Journal articles on the topic 'Ammonia fuel blends'

Nowadays there is an increasing interest in carbon-free fuels such as ammonia and hydrogen. Those fuels, on one hand, allow to drastically reduce CO2 emissions, helping to comply with the increasingly stringent emission regulations, and, on the other hand, could lead to possible advantages in performances if blended with conventional fuels. In this regard, this work focuses on the 1D numerical study of an internal combustion engine supplied with different fuels: pure gasoline, and blends of methane-hydrogen and ammonia-hydrogen. The analyses are carried out with reference to a downsized turbocharged two-cylinder engine working in an operating point representative of engine operations along WLTC, namely 1800 rpm and 9.4 bar of BMEP. To evaluate the potential of methane-hydrogen and ammonia-hydrogen blends, a parametric study is performed. The varied parameters are air/fuel proportions (from 1 up to 2) and the hydrogen fraction over the total fuel. Hydrogen volume percentages up to 60% are considered both in the case of methane-hydrogen and ammonia-hydrogen blends. Model predictive capabilities are enhanced through a refined treatment of the laminar flame speed and chemistry of the end gas to improve the description of the combustion process and knock phenomenon, respectively. After the model validation under pure gasoline supply, numerical analyses allowed to estimate the benefits and drawbacks of considered alternative fuels in terms of efficiency, carbon monoxide, and pollutant emissions.

To utilize ammonia-based fuels, it is fundamental to understand chemical mechanisms of combustion process, in which reaction characteristics of such a chemical are described in detail. Detailed chemical-kinetics mechanism of ammonia was modelled by an automatic reaction mechanism generation program to investigate characteristics of premixed combustion for ammonia/hydrogen fuel mixture. To develop an accurate model for practical combustion applications, validation of the reaction mechanism was carried out in terms of laminar flame speed under different conditions. Results suggested that the established mechanism model has satisfying performance under different ammonia/hydrogen ratio conditions. Moreover, comparison with other mechanism models demonstrated that the developed model can be used to describe flame propagation of ammonia/hydrogen fuels. Then characteristics of laminar flame speed were predicted under various ammonia concentration and equivalence ratio conditions. Sensitivity analyses showed that ammonia mole fraction has a prominent impact on kinetics of flame speed for ammonia/hydrogen blends. Flame structure analyses showed that hydrogen can enhance ammonia flames with higher light radical concentrations whilst deteriorate NOx emission in exhaust gases.

Recent studies have demonstrated that ammonia is an emerging energy vector for the distribution of hydrogen from stranded sources. However, there are still many unknown parameters that need to be understood before ammonia can be a substantial substitute in fuelling current power generation systems. Therefore, current attempts have mainly utilised ammonia as a substitute for natural gas (mainly composed of methane) to mitigate the carbon footprint of the latter. Co-firing of ammonia/methane is likely to occur in the transition of replacing carbonaceous fuels with zero-carbo options. Hence, a better understanding of the combustion performance, flame features, and radical formation of ammonia/methane blends is required to address the challenges that these fuel combinations will bring. This study involves an experimental approach in combination with numerical modelling to elucidate the changes in radical formation across ammonia/methane flames at various concentrations. Radicals such as OH*, CH*, NH*, and NH2* are characterised via chemiluminescence whilst OH, CH, NH, and NH2 are described via RANS κ-ω SST complex chemistry modelling. The results show a clear progression of radicals across flames, with higher ammonia fraction blends showing flames with more retreated shape distribution of CH* and NH* radicals in combination with more spread distribution of OH*. Simultaneously, equivalence ratio is a key parameter in defining the flame features, especially for production of NH2*. Since NH2* distribution is dependent on the equivalence ratio, CFD modelling was conducted at a constant equivalence ratio to enable the comparison between different blends. The results denote the good qualitative resemblance between models and chemiluminescence experiments, whilst it was recognised that for ammonia/methane blends the combined use of OH, CH, and NH2 radicals is essential for defining the heat release rate of these flames.

Carbon emissions reduction via the increase of sustainable energy sources in need of storage defines chemicals such as ammonia as one of the promising solutions for reliable power decarbonisation. However, the implementation of ammonia for fuelling purposes in gas turbines for industry and energy production is challenging when compared to current gas turbines fuelled with methane. One major concern is the efficiency of such systems, as this has direct implications in the profitability of these power schemes. Previous works performed around parameters prediction of standard gas turbine cycles showed that the implementation of ammonia/hydrogen as a fuel for gas turbines presents very limited overall efficiencies. Therefore, this paper covers a new approach of parameters prediction consisting of series of analytical and numerical studies used to determine emissions and efficiencies of a redesigned Brayton cycle fuelled with humidified ammonia/hydrogen blends. The combustion analysis was done using CHEMKIN-PRO (ANSYS, Canonsburg, PA, USA), and the results were used for determination of the combustion efficiency. Chemical kinetic results denote the production of very low NOx as a consequence of the recombination of species in a post combustion zone, thus delivering atmospheres with 99.2% vol. clean products. Further corrections to the cycle (i.e., compressor and turbine size) followed, indicating that the use of humidified ammonia-hydrogen blends with a total the amount of fuel added of 10.45 MW can produce total plant efficiencies ~34%. Values of the gas turbine cycle inlet parameters were varied and tested in order to determine sensibilities to these modifications, allowing changes of the analysed outlet parameters below 5%. The best results were used as inputs to determine the final efficiency of an improved Brayton cycle fuelled with humidified ammonia/hydrogen, reaching values up to 43.3% efficiency. It was notorious that humidification at the injector was irrelevant due to the high water production (up to 39.9%) at the combustion chamber, whilst further research is recommended to employ the unburned ammonia (0.6% vol. concentration) for the reduction of NOx left in the system (~10 ppm).

Abstract Ammonia, as a carbon-neutral fuel, draws people attentions recently. NH3/CH4 blends is considered as a kind of fuel. A numerical simulation of the effects of CO2 dilution on the combustion characteristics and NO emission of NH3/CH4 counterflow diffusion flame was conducted in this study. Diffusion flame structure, the influence of CO2 radiation characteristics on temperature and NO emission characteristics were studies at normal temperature and pressure. The dilution and radiation of CO2 reduce the flame temperature significantly. NO concentration decreased with the CO2 mole fraction increase effectively. The study extends the basic combustion characteristics of NH3 containing fuel.

Abstract The employment of gas turbine in combination with diesel engines and steam generators is a well-known power generation technique in modern marines and ship propulsion. Previously, it rendered its foundations in marine industry through higher power weight ratios and lower NOx emissions if compared to pure diesel engine driven marines. As climate change concerns are becoming more serious, the decarbonization of marine combustion products is becoming of environmental concern. In the present study a modified design of the burner and combustor was suggested to allow for the longer residence time required for releasing the combustion products from the ‘slow’ burning ammonia molecule. Afterwards, the more formidable challenge of relatively higher NOx emissions was treated through analysis of the effect of altering the equivalence ratio, hydrogen blending, increasing the combustor working pressure and staging the combustion. The latest tactic resulted in lowering values of exit NOx to around 30 ppmv, which is a quite promising result.

