Recent Submissions

  • DFT Investigation of the Hydrogen Adsorption on Graphene and Graphene Sheet Doped with Osmium and Tungsten

    Alshareef, Balqees (2022-10-25) [Poster]
    Significant interest has been focused on graphene materials for their unique properties as Hydrogen storage materials. The development of their abilities by modifying their configuration with doped or decorated transition metals was also of great interest. In this work, using the DFT/B3LYP/6-31G/LanL2DZ level of theory, graphene sheet (GS) as one of the materials of interest was doped with two transition metals, Osmium (Os) and Tungsten (W). Two active sites on the GS were tested (C4 and C16) resulted into adsorbed systems, H2@C4-GS and H2@C16-GS. C16 position showed the largest adsorption energy compared to that at C4. Therefore, C4 was replaced by the two metals and two adsorbed systems were formed: H2@Os-GS and H2@W-GS. The binding energy of H2@Os-GS was found to be greater than that of H2@W-GS.
  • Experimental study of hydrogen, syngas and methane ignition in CO2 bath gas

    Kashif, Touqeer Anwar (2022-10-25) [Poster]
    Direct-fired supercritical power cycles, operating on natural gas or syngas from coal gasification, have been proposed as future energy technologies which exhibit 100% carbon capture at a price competitive with existing fossil fuel technologies. In this work, ignition delay times (IDTs) of hydrogen, syngas, and methane were measured in a high concentration of CO2 bath gas at 20 bar of pressure. Measured datasets studied were compared with chemical kinetic simulations using AramcoMech 2.0 and the University of Sheffield supercritical CO2 (UoS sCO2) chemical kinetic mechanisms. The UoS sCO2 mechanism was recently developed to model IDTs of methane, hydrogen, and syngas in CO2 bath gas. The performance of both mechanisms was evaluated quantitively by comparing the average absolute error between the simulated and experimental IDTs, which showed UoS sCO2 2.0 as the superior mechanism for modeling IDTs in CO2 bath gas.
  • Investigation of a multiple spark ignition approach to burn ammonia in a spark ignition engine: An optical study

    Uddeen, Kalim (2022-10-25) [Poster]
    The future of internal combustion (IC) engine relies on carbon free fuels to mitigate climate change. Ammonia (NH3) is a promising carbon-free fuel which can be used as an energy carrier for hydrogen (H2) and directly as a combustible fuel inside the engines. However, burning pure ammonia fuel is difficult due to its low flammability, burning velocity, and consequent large cycle-to-cycle variation. This study used a multiple-spark-plug approach to burn pure ammonia gas with reduced combustion duration and higher engine power output. The natural flame luminosity (NFL) imaging method was used to capture the multiple flames initiated by various ignition sites. In order to perform the experiment a customized liner having four spark plugs installed at equal spacing, and to compare the results with conventional SI conditions, one spark plug was mounted at the center of the cylinder head. The results show that firing the single central spark plug generated lower in-cylinder pressure and heat release rate (HRR) along with higher combustion duration due to the low flame speed. However, adding more spark plugs increased the cylinder pressure generation and HRR along with creating shorter combustion duration for the same operating conditions. In addition, multiple flames produced by multiple plugs increased the engine power output and reduced the cyclic variation significantly due to higher pressure generation. Additionally, multiple ignition sources allow ammonia fuel to be burnt at lean conditions even at the low compression ratio. Furthermore, firing multiple spark plugs produced higher NOx emission than the single spark plug case due to the higher in-cylinder temperatures generated by multiple flame kernels. At relative air-fuel ratio (lambda) 1.2, higher NOx emission were obtained, because greater amounts of oxygen in the air-fuel mixture permit the oxidation of nitrogen (present in the fuel) into NOx. Further moving to lambda = 1.4, reduces the NOx emission due to the lower in-cylinder temperatures generated by leaner mixtures.
  • Low-Cost, Hydrogen Monofuel Power Generation for Portable On-Site Energy Supply

