Publications

The temperature of the hydrogen cylinder needs to be carefully controlled during fuelling process. The maximum temperature should be less than 85℃ according to the ISO draft code. If the fuelling period is reduced the maximum temperature should increase. In this study temperature change of a Type IV cylinder was measured during the hydrogen fuelling process up to 35 MPa. Fuelling period was 3 to 5 minutes. Twelve thermocouples were installed to measure inside gas temperature and seven were attached on the outside of the cylinder. An infrared camera was also used for measuring temperature distribution of outside of cylinder. The maximum gas temperature was higher than 85℃ inside of the cylinder. Significant temperature difference between the upper and lower part of the vessel was observed. Temperature near the plug and the valve was quickly increased and maintained higher than that of the other region. Temperature increases for the partial refuelling process were also discussed.

In the context of hydrogen production from biomass or organic waste with dark fermentation this study analysed 55 studies (339 experiments) in the literature looking for the effect of operating parameters on the process performance of dark fermentation. The effect of substrate concentration pH temperature and residence time on hydrogen yield productivity and content in the biogas was analysed. In addition a linear regression model was developed to also account for the effect of nature and pretreatment of the substrate inhibition of methanogenesis and continuous or batch operating mode. The analysis showed that the hydrogen yield was mainly affected by pH and residence time with the highest yields obtained for low pH and short residence time. High hydrogen productivity was favoured by high feed concentration short residence time and low pH. More modest was the effect on the hydrogen content. The mean values of hydrogen yield productivity and content were respectively 6.49% COD COD−1 135 mg L−1 d −1 51% v/v while 10% of the considered experiments obtained yield productivity and content of or higher than 15.55% COD COD−1 305.16 mg L−1 d −1 64% v/v. Overall this study provides insight into how to select the optimum operating conditions to obtain the desired hydrogen production.

Any experimental study of catalysts and catalytic recombining devices for removal of hydrogen gas from industrial environments is known to carry a risk of ignition of hydrogen. Experiments conducted in an atmosphere with a high concentration of hydrogen present a particular danger. Here a technique is reported that allows conducting such experiments with relative safety. This technique has been developed and applied by the company ‘Russian Energy Technologies’ for the last five years without any significant incident.<br/>A “Gas stream method” for testing and analysis of the characteristics of a catalyst for hydrogen/oxygen recombination is proposed. Tests with a variety of catalysts in a passive recombining device were carried out in a climatic chamber (86 l in volume) with a hydrogen/air mixture containing up to 20% (v/v) hydrogen flowing through it. The balance equation for hydrogen and oxygen flows entering reacting and exiting the chamber led to a formula for calculating the efficiency of a catalyst or a catalytic device under stationary conditions.<br/>Fluctuations in local temperatures of the catalyst and other parts of the chamber along with variation in the concentration of hydrogen gave the authors an insight into the thermal regime of an active catalyst. This enabled them to develop new catalysts for removal of hydrogen from the environment using industrial recombining devices.

In the context of the French DIMITRHY project ANR-08-PANH006 experiments have been carried out to measure helium injections in a cubic 1 m3 box - GAMELAN in a reproducible and quantitative manner. For the present work we limit ourselves to the unique configuration of a closed box with a small hole at its base to prevent overpressure. This case leads to enough difficulties of modelisations to deserve our attention. The box is initially filled with air and injections of helium through a tube of diameter 20 mm is operated. The box is instrumented with catharometres to measure the helium volume concentration within an accuracy better than 0.1%. We present the CFD (Fluent and CASTEM ANSYS-CFX and ADREA-HF) calculations results obtained by 5 different teams participating to the benchmark in the following situation: the case of a plume release of helium in a closed box (4NL/min). Parts of the CFD simulations were performed in the European co-funded project HyIndoor others were performed in the French ANR-08-PANH006 DimitrHy project.

Hydrogen is a key parameter to monitor radioactive disposal facility such as the envisioned French geological repository for nuclear wastes. The use of microcantilevers as chemical sensors usually involves a sensitive layer whose purpose is to selectively sorb the analyte of interest. The sorbed substance can then be detected by monitoring either the resonant frequency shift (dynamic mode) or the quasi-static deflection (static mode). The objective of this paper is to demonstrate the feasibility of eliminating the need for the sensitive layer in the dynamic mode thereby increasing the long-term reliability. The microcantilever resonant frequency allows probing the mechanical properties (mass density and viscosity) of the surrounding fluid and thus to determine the concentration of a species in a binary gaseous. Promising preliminary work has allowed detecting concentration of 200 ppm of hydrogen in air with non-optimized geometry of silicon microcantilever with integrated actuation and read-out.

