Browse Topic: Refueling
The Korea Research Institute of Standards and Science (KRISS, President: Dr. Lee Ho Seong) has developed equipment that monitors the quality of hydrogen fuel supplied to vehicles through hydrogen refueling stations in real-time. This equipment is expected to prevent hydrogen vehicle accidents caused by impurities in the hydrogen fuel and improve the quality of hydrogen production.
Over the past few decades, Compressed Natural Gas (CNG) has gained popularity as an alternative fuel due to its lower operating cost compared to gasoline and diesel, for both passenger and commercial vehicles. In addition, it is considered more environmentally friendly and safer than traditional fossil fuels. Natural gas's density (0.7–0.9 kg/m3) is substantially less than that of gasoline (715–780 kg/m3) and diesel (849–959 kg/m3) at standard temperature and pressure. Consequently, CNG needs more storage space. To compensate for its low natural density, CNG is compressed and stored at high pressures (usually 200-250 bar) in on-board cylinders. This results in an effective fuel density of 180 kg/m3 at 200 bar and 215 kg/m3 at 250 bar. This compression allows more fuel to be stored, extending the vehicle's operating range per fill and minimising the need for refuelling. Natural Gas Vehicles (NGVs), particularly those in the commercial sector like buses and lorries, need numerous CNG cylinders in order to maximise vehicle range on a single fill. However, increasing the number of on-board cylinders results in a proportional increase in refuelling time, which can have a detrimental impact on operational costs for commercial fleet owners. The CNG fuel system, which usually consists of large-volume petrol cylinders (up to 800 litres), is an essential part of vehicle development. A quick petrol fill-up time is ideal because these vehicles must frequently refuel because they frequently travel vast miles each day. At the moment, the refuelling time is calculated by evaluating the CNG filling time following prototype development. Design modifications to the fuel system are necessary if the filling time is too long, which results in severe time and cost penalties as well as delays in the development cycle of new vehicle products. A mathematical model based on a number of influencing factors has been created by combining AI and ML technology. At the initial Zero design release gateway, this model will forecast the time needed to fill up with CNG petrol on all commercial vehicle platforms. This early prediction will enable additional optimization to improve gas filling time. The goal of this research work is to optimize the filling time for various platform before physical vehicle builds.
Low-Cost Mobile Hydrogen Refuelling Stations: A Cost-Effective Solution for India's Sustainable Transportation” The likely depletion of fossil fuel reserves in the next fifty years and growing environmental concerns caused by petroleum fuel-based vehicles highlight the urgent need for sustainable alternatives. India, a developing country, requires a significant amount of energy to sustain its growth, most of which is imported. Hydrogen is one of the cleanest fuels and offers sustainable pathways to a low-carbon future. The government of India has already launched a Green Hydrogen mission and has set up a very ambitious target for 2030. However, the absence of adequate refueling infrastructure is a significant blockade to India's widespread adoption of hydrogen-powered vehicles. The mobile hydrogen refueling station (MHRS) is a flexible system that enables lower initial capital costs than fixed hydrogen refueling stations and allows for the gradual build-up of hydrogen mobility fleets. Such a system could be very useful in India, and it integrates advanced safety features, including hydrogen leak detectors, pressure and temperature sensors, flame detectors, and gas composition analyzers, to ensure the safe dispensing of hydrogen. Such a system can significantly boost local economies by creating employment opportunities at various hydrogen supply chain stages and reducing air pollution. These can dispense hydrogen at both 350 bar and 700 bar pressures, ensuring compliance with international safety standards such as ISO 14687 and ISO/TR 15916. This paper studies the design and economics of a low-cost, scalable Mobile Hydrogen dispensing system. It evaluates its cost-effectiveness, scalability, safety, socio-economic, and environmental impact (using Life Cycle Analysis) in a developing country like India. The results of the study are very promising and suggest that MHRS has a sustainable future in India.
