multidimensional detailed chemistry. The study was carried out on predicted CO, and NOx emission levels by the engine cylinder before exhaust valve opening. Correlations proposed for predicted NO, CO, and NOx levels function of fuel, O2, N2 concentrations and the maximum in-cylinder pressure rather than temperature. Predicted values of averaged pressures, O2, CO, and CO2 levels in the exhaust manifold were validated by the measured ones for a set of five loads at 1500 rpm. CO, NO, and NOx concentrations at the exhaust obtained by calculations lies perfectly with measured values. Otherwise, numerical simulations lead us to analyze injection timing, duration and fuel amount injected effect on the engine performances, ignition delay, combustion duration as well as CO and NOx emission levels.

Performance and Emission Analysis of Corn Oil and Rice Bran Oil using Ethanol, Methanal and Sodium Hydroxide Additives

The fuel consumption rate has been increased in our world compared to older days. Most of the fuels which we use are fossil fuel which has high emissions of greenhouse gases which leads to pollution and global warming. Fuels are getting higher price range nowadays. So, we are trying to find a better alternative fuel which will be cost efficient and less harmful to the planet. In this study we try to solve the problem by experimenting and evaluating the mixture of oils which may reduce emissions of harmful gases. In this project we are using corn oil, rice bran oil with additives and mixing them with conventional fuel i.e., diesel to convert the collected oils into a biodiesel. This process is commonly known as transesterification. The biodiesels are mixed in three different forms like B30, B40, and B50, in which B30 contains 70% of diesel and 15% of corn oil and 15% of rice bran oil. B40 contains 60% of diesel, 20% of corn oil and 20% of rice bran oil. B50 contains 50% of diesel, 25% of corn oil and 25% of rice bran oil. We are mixing these oils with diesel and other additives in three different ratios in-order to get the maximum performance and lowest emission from a diesel engine. These samples are used as an alternative to conventional diesel in a diesel engine and the engine’s performance was evaluated. The performance of the engine is evaluated by parameters which include brake thermal efficiency, volumetric efficiency, specific fuel consumption and torque. The emission parameters are also tested which includes the emission level of CO, CO2, NOX, SOX and HC. These tests are done under different load conditions varying form no load up to 10kg. The results from the three samples (B30, B40 and B50) are compared to the conventional diesel which is being used in most conditions.

Performance and Emission Analysis of Four-Stroke Diesel Engine Single Cylinder on Toroidal Piston Modification with B30 Fuel

Improvement of the performance of the diesel engine can be done by expanding the combustion chamber. One of the objectives of this research is to obtain optimal piston performance by modifying the piston crown to be 1mm deeper than the standard piston using B30 fuel. This research is also proof of previous research with a simulation that concluded that the performance of a diesel engine using a modified toroidal combustion chamber (TCC) +1mm piston has better performance than a standard piston. This research will analyze the comparison of the performance of a diesel engine using a standard piston and a modified piston on the diesel engine, using an experimental method with B30 biodiesel fuel with engine speed (RPM) variation of 1900 and 2100, also the dummy loads used are 1000, 2000, 3000, and 4000 Watts (W). From the results of the performance tests, it is concluded that the standard piston produces better performance than the modified piston with a very small difference in value in terms of torque, power, and SFOC. The level of NOx emissions produced by the standard RPM 1900 with 1000 W load is 1,483 g/KWh, at a load of 2000 W is 1,011 g/KWh, at a load of 3000 W is 1.375 g/KWh, at a load of 4000 W is 2,372 g/KWh, for standard piston RPM 2100 NOx emission levels produced at 1000 W load is 1,902 g/KWh, at 2000 W load is 1,450 g/KWh, at 3000 W load is 1.368 g/KWh, at 4000 W load is 1,066 g/KWh. The level of NOx emissions produced using a modified piston at 1900 RPM at 1000 W load is 1.865 g/KWh, at 2000 W load is 1.326 g/KWh, at 3000 W load is 1,250 g/KWh, at 4000 W load is 0.857 g/KWh, for RPM 2100 uses a modified piston at a 1000 W load is 1,970 g/KWh, at a 2000 W load is 1,583 g/KWh, at a 3000 W load is 1,465 g/KWh, at a 4000 W load is 1,226 g/KWh. NOx emission levels using standard pistons at RPM 1900 with B30 fuel tend to be smaller at low loads and larger at high loads compared to modified pistons, while NOx emission levels using standard pistons at RPM 2100 fueled by B30 are smaller than using a modified piston.

