scholarly journals Effect of Mechanical Ventilation on Accidental Hydrogen Releases—Large-Scale Experiments

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3008
Author(s):  
Agnieszka W. Lach ◽  
André V. Gaathaug
Keyword(s):  
Mechanical Ventilation ◽  
Mass Flow ◽  
Large Scale ◽  
Ventilation System ◽  
Hydrogen Gas ◽  
Forced Ventilation ◽  
British Standard ◽  
Confined Spaces ◽  
Series Of Experiments ◽  
Rate Limit

This paper presents a series of experiments on the effectiveness of existing mechanical ventilation systems during accidental hydrogen releases in confined spaces, such as underground garages. The purpose was to find the mass flow rate limit, hence the TPRD diameter limit, that will not require a change in the ventilation system. The experiments were performed in a 40 ft ISO container in Norway, and hydrogen gas was used in all experiments. The forced ventilation system was installed with a standard 315 mm diameter outlet. The ventilation parameters during the investigation were British Standard with 10 ACH and British Standard with 6 ACH. The hydrogen releases were obtained through 0.5 mm and 1 mm nozzles from different hydrogen reservoir pressures. Both types of mass flow, constant and blowdown, were included in the experimental matrix. The analysis of the hydrogen concentration of the created hydrogen cloud in the container shows the influence of the forced ventilation on hydrogen releases, together with TPRD diameter and reservoir pressure. The generated experimental data will be used to validate a CFD model in the next step.

scholarly journals Target arterial PO2 according to the underlying pathology: a mini-review of the available data in mechanically ventilated patients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Julien Demiselle ◽  
Enrico Calzia ◽  
Clair Hartmann ◽  
David Alexander Christian Messerer ◽  
Pierre Asfar ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Large Scale ◽  
Retrospective Studies ◽  
Prolonged Exposure ◽  
Oxygen Toxicity ◽  
Circulatory Shock ◽  
Mechanically Ventilated ◽  
Ischaemia Reperfusion ◽  
Arterial Po2 ◽  
Underlying Pathology

AbstractThere is an ongoing discussion whether hyperoxia, i.e. ventilation with high inspiratory O2 concentrations (FIO2), and the consecutive hyperoxaemia, i.e. supraphysiological arterial O2 tensions (PaO2), have a place during the acute management of circulatory shock. This concept is based on experimental evidence that hyperoxaemia may contribute to the compensation of the imbalance between O2 supply and requirements. However, despite still being common practice, its use is limited due to possible oxygen toxicity resulting from the increased formation of reactive oxygen species (ROS) limits, especially under conditions of ischaemia/reperfusion. Several studies have reported that there is a U-shaped relation between PaO2 and mortality/morbidity in ICU patients. Interestingly, these mostly retrospective studies found that the lowest mortality coincided with PaO2 ~ 150 mmHg during the first 24 h of ICU stay, i.e. supraphysiological PaO2 levels. Most of the recent large-scale retrospective analyses studied general ICU populations, but there are major differences according to the underlying pathology studied as well as whether medical or surgical patients are concerned. Therefore, as far as possible from the data reported, we focus on the need of mechanical ventilation as well as the distinction between the absence or presence of circulatory shock. There seems to be no ideal target PaO2 except for avoiding prolonged exposure (> 24 h) to either hypoxaemia (PaO2 < 55–60 mmHg) or supraphysiological (PaO2 > 100 mmHg). Moreover, the need for mechanical ventilation, absence or presence of circulatory shock and/or the aetiology of tissue dysoxia, i.e. whether it is mainly due to impaired macro- and/or microcirculatory O2 transport and/or disturbed cellular O2 utilization, may determine whether any degree of hyperoxaemia causes deleterious side effects.

Capacity of prestressed concrete bridge decks under fatigue loading

2021 ◽  
Author(s):  
Eva O. L. Lantsoght ◽  
Cor van der Veen ◽  
Rutger Koekkoek ◽  
Henk Sliedrecht
Keyword(s):  
Prestressed Concrete ◽  
Large Scale ◽  
Fatigue Loading ◽  
Membrane Action ◽  
Variable Amplitude ◽  
Girder Bridges ◽  
Prestressed Girders ◽  
Series Of Experiments ◽  
Prestressed Concrete Bridge ◽  
Compressive Membrane Action

<p>In The Netherlands, existing slab-between-girder bridges with prestressed girders and thin transversely prestressed concrete decks require assessment. The punching capacity was studied in a previous series of experiments, showing a higher capacity thanks to compressive membrane action in the deck. Then, concerns were raised with regard to fatigue loading. To address this, two series of large-scale experiments were carried out, varying the number of loads (single wheel print versus double wheel print), the loading sequence (constant amplitude versus variable amplitude, and different loading sequences for variable amplitude), and the distance between the prestressing ducts. An S-N curve is developed for the assessment of slab-between-girder bridges. The experiments showed that compressive membrane actions enhances the capacity of thin transversely prestressed decks subjected to fatigue loading.</p>

Improved Design Parameters for a Liquid Desiccant Dehumidifier in Confined Spaces

Solar Energy ◽  
2005 ◽  
Author(s):  
D. Dong ◽  
M. Liu
Keyword(s):  
Energy Consumption ◽  
Ventilation System ◽  
Exhaust System ◽  
Design Parameters ◽  
Confined Space ◽  
Confined Spaces ◽  
Exhaust Ventilation ◽  
Moisture Condensation ◽  
Improved Design ◽  
Control Application