Several efforts have been made to develop Flight Test Maneuvers for Handling Qualities evaluations, aimed at quantifying the effects of vehicle characteristics and assistance systems on a Helicopter Air-to-Air Refueling mission profile. However, these Flight Test Maneuvers have not achieved widespread adoption, likely due to the substantial logistical challenges associated with tanker deployment. Depending on a tanker aircraft not only incurs significant costs but also requires extensive organizational effort and prior testing, before Handling Qualities can be evaluated for the aerial refueling capabilities of a new rotorcraft design. Additionally, these available Flight Test Maneuver setups are not standardized or widely applied to the same degree as Mission Task Elements of the Aeronautical Design Standard, which limits repeatability and comparability. A new approach is proposed to address these limitations by introducing a repeatable, standardized method to reveal Handling Qualities deficiencies considering a worst-case situation of Helicopter Air-to-Air Refueling. This approach involves analyzing drogue motion to create a synthetic, deterministic target forcing function, based on the summation of several sine waves. Resulting laws of motion are applied to a target tracking task replicating a drogue chasing scenario by projecting all required references into the pilots' field of view. Piloted simulator studies conducted at the Air Vehicle Simulator (AVES) of the German Aerospace Center (DLR) demonstrate a high degree of similarity in pilot control behavior between the proposed Flight Test Maneuver and actual simulated Helicopter Air-to-Air Refueling.
During helicopter air-to-air refueling the rotor of the helicopter might enter the slipstream of the tanker aircraft's propeller. Based on blade element momentum theory, the impact of the accelerated air within the propeller slipstream on rotor blade aerodynamics (thrust, rolling and pitching moments) can be solved analytically. Also, DLR's comprehensive rotorcraft code has been used with the Pitt-Peters induced inflow plus rotor-rotor interference model. Additionally, DLR's free-wake code was used for both the propeller and the helicopter main rotor, including mutual wake-wake-interactions. The helicopter rotor's collective and cyclic controls needed for disturbance rejection are computed with all these models for a typical air-to-air refueling scenario without and with blade flapping motion. A propeller wake affecting the retreating side of the rotor requires much larger control inputs to retrim than an impingement on the advancing side. The results of all modelling approaches are compared to each other and generally a reasonably good agreement is found, despite their very different levels of complexity and computational effort.
Decarbonizing regional and long-haul freight is challenging due to the limitations of battery-electric commercial vehicles and infrastructure constraints. Hydrogen fuel cell medium- and heavy-duty vehicles (MHDVs) offer a viable alternative, aligning with the decarbonization goals of the Department of Energy and commercial entities. Historically, alternative fuels like compressed natural gas and liquefied propane gas have faced slow adoption due to barriers like infrastructure availability. To avoid similar issues, effective planning and deploying zero-emission hydrogen fueling infrastructure is crucial. This research develops deployment plans for affordable, accessible, and sustainable hydrogen refueling stations, supporting stakeholders in the decarbonized commercial vehicle freight system. It aims to benefit underserved and rural energy-stressed communities by improving air quality, reducing noise pollution, and enhancing energy resiliency. This research also provides a blueprint for replacing diesel in over-the-road Class 8 freight truck applications with hydrogen fueling solutions. The study focuses on the Texas Triangle Megaregion (I-45, I-35, and I-10), the I-10 corridor between San Antonio, TX, and Los Angeles, CA, and the I-5/CA-99 corridors between Los Angeles, CA, and San Francisco, CA. This area represents a significant portion of U.S. heavy-duty freight movement, carrying ~8.5% of the national freight volume. Using the OR-AGENT (Optimal Regional Architecture Generation for Efficient National Transport) modeling framework, the study conducts an advanced assessment of commercial vehicles, road and freight networks, and energy systems. The framework integrates data on freight mobility, traffic, weather, and energy pathways to deliver a region-specific, optimized vehicles powertrain architectures, infrastructure deployment solutions, operational logistics, and energy pathways. By considering all vehicle origin-destination pairs utilizing these corridors and all feasible fueling station location options, the framework's genetic algorithm identifies the minimum number and optimal locations of hydrogen refueling stations, ensuring no vehicle is stranded. It also determines fuel schedules and quantities at each station. A roadmap for station deployment based on multiple adoption trajectories ensures a strategic rollout of hydrogen refueling infrastructure.
