Prediction of hydrogen–ammonia blends autoignition

Chemical cues play an important role in the host-seeking behavior of blood-feeding mosquitoes (Diptera: Culicidae). A field study was carried out in The Gambia to investigate the effects of human odor or synthetic odor blends on the attraction of mosquitoes. MM-X traps baited with 16 odor blends to which carbon dioxide (CO2) was added were tested in four sets of experiments. In a second series of experiments, MM-X traps with 14 odor blends without CO2 were tested. A blend of ammonia and L-lactic acid with or without CO2 was used as control odor in series 1 and 2, respectively. Centers for Disease Control and Prevention (CDC) traps were placed in a traditional house and an experimental house to monitor mosquito densities during the experiments. The MM-X traps caught a total number of 196,756 mosquitoes, with the most abundant species belonging to the genera Mansonia (70.6%), Anopheles (17.5%), and Culex (11.5%). The most abundant mosquito species caught by the CDC traps (56,290 in total) belonged to the genera Mansonia (59.4%), Anopheles (16.0% An. gambiae s.l. Giles, and 11.3% An. ziemanni Grünberg), and Culex (11.6%). MM-X traps baited with synthetic blends were in many cases more attractive than MM-X traps baited with human odors. Addition of CO2 to synthetic odors substantially increased the catch of all mosquito species in the MM-X traps. A blend of ammonia + L-lactic acid + CO, + 3-methylbutanoic acid was the most attractive odor for most mosquito species. The candidate odor blend shows the potential to enhance trap collections so that traps will provide better surveillance and possible control.

Chemical cues play an important role in the host-seeking behavior of blood-feeding mosquitoes (Diptera: Culicidae). A field study was carried out in The Gambia to investigate the effects of human odor or synthetic odor blends on the attraction of mosquitoes. MM-X traps baited with 16 odor blends to which carbon dioxide (CO2) was added were tested in four sets of experiments. In a second series of experiments, MM-X traps with 14 odor blends without CO2 were tested. A blend of ammonia and l-lactic acid with or without CO2 was used as control odor in series 1 and 2, respectively. Centers for Disease Control and Prevention (CDC) traps were placed in a traditional house and an experimental house to monitor mosquito densities during the experiments. The MM-X traps caught a total number of 196,756 mosquitoes, with the most abundant species belonging to the genera Mansonia (70.6%), Anopheles (17.5%), and Culex (11.5%). The most abundant mosquito species caught by the CDC traps (56,290 in total) belonged to the genera Mansonia (59.4%), Anopheles (16.0% An. gambiae s.l. Giles, and 11.3% An. ziemanni Grünberg), and Culex (11.6%). MM-X traps baited with synthetic blends were in many cases more attractive than MM-X traps baited with human odors. Addition of CO2 to synthetic odors substantially increased the catch of all mosquito species in the MM-X traps. A blend of ammonia + l-lactic acid + CO2 + 3-methylbutanoic acid was the most attractive odor for most mosquito species. The candidate odor blend shows the potential to enhance trap collections so that traps will provide better surveillance and possible control.

Ammonia blends have great potential to be utilized in gas turbine combustors as carbon-free fuels. This paper investigates and compares the lean blow-off behavior of premixed bluff-body stabilized hydrocarbon flames and ammonia/hydrogen/nitrogen flames both experimentally and numerically. Simultaneous high-speed PIV and OH-PLIF are employed to resolve temporal flame and flow field information, allowing the curvature and hydrodynamic strain rates along the flame surfaces to be calculated. OH* and NH2*, chemiluminescence images are also used to examine flame structures at the same bulk flow velocity but at four equivalence ratios which span a range of flame stability behaviour from far away from to near lean blow-off. The NH3/H2/N2 flames blow off at leaner conditions as the hydrogen volume fractions increase. A NH3/H2/N2 (70%/22.5%/7.5%) flame is slightly more resilient to lean blow-off compared with methane and propane flames at a velocity of 20 m/s despite having a significantly lower laminar flame speed. The flame structure for all fuel blends change from a ‘V-shape’ to ‘M-shape’ when approaching lean blow-off, as observed in the Abel deconvoluted OH* fields for methane and propane flames and NH2* fields for ammonia fuel blends, which can result in incomplete reactions and finally trigger the lean blow-off. However, the strong OH* intensity in the shear layer near flame root for the NH3/H2/N2 flames indicate that a robust reaction is maintained in this region for this fuel blend, increasing flame stability. The flame and recirculation zone lengths both decrease with equivalence ratio. Widely-distributed positive curvature along the flame surface of the ammonia fuel blend flames which have a Lewis number less than unity, may also enhance combustion for these flames. As blow-off is approached hydro-carbon flame fronts undergo increasing strain rates along their flame fronts, which may be due to their migration towards the inner shear layer region of the flow. In comparison the strain rates along NH3/H2/N2 flames fronts do not change significantly as blow-off is approached due to less dramatic changes to the flame shape. The faster consumption rates of hydrogen than ammonia near the flame root for the ammonia blend flames, and the lower temperature loss compared with the adiabatic temperature may also contribute to the stabilization of ammonia blends near lean blow-off.