MONITORING & ASSESSMENT OF N2O, NOX EMISSIONS FROM FERTILIZER PLANT (NITRIC ACID) FOR THE ENVIRONMENTAL SUSTAINABILTY


 
 
 Nitrous oxide (N2O) is an invisible product of nitric acid by Ostwald process. Formed during oxidation of ammonia over platinum / Rhodium gauzes; there is a need for technology to reduce the release of nitrous oxide from nitric acid plants.N2O technology can play a major role in reducing greenhouse gas emissions. The major impact of N2O on the environment such as greenhouse gas and stratospheric ozone depletory, primary options environmentally uncontroversial materials with a long operating lifetime.Secondary controls EnviNOx does not interact in any way with the plant product or its precursors.The higher Applications in other kinds of industrial waste gas streams are also being developed. Selected catalytic Regeneration (SCR) is a well-known technology for controlling the release of nitrogen oxide (NOx) emitted by fire from various energy / chemical plants. This strategy requires a reducing agent such as ammonia to reduce NOx.This research is based directly on Practical/technical control and aims to obtain, update researchers' information on the various aspects of the Clean Development Mechanism to gain N2O emissions are reduced by ∼98–99% and higher, while NOX emission levels of 1 to ∼40 ppm are achieved. The results of ongoing investigations are promising.
 
 

Experimental evaluation of low-displacement compression ignited engines operating with hydroxy gas as a supplementary gaseous fuel

A large proportion of annual production of worldwide greenhouses gases results from the use of internal combustion engines. This experimental work evaluates the influence of dual-fuel operation on the overall emissions of a low-displacement compression-ignition engine based on operational conditions such as torque, rotational speed, and load. Hydroxy gas is used as a supplementary gaseous fuel while using pure diespel or palm oil biodiesel as baseline fuels. The CO, CO2, NOx, and HC emissions levels were carefully characterized through experimental measurements and statistical analysis. The influence of hydroxy enrichment was also examined on the engine's fuel consumption. The study incorporates an in-house hydroxy generator to store and supply the gas in the intake air system using an electrolyzer. The results demonstrated that the ANOVA analysis provides accurate predictions compared to experimental measurements with less than 5% relative error. The use of hydroxy reduces the SFC by up to 25%, which represents an economic advantage of dual-fuel operation, additionally it decreases CO, HC, and CO2 emissions. However, with hydroxy enrichment, NOx emissions levels escalate at medium and high loads. Overall, hydroxy enrichment demonstrates to be a robust alternative from an environmental and economic perspective. Future research will be focused on evaluating the biodiesel – hydroxy dual operation, broadening the spectrum of biodiesel concentration percentages, and selecting different raw materials for biofuel production.

Maximum reduction in greenhouse gas emissions by complete replacement of natural gas with pure hydrogen as a sole low reactive fuel in a RCCI engine

In order to maximum reduction in hydrocarbon fuels consumption as the largest source of greenhouse gas emissions, the aim of this study is to evaluate a RCCI engine performance fueled with diesel fuel and pure hydrogen as sole low reactive fuel. For this purpose, a single-cylinder heavy-duty diesel engine with bathtub piston bowl profile and compression ratio of 14.88:1 is assessed that operates at its mid-load range from 9.4 to 13.5 bar gross IMEPs. In order to overcome the NOx challenge resulted from using pure hydrogen, the use of suitable amount of EGR and nitrogen addition as air-hydrogen diluents along with the advanced SOI timing were employed. The simulation results show that in a hydrogen-fueled RCCI engine, while reducing the diesel fuel energy share as the only supplier of air-hydrogen mixture ignition energy to about 13%, the HES percentage can be enhanced up to 87%. Although, the SOC will occur with a long delay and the CA50 will take place about 15°CA after the TDC compared to the experimental data, however, the maximum loss of the engine load is less than 6% with the GIE of more than 48% without any exposure to diesel knock. Moreover, not only the EURO VI level of the CO and UHC emissions and the EPA level of Formaldehyde emission can be met, but also, the EURO VI level of NOx emission as the most important challenge of a hydrogen-fueled engine is achievable.