There is wide consensus that Spirulina can serve as a tool for wastewater management and simultaneously provide feedstock for biorefining. However, the economic aspects associated with its use remain a significant challenge. Spirulina cultivated in wastewater decreased the concentrations of both ammonia and nitrate and also served as a biodiesel source. The oil obtained in the feedstock was subjected to transesterification and turned into biodiesel. The biodiesel was subsequently analyzed in a test motor (water-cooled, four-stroke, single-cylinder compression ignition with injection). The tests were conducted at a constant 1500 rpm, and the output power was 3.7 kW. Mixtures of diesel and biodiesel were also enriched with carbon nanotubes (CNTs). The amount of CNTs added to the diesel was 30 mg L−1. The algae and de-oiled biomass were characterized using XRD analysis, and an ultrasonicator was used to mix the CNTs with diesel and spirulina blends. A series of tests were conducted at different load conditions (25%, 50%, 75%, and 100%) for all fuel blends. Test results were compared with a neat diesel engine with a CR of 17.5:1. Among the fuel blends, the B25 reported improved brake thermal efficiency and reduced emissions. The outcomes are a reduction in thermal efficiency of 0.98% and exhaust gas temperature of 1.7%. The addition of Spirulina biodiesel blends had a positive impact on the reduction of greenhouse gas emissions, including reductions of 16.3%, 3.6%, 6.8%, and 12.35% of CO, NOx, and smoke, respectively. The specific fuel consumption and CO2 emissions were reduced by 5.2% and 2.8%, respectively, for B25 fuel blends compared to plain diesel and B50. Concerning cost competitiveness, vigorous research on microalgae for the production of biodiesel can cut production costs in the future.

This work presents an experimental study on the influence of the pilot flame characteristics on the flame morphology and exhaust emissions of a turbulent swirling flame. A reduced-scale burner, inspired by that fitted in the AE-T100 micro gas turbine, was employed as the experimental platform to evaluate methane (CH4) and an ammonia-methane fuel blend with an ammonia (NH3) volume fraction of 0.7. The power ratio (PR) between the pilot flame and the main flame and the fuel composition of the pilot flame was investigated. The pilot power ratio was varied from 0 to 20% for both fuel compositions tested. The NH3 volume fraction in the pilot flame ranged from pure CH4 to pure NH3 through various NH3–CH4 blends. Flame images and exhaust emissions, namely CO2, CO, NO, and N2O were recorded. It was found that increasing the pilot power ratio produces more stable flames and influences most of the exhaust emissions measured. The CO2 concentration in the exhaust gases was roughly constant for CH4-air or NH3–CH4–air flames. In addition, a CO2 concentration reduction of about 45% was achieved for XNH3 = 0.70 compared with pure CH4, while still producing stable flames as long as PR ≥ 5%. The pilot power ratio was found to have a higher relative impact on NO emissions for CH4 than for NH3–CH4, with measured exhaust NO percentage increments of about 276% and 11%, respectively. The N2O concentration was constant for all pilot power ratios for CH4 but it decreased when the pilot power ratio increased for NH3–CH4. The pilot fuel composition highly affected the NO and N2O emissions. Pure CH4 pilot flames and higher power ratios produced higher NO emissions. Conversely, the NO concentration was roughly constant for pure NH3 pilot flames, regardless of the pilot power ratio. Qualitative OH-PLIF images were recorded to further investigate these trends. Results showed that the pilot power ratio and the pilot fuel composition modified the flame morphology and the OH concentration, which both influence NO emissions.

As fossil fuels continue to be extracted and used, issues such as environmental pollution and energy scarcity are surfacing. For the transportation industry, the best way to achieve the goal of “carbon neutrality” is to research efficient power systems and develop new alternative fuels. As the world’s largest product of chemicals, ammonia is a new renewable fuel with good combustion energy. It can be used as an alternative fuel to reduce carbon emissions because of its proven production process, low production and transportation costs, safe storage, the absence of carbon-containing compounds in its emissions, and its future recyclability. This paper firstly introduces the characteristics of ammonia fuel engine and its problems; then it summarizes the effects of various ammonia-blended fuels on the combustion and emission characteristics of the engine from the combustion problem of ammonia-blended engine; then the fuel storage of ammonia-blended hydrogen is discussed, the feasibility of hydrogen production instead of hydrogen storage is introduced.

Abstract The use of ammonia as a fuel still poses a series of challenges to be overcome, both in terms of optimization and energy efficiency of the production process, and with regard to its combustion in internal combustion engines. The two main obstacles along this way are undoubtedly the high ignition temperature and the low propagation speed of the flame front due to the slow chemical kinetics of ammonia combustion process. All these issues lead to the need to use this fuel in blended mode with other more “easy burning” fuels. This need is even more felt in cases of non-stationary combustion, such as for alternative internal combustion engines but, on the other hand, it can determine an increase in engine efficiency. In this work, these ammonia technological constraints are exposed and discussed, outlining the most recent technological solutions and those under development, which will allow an increasingly widespread use of this energy carrier as a fuel in internal combustion engines. Finally, the environmental aspects related to the greater potential emission of NOx and the techniques to limit their occurrence are analyzed.

Due to the difficulty to directly study ammonia, the present work investigated the engine performance of lean iso-octane/air mixture to approximate ammonia combustion behaviour. The study was conducted using a single cylinder modified diesel engine that features a spark plug and glow plug in the sub-chamber. The investigations varied the engine speeds (1000 and 1500 RPM), glow plug voltages (6 and 10 volts), excess air ratios (1.4 to 1.8), and ignition timings (-2 to -5 °BTDC). The results suggested improved engine performances with a lower excess ratio and higher glow plug voltage due to more complete and stable combustion. By increasing the engine speed, the lean burn limit was extended and improved the engine performances. Because of the sub-chamber feature, delaying the ignition timing improved the engine performances. A larger excess air ratio was found to increase the sensitivity of the engine performances with the ignition timing. The brake mean effective pressure for all conditions has a coefficient of variation of less than 7%, indicating stable combustion. The results suggested that the current setup can be used to investigate ammonia blended fuel and direct ammonia combustion in future works.

Due to growing concerns about carbon emissions, Carbon Capture and Storage (CCS) techniques have become an interesting alternative to overcome this problem. CO2-Argon-Steam-Oxy (CARSOXY)-fuel gas turbines are an innovative example that integrates CCS with gas turbine powergen improvement. Replacing air-fuel combustion by CARSOXY combustion has been theoretically proven to increase gas turbine efficiency. Therefore, this paper provides a novel approach to continuously supply a gas turbine with a CARSOXY blend within required molar fractions. The approach involves H2 and N2 production, therefore having the potential of also producing ammonia. Thus, the concept allows CARSOXY cycles to be used to support production of ammonia whilst increasing power efficiency. An ASPEN PLUS model has been developed to demonstrate the approach. The model involves the integrations of an air separation unit (ASU), a steam methane reformer (SMR), water gas shift (WGS) reactors, pressure swing adsorption (PSA) units and heat exchanged gas turbines (HXGT) with a CCS unit. Sensitivity analyses were conducted on the ASU-SMR-WGS-PSA-CCS-HXGT model. The results provide a baseline to calibrate the model in order to produce the required CARSOXY molar fraction. A MATLAB code has also been developed to study CO2 compression effects on the CARSOXY gas turbine compressor. Thus, this paper provides a detailed flowsheet of the WGS-PSA-CCS-HXGT model. The paper provides the conditions in which the sensitivity analyses have been conducted to determine the best operable regime for CARSOXY production with other high valuable gases (i.e., hydrogen). Under these specifications, the sensitivity analyses on the (SMR) sub-model spots the H2O mass flow rates, which provides the maximum hydrogen level, the threshold which produces significant CO2 levels. Moreover, splitting the main CH4 supply to sub-supply a SMR reactor and a furnace reactor correlates to best practices for CARSOXY. The sensitivity analysis has also been performed on the (ASU) sub-model to characterise its response with respect to the variation of air flow rate, distillation/boiling rates, product/feed stage locations and the number of stages of the distillation columns. The sensitivity analyses have featured the response of the ASU-SMR-WGS-PSA-CCS-HXGT model. In return, the model has been qualified to be calibrated to produce CARSOXY within two operability modes, with hydrogen and nitrogen or with ammonia as by-products.