<div class="section abstract"><div class="htmlview paragraph">Ammonia is a promising carbon-free alternative fuel for use in combustion systems. The main associated challenges are its relatively low reactivity and high NOx emissions compared to conventional fuels. Therefore, the combustion behaviour of ammonia and ammonia blends still needs to be better understood over a wide range of conditions. To this end, a comprehensive chemical kinetic mechanism C3MechV3.4, which is an update of C3MechV3.3, has been developed for improved predictions of the combustion of ammonia and ammonia blends. C3MechV3.4 has been validated using a wide range of experimental results for pure ammonia and ammonia/hydrogen, ammonia/methanol and ammonia/<i>n</i>-heptane blends. These validations target different data sets including ignition delay times, species profiles measured as a function of time, and/or temperature and laminar flame speeds over a wide range of conditions. The updated developed mechanism gives good predictions for pure ammonia and its blends with hydrogen, methanol and <i>n</i>-heptane. The most important reactions affecting predictions in different regimes for the various ammonia mixtures are discussed.</div></div>

Study on the performance of premixed natural gas/ammonia engine with diesel ignition

Nitrogen-doped carbons (NCs) are emerging as high-performance and inexpensive materials for electrochemical energy storage and conversion. The combined merits of carbon and nitrogen dopants allow NCs to possess the advantages of carbon as well as the unique functionalities of N moieties. Conventionally, NCs are produced by pyrolysis of nitrogen-rich organic precursors such as naturally abundant biopolymers. However, these NCs generally exhibit poor electrochemical performance due to their limited surface area and the loss of N moieties at elevated temperatures. In this work, we modified the widely practiced pyrolysis protocol by blending 20 vol % of ammonia gas into a nitrogen atmosphere at the early stage of pyrolysis. The carbonization of chitosan, a naturally abundant biopolymer, in the N2/NH3 (20 vol %) gas mixture led to N doped carbon aerogels (NCAs) with a roughened surface, an increased surface area, an augmented micropore volume, and a high content (up to 11.3%) of nitrogen-containing functionali...

Exergoeconomic analysis and optimization of a new hybrid fuel cell vehicle

An aqueous ammonia based CO2 capture offers several advantages over the conventional monoethanolamine (MEA) solvent, including a high CO2 loading capacity, low stripper heat duty, a lower degradation rate of solvent, low equipment corrosion, and the ability to capture multipollutants. However, in order to make an aqueous, ammonia-based CO2 capturing process economically feasible, attention must be paid to the following issues: ammonia slip due to the high evaporation rate of ammonia, energy input for CO2 regeneration, and CO2 removal efficiency improvements. In conventional, aqueous ammonia-based CO2 capture, the process either needs to operate at very low temperatures or must include wash-water columns to mitigate ammonia slips, which increase the capital and operational costs of the system. In this paper, a blended solution of 2-amino-2-methyl-1-propanol (AMP) and ammonia was used to analyze the CO2 capture efficiency, ammonia slip, and stripper heat duty. Our results show that, using the blended (30 wt.% AMP + 3 wt.% NH3) solution for CO2 capture, the ammonia slip was reduced by 64% at a lean CO2 loading of 0.07, CO2 capture efficiency was increased by 17.2%, and the heat duty requirement for CO2 regeneration was reduced by 80% at a stripper inlet temperature of 60°C. Moreover, the loss of AMP due to evaporation was 0.042 kg/day.

The role of aliphatic carboxylic acids in host-seeking response of the malaria mosquito Anopheles gambiae sensu stricto was examined both in a dual-choice olfactometer and with indoor traps. A basic attractive blend of ammonia + lactic acid served as internal standard odor. Single carboxylic acids were tested in a tripartite blend with ammonia + lactic acid. Four different airflow stream rates (0.5, 5, 50, and 100 ml/min) carrying the compounds were tested for their effect on trap entry response in the olfactometer. In the olfactometer, propanoic acid, butanoic acid, 3-methylbutanoic acid, pentanoic acid, heptanoic acid, octanoic acid, and tetradecanoic acid increased attraction relative to the basic blend. While several carboxylic acids were attractive only at one or two flow rates, tetradecanoic acid was attractive at all flow rates tested. Heptanoic acid was attractive at the lowest flow rate (0.5 ml/min), but repellent at 5 and 50 ml/min. Mixing the air stream laden with these 7 carboxylic acids together with the headspace of the basic blend increased attraction in two quantitative compositions. Subtraction of single acids from the most attractive blend revealed that 3-methylbutanoic acid had a negative effect on trap entry response. In the absence of tetradecanoic acid, the blend was repellent. In assays with MM-X traps, both a blend of 7 carboxylic acids + ammonia + lactic acid (all applied from low density polyethylene-sachets) and a simple blend of ammonia + lactic acid + tetradecanoic acid were attractive. The results show that carboxylic acids play an essential role in the host-seeking behavior of An. gambiae, and that the contribution to blend attractiveness depends on the specific compound studied.Electronic supplementary materialThe online version of this article (doi:10.1007/s10886-009-9668-7) contains supplementary material, which is available to authorized users.

