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Environmental barrier

Hydro-electricity is the most developed renewable resource worldwide, even if it has to face social and environmental barriers [29]. In fact societal preferences are difficult to predict, while hydro-sites are often difficult to reach, which results in high transmission and capital investment costs. These are difficult to be accepted by private power companies. The global economic hydropower potential ranges between 7000 and 9000 TWh per year. Particularly mral communities without electricity appear to be convenient for small (<10 MWe), mini- (<1 MWe), and micro- (<100 kWe) scale hydro schemes. They have low environmental impacts, and generation costs are around 6-12 c/kWh. Emissions of GHG linked with hydro-electricity operation are due to flooding of land upstream of a dam that can imply a loss of biological carbon stocks and can produce methane emissions due to vegetation decomposition. [Pg.292]

Environmental barrier coatings are a type of laminar composite. As with heat transfer, diffusion in laminar composites can be modeled as steady state diffnsion throngh a composite wall, as iUnstrated in Fignre 4.56. Here, hydrogen gas is in contact with solid material A at pressnre Pi and in contact with solid B at pressnre P2. At steady state, the molar flux of hydrogen throngh both walls mnst be the same (i.e., Jh ax = Bj) and Fick s Law [Eq. (4.4)] in the x direction becomes... [Pg.368]

Tubing with thicker walls, typically in the range of 0.080 to 0.170 in. (2 to 4 mm), is fabricated mainly from polyolefins and is used in to cover splices in telecom, CATV and electric-power industries. Often, such tubing is combined with mastic or hot melt that aids in forming an environmental barrier for the splice. Diameters of the heavy wall tubing may be up to 7 inches (178 mm) or even 12 to 24 inches (300 to 600 mm) when used as corrosion-protection sleeves on weld joints of gas and oil pipelines.92... [Pg.169]

Environmental barriers, such as a desk or prescription counter, may pose a physical barrier to communication and should be avoided, if possible. Adequate privacy is also important, especially when patients are discussing sensitive medical matters and others could overhear. Ideally, the counseling area should be free of distractions, such as ringing telephones or other conversations. The counseling area should have enough space for the phar-... [Pg.20]

Polymeric substrate materials in use include highly filled phenolic and epoxy resins for rigid printed circuit boards, polyimides and polyesters for circuit substrates as well as for more general applications, special foamed poly(tetrafluoroethylene) polymers and copolymers, foamed composite materials of the latter, special epoxy fiberglass composites, and polyimide support layers for TAB. In addition, epoxies and silicone polymers are used increasingly in applications as encapsulants, as humidity and environmental barriers within packages, and as packaging materials themselves. [Pg.12]

E. E. NuxoU, T. Shimotori, W. A. Arnold, E. L. Cussler, Iron nanoparticles in reactive environmental barriers, paper presented otAIChE Annual Meeting, 2003. [Pg.673]

Increase Temperature Stability Fiber-reinforced CMCs have been demonstrated to survive in the severe environment of a gas turbine engine for 2500 hours at temperatures up to 1200°C. The use of environmental barrier coatings (EBCs) such as oxide layers on SiC appears to help extend durability, but more research is needed to determine whether they present a long-term solution. [Pg.682]

Where the coating itself does not provide all the desired properties, top coats or top finishes will be applied as a final environmental barrier, providing UV stability, durability, inertness and self-cleaning attributes. Top finish choices include acrylics, acryUcs/polyurethanes and PVF films. [Pg.36]

Endurance testing in Solar s Centaur 505 engine has demonstrated that CVI SiC/SiC components can be introduced in Industrial Gas Turbines (Solar Turbines). To date, more than 47,000 hours of engine field test experience has been accumulated with protective environmental barrier coatings (EBCs). The longest single test duration was 15144 hours in Solar s Centaur 505 engines at industrial sites [4]. [Pg.58]

K.N. Lee, D.S. Fox, R.C. Robinson, and N.P. Bansal, Environmental Barrier Coatings for Silicon-Based Ceramics, in High Temperature Ceramic Matrix Composites, W. Krenkel, R. Naslain, and H. Schneider, Eds, Wiley-VCH, Weinheim, Germany, (2001), pp. 224-229. [Pg.98]

D. Zhu, N. P. Bansal, K. N. Lee, and R. A. Miller, Thermal Conductivity of Ceramic Thermal Barrier and Environmental Barrier Coating Materials, NASA/TM-2001-211122, Sept. 2001. [Pg.248]

Steve D, Eric B, Jim K, Andy W, Curt J (2003) Weibull strength parameter requirements for Si3N4 Turbine rotor reliability. Paper presented at the environmental barrier coatings workshop, Gaylord Opryland Resort Convention Center, Nashville, TN, USA, 18-19 Nov 2003 http //www.oml.gOv/sci/de materials/documents/DuffyEBC2003 000.pdf. Accessed on 18 May 2010... [Pg.239]


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See also in sourсe #XX -- [ Pg.851 ]




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