In this paper, the research on biodiesel or blending with other fuels is reviewed. Based on the current status of biodiesel research, this paper introduces the current research progress, combustion and emission characteristics, blending with other fuels, and development direction of biodiesel. The combustion, emission, and spray of biodiesel are not exactly the same as diesel, so it is not suitable to be used directly in diesel engines. Biodiesel can be blended with diesel, ethanol, ammonia and other fuels to improve its power performance and reduce harmful emissions. This review can serve as an important reference for those who want to engage in biodiesel research, and a quick understanding of biodiesel research before.

Ammonia (NH3) has emerged as an attractive carbonless fuel that can be co-fired with hydrocarbon fuel to reduce carbon dioxide emissions. To understand the influence of NH3 on soot formation when co-fired with hydrocarbons, the soot formation propensity is experimentally investigated via a laminar diffusion jet flame. A stable ethylene (C2H4) jet flame doped with NH3 at different volume percentages was established for the investigation of soot formation tendency. OH* chemiluminescence imaging revealed the change of flame structure, in which the signals emitted from the heat release region weakened with increasing NH3 addition, while the peak intensity shifted from the flame wings towards flame centerline region. The laser extinction method used to measure the soot volume fraction (SVF) at different heights above the burner, which showed the effect of NH3 on soot suppression is significant, owing to the interaction between N-containing compounds with carbon atoms that result in the reduction of key intermediate products required for the formation of benzene and polycyclic aromatic hydrocarbons (PAH). The effect of soot inhibition appears to be stronger for the low NH3 blend fraction. The chemistry effect of NH3 on soot reduction for C2H4 flame is ascertained by comparing with N2-doped C2H4 flame at the same volume percentage. This work highlights the need for improved understanding of hydrocarbon fuel with NH3 to enable detailed understanding on the soot generation and oxidation process.

Abstract. A sampling campaign with seven different types of vehicles was conducted in 2009 at the vehicle test facilities of the Joint Research Centre (JRC) in Ispra (Italy). The vehicles chosen were representative of some categories circulating in Europe and were fueled either with standard gasoline or diesel and some with blends of rapeseed methyl ester biodiesel. The aim of this work was to improve the knowledge about the emission factors of gas phase and particle-associated regulated and unregulated species from vehicle exhaust. Unregulated species such as black carbon (BC), primary organic aerosol (OA) content, particle number (PN), monocyclic and polycyclic aromatic hydrocarbons (PAHs) and a~selection of unregulated gaseous compounds, including nitrous acid (N2O), ammonia (NH3), hydrogen cyanide (HCN), formaldehyde (HCHO), acetaldehyde (CH3CHO), sulfur dioxide (SO2), and methane (CH4), were measured in real time with a suite of instruments including a high-resolution aerosol time-of-flight mass spectrometer, a resonance enhanced multi-photon ionization time-of-flight mass spectrometer, and a high resolution Fourier transform infrared spectrometer. Diesel vehicles, without particle filters, featured the highest values for particle number, followed by gasoline vehicles and scooters. The particles from diesel and gasoline vehicles were mostly made of BC with a low fraction of OA, while the particles from the scooters were mainly composed of OA. Scooters were characterized by super high emissions factors for OA, which were orders of magnitude higher than for the other vehicles. The heavy duty diesel vehicle (HDDV) featured the highest nitrogen oxides (NOx) emissions, while the scooters had the highest emissions for total hydrocarbons and aromatic compounds due to the unburned and partially burned gasoline and lubricant oil mixture. Generally, vehicles fuelled with biodiesel blends showed lower emission factors of OA and total aromatics than those from the standard fuels. The scooters were the main emitters of aromatic compounds, followed by the gasoline vehicle, the diesel vehicles and the HDDV.

The aim of this work is to prepare flame-retardant biobased poly(lactic acid) materials through incorporating a novel flame retardant dihydroxy-containing ammonium phosphate (DAP) derived from 2-chloro-5,5-dimethyl-1,3,2-dioxaphosphinane-2-oxide (DOP) and 2-amino-2-methyl-1,3-propanediol (AMPD). Interestingly, PLA modified with only 0.5% DAP passed UL-94 V-0 rating, and possessed a limiting oxygen index (LOI) value of 24.6%, which would further increase with the increasing loading of DAP. PLA/DAP did not exhibit obviously improved results in terms of heat release rate (HRR), as the loading of DAP was relatively low. It was found that DAP showed little effect on the thermal stability of PLA and the onset decomposition temperatures of PLA and PLA/DAP blends were very close. Besides, the degree of crystallization increased because of the plasticized effect of DAP. Based on the analyses of flame-retardant mechanism of DAP, it disclosed that DAP decomposed to generate incombustible compounds, such as water and ammonia, to dilute the concentration of oxygen and fuels, and then release some phosphorus-containing fragments that could produce phosphorus-containing free radicals to interrupt free-radical reactions, and finally noncombustible melt dripping was produced so as to bring away large amount of heat and stop the feedback of heat to the matrix.

Over the next decade, the production and use of hydrogen in various sectors of the global economy is anticipated to grow significantly. It is an already important feedstock in the production of ammonia and desulfurization of fuels in addition to being used in metals refining and as a coolant in thermal electric power plants. More recently, hydrogen is being considered for long-term seasonal energy storage for energy derived from renewables like solar and wind. To alleviate the severe costs of building out completely new infrastructure, the U.S. natural gas pipeline represents an enticing proposition for hydrogen storage and a potential distribution network from centralized production facilities. Embrittlement concerns of the pipeline with hydrogen limit the hydrogen partial pressure/concentration of hydrogen to be stored. Because many end use applications often require high purity hydrogen, it is necessary to separate/de-blend hydrogen from natural gas and compress it at the point-of-use. This talk presents high-temperature polymer electrolyte membrane (HT-PEM) electrochemical hydrogen pumps for separating hydrogen from gas mixtures. Hydrogen purification to +99% from syngas (25mol% hydrogen and 40mol% carbon monoxide (CO)) at 1 A cm-2 and cell voltage of 0.4 V with an electrochemical hydrogen pump was demonstrated. About 90% of hydrogen used in the United States today derives from steam-reformed natural gas that contains large concentrations of CO – which is a potent platinum electrocatalyst poison at temperatures below 100 °C. The hydrogen purification from syngas was possible with an electrochemical hydrogen pump operated at 220 °C and by using: i.) an ion pair HT-PEM that exploits electrostatic interactions to prevent phosphoric acid leaching at elevated temperatures from the membrane matrix and in the presence of water and ii.) a phosphonic acid ionomer electrode binder. The membrane electrode assembly (MEA) with the said materials and platinum on carbon (Pt/C) electrocatalyst was also effective for purifying hydrogen from other types of reformed hydrocarbons with different CO and hydrogen concentrations. Unexpectedly, operating the HT-PEM hydrogen pump at 220 °C minimized CO impact on cell polarization. At this temperature, cell polarization was governed by the hydrogen concentration in the gas feed. These observations motivate future work to develop new electrodes and electrode binders that can extract, purify, and compress hydrogen with feed streams that have low hydrogen content and contain other constituents in natural gas (methane, ethane, t-butyl mercaptan, etc).

