Publications

According to the Global technical regulation on hydrogen and fuel cell vehicles (FCV) fuel cell discharge system at the vehicle exhaust system`s point of discharge the hydrogen concentration level shall not exceed 4 % average by volume during any moving three-second time interval during normal operation including start-up and shut down [1]. FC stack need to washout by the concentrated hydrogen as the purge gas and how to exhaust gas without exceeding 4 % is the most concerns. Also how to measure hydrogen pulse of millisecond in exhaust is also the rising up issue. In this paper model of FCV hydrogen discharge system was composed and variety of simple experiments were carried out to control the H2 concentration and release. In the case which the semiconductor sensor with porous material (average size less than quench distance) were applied to check H2 concentration the short pulse of high concentration of H2 in millisecond was hard to find. In this experiment the simple exhaust gas model H2/N2 flow was used instead of Air/H2. In the exhaust gas test experiment was conducted under the atmospheric condition in room temperature with small pressure difference and the fast solenoid valve to create quick hydrogen control. Most of the experiments except the turbulent flow experiments laminar flow is expected to be dominated when steady state condition is satisfied but the most result discussed here is the measurement of H2 concentration during the start point at the time of discharge within seconds. The results showed when H2 was added to N2 flow the boundary layer between N2 and H2 contained the high concentration of H2 at the initial wave front and decrease to reach steady state. This H2 pulse is typical in the FCV exhaust gas and topics of this paper.

Environmental pollution and energy shortage are substantial fears to the modern world's long-term sustainability. Water splitting is an essential technique for eco - friendly and sustainable energy storage as well as a pollution-free method to produce hydrogen. In this regards Metal–organic frameworks have emerged as the most competent multifunctional materials in recent times due to its large surface areas adjustable permeability easy compositional alteration and capability for usage as precursors with a wide range of morphological forms. Further MOF-derived carbon-based nanomaterials also offer significant benefits in terms of tunable morphological features and hierarchical permeability as well as ease of functionalization making them extremely effective as catalysts or catalysts supports for a wide variety of important reactions. Recent developments in carbon-based MOFs as catalysts for overall water splitting are discussed in this review. We explore how MOFs and carbon-based MOFs might well be beneficial as well as which methods should be explored for future development. We divided our review into two sections: photocatalytic and electrocatalytic water splitting and we gathered published literature on carbon-based MOFs materials for their outstanding activity offers helpful methods for catalysts design and analysis as well as difficulties This study highlights the developments in MOF derived materials as photo and electro catalysts by explaining respective approaches for their use in overall water splitting.

As the energy crisis and environment pollution growing severely the hydrogen fuel motor vehicle has got more and more attention many automobile companies and research institutions invest significant R&D resources to research and develop the hydrogen fuel vehicles. With the development of the hydrogen fuel cell vehicles and hydrogen fuel motor vehicles the hydrogen had more to more extensive application. According to the categories of the hydrogen fuel vehicles the characteristics of hydrogen fuel vehicle fire risk and accidents are analyzed in this paper. As for hydrogen fuel cell vehicles the function of its key components such as the fuel cell the high-pressure storage tank is presented firstly. Then based on the low density fast diffusion and flammable of hydrogen the probable scenarios of accident such as fuel leak jet flame are analyzed and the fire risk of the key components and the whole vehicle is evaluated. Finally the development trend of the emergency warning system of hydrogen fuel cell vehicles is analyzed and some recommendations are proposed referring to the detection pre-warning and control technologies used in the industrial sites. Aiming at the hydrogen car structure characteristics and the fire accident modes and accidents evolution rules the emergency disposal technology system for hydrogen fuel motor vehicles is put forward.

High gas temperatures can be reached inside a hydrogen tank during the filling process because of the large pressure increase (up to 70-80 MPa) and because of the short time (~3 minutes) of the process. High temperatures can potentially jeopardize the structural integrity of the storage system and one of the strategies to reduce the temperature increase is to pre-cool the hydrogen before injecting it into the tank. Computational Fluid Dynamics (CFD) tools have the capabilities of capturing the flow field and the temperature rise in the tank. The results of CFD simulations of fast filling with pre-cooling are shown and compared with experimental data to assess the accuracy of the CFD model

A two-layer reduced order model of high pressure hydrogen jets was developed which includes partitioning of the flow between the central core jet region leading to the Mach disk and the supersonic slip region around the core. The flow after the Mach disk is subsonic while the flow around the Mach disk is supersonic with a significant amount of entrained air. This flow structure significantly affects the hydrogen concentration profiles downstream. The predictions of this model are compared to previous experimental data for high pressure hydrogen jets up to 20 MPa and to notional nozzle models and CFD models for pressures up to 35 MPa using ideal gas properties. The results show that this reduced order model gives better predictions of the mole fraction distributions than previous models for highly underexpanded jets. The predicted locations of the 4% lower flammability limit also show that the two-layer model much more accurately predicts the measured locations than the notional nozzle models. The comparisons also show that the CFD model always underpredicts the measured mole fraction concentrations.