The aim of this article is to review hydrogen combustion applications within the energy transition framework. Hydrogen blends are also included, from the well-known hydrogen enriched natural gas (HENG) to the hydrogen and ammonia blends whose chemical kinetics is still not clearly defined. Hydrogen and hydrogen blends combustion characteristics will be firstly summarized in terms of standard properties like the laminar flame speed and the adiabatic flame temperature, but also evidencing the critical role of hydrogen preferential diffusion in burning rate enhancement and the drastic reduction in radiative emission with respect to natural gas flames. Then, combustion applications in both thermo-electric power generation (based on internal combustion engines, i.e., gas turbines and piston engines) and hard-to-abate industry (requiring high-temperature kilns and furnaces) sectors will be considered, highlighting the main issues due to hydrogen addition related to safety, pollutant emissions, and potentially negative effects on industrial products (e.g., glass, cement and ceramic).

Rising global emissions from transportation have heightened the need for alternative fuels. Ammonia, methanol, hydrogen, and other renewable fuels have been tested mostly individually, which doesn’t generate enough power output as per their properties, or with conventional fuels, which lack renewability. There has been limited research on using ammonia and methanol blended fuel in engines. Therefore, this study aims to address this gap by conducting a comprehensive simulative analysis of ammonia-methanol flex-fuel blends for a steady-state genset engine with an experimentally validated GT-power model, positioning them as a 100% renewable fuel option for engines. The study primarily focuses on three characteristics: performance, combustion, and emission, evaluated under different operating conditions involving key parameters such as injection timing, spark timing, and at various blend ratios of both fuels. Results demonstrate that increasing ammonia content in methanol blends leads to moderate performance changes, with slight dips in engine performance parameters like torque and indicated mean effective pressure (IMEP), despite constant energy input. These reductions are minor, ranging from 4% to 16% compared to pure methanol. The most significant benefits are observed in emissions, with CO 2 levels decreasing up to 80%, showcasing ammonia and methanol flex-fuels as potential green alternatives for the future.

Numerical investigation of the effects of hydrogen/ammonia addition to n-heptane combustion and emissions for a dual injection compression-ignition engine.

This comprehensive techno-economic analysis focuses on a proposed power plant that uses cleaner alternatives to traditional combustion methods. The study meticulously examines ternary blends of ammonia, refuse-derived fuels (RDFs), and coal. Utilizing an Aspen Plus simulation equilibrium model, a thorough review of the relevant literature, and evaluation reports on biomass-to-energy power plants and ammonia combustion, the analysis spans 20 years. It considers vital financial metrics such as the net present value (NPV), internal rate of return (IRR), and payback period (PBP). The findings indicate that the combustion of pure coal is the most energy-efficient but has the highest global warming potential (GWP). In contrast, ammonia and RDF blends significantly reduce GWP, with ammonia showing a 3215% lower GWP than coal. Economically, pure coal remains the most attractive option. However, blends of 80% coal, 10% ammonia, and 10% RDF also show promise with a PBP of 11.20 years at a 15% discount rate. These results highlight the potential of ammonia and RDF blends to balance environmental and economic considerations in power generation.

Transportation, being a significant contributor to rising global emissions, underscores the need for alternative fuels like ammonia, methanol, hydrogen, and others. Transient scenarios are crucial to study because they reflect real-world driving conditions where engines frequently transition between different loads and speeds, significantly impacting emissions and performance. There is a significant gap in research on using ammonia and methanol blended fuels in engines, particularly under transient conditions, due to the complexity and challenges in combustion control. This study aims to address this gap by conducting a comprehensive simulative investigation of ammonia-methanol flex-fuel blends for a transient marine engine. Utilizing an experimentally validated GT-Power model, the study evaluates three key characteristics: performance, combustion, and emissions, under various operating conditions involving parameters such as injection timing, spark timing, and different blend ratios of both fuels. The study reveals that increasing the ammonia content in methanol blends results in moderate changes to engine performance, with slight decreases in indicated mean effective pressure and indicated efficiency, despite maintaining constant energy input. These performance reductions are minor compared to pure methanol. However, the most significant advantages are seen in emissions, with carbon dioxide levels decreasing by up to 80% when comparing blends of 25% Methanol and 75% Ammonia to 100% Methanol, highlighting the potential of ammonia-methanol flex-fuels as environmentally friendly alternatives. Furthermore, the air-fuel ratio fluctuation was also observed to be reduced with methanol-ammonia blends, which can make the engine drivability smoother during transient operation with sudden load changes that will minimized the engine vibration during transition stage. This research positions ammonia-methanol blends as a 100% renewable fuel option for engines, offering significant potential for reducing emissions and improving environmental sustainability in the transportation sector.

Ammonia blends for gas-turbines: Preliminary test and CFD-CRN modelling