Polymers for O-rings valve seats gaskets and other sealing applications in the hydrogen infrastructure face extreme conditions of high-pressure H2 (0.1 to 100 MPa) during normal operation. To fill current knowledge gaps and to establish standard test methods for polymers in H2 environments these materials can be tested in laboratory scale H2 manifolds mimicking end use pressure and temperature conditions. Beyond the influence of high pressure H2 the selection of gases used for leak detection in the H2 test manifold their pressures and times of exposure gas types relative diffusion and permeation rates are all important influences on the polymers being tested. These effects can be studied ex-situ with post-exposure characterization. In a previous study four polymers (Viton A Buna N High Density Polyethylene (HDPE) and Polytetrafluoroethylene (PTFE)) commonly used in the H2 infrastructure were exposed to high-pressure H2 (100 MPa). The observed effects of H2 were consistent with typical polymer property-structure relationships; in particular H2 affected elastomers more than thermoplastics. However since high pressure He was used for purging and leak detection prior to filling with H2 a study of the influence of the purge gas on these polymers was considered necessary to isolate the effects of H2 from those of the purge gas. Therefore in this study Viton A Buna N and PTFE were exposed to the He purge procedure without the subsequent H2 exposure. Additionally six polymers Viton A Buna N PTFE Polyoxymethylene (POM) Polyamide 11 (Nylon) and Ethylenepropylenediene monomer rubber (EPDM) were subjected to high pressure Ar (100 MPa) followed by high pressure H2 (100 MPa) under the same static isothermal conditions to identify the effect of a purge gas with a significantly larger molecular size than He. Viton A and Buna N elastomers are more prone to irreversible changes as a result of H2 exposure from both Ar and He leak tests as indicated by influences on storage modulus extent of swelling and increased compression set. EPDM even though it is an elastomer is not as prone to high-pressure gas influences. The thermoplastics are generally less influenced by high pressure regardless of the gas type. Conclusions from these experiments will provide insight into the influence of purging processes and purge gases on the subsequent testing in high pressure gaseous H2. Control for the influence of purging on testing results is essential for the development of robust test methods for evaluating the effects of H2 and other high-pressure gases on the properties of polymers.

An accident modelling approach is used to assess the safety of a hydrogen station as part of a ground transportation network. The method incorporates prevention barriers associated to human factors management and organizational failures in a risk assessment framework. Failure probabilities of these barriers and end-states events are predicted using Fault Tree Analysis and Event Tree Analysis respectively. Results from the case study considered revealed the capability of the proposed method in estimating the likelihood of various outcomes as well as predicting the future probability. In addition the scheme offers opportunity to provide dynamic adjustment by updating the failure probability with actual plant data. Results from the analysis can be used to plan maintenance and management of change as required by the plant condition.

We at Kawasaki Heavy Industries have proposed a "CO2-Free H2 supply chain" using abundant brown coal of Australian origin as the energy source. This chain will store CO2 generated during the process for producing hydrogen from brown coal in a project (Carbon Net) that the Australia Government is promoting. Thus Japan can import CO2-free hydrogen. The supply chain consists of the hydrogen production system the hydrogen transport/storage system and the hydrogen use system. Related to their designs we have to consider their hazards polluted scenarios and safety measures via a safety assessment process that is compliant with international risk assessment standards. To verify safety designs related experiments and analyses will be conducted. This paper describes the approach to safety design for especially the related liquid hydrogen facilities.

In the present study the phenomena of blast wave and fireball generated by high pressure (35 MPa) hydrogen tank (72 l) rupture have been investigated numerically. The realizable k-ε turbulence model was applied. The simulation of the combustion process is based on the eddy dissipation model coupled with the one step chemical reaction mechanism. Simulation results are compared with experimental data from a stand-alone hydrogen fuel tank rapture following a bonfire test. The model allows the study of the interaction between combustion process and blast wave propagation. Simulation results (blast wave overpressure fireball shape and size) follow the trends observed in the experiment.

To examine the effect of initial turbulence on vented explosions experiments were performed for lean hydrogen–air mixtures with hydrogen concentrations ranging from 12 to 15% vol. at elevated initial turbulence. As expected it was found that an increase in initial turbulence increased the overall flame propagation speed and this increased flame propagation speed translated into higher peak overpressures during the external explosion. The peak pressures generated by flame–acoustic interactions however did not vary significantly with initial turbulence. When flame speeds measurements were examined it was found that the burning velocity increased with flame radius as a power function of radius with a relatively constant exponent over the range of weak initial turbulence studied and did not vary systematically with initial turbulence. Instead the elevated initial turbulence increased the initial flame propagation velocities of the various mixtures. The initial turbulence thus appears to act primarily by generating higher initial flame wrinkling while having a minimal effect on the growth rate of the wrinkles. For practical purposes of modelling flame propagation and pressure generation in vented explosions the increase in burning velocity due to turbulence is suggested to be approximated by a single constant factor that increases the effective burning velocity of the mixture. When this approach is applied to a previously developed vent sizing correlation the correlation performs well for almost all of the peaks. It was found however that in certain situations this approach significantly under predicts the flame–acoustic peak. This suggests that further research may be necessary to better understand the influence of initial turbulence on the development of flame–acoustic peaks in vented explosions.