The aim of this study is to assess the probability of the damage to hydrogen fuelling station personnel exposed to the hydrogen explosion shock wave. A three-dimensional mathematical model of the explosion of hydrogen-air cloud formed after the destruction of the high-pressure storage cylinders is developed. A computer technology how to define the personnel damage probability field on the basis of probit analysis of the generated shock wave is developed. To automate the process of computing the "probit function-damage probability" tabular dependence is replaced by a piecewise cubic spline. The results of calculations of overpressure fields impulse loading and the probability of damage to fuelling station personnel exposed to the shock wave are obtained. The mathematical model takes into account the complex terrain and three-dimensional non-stationary nature of the shock wave propagation process. The model allows to obtain time-spatial distribution of damaging factors (overpressure in the shock wave front and the compression phase impulse) required to determine the three-dimensional non-stationary damage probability fields based on probit analysis. The developed computer technology allows to carry out an automated analysis of the safety situation at the fuelling station and to conduct a comparative analysis of the effectiveness of different types of protective facilities.

Hydrogen technologies are expected to play a key role in implementing the transition from a fossil fuel- based to a more sustainable lower-carbon energy system. To facilitate their widespread deployment the safe operation and hydrogen systems needs to be ensured together with the evaluation of the associated risk.<br/>HIAD has been designed to be a collaborative and communicative web-based information platform holding high quality information of accidents and incidents related to hydrogen technologies. The main goal of HIAD was to become not only a standard industrial accident database but also an open communication platform suitable for safety lessons learned and risk communication as well as a potential data source for risk assessment; it has been set up to improve the understanding of hydrogen unintended events to identify measures and strategies to avoid incidents/accidents and to reduce the consequence if an accident occurs.<br/>In order to achieve that goal the data collection is characterized by a significant degree of detail and information about recorded events (e.g. causes physical consequences lesson learned). Data are related not only to real incident and accidents but also to hazardous situations.<br/>The concept of a hydrogen accident database was generated in the frame of the project HySafe an EC co-funded NoE of the 6th Frame Work Programme. HIAD was built by EC-JRC and populated by many HySafe partners. After the end of the project the database has been maintained and populated by JRC with publicly available events. The original idea was to provide a tool also for quantitative risk assessment able to conduct simple analyses of the events; unfortunately that goal could not be reached because of a lack of required statistics: it was not possible to establish a link with potential event providers coming from private sector not willing to share information considered confidential. Starting from June 2016 JRC has been developing a new version of the database (i.e. HIAD 2.0); the structure of the database and the web-interface have been redefined and simplified resulting in a streamlined user interface compared to the previous version of HIAD. The new version is mainly focused to facilitate the sharing of lessons learned and other relevant information related to hydrogen technology; the database will be public and the events will be anonymized. The database will contribute to improve the safety awareness fostering the users to benefit from the experiences of others as well as to share information from their own experiences.

Shipping is a very important source of pollution worldwide. In recent years numerous actions and measures have been developed trying to reduce the levels of greenhouse gases (GHG) from the marine exhaust emissions in the fight against climate change boosting the Sustainable Development Goal 13. Following this target the action of hydrogen as energy vector makes it a suitable alternative to be used as fuel constituting a very promising energy carrier for energy transition and decarbonization in maritime transport. The objective of this study is to develop an ex-ante environmental evaluation of two promising technologies for vessels propulsion a H2 Polymeric Electrolytic Membrane Fuel Cell (PEMFC) and a H2 Internal Combustion Engine (ICE) in order to determine their viability and eligibility compared to the traditional one a diesel ICE. The applied methodology follows the Life Cycle Assessment (LCA) guidelines considering a functional unit of 1 kWh of energy produced. LCA results reveal that both alternatives have great potential to promote the energy transition particularly the H2 ICE. However as technologies readiness level is quite low it was concluded that the assessment has been conducted at a very early stage so their sustainability and environmental performance may change as they become more widely developed and deployed which can be only achieved with political and stakeholder’s involvement and collaboration.

Vented deflagration tests were conducted by UNIPI at B. Guerrini Laboratory during the experimental campaign for HySEA project. Experiments included homogeneous hydrogen-air mixture in a 10-18% vol. range of concentrations contained in an about 1 m3 enclosure called SSE (Small Scale Enclosure). Displacement measurements of a test plate were taken in order to acquire useful data for the validation of FE model developed by IMPETUS Afea. In this paper experimental facility displacement measurement system and FE model are briefly described then comparison between experimental data and simulation results is discussed.

Hydrogen safety issue in a ventilation system of a generic nuclear containment is studied. In accidental scenarios a large amount of burnable gas mixture of hydrogen with certain amount of oxygen is released into the containment. In case of high containment pressure the combustible mixture is further ventilated into the chambers and the piping of the containment ventilation system. The burnable even potentially detonable gas mixture could pose a risk to the structures of the system once being ignited unexpectedly. Therefore the main goal of the study is to apply the computational fluid dynamics (CFD) computer code – GASFLOW to analyze the distribution of the hydrogen in the ventilation system and to find how sensitive the mixture is to detonation in different scenarios. The CFD simulations manifest that a ventilation fan with sustained power supply can extinguish the hydrogen risk effectively. However in case of station blackout with loss of power supply to the fan hydrogen/oxygen mixture could be accumulated in the ventilation system. A further study proves that steam injection could degrade the sensitivity of the hydrogen mixture significantly.