Experimental investigation on emission characteristics of high reactivity gasoline compression ignition with different EGR and injection pressure strategies

Using a High Reactivity Gasoline (HRG) in diesel engines is a promising approach to reduce NOx and soot emissions simultaneously without modifying the engine hardware. In this study, an experimental investigation on HRG and diesel emission characteristics was conducted in a six-cylinder heavy duty diesel engine with different exhaust gas recirculation (EGR) rate and injection pressure strategies. Four operation points, A25, A75, C25, and C75 in the European Steady Cycle (ESC), were studied. The pilot-main injection strategy was applied, and injection timing was adjusted to maintain a constant Crank Angle of 50 % heat release (CA50). The results show that, compared with diesel, HRG can achieve lower soot mass emission while maintaining an ultra-low NOx emission level (2–3 g/kWh) with a lower injection pressure, indicating lower cost in the fuel injection and aftertreatment systems. The particle size distribution was also analyzed for both fuels. Under high EGR rates, the accumulation mode particles were dominant for both HRG and diesel. However, under low EGR rates, diesel produced much more nucleation mode particles than HRG. The phenomenon can be explained by the difference in the pyrene and acetylene productions between paraffin and aromatic compositions.

Evaluation of Greenhouse Gas Emission Levels during the Combustion of Selected Types of Agricultural Biomass

This paper presents the results of an experimental study of the emission levels of selected greenhouse gases (CO2, CH4, NOx) arising from the combustion of different forms of biomass, i.e., solid biomass in the form of pellets and liquid biomass in the example of engine biofuel (biodiesel). Both types of biomass under study are rape-based biofuels. The pellets are made from rape straw, which, as a waste product, can be used for energy purposes. Additionally, biodiesel contains rape oil methyl esters (FAME) designed to power diesel engines. The boiler 25 kW was used to burn the pellets. Engine measurements were performed on a dynamometer bench on an S-4003 tractor engine. An analyzer Testo 350 was used to analyze the exhaust gas. CO2 emission studies do not indicate the environmental benefits of using any alternative fuels tested compared to their conventional counterparts. In both the engine and boiler tests for NOx emissions, no environmental benefits were demonstrated from the use of alternative fuels. The measured average NOx emission levels for biodiesel compared to diesel were about 20% higher, and for rapeseed straw pellets, they were more than 60% higher compared to wood pellets. Only in the case of engine tests was significantly lower CH4 (approx. 30%) emission found when feeding the engine with rape oil methyl esters.

Effect of oxidizer dilution on thermophotovoltaic performance of premixed ammonia/hydrogen/air combustion in radial micro-combustor

Present research deals with the combustion characteristics, thermal performance, and emissions analyses of a radial micro-combustor for thermo-photovoltaic application. Simulations are carried out for premixed ammonia/hydrogen/air combustion with different inlet velocities and air dilution levels with N2. Influences of input parameters on the thermal performance of micro-combustor, the total energy conversion efficiency of the micro thermo-photovoltaic system, OH distribution, recirculation zone characteristics, flame blowout limits and NOx-N2O emissions are examined. The results imply that elevating inlet velocity in the studied range enhances the uniformity factor of temperature distribution in the fluid and solid domains. The maximum value of the total energy conversion efficiency was obtained to be 8.2 % corresponding to the 6.6 W of output electric power. On the other hand, the present results showed that a higher dilution level of air (up to 84 % N2 on volume basis) results in a significant increase in temperature distribution uniformity and consequently a decrease in mean temperature and total thermo-photovoltaic efficiency. Moreover, such increment in dilution level results in higher N2O emission at lower velocities and consequently a significant decrease in NOx emission level up to 58 %. Finally, reaction pathway analysis showed that the main NO production pathway remains unchanged in NH3 → NH2 → HNO → NO route with increasing inlet velocity and dilution level.

Analysis of jatropha oil-kerosene fuel mixtures on the performance of a variable-load direct injection CI engine

Jatropha oil was blended with kerosene in ratios; JOK0, JOK20, JOK30, JOK40 and JOK50 and benchmarked against conventional diesel fuel. The blended fuel samples was test-run on a TD110-TD115 TQ small CI engine test rig, and emission levels for the fuel samples were examined using an SQV automobile exhaust gas analyzer. The JOK20 fuel sample offered a better performance in terms of higher BP, BTE, and EGT followed by; JOK30, JOK40 and JOK50 blends; and also exhibited lower SFC, BSEC and AFR, hence less fuel consuming than diesel fuel. A reduction in CO emission was recorded for JOK20, and a significant cut was also observed for JOK30, JOK40 blends with load increase.; while, JOK30, JOK40 and JOK50 samples exhibited higher CO2 and lower UHC emission levels than diesel. No traceable level of NOx emission was recorded for JOK20 fuel sample.