The quantity of municipal solid waste (MSW) generation is escalating at an alarming rate with every passing year alongside the modernization of our economy. Unfortunately, the majority of this waste remains uncollected or ends up in open dumping and followed by uncontrolled burning. Citing the deep-rooted consequences, open dumping should be absolutely abandoned and scientific interventions should be aggressively exercised to reclaim the municipal brownfields. The present research work undertook the judicial task of assessing the comparative feasibility of biomining and scientific capping as a technology selection for reclamation of about a decade old 120 million tons of waste chunk laying at Jawahar Nagar dump yard. Primary dump samples were collected from various locations, considering depth as a variable. While leachate and groundwater samples were collected from Malkaram lake and preinstalled borewells receptively. Additionally, the ambient air quality and noise level also been ascertained within the buffer zone. The blended representative solid sample was segregated using a 70 mm mesh size trommel into organic and inorganic fractions. The organic fraction was composted using a lab-scale aerobic static pile composting (ASPC) while the trommel reject was processed as refuse derived fuel (RDF). Evidently, the compost lagged quality and depicted nutrient deficiency. While the burning of RDF produced siloxane gas, significantly due to elevated silicon level in the primary waste. Furthermore, due to the prolonged leaching tenure and seasonal dilution, the concentration of legacy leachate was relatively weaker. Borewell samples collected from a depth of 20 feet also portrayed minor contamination up to 500 meters horizontal radius. The issue of leachability can solely be resolved with the capping of the existing dump and the end product quality derived from the biomining process is highly questionable. Thus, handling such large quantity capping is a befitting option over biomining for Jawahar Nagar dumpsite. INTRODUCTION Presently, in India due to rapid urbanization and industrialization, the generation of MSW has been increasing tremendously and also expected to continue a similar trend in the future (Scott, 1995; Bhat et al., 2017; Sethurajan et al., 2018; Sharma et al., 2018). Annually, the comprehensive urban MSW generation in India is more than 62 million tons. Metro cities are the mammoth contributor of the entire chunk and waste production had already reached an alarming figure of 50,000 tonnes/day. While the waste generation from the tier 2 cities is also rigorously escalating and presently contribute up to 20,000 tones/day (Sharma et al., 2018). A study conducted by the central pollution control board (CPCB) revealed MSW generation in India is increasing at a distressing rate of 5 % per annum with a sharp escalation in the quantities of domestic hazardous waste (Sharma et al., 2018). With major financial constraints, inefficacy of collection, treatment, and disposal incurs further reasons to worry. So far India has miserably failed to set up wholesome source segregation and collection method. Presently, the country spends more than 60% of its annual waste management budget only in collection. Besides, only 20% or less of the collected materials are scientifically handled and treated. Citing the statistics, it is evident that the majority of the MSW is simply gets dumped on the low laying grounds located somewhere on the outskirts of the cities. The precipitation, infiltration, surface water runoff, bird menace, rodent interference etc. triggers the vulnerability of waste and leads to mal odor, ground and surface water contamination, human and environmental health deterioration (Jayawardhana et al., 2016). Further, the perseverance of the inorganic and inert fractions leads to soil contamination, poses a fire threat, and also may incur carcinogenicity and acute toxicity among the animals (Mir et al., 2021). There are numerous techniques for the reclamation and remediation of the dumpsites, includes processes such as capping and closure, in-situ vitrification, sub-surface cut-off walls, and waste biomining (Chakrabarti and Dubey, 2015; Thakare and Nandi, 2016). Waste biomining is a stable way to get rid of the entire range of problems associated with open dumping and reclaim valuable land (Kaksonen et al., 2017). There are several instances including reclamation of Mumbai Gorai dump yard by IL & FS Environment, 70 – 80 years old 12,00,000 tons of dump clearance by Nagar Nigam Indore within a minute span of 3 years and many more. But the process of biomining is highly sensitive and case-specific. The success of the process solely depends on factors such as characteristics of the waste, efficacy of the effective microorganism culture, acceptability of the processed end product at the local market etc. (Jerez, 2017; Banerjee et al., 2017; Venkiteela, 2020). Contrarily, though the scientific capping is not an end-to-end solution but still advisable in the cases where the quantity of waste is gigantic, land scarcity is prevalent, no nearby industries to consume the end products etc. Mehta et al. (2018) have also supported the above claim based on the assessment of locations specific MSW dump reclamation case studies. While in another Nagpur-based case study conducted by Ashootosh et al. (2020) reported the superiority of the biominingprocess over simple land capping due to the favorability of the local conditions. Capping eliminates the environmental interference and thereby reduces biosphere contamination and leachate generation. Further, it captivates rodent and vector breeding and thereby curtails the spreading of communicable diseases and improves aesthetics. But right consolidation through compaction and execution is utmost necessary in the above case. As non-compaction and faulty sloping will easily lead to heavy settlement and slope failure (Berkun et al., 2005; Al-Ghouti et al., 2021). The present study has been pursued with the primary objective to run a techno-commercial assessment between scientific capping and biomining. While the secondary objective was to ascertain the level of contamination and propose mitigative measures. MATERIALS AND METHODStudy Area Spanning over 350 acres of a precious piece of land at the outskirts of Hyderabad city, Jawahar Nagar dumping yard was brutally utilized by the Greater Hyderabad Municipal Corporation (GHMC) for open dumping for a prolonged tenure of 10 years. It housed nearly 12 lakh metric tons of heterogeneous solid and domestic hazardous waste and continues polluting until 2015, until the Ramky group was offered to cap the legacy dumping and scientifically handle the site. The present study has been facilitated at Hyderabad Municipal Solid Waste Limited, formerly known as Jawahar Nagar dump yard to analyze and assess the feasibility of bio-mining as handling and management alternate to the existing practice of scientific capping. The epicenter of processing and disposal facility is lying approximately on the cross-section of 17°31'24.45"N and 78°35'23.37"E. As per the contract, the comprehensive legacy dumping to be capped in three phases over about 150 acres of area and Ramky has significantly entered the phase two of the operation only within a span of five years by successfully capping more than half of the legacy footprint. Sampling Methodology The waste pile was divided into three layers namely, base, middle, and top. A uniform amount of sample was collected from the successive layers of all five different corners which cover north, south, east, west, and central of the garbage pile. Sampling inspections were performed using a manual auger besides large samples were collected using a JCB excavator. The top six-inch layer of the pile was removed to avoid any contamination while collecting the samples and 5-10 kg of sample was collected from each of the locations. Further, intermediate and bottom layer samples were collected by digging a 500 mm diameter hole through the heap. A composite was prepared by a homogenized blending of all the fifteen grub samples. The blend was distributed into four equal quadrants and the top and bottom quadrants were eliminated diagonally while the left-over quadrants were mixed thoroughly. This process was repeated until a sample of the required bulk of 20 kg is obtained. Surface and subsurface water samples from borewell were collected in and around the facility. Piezometric monitoring borewells located near the landfills were utilized for the subsurface sample collection. While a rainwater pond turned leachate lake named Malkaram was determined as the primary source for leachate collection. Buffer samples were collected from Ambedkar Nagar, the nearby colony exiting at a distance of only 300 meters. Lab-scale Experimentation The representative sample was characterized for composition and further screened through a 70 mm mesh size trommel. The trommel permeate was considered as the organic fraction while the reject was mostly inorganics and inert. The organics were subjected to ASPC. The quantity of the air required is arrived using the method delineated below (Figure 1). MSW Pile size: 2m x 0.5m x 0.5m Volume of pile: 0.5 m3 Average Density of MSW: 620 Kg/m3 Weight of pile: 310 Kg Nitrogen required for matured compost: 9300 mg/kg dry : 9300 X 310 mg : 2.88 x 106 mg : 2.88 Kg Total air required: 2.88 x 100/76 [as Nitrogen in air is 76% by weight] : 3.79 Kg of dry air : 3.79/1.225 m3 [@ 15 deg C density of air 1.225 kg/m3] : 3.1 m3 This air is to be supplied for 100 min / day for 0.5 m pile Air flow rate required: 3.1 x 60/100 = 1.86 m3/h (for practical purpose a flowrate of 2 m3/h was maintained). The maturation period was considered as 28 days and post-maturation, the stabilized material was further cured for 24 hours and screened using 12 mm and 4 mm trommel respectively to obtain the desired product quality and particle size. Whereas, the trommel reject was evenly spreader on the copper trays and dried in an oven at 1050C for 2 hours. The dried material was micronized to the size of 50 mm or below using a scissor and inert such as glass, sand, stone etc. were segregated manually (Mohan and Joseph, 2020). Concurrently, a bench-scale capped landfill prototype was built using the below-mentioned procedure to evaluate the factors such as settlement and slope stability. A 30 mm thick low permeable soil was laid on the top of the waste, followed by a 60 mm layer of compacted clay liner (CCL). Each join between successive liner material was closely monitored. A 1.5 mm thick HDPE liner was placed on the top of the CCL. A 285 GSM geotextile membrane was placed as the successive above layer followed by a 15 mm thick drainage media layer. A further layer of geotextile membrane was placed on top of the drainage media for better stabilization, grip, and strength. The top vegetative soil layer of 45 mm thickness was laid off on top of the geotextile media and St. Augustine grass was rooted (Cortellazzo et al., 2020; Ashford et al., 2000). 2.4 Sample Analysis pH, Electrical Conductivity (EC) and Turbidity of the samples were analyzed using pH, EC-TDS, and Nephelometer of Mettler Toledo. The pH meter was calibrated with the buffer solution of 4.0, 7.0 & 9.12 at a controlled temperature. EC-TDS meter was calibrated with 0.1 M KCL having 12.8 mS/cm of conductivity. Nephelometer was calibrated with Formazine solution of 10 & 100 NTU. Total Dissolved Solids (TDS), (mg/L) was performed using the gravimetric method at 1800C in the oven. Titrimetric parameters such as Total Alkalinity as CaCO3 (mg/L), Total Hardness as CaCO3 (mg/L), Chloride as Cl- (mg/L), Calcium as Ca2+ (mg/L), Residual Free Chlorine (RFC), (mg/L) were analyzed using APHA (American Public Health Associations) method, 23rd Edition, 2017. Total Kjeldahl Nitrogen (mg/L) and Ammonical Nitrogen (mg/L) were performed through distillation followed by titration with H2SO4 as a titrant. Sulphide as S2- was done with the Iodometric method after distillation. Each titrimetric parameter was analyzed in triplicate after standardizing the titrant with required reagents and crossed checked by keeping a check standard. Sodium as Na (mg/L) and Potassium as K (mg/L) were performed using Flame Photometer. The photometer was calibrated with different standards from 10 to 100 (mg/L) standard solutions. The leachate sample was diluted enough to get the value within the standard range and cross-checked with check standards at the same time. Chemical Oxygen Demand (COD), (mg/L) was performed using the open reflux method for 2 hours at 1500C in COD Digestor. Biochemical Oxygen Demand (BOD), (mg/L) was performed using the alkali iodide azide method for 3 days. The samples were kept in a BOD incubator at 270C for 3 days. It was kept in duplicate to have a check on quality control. Sulphate was analyzed by the gravimetric method instead of turbidimetric or through UV-Visible spectrophotometer as its concentration was found more than 40 mg/L. Nitrate as NO3- was analyzed after filtration at 220-275 nm, while Hexavalent Chromium as Cr6+ was analyzed at 540 nm in the UV-Vis. Parameters like Cyanide as CN-, Fluoride as F-, and Phenolic Compounds were gone through a distillation process followed by UV-Vis. The distillation process ensures the removal of interferences presents either positive or negative. For the parameters like Total Iron or Ferric Iron, the samples were digested properly with the required reagents on the hot plate before analyzing in UV-Vis. For the metal analysis the water samples were digested at a temperature of 1000C using aqua regia as a media. The samples were digested to one-fourth of the volume on a hot plate. The recommended wavelengths as per APHA 3120 B were selected for each of the metals. The standard graph was plotted for each of the metals before analysis and crossed checked with the check standard at the same time. Parameters such as bulk density and particle size were performed through the certified beaker and sieve. The percentage of moisture content was estimated using the oven by keeping the compost sample for 2 hours at 1050C. C/N ratio was estimated through CHNS analyzer keeping sulfanilamide as a check standard. The analysis was performed by extracting the desired component in the desired solution prescribed in the method followed by converting the same from mg/L to mg/Kg. RESULTS AND DISCUSSION An exhaustive bench-study has been pursued and real-time samples were collected and analyzed for all possible parameters to determine the pros and cons attributed to both processes. The investigation begins by collecting the samples and concluded by impact assessment studies inclusive of the buffer zone. Both solid, liquid, and gaseous samples were precisely investigated to opt for the best solution. A detailed finding of the investigation is summarized below. Primarily, the representative solid sample was characterized through a manual separation process and the results are portrayed in Figure 1. Compost Characterization ASPC of the organic fraction has resulted in a recovery of 46.7% of the initial load. While 53.3% of the influent mass were inert and barely degradable fraction contributes to reject, the rest 4.1% is miscellaneous process loss. The processed compost was extensively analyzed including for metal contamination and the same is tabulated in Table 1. The value of C/N ratio, OC, TN, K2O, P2O5, and NPK evidently portrays the shortcoming in terms of nutrient availability. Though it is highly enriched in organic carbon and thus the same can be effectively utilized as a soil preconditioner. Ayilara et al. (2020) also reported a similar finding, where the city compost sourced from MSW lagged major plant nutrients. RDF Characterization Processed trommel rejects constitute cloth, rexine, leather, jute, paper, plastics, coir and other inert contributed to RDF. The fraction of inert was as high as 37.2% of the overall RDF mass and it mostly constituted glass and sand. The combined weight of sand and glass fragments contributed 73.5% of the total inert, while the rest was stone and small brickbats. The higher level of silicon associated with the presence of glass and sand yielded siloxane and triggered the possibility of kiln corrosion. A detailed RDF analysis report is enclosed in Table 2. The values explicitly portray the quality of RDF is moderately lower and higher salts concentration is extremely prevalent. With relatively lower NCV and such high salt concentration, the above specimen will certainly pose a corrosion threat to the kiln and shall be either neglected as kiln feed or can be utilized after dilution with Grade III RDF quality. Further, such high ash generation will also induct high transportation and landfill charges. Leachate Characterization The Malkaram leachate lake is the end result of prolonged, slow, and steady mixing of the legacy leachate through the existing fissure cracks in the sheath rock bottom profile. Apparently, the concentration of leachate is significantly lower due to the dilution. Samples were analyzed in triplicates and the mean value is tabulated here in Table 3. The metal concertation and rest of the parameter values are well within the secondary treatment influent range, except for TDS. Thus, a modular aerobic biological treatment unit such as moving bed biofilm bioreactor (MBBR) or membrane bioreactor (MBR) would be a well-suited pick. However, a reverse osmosis (RO) system needs to be installed to get rid of the high TDS content. The permeate of RO can be reused back into the system. Whereas, the reject can be converted into dried powder through forced evaporation mechanisms. The higher concentration of salts in RDF collaterally justifies the elevated TDS level in leachate. In a leachate impact assessment study performed by El-Salam and Abu-Zuid (2015) the reported BOD/COD ratio of 0.69 is greater than double the value of 0.301 reported in Table 3. Though the difference in both the values are quite high, it is relatable and justifiable by the huge age difference of the source waste. The primarily characterized data is of a fresh leachate generated from regular MSW, while the later one is from a decade old waste that barely has any unstabilized organic content. Groundwater Contamination The obvious reason for downward leachate infiltration and osmotic movement facilitates groundwater contamination. Both surface and subsurface water samples were collected within the dump yard and the buffer zone and analyzed using the standard methods. The results are portrayed in Table 4. The slightly alkaline pH of the borewell sample is an indication of the ongoing anaerobic process. The dissolved oxygen value of 3.5 mg/L further validates the correlation. Higher TDS and hardness values are self-indicative of elevated salt concentration in source waste. Eventually, the same interfered with the RDF quality. Positively in the case of all the parameters, a successive decrement in pollution concentration has been spotted from dump ground towards the buffer zone. In a similar study conducted by Singh et al. (2016) at Varanasi, Uttar Pradesh the reported concentration of the parameters is significantly higher than reported in Table 4. The basic reason behind variation is the dissimilarities of the local soil profile. The sandy and clay loam soil profile of Varanasi allows a greater rate of percolation and infiltration. While the bottom sheath rock profile at Jawahar Nagar permits the only a minute to little percolation rate. The difference in percolation rate is directly correlated to the concentration levels in this case. Contrarily, Kurakalva et al. (2016) have reported much-elevated pollutant concertation both in ground and surface water for a study conducted at the same site in 2016. The higher concentration is relatable to the fact of the non-closure of the open dump back then. Capping activity had at Jawahar Nagar gained its pace 2018 onwards and capping for the primary section of 70 acres got concluded only during mid of 2019. Due to the decrement in runoff and percolation, the quality of both surface and subsurface water has improved drastically. Impact Assessment The odor and groundwater contamination are two of the primary issues that triggered a massive public agitation initially. The root causes of both the issues are identified as rainwater percolation and anaerobic digestion respectively. Eventually, the completion of the capping process would resolve both the problems effectively. Other non-tangential impacts include nausea; headache; irritation of the eye, nasal cavity, and throat; diarrhoeal diseases; vector-borne disease, cattle toxicity etc. Scientific capping can easily cater as the wholesome solution for all (Cortellazzo et al., 2020). Yu et al. (2018) had performed an extensive study to comprehend the relativity of respiratory sickness and MSW borne air pollution. The study made a couple of dreadful revelations such as gases released due to the anaerobic digestion of MSW such as methane, hydrogen sulphide, and ammonia incur detrimental impact on Lysozyme and secretory immunoglobulin A (SIgA). While SO2 was reported as the lung capacity and functionality reducer. Further, a gender-specific study executed by the same research group revealed, air pollution impacts more severely on male children than the female and retards immune functions. Presently, the area of 351 acres has been developed as Asia’s one of the largest state of the art municipal solid waste processing and disposal facility by Ramky Enviro Engineers Limited. This ensured zero dumping and no further environmental interventions. As legal compliance, the facility monitors the quality of groundwater and ambient air quality in and around the facility on monthly basis to assure the biosafety. The variation in concentration of various monitoring parameters between 2012 to 2020 is summarized in Figure 2. The concentration of each of the parameters are showcased in ppm and a standard equipment error was settled at 3% for respirable dust sampler and multi-gas analyzer (Taheri et al., 2014). Despite all parameter values have gradually increased except for methane, the facility still managed to maintain them well under the regulatory limits. The decrement in methane concentration is directly correlated to the practice of aerobic composting and aeration-based secondary treatment that prevented the formation of the anaerobic atmosphere and henceforth methane generation. While for the rest of the parameters the increment in values is quite substantial and predictable due to the sudden escalation in MSW generation in the past decade in correlation with Gross domestic product (GDP) enhancement. The observed and interpreted impacts due to the elevated pollutant level are in-line with the georeferenced findings reported by Deshmukh and Aher (2016) based on a study conducted at Sangamner, Maharashtra. CONCLUSION The study critically analyzed and investigated every techno-environmental and socio-economic aspect correlated to open dumping. The bench-scale experimentation revealed the efficiency of the single liner scientific capping is fair enough to eliminate any further rainwater infiltration, however, it has no control over the generation of leachate due to the inherent moisture. Internal moisture related issue was anyhow compensated with pertinent compaction prior to dispose of the waste. Contrarily, both the products derived through the biomining process namely, compost and RDF lagged quality due to scantier nutrient content and higher salt and silicon content respectively. Besides, impact assessment studies concede the pollutant concentration in groundwater in and around the plant has drastically diminished post-July 2019 due to the partial completion of waste capping. It also abetted lowering the dust and odor issues relatively in the surrounding. ACKNOWLEDGMENT The authors would like to sincerely acknowledge GHMC, Hyderabad Integrated Municipal Solid Waste Limited, and Ramky Enviro Engineers Limited for enabling us to pursue the sample collection and other necessary onsite activities. Further, the authors would like to register profound acknowledgment to EPTRI for supporting us with the essential experimental facilities. REFERENCES Sharma, A., Gupta, A.K., Ganguly, R. (2018), Impact of open dumping of municipal solid waste on soil properties in mountainous region. 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Ammonia, when blended with hydrocarbon fuels, can be used as a composite fuel to power existing internal combustion (IC) engines. Feasibility of developing ammonia gasoline liquid fuel blends and the use of ethanol as an emulsifier to enhance the solubility of ammonia in gasoline were studied using a small thermostated vapor liquid equilibrium (VLE) high-pressure cell. Engine dynamometer tests were conducted for developed fuel blends to measure the performance. Gasoline with 30% ethanol can retain 17.35% of ammonia in the liquid phase by volume basis. Engine dynamometer results show ammonia-rich fuels result in an increased torque and power output especially at higher engine speeds.

