Alternative Environmentally Friendly Insulating Gases for SF6

Sulfur hexafluoride (SF6) shows excellent insulation performance as an insulating gas. It is suitable for various climate conditions due to its low boiling point (−64 °C). Therefore, it has been widely used in power grid equipment. However, its global warming potential (GWP) is 23,500 times higher than that of CO2. Thus, it is imperative to find an environmentally friendly insulating gas with excellent insulation performance, lower GWP, and which is harmless to equipment and workers to replace SF6. In this review, four possible alternatives, including perfluorocarbons, trifluoroiodomethane, perfluorinated ketones, and fluoronitrile are reviewed in terms of basic physicochemical properties, insulation properties, decomposition properties, and compatibility with metals. The influences of trace H2O or O2 on their insulation performances are also discussed. The insulation strengths of these insulating gases were comparable to or higher than that of SF6. The GWPs of these insulating gases were lower than that of SF6. Due to their relatively high boiling point, they should be used as a mixture with buffering gases with low boiling points. Based on these four characteristics, perfluorinated ketones (C5F10O and C6F12O) and fluoronitrile (C4F7N) could partially substitute SF6 in some electrical equipment. Finally, some future needs and perspectives of environmentally friendly insulating gases are addressed for further studies.

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The burning of metals

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1961.0083 ◽

1961 ◽

Vol 261 (1306) ◽

pp. 357-370 ◽

Cited By ~ 16

Keyword(s):

Oxygen Pressure ◽

Boiling Point ◽

Vapour Phase ◽

Reaction Rates ◽

Refractory Oxide ◽

Experimental Conditions ◽

Metal Mixture ◽

Boiling Points ◽

High Boiling Point ◽

Molten Oxide

A preliminary study has been made of the mechanism by which metals burn. Experiments have been carried out with wires of aluminium, iron, magnesium, molybdenum, titanium and zirconium in oxygen and oxygen + nitrogen mixtures. The rate of propagation of the combustion zone along the wire is dependent upon the oxygen pressure in the atmosphere, suggesting that combustion is largely controlled by gaseous diffusion through the atmosphere. Some of the factors influencing the mode of burning and the reaction rates have been studied, and the temperatures attained under the given experimental conditions have been measured. The mode of burning is determined by the relative melting and boiling points of the metal and its oxide. Metals with low boiling points, such as aluminium and magnesium, burn in the vapour phase. Metals which have high boiling points, but which melt readily, bum at the surface of a molten oxide + metal mixture, provided the oxide also melts readily but has a high boiling point. Iron and titanium are examples of such metals. If, as with zirconium, the metal has a high boiling point and possesses a refractory oxide, a solid oxide film, which slows the reaction, can be formed on the metal surface. Metals such as molybdenum, which form oxides that readily sublime burn at the surface of the metal. Colour temperatures attained during the burning of iron, titanium and zirconium in oxygen were found to be higher the greater the pressure of oxygen. The temperatures were in the range 2600 to 3600°K, and were highest for the metal with the greatest heat of oxidation when measured per gram of oxygen consumed. The burning of a metal sphere to a molten oxide + metal mixture in a convection-free monomolecular gas has been treated theoretically. The variation of combustion temperature with oxygen pressure predicted by the theory agrees satisfactorily with that obtained experimentally.

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Improved recovery of higher boiling point volatiles during solvent-assisted flavour evaporation

Food Analytical Methods ◽

10.1007/s12161-021-02074-5 ◽

2021 ◽

Author(s):

Rosa C. Sullivan ◽

Colette C. Fagan ◽

Jane K. Parker

Keyword(s):

Volatile Compounds ◽

Boiling Point ◽

Internal Standard ◽

Published Data ◽

High Fat ◽

New Approach ◽

Boiling Points ◽

High Boiling Point ◽

Low Levels ◽

High Yields

AbstractPreviously published data show that high levels of fat (50%) affect the yield of volatile compounds during solvent-assisted flavour evaporation (SAFE). We present new data demonstrating that even low levels of fat (< 10%) lead to significantly lower yields of high boiling point volatiles during SAFE. Relative recovery during SAFE of a range of volatiles from a cheese extract was measured at varying fat concentrations (1.1–8.7%) using a single internal standard. Volatiles with higher boiling points had significantly lower relative recoveries, and volatiles were substantially less well recovered from higher fat extracts. When endeavoring to obtain solvent extracts of fatty foods for the purposes of GC-O, it is important to choose the extraction technique which produces solvent extracts closely representing the true composition of the food. We present dilution of solvent extracts prior to SAFE as a potential new approach for high-fat foods which enables high yields of volatiles regardless of boiling point. These data also show that in the absence of C13-labelled standards for quantitation, it is critical to maintain a consistent fat content between samples during SAFE.

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Characteristic Aroma Features of Tencha and Sencha Green Tea Leaves Manufactured by Different Processes

Natural Product Communications ◽

10.1177/1934578x1601100835 ◽

2016 ◽

Vol 11 (8) ◽

pp. 1934578X1601100 ◽

Cited By ~ 1

Author(s):

Toshio Hasegawa ◽

Yuta Shimada ◽

Hiroki Saito ◽

Takashi Fujihara ◽

Kenji Haraguchi ◽

...