Evaluation of the Effect of Low-Carbon Fuel Blends’ Properties in a Light-Duty CI Engine

<div class="section abstract"><div class="htmlview paragraph">De-fossilization is an increasingly important trend in the energy sector. In the transport sector the de-fossilization efforts have been centered in promoting the electrification of vehicles, nonetheless other pathways, like the use of carbon neutral or carbon-offsetting fuels under current vehicle fleets, are also worth considering. Low-carbon fuels (LCF) can be synthetized from sources that can take advantage of the carbon already present in the atmosphere (either by technologies like direct carbon capture or biological processes like photosynthesis in biofuels) and use energy from renewable sources for the necessary industrial processes. Although, LCFs can be compared to fossil fuels as energy sources for internal combustion engines, their composition is not the same and their properties can modify the engine combustion and emissions. This work evaluates the use of several diesel-like LCFs in a light duty compression ignition engine and correlates the fuel consumption, NOx, soot and CO<sub>2</sub> emissions to the fuel properties. Results indicate that the combined effect of a low density, low aromatic proportion, high energy density and high cetane number Fischer-Tropsch/FAME fuel blend can maintain the fuel consumption and soot emissions close to results with diesel at most engine conditions and reduce NOx emissions 0.5 - 2.5g/kWh. It was also observed that fuels with higher proportions of OMEx (with lower energy density and increased oxygen proportion) can reduce the soot emissions for the same level of NOx emissions with a fuel consumption penalty. Tank-to-wheel CO<sub>2</sub> emissions show little variation between fuels, while the well-to-wheel emissions are proportional to the renewable content.</div></div>

Research on Analysis Method of Remote Sensing Results of NO Emission from Diesel Vehicles

Remote sensing technology has been used for gasoline vehicle gaseous emissions monitoring for nearly 30 years. However, the application effect of the remote sensing detection of diesel vehicle tailpipe emission concentrations is unsatisfactory. Therefore, several approaches were proposed to analyze the remote sensing results for gaseous exhaust emissions from diesel vehicles, including the concentration ratios of gaseous emission components to carbon dioxide (CO2) and fuel-based emission factors. Based on our experimental results, these two metrics have some high values in low-speed or low-load conditions of vehicles, which introduces uncertainty when evaluating vehicle emission levels. Therefore, an inversion calculation method originally developed for remote sensing light duty diesel vehicle gaseous emissions was used for the remote sensing of nitrogen monoxide (NO) tailpipe concentrations in heavy duty diesel vehicles, and validated by PEMS tested emission results. For the first time, the above three options for evaluating the NOx emission level of diesel vehicles, including the concentration ratio of NO to CO2, the fuel-based NO emission factor and the estimated tailpipe NO emission concentration were investigated, and some influencing factors were also discussed. The remote sensing tailpipe NO emission concentration can be directly used to evaluate diesel vehicle NO emission levels compared with the two other metrics.

Pilot impact on turbulent premixed methane/air and hydrogen-enriched methane/air flames in a laboratory-scale gas turbine model combustor

The impact of pilot flame operation on the combustion of pure methane and hydrogen-enriched methane (H2/CH4: 50/50 in vol%) fuels was investigated in a gas turbine model combustor under atmospheric conditions. The burner assembly was designed to mimic the geometry of an industrial burner, the Siemens DLE Burner, in which a concentric annular ring equipped with pilot flame burners is implemented in the dome of the combustor. Two pilot burner configurations have been investigated: a non-premixed and a partially premixed pilot arrangement. The performance of the pilot burners was evaluated for varying Reynolds number (Re) and H2 enrichment. High-speed OH∗ chemiluminescence imaging, as well as simultaneous planar laser-induced fluorescence measurements of the OH radicals and formaldehyde (CH2O) were used for evaluating the dynamics and structures of the flames for different conditions. Furthermore, emission measurements were carried out to determine the influence of hydrogen dilution on the NOx and CO emission levels. The main findings are (a) the effect of the pilot flame is sensitive to the Reynolds number of the main flame and the type of the pilot flame, (b) the stability range becomes narrower with increasing hydrogen ratio, due to the tendency to flashback, (c) non-premixed pilot flames lower the NOx and increase the CO emissions, albeit rather small differences in the emissions have been detected, and (d) the NOx and CO emissions become significantly lower with increasing hydrogen ratio.

