Very low temperatures stress a circuit breaker in a complex manner. Mixed-gas circuit breakers were developed for use at temperatures as low as -50C. These breakers utilize a gas mixture of SF6 and CF4 or SF6 and N2 to prevent condensation of the SF6 gas and have been type tested at -50C to ensure travel characteristics, operating times, and gas tightness are acceptably affected. Today’s mixed-...

The gas permeability of α-alumina, yttria-stabilized zirconia (YSZ), and silicon carbide porous ceramics toward H₂, CO₂, and H₂-CO₂ mixtures were investigated at room temperature. The permeation of H₂ and CO₂ single gases occurred above a critical pressure gradient, which was smaller for H₂ gas than for CO₂ gas. When the Knudsen number (λ/r ratio, λ: molecular mean free path, r: pore radius) of...

Considering the high costs of the implementation and maintenance of gas distribution networks in urban areas, optimal design of such networks is vital. Today, urban gas networks are implemented within a tree structure. These networks receive gas from City Gate Stations (CGS) and deliver it to the consumers. This study presents a comprehensive model based on Mixed Integer Nonlinear Programming (...

This paper presents a numerical investigation of the laminar mixed convection flow of a radiating gas in an inclined lid-driven cavity. The fluid is treated as a gray, absorbing, emitting, and scattering medium. The governing differential equations including continuity, momentum and energy are solved numerically by the computational fluid dynamics techniques (CFD) to obtain the velocity and tem...

For the design of a special gas-flow proportional counter intended for a new on-line measurement method of airborne radon (Rn) concentration, the amplification properties of four gas compositions were investigated in air-mixed Argon-propane (1%)-based proportional counters. These four gas compositions are: Ar-C3H8 (1%); Ar-C3H8 (1%) + 2% air; Ar-C3H8 (1%) + 6% air and Ar-C3H8 (1%) + 10% air. Th...

Sulfur hexafluoride (SF₆) gas decomposition results from the energy produced by partial discharge (PD). The detection of SO₂ and H₂S content, as important characteristic components of the decomposition products, is significant in the determination of the insulation level of SF₆ gas and the inside insulation faults of gas-insulated equipment. A number of gas sensors use carbon nanotubes (CNTs). ...

the nanoparticles of ni–si mixed oxides were prepared by co-precipitation method using nickel nitrate; ni(no3)2 6h2o and tetraethylorthosilicate (teos). the products were characterized by x-ray diffraction (xrd), transmission electron microscopy (tem), and hydrogen temperature program reduction (h2-tpr). the results revealed that ni–si mixed oxides particles were obtained with average particle ...

This paper explores the decomposition characteristics of a new type of environmentally friendly insulating gas C6F12O and N2 mixed gas under AC voltage. The breakdown behavior of 3% C6F12O and N2 mixed gas in quasi-uniform field was investigated through a breakdown experiment. The self-recovery of the mixed gas was analyzed by 100 breakdown experiments. The decomposition products of C6F12O and ...

Microstructural, topology, inner morphology, and gas-sensitivity of mixed xWO(3)(1-x)Y(2)O(3) nanoparticles (x = 1, 0.95, 0.9, 0.85, 0.8) thick-film semiconductor gas sensors were studied. The surface topography and inner morphological properties of the mixed powder and sensing film were characterized with X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy ...

Aiming at a new type and multi-functional intelligent vortex flowmeter integrating system, which implicates whether it is liquid, gas, steam or the mixture of oil and gas, or in special conditions such as high temperature, high pressure, the medium can be measured intelligently. Especially for mixed media by TPF (Two-phase Flow), such as oil and gas, water vapor, firstly separates the mixed flu...