Ammonia/hydrogen-fueled combustion represents a very promising solution for the future energy scenario. This study aims to shed light and understand the behavior of ammonia/hydrogen blends under flameless conditions. A first-of-its-kind experimental campaign was conducted to test fuel flexibility for different ammonia/hydrogen blends in a flameless burner, varying the air injector and the equivalence ratio. NO emissions increased drastically after injecting a small amount of NH3 in pure hydrogen (10% by volume). An optimum trade-off between NOx emission and ammonia slip was found when working sufficiently close to stoichiometric conditions (ϕ = 0.95). In general, a larger air injector (ID25) reduces the emissions, especially at ϕ = 0.8. A well-stirred reactor network with exhaust recirculation was developed exchanging information with computational fluid dynamics (CFD) simulations, to model chemistry in diluted conditions. Such a simplified system was then used in two ways: 1) to explain the experimental trends of NOx emissions varying the ammonia molar fraction within the fuel blend and 2) to perform an uncertainty quantification study. A sensitivity study coupled with latin hypercube sampling (LHS) was used to evaluate the impact of kinetic uncertainties on NOx prediction in a well-stirred reactor network model. The influence of the identified uncertainties was then tested in more complex numerical models, such as Reynolds-averaged Navier–Stokes (RANS) simulations of the furnace. The major over-predictions of existing kinetic scheme was then alleviated significantly, confirming the crucial role of detailed kinetic mechanisms for accurate predictive simulations of NH3/H2 mixtures in flameless regime.

