Advanced computational fluid dynamics (CFD) models of gas release and dispersion (GRAD) have been developed, tested, validated and applied to the modeling of various industrial real-life indoor and outdoor flammable gas (hydrogen, methane, etc.) release scenarios with complex geometries. The user-friendly GRAD CFD modeling tool has been designed as a customized module based on the commercial general-purpose CFD software, PHOENICS. Advanced CFD models available include the following: the dynamic boundary conditions, describing the transient gas release from a pressurized vessel, the calibrated outlet boundary conditions, the advanced turbulence models, the real gas law properties applied at high-pressure releases, the special output features and the adaptive grid refinement tools. One of the advanced turbulent models is the multifluid model (MFM) of turbulence, which enables to predict the stochastic properties of flammable gas clouds. The predictions of transient three-dimensional (3D) distributions of flammable gas concentrations have been validated using the comparisons with available experimental data. The validation matrix contains the enclosed and nonenclosed geometries, the subsonic and sonic release flow rates and the releases of various gases, e.g., hydrogen, helium, etc. GRAD CFD software is recommended for safety and environmental protection analyses. For example, it was applied to the hydrogen safety assessments including the analyses of hydrogen releases from pressure relief devices and the determination of clearance distances for venting of hydrogen storages. In particular, the dynamic behaviors of flammable gas clouds (with the gas concentrations between the lower flammability level (LFL) and the upper flammability level (UFL)) can be accurately predicted with the GRAD CFD modeling tool. Some examples of hydrogen cloud predictions are presented in the paper. CFD modeling of flammable gas clouds could be considered as a cost-effective and reliable tool for environmental assessments and design optimizations of combustion devices. The paper details the model features and provides currently available testing, validation and application cases relevant to the predictions of flammable gas dispersion scenarios. The significance of the results is discussed together with further steps required to extend and improve the models.

Launch vehicles and other satellite users need launch services that are highly reliable, less complex, easier to test, and cost effective. Being a very small molecule, hydrogen is prone to leakage through seals and micro-cracks. Hydrogen detection in space application is very challenging; public acceptance of hydrogen fuel would require the integration of a reliable hydrogen safety sensor. For detecting leakage of cryogenic fluids in spaceport facilities, launch vehicle industry and aerospace agencies are currently relying heavily on the bulky mass spectrometers, which fill one or more equipment racks, and weigh several hundred kilograms. Therefore, there is a critical need for miniaturized sensors and instruments suitable for use in space applications. This paper describes a novel multi-channel integrated nano-engineered optical sensor to detect hydrogen and monitor the temperature. The integrated optic sensor is made of multi-channel waveguide elements that measure hydrogen concentration in real Time. Our sensor is based on the use of a high index waveguide with a Ni/Pd overlay to detect hydrogen. When hydrogen is absorbed into the Ni/Pd alloy there is a change in the absorption of the material and the optical signal in the waveguide is increased. Our design uses a thin alloy (few nanometers thick) overlay which facilitates the absorption of the hydrogen and will result in a response time of approximately few seconds. Like other Pd/Pd-Ni based sensors the device response varies with temperature and hence the effects of temperature variations must be taken into account. One solution to this problem is simultaneous measurement of temperature in addition to hydrogen concentration at the same vicinity. Our approach here is to propose a temperature sensor that can easily be integrated on the same platform as the hydrogen sensor reported earlier by our group. One suitable choice of material system is silicon on insulator (SOI). Here, we propose a micro ring resonators (MRR) based temperature sensor designed on SOI that measures temperature by monitoring the output optical power.