Artificial neural networks model for predicting the behavior of different injection pressure characteristics powered by blend of biofuel‐nano emulsion

AbstractThis investigation deals with the usage of graphene oxide (GO) nanoparticles with orange peel biodiesel in a conventional CI engine. The different fuel blends used for this experiment are biodiesel 10% + diesel 80% + ethanol 5% + surfactant 5% + GO 50 ppm (B10), biodiesel 20% + diesel 70% + ethanol 5% + surfactant 5% + GO 50 ppm (B20), biodiesel 50% + diesel 40% + ethanol 5% + surfactant 5% + GO 50 ppm (B50) and B100. The addition of ethanol has dual benefits for improving the vaporization of fuel blends and reduction of oxides of nitrogen (NOx) emission. Span80 and Tween80 were chosen as surfactants based on hydrophilic‐lipophilic balance numbers. It is useful for improving the homogeneity of immiscible fuel blends. From this study, the injection pressure (IP) was varied from 180, 200 to 220 bar for better atomization characteristics of nano additive biodiesel blend. The experimental results indicated that an increase in the percentages of biodiesel beyond 20% in the blend, NOx increases, and hydrocarbon (HC) and carbon dioxide (CO) emissions were found to be decreased. It is also observed that the highest brake thermal efficiency (BTE) was found for fuel 20 at the IP of 220 bar. The addition of nano additive has a great influence on fuel droplets and reduction of NOx emission levels. B20 blend was found to higher cylinder pressure and heat release rate when compared to other nano additive blends. Finally, indicated that the nano additive B20 blend is a better alternative to conventional fuel in unmodified CI engines. The RMSE value for the BTE, brake‐specific energy consumption (BSEC), CO, HC, NOx, and smoke is obtained to be 0.036, 0.0216, 0.044, 0.041, 0.0446, and 0.0435, respectively. The mean absolute percentage error value for the BTE, BSEC, CO, HC, NOx, and smoke is obtained to be 1.12, 0.84, 3.04, 4.12, 1.71, and 0.97, respectively.

Impact of low carbon fuels (LCF) on the fuel efficiency and NOx emissions of a light-duty series hybrid commercial delivery vehicle

This work evaluates the potential of using four different low carbon fuels (LCF) in a series hybrid vehicle concept and compares the results to a conventional diesel combustion counterpart. To do this experimental data from a low NOx emission calibration is obtained for each of the different fuels, and 0-D vehicle simulations of an OPEL Movano van model are made to evaluate the performance, in terms of fuel consumption and engine-out NOx, during the Worldwide harmonized Light vehicles Test Cycles (WLTC) using a simplified engine map strategy. The vehicle selection allows to evaluate the scenario of a delivery application with three different payloads 0%, 50% and 100%. The work is motivated by the current automotive industry’s need to reduce emissions and use energy resources efficiently, evaluating different strategies to fulfil both objectives. The evaluation of different energy sources –such as LCF– and powertrains, have been extensively researched topics, however the information is more scarce using a combination of both strategies. The results from this work show that series hybrid vehicle presents a reduction of fuel consumption of up to 5% with 100% payload, across all fuels tested. Nonetheless, engine-out emission levels of NOx show 16% worse performance for the hybrid case due to its operation at higher engine speeds and loads during the charging of the battery.

Entrainment effects on combustion characteristics of various syngases using a perforated burner

This study concentrates on entrainment effects to achieve distributed regime for different syngas compositions (coke oven gas, biogas, and blast-furnace gas). For this purpose, numerical modeling has been performed through a computational fluid dynamics commercial code. In the modeling, The PDF/Mixture Fraction combustion model, standard k-ℇ turbulence model, and P-1 radiation model have been selected to be used. Entrainment without decreasing oxygen concentration in air was provided from the flame holder wall of the newly generated burner at 10%, 20%, and 30% entrainment rates. For only coke oven gas, oxygen concentration was reduced to 15% O2 with the entrainment in order to achieve ultra-low pollutant emissions level. The results showed that the temperature distributions were achieved more uniform for all cases. The flame zones became more thinner for all cases studied. This provided more invisible or colorless flame appearance, and as a result of this, more uniform thermal field was achieved without substantial decrease in combustion performance. Namely, the temperature values between the outlet temperatures for all entrainments have been close to each other (about 1200–1300 K). In terms of evaluation of distributed regime achievement on NOX and CO pollutant emission levels, one can say that ultra-low emission levels (less than 1 ppm) were achieved with entrainment effects without decrease in oxygen concenration in air excluding coke oven gas. Distributed regime could be achieved at lower oxygen concentration with entrainment for coke oven gas combustion.