    Bättig, Rik (2022-10-25) [Poster]
    The importance of lowering greenhouse gas and noxious emissions throughout all sectors is undisputed. As the organizational structure of this conference proposes, the revolution in the mobility and power generation sector is not only a matter of transport and power production technologies but also strongly depends upon appropriate sourcing and distribution of the required energy. In a network of renewable energy sources and green technologies, hydrogen can play a crucial role as an energy vector by e.g., minimizing curtailment, enhancing sector coupling and enabling seasonal shifting of energy. However, there are currently only few green hydrogen supply chains and the market for hydrogen applications in the power and mobility sector has not reached its full potential. A carburetted, spark ignited gasoline fuelled engine of a 5 kW power generator was converted to run on hydrogen. As opposed to large parts of current research, the engine conversion s foremost goal was not to maximise efficiency and power output but rather to find a cost-effective and low-complexity conversion approach to introduce clean fuels to existing engines. To allow for the increased volumetric fuel flow, the riser of the original carburettor was enlarged. The hydrogen flow into the venturi was metered with the help of a pressure regulator from a widely available conversion kit. With the addition of an adjustable pressure regulator, the effects of different hydrogen-fuel-feed pressures on engine performance, operational stability and emission levels were examined experimentally. It was found that the hydrogen-line pressure before startup has to be set precisely (±5 mbar to allow for stable and emission free power generation. While the rated power of the converted engine was lowered to 57% of the original s generator, efficiency was increased by up to 9 percentage points while lowering NOx emissions drastically. In fact, under stable hydrogen supply conditions, it was shown that an aveerage concentration of only 19 ppm NOx is feasible without any exhaust gas aftertreatment. To put the results in perspective, the analytic derivation of lambda values from emission data has been examined intensively. With a fairly constant offset of 4.3% between the measured and calculated lambda value, the stoichiometrically derived formula for lambda proved to yield precise results with little calculation effort. As a main limiting factor for consistently low emission levels, fluctuations in the hydrogen supply grid were found to strongly influence the fuel flow rate which lead to inconsistent air-to-fuel ratios. Furthermore, large, abrupt reductions in engine load were identified to be critical with regard to running stability and backfiring events. The project showed that clean future fuels can be successfully introduced after market to combustion engines with the technology and equipment available today while keeping costs and complexity low. The results of this thesis further indicated that hydrogen is able to increase the efficiency of a carburetted engine without optimising any engine parameters set by the OEM such as spark advance or valve timing.
  • LCA of PEM Fuel Cell Vehicles Powered by Grey and Blue Hydrogen: A Case Study in Saudi Arabia

    Zhao, Chengcheng (2022-10-25) [Poster]
    Decarbonizing the transportation sector is essential to achieving climate stabilization and reaching net zero greenhouse gas emissions by 2050. Hydrogen proton-exchange membrane (PEM) fuel cell vehicles (FCVs) is a promising novel solution to reach this target. There are three primary forms of hydrogen to power the PEM fuel cell vehicle: grey , blue , and green , produced from steam methane reforming (SMR), SMR with carbon capture and storage (CCS), and water electrolysis powered by zero/ low carbon energy sources, respectively. In this study, the focus is on grey and blue hydrogen due to their cost-competitiveness and technological availability. Saudi Arabia heavily relies on fossil fuels such as crude oil and natural gas as its main energy provider. As the sixth largest natural gas reserve, it has tremendous potential for natural gas development. Therefore, grey and blue hydrogen sources are considered to be more accessible and feasible for PEM fuel cell vehicle development in Saudi Arabia. Literature studies on the life cycle assessment (LCA) of heavy-duty vehicles are limited. A research gap exists in the environmental assessment of the application of battery electric (BE) and PEM fuel cell buses in Saudi Arabia, as well as the energy consumption and emissions. Furthermore, the complete LCA can be divided into two parts: fuel cycle and vehicle cycle, and only a few studies have focused on both. This study bridged these research gaps and explored the global warming potential (GWP), abiotic depletion potential (ADP), and acidification potential (AP) of using grey and blue hydrogen in PEM fuel cell vehicles operating in Makkah in Saudi Arabia. It compares the life-cycle emissions of 20 internal combustion engine (ICE) vehicles, 20 battery electric (BE) vehicles, and PEM fuel cell vehicles for heavy-duty transportation with a lifetime of 254,040 km. The emissions and energy use of refueling infrastructure for 3 types of vehicles for 5 years were also determined, as well as the emissions and energy use of hydrogen transportation from eastern Saudi Arabia to Makkah. The emissions from upstream fuel production and delivery (or well-to-pump) are the most critical for the hydrogen PEM vehicles. This is due to the fact that the emissions in the usage phase are almost zero. Hydrogen can be produced and used inside Saudi Arabia employing gas tube trailers for fuel transport and has a potential to reduce the emissions at this stage. Blue hydrogen has most of its production emissions captured, hence it delivers lower total emissions compared to grey hydrogen. The LCA study highlights the importance of developing PEM fuel cell vehicles and provides guidelines to governments and companies for developing hydrogen PEM fuel cell vehicles in Saudi Arabia..
  • Soot Characterization in Ammonia-Diesel Dual Fuel Engines

    Zaher, Mohammed (2022-10-25) [Poster]
    The interest in ammonia (NH3) is on the rise to be used in compression ignition engines by replacing heavy hydrocarbons such as heavy oil and diesel in applications such as marine shipping in effort to reduce their carbon footprint. Diesel could be partially replaced with NH3 in the engine to reduce CO2 emissions, however a minimum percentage of diesel is required to sustain the NH3 ignition and combustion in the engine. The objective of this work is to study the impact of NH3 on the formation of soot in a dual fuel diesel engine by analyzing the exhaust soot mass concentration, morphology, nanostructure and composition, shedding more light on the chemical interactions of NH3 with diesel soot. For the engine operating at 0%, 20%, and 40% NH3 to diesel, a linear reduction in soot mass concentration and size and number of the soot primary particles is found as the percentage of NH3 increases. The soot nanostructure is investigated using Raman analysis of the solid soot particles which shows higher levels of soot graphitization with higher sp2 hybridization of the carbon atoms. Analysis of XPS spectra is done to obtain the atomic percentage of nitrogen bound to the soot surface which shows a substantial increase in the amount of nitrogen detected on the soot surface. The effect of NH3 addition on the nanostructure could be linked to the NH3 reactions with the soot surface at the active sites which limits the ability of the carbon to bind to the soot surface, suppresses soot growth. and increases the nitrogen content of the soot formed.
  • Understanding of MILD Combustion Characteristics of NH3/AIR Flames in N2 and H2O (steam) Diluted Environment at Atmospheric Pressure

