Combustion characteristics of ammonia/air flames for a model swirl burner and an actual gas turbine combustor

Ammonia is expected not only as hydrogen energy carrier but also as carbon free fuel. For an industrial use of ammonia combustor, ammonia flame stabilized on a swirl combustor should be clarified. However, in order to realize an ammonia-fueled combustor, there are some issues to be solved, such as a difficulty of flame stabilization and reductions of NOx and ammonia emission. In this study, stabilization and emission characteristics of ammonia / air flames stabilized by a model swirl burner are investigated. The outer and inner diameters of the swirler are 24 mm and 14 mm, respectively, and the swirl number…


NOx emission analysis and flame stabilization of ammonia-hydrogen-air premixed flames

Based on its well-known merits, ammonia has been gaining special attention as a potential renewable energy carrier which can be replaced in power generation units. One of the major challenges with ammonia as a fuel is NOx emission, which has a complex underlying chemical kinetics. In an earlier chemical kinetics study by the authors, NOx formation sensitivity was thoroughly studied in a wide range of combustion conditions [Nozari & Karabeyoğlu, J.Fuel 2015]. As the next step, premixed ammonia-hydrogen-air flames are studied experimentally in standard temperature and pressure condition. Effects of some major influential parameters on NOx emission levels are investigated:…


Power Generation and Flame Visualization of Micro Gas Turbine Firing Ammonia or Ammonia-Methane Mixture

A demonstration test with the aim to show the potential of ammonia-fired power plant is planned using a micro gas turbine. 50kW class turbine system firing kerosene is selected as a base model. A standard combustor is replaced to a prototype combustor which enables a bi-fuel supply of kerosene and ammonia gas. Diffusion combustion is employed to the prototype combustor due to its flame stability. 44kW power generation was achieved by 100% heat from ammonia gas. Although NOx concentration in the exhaust gas of ammonia combustion exceeded 500ppm, NOx removal equipment reduced NOx concentration below 10ppm. Over 30kW power generation…


Displacing Diesel Fuel with Carbon-Free Anhydrous Ammonia

The team at the University of Minnesota announced last month the award of funding for a demonstration project entitled "Clean Vehicles Fueled by Hydrogen from Renewable Ammonia." This project builds on years of research and investment in renewable ammonia at University of Minnesota, most visibly the prototype wind-to-ammonia production plant operating since 2014 at West Central Research and Outreach Center. Their focus now, however, is shifting to the use of ammonia as a fuel. "The overall objective of the project is to displace up to 50% of the diesel fuel used in tractors with anhydrous ammonia produced from renewable resources."


Numerical investigation of combustion characteristics of ammonia-air mixtures under high pressure lean conditions

In this numerical study we investigate the combustion characteristics of ammonia-air mixtures at elevated pressure and lean conditions which are encountered in gas turbine combustors. The Konnov mechanism is implemented to predict the laminar burning velocity, autoignition, species concentrations and the sensitivity analysis of ammonia decomposition and laminar flame speed. A laminar premixed freely propagating flame model is implemented to calculate burning velocity, mole fractions of species, and contribution of reactions in molar conversion of specific species. Also a homogenous reactor model is used to analyze the temporal mole fraction of radicals and ignition delay time. Effects of adding hydrogen…


Simulation of Fuel Economy of Gasoline-Ethanol-Ammonia Tertiary Fuel Blends for a Series Hybrid Electric Vehicle

With the depletion of petroleum resources around the world, a need to have cleaner and fuel efficient automotive technologies and alternative fuel sources has become prominent. Hybrid electric vehicles and sustainable energy sources have gained a high momentum in fulfilling this requirement. To satisfy both needs ammonia, which has been used for a long period of time as a sustainable and carbon free transport fuel can be combined with hybrid electric vehicles. Ammonia when blended with gasoline can be used as an alternate fuel to power existing internal combustion engines. Such blends similar to ethanol-gasoline fuel blends would provide a…


Fundamental Characteristics of Ammonia/Air Premixed Laminar Flames

Fundamental flame characteristics must be required for the design of ammonia fueled combustors. However, few studies of ammonia combustion have been conducted. In this study, fundamental ammonia/air premixed laminar flame characteristics, such as NO formation/reduction mechanisms and laminar burning velocity, were experimentally and numerically investigated. NO mole fraction in burned gas from ammonia/air premixed flames were investigated using a stainless-steel nozzle burner. Experiments were conducted at various equivalence ratios and pressures. As a result, NO mole fraction in burned gas reduced with the increase in equivalence ratio and pressure. Formation/reduction mechanisms of NO were numerically investigated. Laminar burning velocity and…


Making and Treating NOx formed in NH3 Engines

Ammonia has real promise as a green renewable fuel; however its use is not without some of the drawbacks endemic to high temperature combustion processes. Chief among them is the potential for NOx formation in nitrogen-rich oxidizing environments. Nitric and nitrous oxides are prime culprits that plague both entrenched hydrocarbon internal combustion technology but also emerging technologies like ammonia-as-a-fuel. Nitric oxide is implicated in photochemical ground-level ozone production in urban areas. Nitrous oxide is its own double-edged environmental sword, being both a potent tropospheric green-house gas as well as a principle agent in renewed stratospheric ozone-depletion (Science 2009, v326, p.…


Characteristics of a Spark Ignition Engine Using Direct Ammonia Injection

The effects of direct injection of gaseous ammonia on the combustion characteristics and exhaust emissions of a spark-ignition engine were investigated. Port-injection gasoline was used to enhance the burning of ammonia that was directly injected into the engine cylinder. Appropriate direct injection strategies were developed to allow ammonia to be used in spark-ignition engines without sacrifice of volumetric efficiency. Experimental results show that with gasoline providing the baseline power, total engine power increased as the injection timing of ammonia was advanced and the injection duration was increased. Engine performance with use of gasoline-ammonia was compared to that with gasoline alone.…