A reusable launch vehicle is one of the low-cost rocket launch system concepts suitable for large-scale space transportation, such as construction of solar power satellites and space tourism for the general public. From the result of studying "Kankoh-maru," the RLV design for space tourism, it is found that one RLV is required to be launched once a day for a successful commercial service. This means that the turn-around time for RLVs must be much shorter than that for existing expendable rockets, whose launch rate is a few times per year. The hydrogen aircraft, for which the turn-around time was supposed to be 64 minutes, was designed. Several motor companies make every effort to develop fuel cell-powered vehicles whose propellant is hydrogen. Judging from the above, we must be able to design the RLVs with the much shorter turn-around time like that of the hydrogen aircraft and the safety like that of fuel cell-powered vehicles for the general public. Studying a plan of the turn-around activities for the space shuttle tells us that the propulsion and feed system is one of the systems which require a lot of the turnaround activities. For shortening the turn-around time, it is a way to reduce the number of activities for that system.

Several materials issues and challenges exist for the use of hydrogen in energy applications and form the basis for hydrogen R&D in Canada. Many of the challenges are similar for both domestic and defence applications, but there are several unique end-use requirements. In military applications the overall system should have highest energy density possible and reliably deliver for the duration of the required mission. For high energy density, this means the more hydrogen per unit weight and/or volume that can be generated, stored or carried, the better. Safety of carrying hydrogen on or near soldier is an important issue. In the military, both reversible hydrogen storage versus single use, have a place in some military applications with the classic example being metal hydrides versus chemical hydrides. Understanding and developing alternative hydrogen producing fuels with high energy densities is an important R&D effort.

This report discusses the use of small cryogenic coolers for cooling the Muon Ionization Cooling Experiment (MICE) liquid cryogen absorbers. Since the absorber must be able contain liquid helium as well liquid hydrogen, the characteristics of the available 4.2 K coolers are used here. The issues associated with connecting two-stage coolers to liquid absorbers are discussed. The projected heat flows into an absorber and the cooldown of the absorbers using the cooler are presented. The warm-up of the absorber is discussed. Special hydrogen safety issues that may result from the use of a cooler on the absorbers are also discussed.

Research into the performance of proton exchange membrane fuel cell (PEMFC) and its degradation ("poisoning") by the presence of carbon monoxide, a common byproduct of most common hydrogen production methods, requires storage of a large quantities of hydrogen/carbon monoxide mixture in high pressure tanks. The possibility of unintended release of the gas calls for a safety study of H-2/CO mixture leaks, as well as potential higher rate releases. This presentation covers the safety aspects of the numerical study of a H-2/CO mixture release at a wide range of release parameters, including release velocity, orientation, initial diameter, and initial gases fraction ratio. The study provides a simulation of a) the extent of flammable concentrations of H-2, corrected for the presence of CO; b) the extent of CO concentration exceeding OSHA recommended health safety limits. The presence of CO in the mixture required reassessment of hydrogen flammability limits, although the correction proved to be relatively small for the CO fractions used in the present. The maximum extents and evolution of H-2 and CO envelops had been modeled and compared. An important conclusion is the possibility of using hydrogen detectors to predict CO concentration levels with accuracy sufficient for practical purposes. (c) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Canadian Hydrogen and Fuel Cell Association

Hydrogen energy offers great promise as an energy alternative. Hydrogen technologies can reduce and eliminate the release of carbon dioxide from fossil-fuel combustion, the main cause of global warming. One of the main challenges is hydrogen storage. Storing hydrogen in the solid-state hydride form holds a volumetric advantage over compressed and liquid hydrogen states. Solid hydrogen storage systems also have features of low-pressure operation, compactness, safety, tailorable delivery pressure, excellent absorption/desorption kinetics, modular design for easy scalability, and long cycle life. In this paper, solid hydrogen storage systems (such as portable power canisters, lightweight fiber wrapped vessels, and aluminum tubular vessels, developed by Texaco Ovonic Hydrogen Systems LLC) will be discussed. A system of four canisters each storing approximately 80 grams of reversible hydrogen is shown to run a 1 kW PEM fuel cell for more than 247 minutes at full power. Canisters show no plastic deformation after more than 500 charge/discharge cycles. The measured strain on canister surfaces indicates that DOT stress limits are not exceeded. The canisters are in the early commercialization stage for uninterrupted power supply (UPS) and auxiliary power unit (APU) applications. A lightweight fiber-wrapped vessel engineered with metal hydride and internal heat exchanger is being developed for onboard applications. At the system level, the vessel has a volumetric energy density of 50 grams of hydrogen per liter and a gravimetric density of 1.6 wt.%2 The vessel is capable of storing 3 kg of hydrogen with a fast refueling capability. Ninety percent of the storable hydrogen can be refueled in 10 minutes at 1500 psig. The vessel can easily release the hydrogen at a rate of 350 sipm at 70degreesC. Aluminum tubular vessels are being designed and tested for bulk storage and infrastructure applications including stationary power, hydrogen shipment and hydrogen service stations. ne tubular vessel dimensions may be designed for specific applications. For example, a tubular vessel 6 inches in diameter and 62 inches in length can store up to 1 kg of hydrogen.