Keyword(s):

Green Tea ◽

Boiling Point ◽

Tea Leaves ◽

Important Food ◽

Boiling Points ◽

Gas Chromatography Olfactometry ◽

Aroma Characteristics ◽

Hexane Extracts ◽

Green Tea Leaves ◽

High Boiling Point

There are many varieties of tea ( Camellia sinensis) obtained by different processing methods. In Japan, sencha tea has been used to brew beverages for centuries, and tencha leaves are used to make powdered green tea, matcha, which is used as an important food additive to impart the odor of green tea. We investigated the differences between the odors of sencha and tencha and their aroma profiles. We used our new technique to evaluate the odor of green tea, based on the theory that the aroma characteristics of materials arise from the interactions of groups of compounds with similar structures. Hexane extracts from sencha and tencha leaves were analyzed by gas chromatography-olfactometry. We detected several important compounds for tencha. The hexane extracts were separated by distillation, and groups of compounds with different boiling points were obtained. We investigated the group of high-boiling point constituents, which had a matcha-like odor and consisted of a group of odor constituents common to sencha and tencha. Tencha had a characteristic seaweed-like odor, and the low-boiling point constituents caused the differences in the tencha and sencha odors.

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Specification of technical grade sulfur hexafluoride (SF6) for use in electrical equipment

10.3403/30103690u ◽

2015 ◽

Keyword(s):

Sulfur Hexafluoride ◽

Electrical Equipment ◽

Technical Grade

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Specification of technical grade sulfur hexafluoride (SF6) for use in electrical equipment

10.3403/30103690 ◽

2005 ◽

Keyword(s):

Sulfur Hexafluoride ◽

Electrical Equipment ◽

Technical Grade

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Synergistic impacts of global warming and thermohaline circulation collapse on amphibians

Communications Biology ◽

10.1038/s42003-021-01665-6 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Julián A. Velasco ◽

Francisco Estrada ◽

Oscar Calderón-Bustamante ◽

Didier Swingedouw ◽

Carolina Ureta ◽

...

Keyword(s):

Climate Change ◽

Global Warming ◽

Thermohaline Circulation ◽

Climate Model ◽

Global Climate ◽

Extinction Risk ◽

Meridional Overturning Circulation ◽

Mitigation Strategies ◽

Amphibian Species ◽

Climate Conditions

AbstractImpacts on ecosystems and biodiversity are a prominent area of research in climate change. However, little is known about the effects of abrupt climate change and climate catastrophes on them. The probability of occurrence of such events is largely unknown but the associated risks could be large enough to influence global climate policy. Amphibians are indicators of ecosystems’ health and particularly sensitive to novel climate conditions. Using state-of-the-art climate model simulations, we present a global assessment of the effects of unabated global warming and a collapse of the Atlantic meridional overturning circulation (AMOC) on the distribution of 2509 amphibian species across six biogeographical realms and extinction risk categories. Global warming impacts are severe and strongly enhanced by additional and substantial AMOC weakening, showing tipping point behavior for many amphibian species. Further declines in climatically suitable areas are projected across multiple clades, and biogeographical regions. Species loss in regional assemblages is extensive across regions, with Neotropical, Nearctic and Palearctic regions being most affected. Results underline the need to expand existing knowledge about the consequences of climate catastrophes on human and natural systems to properly assess the risks of unabated warming and the benefits of active mitigation strategies.

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Influence of technical and electrical equipment in life cycle assessments of buildings: case of a laboratory and research building

The International Journal of Life Cycle Assessment ◽

10.1007/s11367-021-01919-9 ◽

2021 ◽

Author(s):

E. Hoxha ◽

D. Maierhofer ◽

M.R.M Saade ◽

A. Passer

Keyword(s):

Global Warming ◽

Environmental Impacts ◽

Global Warming Potential ◽

Electrical Equipment ◽

Primary Energy ◽

Electronic Equipment ◽

Detailed Result ◽

Detailed Calculation ◽

System Boundary ◽

Operational Energy

Abstract Purpose A detailed assessment of the environmental impacts of the building requires a substantial amount of data that is time- and effort-consuming. However, limitation of the system boundary to certain materials and components can provide misleading impact calculation. In order to calculate the error gap between detailed and simplified assessments, the purpose of this article is to present a detailed calculation of the environmental impacts of the building by including in the system boundary, the technical, and electrical equipment. Method To that end, the environmental impacts of a laboratory and research building situated in Graz-Austria are assessed following the EN-15978 norm. Within the system boundaries of the study, the material and components of building fabric, technical, and electronic equipment for the building lifecycle stages of production, construction, replacement, operational energy and water, and end-of-life are considered. The input data regarding the quantity of materials is collected from the design and tendering documents, invoices, and from discussion with the head of the building’s construction site. Primary energy and global warming potential indicators are calculated on the basis of a functional unit of 1 m2 of energy reference area (ERA) per year, considering a reference building service life of 50 years. Results and discussion The primary energy indicator of the building is equal to 1698 MJ/m2ERA/year. The embodied impacts are found to be responsible for 28% of which 6.4% is due to technical and electronic equipment. Furthermore, the embodied impacts for the global warming potential, equal to 28.3 kg CO2e/m2ERA/year, are responsible for 73%. Together, technical and electrical equipment are the largest responsible aspects, accounting for 38% of the total impacts. Simplified and detailed result comparisons show a gap of 29% and 7.7% for global warming and primary energy indicators. These differences were from the embodied impacts and largely from the exclusion of electrical equipment from the study’s system boundary. Conclusions Technical and electrical equipment present a significant contribution to the overall environmental impacts of the building. Worthy of inclusion in the system boundary of the study, the environmental impacts of technical and electrical equipment must be calculated in detail or considered with a reliable ratio in the early design phase of the project. Further research is necessary to address the detailed impact calculation of the equipment and notably the minimization of their impacts.

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