Investigations of a desiccant dehumidifier system have been performed for humidity control application in confined spaces. A previous study revealed that the base dehumidifier system can reduce moisture condensation by 22% over a conventional exhaust ventilation system. The current study aims to develop improved design requirements for a desiccant dehumidifier. The energy consumption of an exhaust ventilation system and an improved dehumidifier system was compared. To investigate the improved desiccant dehumidification system, numerical simulations were conducted and an objective function was established. This paper presents simulated results for an existing desiccant dehumidification system and an improved system, in which improved parameters are used. Use of the improved design parameters can reduce moisture condensation by 26.6% over a base dehumidifier system and shorten the dehumidifier performance period by 14%. Energy consumption with the sole use of an exhaust system is compared with that of the improved dehumidifier system under the same conditions. The results show that energy consumption can be substantially reduced, by 63%, in the improved dehumidifier system with the same amount of moisture condensation on surfaces of the confined space.

In-Situ Diffraction Studies of Gas Storage Materials on a Laboratory X-Ray System

2013 ◽  
Vol 1544 ◽  
Author(s):  
Marco Sommariva ◽  
Harald van Weeren ◽  
Olga Narygina ◽  
Jan-André Gertenbach ◽  
Christian Resch ◽  
...  
Keyword(s):  
Large Scale ◽  
Fossil Fuels ◽  
Reaction Chamber ◽  
Hydrogen Gas ◽  
Gas Pressure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Modifications ◽  
Model Studies

ABSTRACTThe sorption processes for hydrogen and carbon dioxide are of considerable, and growing interest, particularly due to their relevance to a society that seeks to replace fossil fuels with a more sustainable energy source. X-ray diffraction allows a unique perspective for studying structural modifications and reaction mechanisms that occur when gas and solid interact. The fundamental challenge associated with such a study is that experiments are conducted while the solid sample is held under a gas pressure. To date in-situ high gas pressure studies of this nature have typically been undertaken at large-scale facilities such as synchrotrons or on dedicated laboratory instruments. Here we report high-pressure XRD studies carried out on a multi-purpose diffractometer. To demonstrate the suitability of the equipment, two model studies were carried out, firstly the reversible hydrogen cycling over LaNi5, and secondly the structural change that occurs during the decomposition of ammonia borane that results in the generation of hydrogen gas in the reaction chamber. The results have been finally compared to the literature. The study has been made possible by the combination of rapid X-ray detectors with a reaction chamber capable of withstanding gas pressures up to 100 bar and temperatures up to 900 °C.

scholarly journals Self-contained ventilation system of civil buildings built into window structures

2018 ◽  
Vol 196 ◽  
pp. 02007
Author(s):  
Arman Kostuganov ◽  
Yuri Vytchikov ◽  
Andrey Prilepskiy
Keyword(s):  
Mechanical Ventilation ◽  
Thermal Protection ◽  
Ventilation System ◽  
Field Tests ◽  
Building Construction ◽  
Labor Input ◽  
Building Envelopes ◽  
Extra Space ◽  
Research Stage ◽  
Ventilation Systems

The article describes development and application of self-contained ventilation systems in civil buildings. It suggests several models of air exchange within the building, compares these models and points out the variant of ventilating with self-contained mechanical systems with utilization of heat. The researchers conclude that structurally self-contained systems of mechanical ventilation with utilization of heat are most efficiently built into window constructions. This installation variant makes it possible to keep the interior, avoid building construction strengthening, shorten time and labor input of construction-assembling works, allow rational use of the vertical building envelopes area without extra space using. The paper key issue is the development of constructive solutions of self-contained ventilation systems main elements to ensure the possibility of their use in window structures. This research stage was developed with account of previous results of field tests and of such ventilation systems theoretical descriptions. The authors assess limit dimensions of the systems suitable for installment into window constructions of civil buildings in the view of modern Russian requirements to thermal protection. The research suggests a general constructive solution of such a ventilation system and a heat exchanger model which can be used as an air heat utilizer in these systems.

scholarly journals Carbon Nanotube Sheet-Synthesis and Applications

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 2023
Author(s):  
Megha Chitranshi ◽  
Anuptha Pujari ◽  
Vianessa Ng ◽  
Daniel Chen ◽  
Devika Chauhan ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Large Scale ◽  
Hydrogen Gas ◽  
Synthesis Process ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Metal Ceramic ◽  
Commercial Applications ◽  
Manufacturing Problems

Decades of extensive research have matured the development of carbon nanotubes (CNTs). Still, the properties of macroscale assemblages, such as sheets of carbon nanotubes, are not good enough to satisfy many applications. This paper gives an overview of different approaches to synthesize CNTs and then focuses on the floating catalyst method to form CNT sheets. A method is also described in this paper to modify the properties of macroscale carbon nanotube sheets produced by the floating catalyst method. The CNT sheet is modified to form a carbon nanotube hybrid (CNTH) sheet by incorporating metal, ceramic, or other types of nanoparticles into the high-temperature synthesis process to improve and customize the properties of the traditional nanotube sheet. This paper also discusses manufacturing obstacles and the possible commercial applications of the CNT sheet and CNTH sheet. Manufacturing problems include the difficulty of injecting dry nanoparticles uniformly, increasing the output of the process to reduce cost, and safely handling the hydrogen gas generated in the process. Applications for CNT sheet include air and water filtering, energy storage applications, and compositing CNTH sheets to produce apparel with anti-microbial properties to protect the population from infectious diseases. The paper also provides an outlook towards large scale commercialization of CNT material.

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