Towards a comprehensive understanding of mode transition between biodiesel-biobutanol dual-fuel ICCI low temperature combustion and conventional CI combustion – Part Ⅰ: Characteristics from medium to high load

This research work studied the mode switching between ICCI low temperature combustion and conventional CI combustion in a single-cylinder diesel engine. The combustion characteristics during the mode switching process with various control parameters, such as injection timing, numbers, duration, exhaust gas recirculation (EGR) rates, were detailed analyzed at medium and high engine loads. Experimental results show that the smoothness mode switching between ICCI combustion and CI combustion can be achieved within one cycle after switching another combustion mode at medium and high engine loads, and less fluctuation of IMEP is observed. At medium load, there is a wide range of butanol energy ratio (EButanol) to achieve smooth mode transition with stable combustion. However, at high engine load, higher EButanol and earlier biodiesel second direct injection timing are inadequate for the mode transition because of the higher combustion noise. EGR strategy is used to improve the smoothness of CA50 and exhibit NOx emissions. It is not needed the cycle-by-cycle injection modulation to achieve the smoothness of CA50 and the same level of NOx emissions when the EGR rate is 34.2% under ICCI combustion and 37.6% under CI combustion, respectively, with insignificant changes of IMEP and acceptable maximum pressure rise rate.

The decreasing effect of ammonia enrichment on the combustion emission of hydrogen, methane, and propane fuels

In the present study, non-premixed combustion and NOx emission of H2, NH3, C3H8, and CH4 fuels have been studied in a combustion test unit under lean mixture conditions (λ = 4) at 8.6 kW thermal capacity. Furthermore, the combustion and NOx emission of the H2, C3H8, and CH4 fuels have been investigated for various NH3 enrichment ratios (5, 10, 20, and 50%) and excess air coefficients (λ = 1.1, 2, 3, and 4) at the same thermal capacity. The obtained results have been compared for each fuel. Numerical simulation results show that H2 emits intense energy through the reaction zone despite the lowest fuel consumption in mass, among others, due to its high calorific value. Therefore, it has a higher flame temperature than others. At the same time, C3H8 has the lowest flame temperature. Besides, NH3 has the shortest flame length among others, while C3H8 has the most extended flame form. The highest level of NOx is released from the NH3 flame in the combustion chamber, while the lowest NOx is released from the CH4. However, the lowest NOx emission at the combustion chamber exit is obtained in NH3 combustion, while the highest NOx emission is obtained with H2 combustion. It results from the shortest flame length of NH3, short residence time, and backward NOx reduction to N2 for NH3. As for H2, high flame temperature and relatively long flame, and high residence time of the products trigger NOx formation and keep the NOx level high. On the other hand, excess air coefficient from 1.1 to 2 increases NOx for H2, CH4, and NH3 due to their large flame diameters, unlike propane. Then, NOx emission levels decrease sharply as the excess air coefficient increases to 4 for each fuel. NH3 fuel also emits minimum NOx in other excess air coefficients at the exit, while H2 emits too much emission. With NH3 enrichment, the NOx emissions of H2, CH4, and C3H8 fuels at the combustion chamber exit decrease gradually almost every excess air coefficient apart from λ = 1.1. As a general conclusion, like renewable fuels, H2 appears to be a source of pollution in terms of NOx emissions in combustion applications. In contrast, NH3 appears to be a relatively modest fuel with a low NOx level. In addition, the high amount of NOx emission released from H2 and other fuels during the combustion can be remarkably reduced by NH3 enrichment with an excess air combustion.

Gas turbine engine firing ammonia

Japan decided the sixth Strategic Energy Plan that show 1% hydrogen/ammonia 1% hydrogen/ammonia will be positioned in power generation mix in FY2030. Ammonia is a hydrogen carrier and carbon free fuel. R&D project on gas turbine engines firing ammonia are carried on. AIST tried R&D of 50kW micro gas turbine firing ammonia. Combustor and fuel supply system were remodeled. Electric power generation firing Kerosene-ammonia / methane-ammonia / only ammonia was succeeded with low NOx emission by Selective Catalytic Reduction (SCR). Low NOx combustor was also developed by rich-lean staged combustion concept and reduce NOx emission level to 1/5 and succeeded to reduce size of SCR unit. Ammonia is transported and stored as liquified gas. In the case of ammonia gas supply system is necessary as ammonia vaporizer. Spray combustion R&D of liquid ammonia spray combustion technology for gas turbine combustor is also tried to simplify fuel system. R&D of technology to start up gas turbine using ammonia is also tried.