KAUST Research Conference Hydrogen Based Mobility and Power

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Now showing 1 - 5 of 11
  • Poster

    Understanding of MILD Combustion Characteristics of NH3/AIR Flames in N2 and H2O (steam) Diluted Environment at Atmospheric Pressure

    (2022-10-25) Singh, Anand

    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.

  • Poster

    Investigation of a multiple spark ignition approach to burn ammonia in a spark ignition engine: An optical study

    (2022-10-25) Uddeen, Kalim

    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.

  • Poster

    Unveiling the Optimal Interfacial Synergy of Plasma-Modulated Trimetallic Mn-Ni-Co Phosphides: Tailoring Deposition Ratio for Complementary Water Splitting

    (2022-10-25) Abousalem , Kholoud

    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.

  • Poster

    LCA of PEM Fuel Cell Vehicles Powered by Grey and Blue Hydrogen: A Case Study in Saudi Arabia

    (2022-10-25) Zhao, Chengcheng

    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..