Ammonia as a carbon-free fuel has great potentiality to be utilized in power generation sectors such as micro gas turbines (MGT) to mitigate carbon dioxide emission from combustion systems. It is also easy to store and transport at room temperature compared to hydrogen, and in liquid form has equal volumetric energy density to liquid hydrogen. However, some challenges regarding its NOx pollution and flame stabilization inhibit its usage in these areas which requires further studies. In the present study, thermal performance and NOx emission of an MGT combustor fueled with ammonia-natural gas blends has been analyzed numerically through chemical reactant networks (CRN). The combustor’s inlet conditions are at atmospheric conditions and diffusion flame is stabilized using air swirler. In the first part of the paper, the CRN model has been developed based on empirical and semi-empirical equations. Series of experiments have been carried out to find the required parameters for the CRN model. Also, the results of NOx emission and temperature distribution have been validated with the experimental results. In the second part, effects of ammonia addition to the natural gas fuel are studied for various ammonia percentages using the CRN. The results show that by increasing ammonia molar percentage in the fuel, NO emission rises dramatically and reaches up to 330 PPM, but after a certain threshold (about 12.5 molar percent of ammonia) further ammonia addition reduces NO emission. Moreover, the overall temperature of the combustor decreases with ammonia addition due to lower LHV (lower heating value) of ammonia relative to natural gas. However, the overall efficiency of the combustor does not change significantly. The results also reveal that most of the NO is produced in the primary and secondary zones of the combustor. NO2 is mostly created in the secondary zone of the combustor and comprises about 10% of total NOx emission.