The generation of hydrogen-gas from metallic waste is an important issue for the safety analysis of geological disposal facilities for transuranic (TRU) radioactive waste in Japan. The objective of this study is to clarify the gas-generation behavior of stainless steel and carbon steel in non-oxidizing alkaline synthetic groundwater (pH 12.8 and 10.5) at 30 degrees C simulating geological disposal environments. At pH 12.8, the observed gas-generation rate from stainless steel in the initial period of immersion was 1.0 x 10(2) Nml/m(2)/y and 1.0 x 10 Nml/m(2)/y after 200 days (N represents the standard state of gas at 0 degrees C and 1 atm). At pH 10.5, gas generation was not observed for 60 days in the initial period. At 60 days, the gas-generation observed was 5.0 x 10 Nml/m(2)/y. After 250 days, the gas-generation rate approaches zero. At pH 12.8, the observed gas generation rate of carbon steel in the initial period of immersion was 1.5 x 10(2) Nml/m(2)/y and the gas generation rate began to decrease after 200 days. After 300 days, it was 25 Nml/m(2)/y. At pH 10.5, the gas generation rate in the initial period was 5.0 x 102 Nml/m(2)/y and was 1.0 x 10 Nml/m(2)/y after 200 days.

For safety reasons, while handling fuel cells, hydrogen concentrations of 0.1 - 3%2and above need to be detected. Low power hydrogen sensors, based on a Field Effect Transistor (FET), have been in use for about 25 years. In the past platinum and palladium were often used as gas sensitive layers. Unfortunately in the required concentration range, the Pt based sensors have a poor selectivity at room temperature and were not stable at operating temperatures above 60 degrees C. To solve this problem Pt with a porous tin oxide (SnO(2)) top layer is used as a chemically sensitive electrode in a Floating Gate Field Effect Transistor (FG - FET). The results show that the SnO(2) film on Pt stabilizes the sensor signal response between room temperature and 135 degrees C. Also the sensor response time with t(50)

Fuel cell bus with hydrogen tanks on its roof is different from traditional one. Its mass is greater than traditional one and its centre of gravity is higher, which makes its rollover more easy and dangerous. During the rollover, the great deformation of the body structure will menace the occupants' safety, and in addition, the hydrogen leaking will threaten the lives of the occupants. So measures should be taken to ensure the deformation of body structure would not hurt the Occupants, and the hydrogen pipelines would not have gas leakage. In the light of this objective, the finite element models of fuel cell bus, survive region and anti-intruding region are established, and the simulation of the bus rollover is carried out according to ECER66. The rollover results indicate that the bus is good at resisting the deformation of the rollover, and at the same time it provides data reference for improving the design of fuel cell bus. Furthermore, the pillar intruding coefficient and the clearance between anti-intruding region and tank cover are introduced in the paper to measure the safety abundance ratio of the survival region and the hydrogen pipeline of the fuel cell bus. According to these data, the description of safety of fuel cell bus can be quantified.