In order to give full play to the economic and environmental advantages of liquid organic hydrogen carrier(LOHC) technology in hydrogen storage and transportation as well as its technological advantages as a hydrogen source for hydrogen refueling station(HRS) supply, it promotes the change of hydrogen supply method in HRSs and facilitates its technological landing in the terminal of HRSs. In this paper, combining the current commercialization status of organic liquid technology and the current construction status of HRS in China, we establish a traditional long-tube trailer HRS model through Matlab Simulink, carry out modification on the existing process, maximize the use of the original equipment, and introduce the hydrogen production end of the station with organic liquid as an auxiliary hydrogen source. Research and design of the two hydrogen sources of gas extraction strategy and the station control strategy and the formation of Stateflow language model, to realize the verification of the LOHC technology auxiliary hydrogen supply program. Different LOHC hydrogen production quantities are set to analyze their effects on the cost of hydrogen supply, energy consumption, and high-pressure hydrogen inventory (safety) in the HRS. The results show that in the case of LOHC for auxiliary hydrogen supply, a specific amount of hydrogen production can ensure the full utilization of the trailer at the station and avoid overnight stationing. In terms of hydrogen supply costs, LOHC for auxiliary hydrogen supply is cost-effective, with overall transportation costs decreasing by 25.9%-56.1% as the amount of LOHC production increases.
Refueling mid air is considered as important force multiplier for e.g. conducting search and rescue operations. Due to close proximity to the tanker, the refueling hose and drogue as well as the receiver can be strongly affected by the tanker's wake. Thus, the refueling drogue extended from the tanker by a hose is often oscillating from turbulence. Contact with the tanker has to be established by positioning the receiver's refueling probe within the tanker's drogue. During qualification training pilots are instructed to not focus on the drogue, due to its oscillations. This is done since chasing the drogue often leads to over-controlling and therefore mostly to a failed contact attempt. The presented research aims for improving today's Helicopter Air-to-Air Refueling (HAAR) as well as related training efficiency by a gain of understanding in this phenomenon. Therefore, the HAAR real-time simulation scenario at German Aerospace Center's (DLR) Air Vehicle Simulator (AVES) was extended with a multi body hose and a probe/drogue contact model to enable realistic contact initiation. During a piloted campaign, a total of six pilots with different levels of HAAR experience conducted the maneuver. This paper presents an analysis of obtained eye tracking data with regards to gaze entropy, total fixation duration on defined areas of interest and corresponding time history of control inputs. Potential links between gaze entropy and perceived workload that might be observed in the data are also discussed. Results show that the metrics can highlight differences in successful and unsuccessful attempts for contact of HAAR experienced and inexperienced pilots.
Defense Innovation Unit Washington D.C. info@DIU.mil
Low-carbon fuels promise greener alternatives, but can they deliver? Even as electric vehicles dominate today's alternative powertrain market for passenger cars, the future of how we will all someday drive without burning petroleum is cloudier than ever. To decarbonize transportation, governments and companies around the world are promoting various future technologies, including hydrogen and synthetic fuels, as alternatives to the alternative. In the U.S., the road to a hydrogen future recently hit a few road-blocks. In February 2024, Shell announced it would dramatically scale back its H2 refueling station plans in California and close some of its few stations. This dealt a blow to local H2-vehicle drivers as well as the state's plans for a robust hydrogen infrastructure. When Hyundai announced in October 2021 that it would support Shell's plans to add 48 additional H2 refueling stations in California, it said that “hydrogen refueling infrastructure growth is critical to rapidly increase consumer adoption of zero-emission fuel cell vehicles.”
Armed with 5G network technology, artificial intelligence (AI), and edge computing resources, a pilot project under development at Naval Air Station Whidbey Island aims to create an optimized refueling system designed to boost readiness for military aircraft operating there as well as those stopping for fuel en route to other locations.
Hydrogen as a clean, renewable alternative to fossil fuels is part of a sustainable-energy future; however, lingering concerns about flammability have limited widespread use of hydrogen as a power source for electric vehicles. Hydrogen vehicles can refuel much more quickly and go farther without refueling than today’s electric vehicles, which use battery power. But one of the final hurdles to hydrogen power is securing a safe method for detecting hydrogen.
NASA Goddard developed the Cooperative Service Valve (CSV) to facilitate the resupply of media, such as propellants and pressurants, to satellites. The CSV replaces a standard spacecraft fill and drain valve.
