Quantitative risk assessment on a hydrogen refuelling station

The Directive 2014/94/UE (DAFI, Alternative Fuel Initiative Directive) on the deployment of alternative fuels (i.e. hydrogen) infrastructures has been recently transposed into national law in Italy. Consequently, the technical regulation on fire prevention for H2fuelling stations has been updated, in order to consider the current maximum delivery pressure (700 bar) of gaseous hydrogen for road vehicles. This technical regulation establishes the prescriptive safety distance from a piece of equipment. In the case of a new station, an assessment of the frequency of the event and its potential consequences is necessary. This is to understand which risk can reasonably be mitigated by a safety distance or whether additional mitigation or prevention measures should be taken. This paper presents the quantitative risk assessment (QRA) study on a hydrogen station planned to be installed, study which aims at determining the safety distances. Such study utilizes the Sandia-developed QRA tool, Hydrogen Risk Analysis Model (HyRAM), to calculate risk values when developing risk-equivalent plans. HyRAM combines reduced order deterministic models that characterize hydrogen release and flame behavior with probabilistic risk models to quantify risk values. Thanks to HyRAM tool it is possible to estimate physical effects and consequences on people and structures and plants, related to risk scenarios, by means of a damage model library. Use of risk assessment may allow station owners and designers to flexibly define station-specific mitigations, with the purpose of achieving equal or better levels of safety with respect to prescriptive recommendation levels, as suggested by ISO19880-1 (2018)

Effective fire extinguishing systems for lithium-ion battery

Lithium-ion batteries are a popular choice of power source for a variety of energy and power demanding applications for both stationary applications and electromobility. Among electrochemical storage systems, Lithium-ion batteries were found to be promising candidate, due to their high power and high energy density. In order to assemble high power batteries for plug-in hybrid electric vehicles and pure electric vehicles, several hundreds of large-format Lithium-ion cells will be required, and even more cells for power/energy demanding stationary applications. However, safety remains a significant concern, as battery failure leads to ejection of hazardous materials and rapid heat release. The failure of a single cell can generate a large amount of heat which can then initiate, in the worst case, the thermal runaway of neighbouring cells, leading to failure throughout the battery pack. The heat accumulation can also run into the venting of a cell, with the emission of flammable organic solvent inside the battery pack. Battery failure can be initiated via a number of different abuse scenarios, such as overheating, overcharging, puncture/crushing, water immersion, or external short circuit. Development of effective mitigation strategies necessitates a study on battery failure events and a better understanding of important characteristics relating to safety, such as heat release, hazardous materials ejection, and thermal propagation. On the other hand, when a fire event is initiated, proper intervention strategies have to be defined in order to avoid it becoming catastrophic. In this paper are reported the results of thermal abuse tests on single Lithium-ion cells and a battery pack. The tests were performed with the technical equipment and resources of National Fire Corps. Screening tests for battery fire extinguishing agents were also performed. The effectiveness of an agent was evaluated through experiments on the cooling effect of fire extinguishing agents. Among the various agents, water and foam were found to be the most effective

Experimental Study on Different Extinguishing Agents for Fire of Lithium Ion Batteries for Electric Mobility

This paper shows the research work based on experimental tests for identifying the most efficient extinguishing agent against LIBs fire. Experimental tests were conducted in cooperation with the National Fire Corps of Rome. For these experimental test LIBs typically used in electric, Hybrid or plug-in Hybrid vehicle have been chosen. The tested cell was placed on a metal grate inserted between two electric plates. The heat generated from the two plates induced the cell to thermal runaway and then to fire. In Total 11 Kokam SPLB pouch cells of 40 Ah and 3.7 V each have been used. Four different extinguishing agents have been tested: Water, F500, Foam and AVD. The results of each experimental tests were analysed in terms of chemical and physical action. An optimization model was developed for identifying the most efficient agent between all those tested. The results obtained from the experimental tests are preliminary results of the research concerning the extinguishing agents for fire of LIBs. The operating conditions chosen for these tests can be defined as ideal: the cell was not hidden by any obstacle (battery module or vehicle compartments)

Hydrogen Refueling Stations: Prevention and Scenario Management. Large Scale Experimental Investigation of Hydrogen Jet-Fires

Hydrogen is becoming an attractive alternative for energy storage and transportation, because of the elevated energy content per unit of mass and possibility to have zero carbon-emission vehicles. For these reasons, hydrogen's share in global market is expected to grow substantially in the coming years. Today, hydrogen-fueled buses and cars are already available, and several refueling stations are operating in different countries around the world. A key role of the deployment of hydrogen fueled-vehicles is the presence of a widespread network of refueling stations, especially close to residential and industrial areas. This fact poses attention to the safety aspects related to hydrogen, with particular interest to its high flammability that can lead to catastrophic consequences for personnel and equipment. As a matter of fact, hydrogen is a comparatively less safe fuel compared to conventional fuels such as gasoline and diesel. Hydrogen infrastructures are characterized by operating pressure up to 1000 bar that, in case of an unintended loss of containments, produce a highly under expanded turbulent jet. If ignited, this hydrogen jet may give rise to very severe scenarios, mainly related to high temperatures and the oriented flows. As recently suggested by Moradi and Groth (Moradi and Groth, 2019), there is a lack of experimental and on-site data for almost all of the storage and delivery technologies relevant to the hydrogen infrastructures. Experimental data is vital to support model validation, especially in the case of the very peculiar combustion process of hydrogen. In this way, a real-scale experimental campaign is proposed to investigate the main characteristic of the hydrogen jet fire resulting from its rapid fired depressurizations. Focus of the experimental campaign is evaluation of safety distance for person and device (i.e. pressurized tanks) in order to avoid critical conditions and domino effects in real refueling station. Different initial conditions, i.e., storage pressures, are exploited, and the resulting jet across specified orifice is investigated. More specifically, temperatures at various locations are measured through an arrangement of thermocouples. Values up to 1200 °C were obtained in the core of the jet. Moreover, it was found that the recorded temperatures, especially those at the outer portion of the jet, are very sensitive to the initial conditions