Abstract Primary alcohols such as methanol, ethanol, and butanol have exhibited excellent potential as possible alternative fuels for spark ignition (SI) engines because they are renewable, cleaner, and safer to store and transport. However, it is important to investigate the technical feasibility of adapting these primary alcohols in existing SI engines. In this research, a multi-point port fuel injection (MPFI) system equipped SI engine was used for assessing and comparing the combustion, performance, and emission characteristics of various alcohol-gasoline blends (gasohols) vis-à-vis baseline gasoline. The experiments were performed at different engine loads at rated engine speed. Experimental results exhibited relatively superior combustion characteristics of the engine fueled with gasohol than the baseline gasoline, especially at medium engine loads. Among different test fuels, the methanol-gasoline blend (GM10) exhibited relatively more stable combustion characteristics than the ethanol-gasoline blend (GE10) and butanol-gasoline blend (GB10). In this study, relatively superior engine performance of the gasohol-fueled engine was observed at all engine loads and speeds. GB10 exhibited the highest brake thermal efficiency (BTE), followed by GM10 amongst all test fuels. The effect of improved combustion was also reflected in the emission characteristics, which exhibited that GB10 emitted relatively lower carbon monoxide (CO) and hydrocarbons (HCs) than other test fuels. GB10 emitted relatively higher nitrogen oxides (NOx) than GM10 and GE10. Unregulated emission results exhibited that the engine fueled with gasohols emitted relatively lower sulfur dioxide (SO2), ammonia (NH3), and various other saturated and unsaturated HCs than the baseline gasoline. The GM10-fueled engine was relatively more effective in reducing unregulated emissions among all test fuels. This study concluded that methanol and butanol blending with gasoline resulted in superior engine performance and reduced harmful emissions in MPFI transport engines. This offered an excellent option to displace fossil fuels partially and reduce emissions simultaneously.

Abstract Ammonia is a promising hydrogen and energy carrier but also a challenging fuel to use in gas turbines, due to its low flame speed, limited flammability range, and the production of NOx from fuel-bound nitrogen. Previous experimental and theoretical work has demonstrated that partially-dissociated ammonia can match many of the laminar flame properties of methane flames. Among the remaining concerns pertaining to the use of NH3/H2/N2 blends in gas turbines is their thermoacoustic behavior. This paper presents the first measurements of flame transfer functions (FTFs) for turbulent, premixed, NH3/H2/N2-air flames and compares them to CH4-air flames that have a similar unstretched laminar flame speed and adiabatic flame temperature. FTFs for NH3/H2/N2 blends were found to have a lower gain than CH4 FTFs at low frequencies. However, the cut-off frequency was found to be greater, due to a shorter flame length. For both CH4 flames and NH3/H2/N2 flames the confinement diameter was found to have a strong influence on peak gain values. Chemiluminescence resolved along the longitudinal direction shows a suppression of fluctuations when the flame first interacts with the wall followed by a subsequent recovery, but with a significant phase shift. Nevertheless, simple Strouhal number scalings based on the flame length and reactant bulk velocity at the dump plane result in a reasonable collapse of the FTF cut-off frequency and phase curves.

Crude oil exhaustion and greenhouse emissions have remained a global concern till date. Domestic production of biofuel blends and micro-emulsion as substitutes for conventional fuel in tackling greenhouse gas emission has challenges like feedstock inadequacy, fuel-energy content, compatibility, oxidation stability and other automotive fuel property issues. Strategies to address these issues are discussed in this study. Case study of Nigeria shows that an annual conversion rate of 6.9/3.3% (2.1: 1) of cassava wastes will meet its E10/E5 blend from local production capacity. An effort has been made to correlate existing ethanol and biodiesel yields, ƐѱE and ƐѱB with expected oil yield as a function of gasoline and diesel shares, αE and αB per hectare of cultivation, to generate total oil yield per desired short and medium term biofuel targets utilizing selected feedstock at applicable yield bounds. A typical E10 gasohol from cassava will need 16,133 and 28,543 hectares from cassava plantation to meet its annual short and medium term biofuel targets. The r2-square value of 0.6402 for CF/SPeel and 0.9044 for CF/SPulp is an indication that more litre/tonne volume of ethanol could be produced from CF/SPeel except for in consistency when ammonia extract and urea are used as nitrogen source. Specific energy for direct ethanol fuel cell (DEFC) from daily production capacity equivalence of E10 per annum is estimated at 2.34GWh/Kg. Biofuel and fuel cells are good alternatives to explore as replacement of fossil fuel in automotive application.