Government regulations restrict the evaporative emissions during refueling to 0.20 grams per gallon of dispensed fuel. This requires virtually all of the vapors generated and displaced while refueling to be stored onboard the vehicle. The refueling phenomenon of spitback and early-clickoff are also important considerations in designing refueling systems. Spitback is fuel bursting past the nozzle and into the environment and early-clickoff is the pump shutoff mechanism being triggered before the tank is full. Development of a new refueling system design is required for each vehicle as packaging requirements change. Each new design (or redesign) must be prototyped and tested to ensure government regulations and customer satisfaction criteria are satisfied. Often designs need multiple iterations, costing money and time in prototype-based validation procedures. To conserve resources, it is desired to create a Computational Fluid Dynamics (CFD) tool to assist in design validation. A model that simulates the entire refueling system will be discussed here. This includes boundary conditions of the pump nozzle, the vapor return line, and an orifice that mimics the pressure drop across an activated carbon canister. Experiments are performed both to characterize boundary conditions for the CFD and to validate results from the model. Fuel tank pressure data gathered from both simulation and experiments shows good correlation. Steady state pressures of each method trend the same and have similar magnitude at multiple fuel flow rates. These results show the capability of the refueling system model as a development tool.
Global civil aviation growth at 5+% yearly poses extreme environmental challenges. Advances have appeared gradually through improved aerodynamic shapes, using carbon fibres, and enhanced engines; however, as these technologies mature, direct efficiency advances require increasing effort. Often Passenger convenience is forgotten e.g. the long-range air traffic has developed on hub-spoke basis implying extra feeder flights, transit passenger inconveniences, capacity issues. Efficiency metrics emphasize “Why, How & What”, with an understanding of the range sensitivities, operational concepts and performance goals via the important “X-factor”. For given range, current aircraft are “greener” than previous generations. Medium range aircraft s are always greener than those for short or long ranges. However, currently, the major trend is for the latter: twin-aisle A350, A380, B787, B777X (10+% payload, 40+% fuel to MTOW). Shorter range single-aisle aircraft are “feeders” or newer derivatives: A320, B737 class (20+% payload, 20+% fuel to MTOW). New technologies could feature in future e.g. Natural Laminar flow, riblets, enhanced loads allevation, composite tailoring, morphing structures, distributed propulsion, bio-fuels etc. These may make significant improvements and lead to unconventional layouts e.g. blended wing bodies, high aspect ratio wings, oblique wings, and joined wings. Additionally, significant environmental gains can be made via operations e.g. AAR and Formation flying. Air-to-air refuelling (AAR) has been practised and perfected by the Military for 80+ years. Tankers are sky “gas- stations”. The Military objective is for mission success rather than fuel economy. Tankers accompany and refuel short- range aircraft over longer missions. AAR can be a strong enabler for the civil aviation. Small dedicated tankers (A320 size) can operate over short radii, refuelling longer range cruisers. AAR will always retain top hierarchy over any technological advances, offering step change towards highly efficient aviation. We discuss the pros and cons of operational issues, routing and constraints, turbulence, air navigation and environmental impact. Replacing today´s inter-continental system with AAR gives fuel and CO2 reductions of 15-30% depending on range. Additionally, 30-40% weight savings lead manufacturers focus on smaller aircraft. Major COC and DOC reductions of a similar order occur. Noise, emissions, wake effects are favourable, meeting ACARE/NASA goals. A by-product is that laminar-flow aircraft introduction can be eased. Increasing AAR benefits occur as Point A to B system replaces the hub--spoke system. The smaller AAR-cruisers imply ground-based opportunities: smaller airports and new connections, easing the transit passenger handling and reducing travel time. For sustainable aviation growth and future urbanisation, short flights are replaced by other means. The capacity relief becomes available for long flights (only aviation is suitable). Maintaining transport capacity, less AAR enabled cruisers are needed; these operate at 20+% payload to MTOW. More likely is that the total airborne mass is lower. Certification and Operational rules will need revision. New tankers or other types modified from civil aircraft respect most CS-25 regulations. We aim for automatic refuelling (as demonstrated by A330 tanker recently and as in US-UCAV programme). We allude to newer versatile twin-aisle cruisers with differing capacities operating world-wide ranges with AAR, blending with formation flying. All this should “spur/re-vitalise” Aviation. We propose practical demonstrations. A game changer in sight!
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