Blastocystis subtypes in patients with diabetes mellitus from the Midwest region of Brazil

Blastocystis sp. is an enteric protist commonly found in human fecal samples. In Brazil, few studies have been developed, but none of them has explored the presence of Blastocystis in patients with diabetes mellitus. We evaluated the occurrence and molecular identification of Blastocystis sp. among patients with diabetes mellitus in the Midwest region, Goias State, Brazil. Genomic DNA was obtained from 175 fecal samples (99 from the diabetic group and 76 from the control group). PCR was performed using pan-Blastocystis primers from the SSU-rDNA gene. Microscopic examination revealed positivity of 12.1% and 7.9% for Blastocystis in diabetics and in controls, respectively. Amplification of Blastocystis DNA was observed in 34.4% (34 of 99) and 30.3% (23 of 76) from the diabetic and control groups, respectively. Phylogenetic analyses and BLAST searches revealed six subtypes among Blastocystis isolates in the diabetic group, represented by ST1 (38.2%), ST2 (11.8%), ST3 (35.3%), ST6 (2.9%), ST7 (2.9%) and ST8 (8.8%). In the control group, ST1 (21.8%), ST2 (21.8%), ST3 (43.5%), ST6 (4.4%) and ST8 (8.7%) were identified. This study is the first report regarding the occurrence and subtypes distribution of Blastocystis in patients with diabetes mellitus in Brazil. The results reinforce the potential risk of Blastocystis infection in patients with diabetes, in addition, it contributes to the understanding of the genetic diversity of this enigmatic organism

Non-equilibrium "thermal noise" of low loss oscillators

The RareNoise project aims at studying how ground-based gravitational wave detector are affected by the thermodynamic non-equilibrium states which are present in their experimental apparatus. We present the RareNoise experimental work which focuses on the study of the \u27thermal noise\u27 of low loss oscillators subject to steady-state thermal gradients. We also present the first results of the experimental campaign on steady-state non-equilibrium oscillators around room temperature

Mass testing of the JUNO experiment 20-inch PMTs readout electronics

The Jiangmen Underground Neutrino Observatory (JUNO) is a multi-purpose, large size, liquid scintillator experiment under construction in China. JUNO will perform leading measurements detecting neutrinos from different sources (reactor, terrestrial and astrophysical neutrinos) covering a wide energy range (from 200 keV to several GeV). This paper focuses on the design and development of a test protocol for the 20-inch PMT underwater readout electronics, performed in parallel to the mass production line. In a time period of about ten months, a total number of 6950 electronic boards were tested with an acceptance yield of 99.1%

Implementation and performances of the IPbus protocol for the JUNO Large-PMT readout electronics

The Jiangmen Underground Neutrino Observatory (JUNO) is a large neutrino detector currently under construction in China. Thanks to the tight requirements on its optical and radio-purity properties, it will be able to perform leading measurements detecting terrestrial and astrophysical neutrinos in a wide energy range from tens of keV to hundreds of MeV. A key requirement for the success of the experiment is an unprecedented 3% energy resolution, guaranteed by its large active mass (20 kton) and the use of more than 20,000 20-inch photo-multiplier tubes (PMTs) acquired by high-speed, high-resolution sampling electronics located very close to the PMTs. As the Front-End and Read-Out electronics is expected to continuously run underwater for 30 years, a reliable readout acquisition system capable of handling the timestamped data stream coming from the Large-PMTs and permitting to simultaneously monitor and operate remotely the inaccessible electronics had to be developed. In this contribution, the firmware and hardware implementation of the IPbus based readout protocol will be presented, together with the performances measured on final modules during the mass production of the electronics

Validation and integration tests of the JUNO 20-inch PMTs readout electronics

The Jiangmen Underground Neutrino Observatory (JUNO) is a large neutrino detector currently under construction in China. JUNO will be able to study the neutrino mass ordering and to perform leading measurements detecting terrestrial and astrophysical neutrinos in a wide energy range, spanning from 200 keV to several GeV. Given the ambitious physics goals of JUNO, the electronic system has to meet specific tight requirements, and a thorough characterization is required. The present paper describes the tests performed on the readout modules to measure their performances.Comment: 20 pages, 13 figure

Consequence analysis of an accidental hydrogen release in a refuelling station

Widespread deployment and use of hydrogen in the transportation sector for both IC engines and fuel cell technologies can occur only if hydrogen safety issues have been addressed of hydrogen storage, transport and infrastructure. This paper analyses the consequences of an accidental hydrogen release that may occur in a hydrogen refuelling station. The re-fuelling station under consideration comply with the ISO/TS 20100:2008 for technical requirement, according to the Directive 2014/94/UE. The investigated scenarios are caused by a hose break during car and bus refuelling, at 70 and 35 MPa, respectively. The hose break event is assumed due to a person who drives away while connected to the dispenser. Both mitigated and non-mitigated conditions are considered. In the mitigated case a shut off valve is assumed to be activated 5 s after the start of release. In the non-mitigated case it is assumed that the shut off valve is not activated so that the release is continuously fed from the buffer tank located before the dispenser. To model the hydrogen release, a CFD code (Flacs by GexCon) was used to calculate the dispersion and mixing of hydrogen within the station. The hydrogen dispersion results were then used to calculate the corresponding pressure loads from hydrogen- air deflagrations in the station, or the resulting jet lengths and heat fluxes. It was found that overpressures created from hydrogen deflagration do not cause any effect to buildings, equipment’s and people in the station