    Singh, Anand (2022-10-25) [Poster]
    Increasing awareness of climate change has sparked interest in renewable and zero-carbon vector fuels. Ammonia is gaining popularity as a carbon-free fuel that emits no carbon dioxide; however, a large amount of NOx emission during its combustion poses a significant challenge. In the present work, a chemical kinetic study is performed to study the MILD combustion characteristics of NH3/air flames in the N2 and H2O diluted atmosphere at oxygen concentrations, reactant temperatures, and pressure of 11-23%, 1300-1700 K, and 1 atm, respectively. Steam-diluted flames produce less NOx emissions than nitrogen-diluted flames. Furthermore, the exit NOx emissions for nitrogen-diluted flames increase with an increase in oxygen concentration. However, the NOx emissions for steam-diluted flames show non-monotonic behavior, i.e., exit NOx increases up to the oxygen concentration of 21%, and after that, it starts decreasing. Compared to nitrogen-diluted flames, steam-diluted flames exhibit a wider no-ignition regime. In steam-diluted flames, the peak temperature rises less than in nitrogen-diluted flames, corresponding to wider regimes of MILD combustion. Moreover, for steam-diluted flames to achieve MILD combustion at a given oxygen concentration, the reactant temperature must be higher than that for nitrogen-diluted flames.
  • Hydrogen/hydrogen peroxide laminar diffusion opposed-flow flame

    Li, Jiajun (2022-10-25) [Poster]
    Hydrogen Peroxide (HP) has been widely used in rocketry as a propellant. It is also used as a fuel additive to improve combustion efficiency and lower CO2/NOx emissions in energy systems. Given its chemical structure, HP could also be used as an oxidant in combustion applications. Hydrogen is a promising clean energy In this study, one-dimensional numerical simulations were conducted using the opposed-flow non-premixed laminar flame routine of the CHEMKIN-Pro, to better understand the range of stability limits of H2/HP laminar flames. The fuel stream is H2 while the oxidizer stream consists of HP in water (H2O). Parametric studies of HP concentration, oxidizer temperature, strain rate, and pressure were carried out to better understand the flame structure and the chemical kinetic coupling between HP and H2.
  • Modelling of an hydrogen transient jet

    Venner, Lucas (2022-10-25) [Poster]
  • Unveiling the Optimal Interfacial Synergy of Plasma-Modulated Trimetallic Mn-Ni-Co Phosphides: Tailoring Deposition Ratio for Complementary Water Splitting

    Abousalem , Kholoud (2022-10-25) [Poster]
    Designing highly active, durable, and nonprecious metal-based bifunctional electrocatalysts for overall water electrolysis is of urgent scientific importance to realize the sustainable hydrogen production, which remains a grand challenge. Herein, an innovative approach is demonstrated to synthesize flower-like 3D homogenous trimetallic Mn, Ni, Co phosphide catalysts directly on nickel foam via electrodeposition followed by plasma phosphidation. The electrochemical activity of the catalysts with varying Mn:Ni:Co ratios is assessed to identify the optimal composition, demonstrating that the equimolar trimetallic phosphide yields an outstanding HER catalytic performance with a current density of 10?mA?cm?2 at an ultra-low overpotential of ~14?mV, outperforming the best reported electrocatalysts. This is asserted by the DFT calculations, revealing strong interaction of the metals and the P atom, resulting in enhanced water activation and optimized GH* values for the HER process. Moreover, this optimal composition appreciably catalyzes the OER by exposing more intrinsic active species in-situ formed on the catalyst surface during the OER. Therefore, the Mn1-Ni1-Co1-P-(O)/NF catalyst exhibits a decreased overpotential of ~289?mV at 10?mA?cm?2. More importantly, the electrocatalyst sustains perfect durability up to 48?h at a current density of 10?mA?cm?2 and continued 5000 cycling stability for both HER and OER. Meanwhile, the assembled MNC-P/NF||MNC-P/NF full water electrolyzer system attains an extremely low cell voltage of 1.48?V at 10?mA?cm?2. Significantly, the robust stability of the overall system results in a remarkable current retention of ~96% after a continuous 50-h run. Therefore, this study provides a facile design and a scalable construction of superb bifunctional ternary MNC-phosphide electrocatalysts for efficient electrochemical energy production systems.

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