A theoretical analysis based on the second law of thermodynamics was conducted for the ammonia/hydrogen/air premixed flames at different initial pressures. The irreversibility causing exergy losses in premixed flames was divided into five parts, namely, heat conduction, mass diffusion, viscous dissipation, chemical reaction, and incomplete combustion, respectively. The results revealed that as the hydrogen percentage in fuel blends increased from 0% to 100%, the total exergy losses decreased. Specifically, the exergy destructions induced by heat conduction and mass diffusion decreased with the increasing hydrogen percentage. The exergy loss induced by incomplete combustion increased with hydrogen addition, as more incomplete combustion products such as H2, H, and OH were generated with the increasing hydrogen percentage. The exergy destruction by chemical reactions first decreased and then increased with the increasing hydrogen percentage, which was attributed to the combination effects of the increased entropy generation rate and reduced flame thickness. Compared to the other four sources, the exergy destruction induced by viscous dissipation was negligible. Furthermore, at the elevated pressure of 5 atm, the effects of hydrogen blending were similar to those at the atmospheric condition. However, the exergy destructions by heat conduction and mass diffusion increased while the exergy destruction by the chemical reaction and the exergy loss by incomplete combustion were both reduced, with the overall exergy loss decreased by 1–2% as the pressure increased from 1 atm to 5 atm.

Abstract With the increasing need for flexibility in the electricity grid, combined with longer periods of low electricity prices due to an oversupply of renewable electricity, alternative solutions which include the production of carbon-free fuels in combination with the use of combined cycle power plants, are identified as possible solution. These so-called Power-to-Gas-to-Power solutions (P2G2P), with hydrogen and ammonia as fuel, require further research to determine their feasibility. The aim of this paper is to evaluate the impact of P2G2P system integration in a power plant. Different concepts have been applied to an existing ENGIE plant, based in Belgium, with the idea of installing all the technologies on the power plant site. Simulations show that a considerable production time is needed to operate the plant several hours using these e-fuels. Moreover, hydrogen storage requires an extremely huge footprint, hence it looks more reasonable to operate ammonia synthesis to store large quantities of decarbonized fuel, given the site space constraints. Additionally, the global efficiency for the P2H2P (with hydrogen) system is 32%. For the P2A2P (with pure ammonia) and P2A2H2P (part of the produced ammonia is cracked to recover hydrogen, feeding the combustion chamber of the CCGT with a blend of 70% NH3 and 30% H2) systems, this global efficiency is reduced respectively to 24% and 19%. From these results, it is thus apparent that there remain still several challenges that need to be overcome to make P2G2P an efficient way to decarbonise electricity production.

As soot particles from incomplete combustion of fossil fuels pose a great threat to human health, the development of low-carbon or zero-carbon alternative fuels is essential to mitigate climate change. An experimental and numerical study on the pyrolysis properties of ammonia and ethylene mixtures is conducted, focusing on the properties of soot generated by pyrolysis under different conditions and the coupling relationship between soot properties and soot precursors. The results show that the graphitization degree of soot particles generated at higher pyrolysis temperatures is enhanced, but the oxidation reactivity is decreased. When ammonia is blended, the graphitization of soot decreases and the oxidation reactivity increases. The peak mole fractions of soot precursors are negatively correlated with the graphitization degree of soot particles as the temperature increases.

AbstractAmmonia has been considered as a novel fuel for decarbonization purposes. However, emissions from combustion systems are still posing a problem. Therefore, experimental and numerical simulations have been conducted to study the concentration of exhaust emissions (Nitric oxide “NO”, Nitrous oxide “N2O”) from burning the ammonia/hydrogen (NH3/H2) blend 85/15 (vol%). The effects were measured at various thermal powers ranging 10 to 20 kW and with different Reynolds numbers from 20,000—40,000. The experimental points were numerically investigated in the Ansys CHEMKIN-Pro environment employing seven chemical kinetic mechanisms taken from the literature. All experiments have been undertaken at standard atmospheric conditions. The experimental results showed that both NO and N2O gradually increased when the Reynolds number increased from 20,000 to 40,000. Along with that, the concentration of NO emissions at the exhaust reported minimum level when the Re = 20,000 due to lower reactivity radical formation, all that led to a deterioration of the flame characteristics. Also, the integrated radical intensities of NO*, OH*, NH*, and NH2* demonstrate an increasing trend as Re increased from 20,000 to 40,000. In terms of thermal power, N2O suffered an abrupt decrease when the thermal power increased up to 15 kW, while the opposite occurs for NO. In addition, the radicals intensity of OH*, NH*and NH2* figures show an increase in their concentration when the thermal power increased up to 15 kW then decreased with increasing thermal intensity to reach 20 kW, reflecting into increased NO productions and decreased N2O levels. The numerical analysis showed that Stagni, Bertolino, and Bowen Mei were the most accurate mechanisms as these give a good prediction for NO and N2O. The study also showed that the chemical reaction (HNO + O2 ↔ NO + HO2) is the main source of NO formation. While the chemical reaction (NH + NO ↔ N2O + H) is responsible for the formation of N2O by consuming NO and when there will be abundance in NH radicals. Finally, dealing with a blended fuel of high ammonia concentration encourages ammonia chemistry to become more dominant in the flame. It decreases the flame temperature, hence lowering heat loss between the flame and the surrounding.

Hydrotreated vegetable oil (HVO), a glycerol-derived biofuel (blended with diesel fuel at 20% v/v, Mo·bio®) and biodiesel produced through the esterification of residual free fatty acids from the palm oil industry (pure and blended with diesel fuel at 20% v/v), all of them considered as advanced biofuels as defined in the Directive EU/2018/2001, were tested in a Euro 6 diesel vehicle equipped with ammonia-SCR. Tests were carried out in a chassis dyno at warm (24°C) and cold (−7°C) ambient conditions following the Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). The efficiency of the SCR when changing the fuel was also analysed. Regarding vehicle performance, fuel properties were mainly relevant at warm conditions. Because of the lower EGR rate, NOx emissions upstream of the SCR were higher at cold temperature, mainly during the low and the extra-high speed phases of the WLTC. CO and THC emissions were only important at the beginning of the cycle and at −7°C. HVO presented advantages regarding these compounds, while the worse cloud point of biodiesel led to higher emissions. As expected, engine-out NOx emissions were very sensitive to the EGR rate, HVO showing a slightly better behaviour because of its high cetane number. The SCR efficiency was mainly affected by the exhaust gas temperature, although fuel-derived effects were also significant. In fact, a more appropriate NO2/NOx ratio at the catalyst inlet for HVO and a higher hydrocarbon concentration at the low-speed phase for B20 contributed to a lower tail-pipe NOx emissions at −7°C. The oxygen content of biodiesel-based fuels (B100 and B20) led to lower particle number with respect to diesel fuel. Despite its nil aromatic content, the higher EGR rate and the extremely superior autoignition trend of HVO led to higher particle number under high engine load and warm conditions.