The talk with present the key results of the IPCC Working Group III 5th assessment report. Concluding four years of intense scientific collaboration by hundreds of authors from around the world, the report responds to the request of the world's governments for a comprehensive, objective and policy neutral assessment of the current scientific knowledge on mitigating climate change. The report has been extensively reviewed by experts and governments to ensure quality and comprehensiveness.

Climate change 2014 - Mitigation of climate change

This chapter discusses leading problems linked to energy that the world is now confronting and to propose some ideas concerning possible solutions. Oil deserves special attention among all energy sources. Since the beginning of 1981, it has merely been continuing and enhancing the downward movement in consumption and prices caused by excessive rises, especially for light crudes such as those from Africa, and the slowing down of worldwide economic growth. Densely-populated oil-producing countries need to produce to live, to pay for their food and their equipment. If the economic growth of the industrialized countries were to be 4%, even if investment in the rational use of energy were pushed to the limit and the development of nonpetroleum energy sources were also pursued actively, it would be extremely difficult to prevent a sharp rise in prices. It is evident that it is absolutely necessary to pursue actively the development of coal, natural gas, and nuclear power if a physical shortage of energy is not to block economic growth.

World energy outlook

An introduction to heat transfer

Boundary-layer flow of a nanofluid past a stretching sheet

Nanofluids, the fluid suspensions of nanomaterials, have shown many interesting properties, and the distinctive features offer unprecedented potential for many applications. This paper summarizes the recent progress on the study of nanofluids, such as the preparation methods, the evaluation methods for the stability of nanofluids, and the ways to enhance the stability for nanofluids, the stability mechanisms of nanofluids, and presents the broad range of current and future applications in various fields including energy and mechanical and biomedical fields. At last, the paper identifies the opportunities for future research.

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A review on nanofluids: preparation, stability mechanisms, and applications

A superhydrophilic thin film is formed on a metal surface of a boiler vessel to alter the wettability and roughness of the surface, which, in turn, changes the boiling behavior at the surface. The superhydrophilic film is formed by depositing a layer of a first ionic species on the surface from a solution. A second ionic species having a charge opposite to the that of the first ionic species is then deposited from solution onto the surface to produce a bilayer of the first ionic species and the oppositely charged second ionic species. The depositions are then repeated to form a plurality of bilayers, on top of the preceding bilayer. The bilayers are then heated, leaving the second ionic species on the metal surface to form a superhydrophilic film.

Nanoparticle thin-film coatings for enhancement of boiling heat transfer

The purpose of this collaborative Idaho National Engineering and Environmental Laboratory (INEEL) and Massachusetts Institute of Technology (MIT) Laboratory Directed Research and Development (LDRD) project is to investigate the suitability of lead or lead-bismuth cooled fast reactors for producing low-cost electricity as well as for actinide burning. The goal is to identify and analyze the key technical issues in core neutronics, materials, thermal-hydraulics, fuels, and economics associated with the development of this reactor concept. Work has been accomplished in four major areas of research: core neutronic design, plant engineering, material compatibility studies, and coolant activation. The publications derived from work on this project (since project inception) are listed in Appendix A.

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Design of an Actinide Burning, Lead or Lead-Bismuth Cooled Reactor that Produces Low Cost Electricity FY-01 Annual Report, October 2001

The large assembly with small pins (LASP) concept is an evolutionary boiling water reactor (BWR) fuel assembly design aimed at increasing the power density of BWR cores while keeping the same power-to-flow ratio, core inlet conditions, and fuel-to-moderator ratio. It is based on replacing four traditional assemblies and their large interassembly water gap regions with a single large assembly surrounded by a narrower gap region. The traditional BWR cylindrical UO 2 -fueled Zr-clad fuel pin design is retained, but the pins are arranged on a 22 X 22 square lattice. Twenty-five water rods within the assembly maintain the moderating power and accommodate as many finger-type control rods. The technical characteristics of LASP were evaluated and are systematically compared with a traditional 9 X 9 fuel assembly. This design study includes analyses of the steady-state thermal hydraulics, two-dimensional and three-dimensional burnup-dependent neutronics, flow-induced vibrations, and fuel pin thermomechanical behavior. Furthermore, the conceptual mechanical design of the LASP assembly is discussed. The analyses show that LASP can operate at a power density that is 20% higher than the traditional BWR assemblies while maintaining the same safety margin.

A Large Assembly with Small Pins Concept for High-Power-Density BWRs

Nanofluids exhibit a very significant enhancement of the boiling Critical Heat Flux (CHF) at low nanoparticle concentrations. This paper reviews the nanofluid boiling database in a quest for the CHF enhancement mechanism. Briefly, buildup of a nanoparticle layer on the heated surface occurs upon boiling of nanofluids. This layer changes the surface roughness and the nucleation site density and, remarkably, can improve the surface wettability, as shown by a reduction of the static contact angle on the nanofluid-boiled surfaces. Significant differences are also observed in the dynamic behavior of the hot spot at CHF.Copyright © 2007 by ASME

Towards an Explanation of the Mechanism of Boiling Critical Heat Flux Enhancement in Nanofluids

It is well known that boiling and quenching heat transfer depends strongly on the morphology and composition of the solid surface through which the heat transfer occurs The relevant surface features are roughness, wettability (hydrophilicity), porosity, presence of cavities, size and shape of cavities, and thermo-physical properties of the surface material Recent work at MIT has explored the separate effects of surface roughness, wettability and porosity on both Critical Heat Flux (CHF) and quenching heat transfer (Leidenfrost point temperature) Briefly, interconnected porosity within a hydrophilic matrix greatly enhances the CHF (by as much as ∼60%) and the Leidenfrost temperature (by as much as ∼150 °C) Surprisingly, surface roughness has a comparably minor effect on both CHF and quenching There are opportunities to exploit in Light Water Reactor (LWR) nuclear plants, where CHF and quenching determine the thermal margins in during loss-of-flow and loss-of-coolant accidents, respectively, and the surface of the fuel naturally develops porous hydrophilic layers because of CRUD deposition and corrosion This paper reviews the MIT experimental database generated using engineered surfaces with carefully-controlled characteristics, and discuss its applications to LWR safety, both design-basis and beyond-design-basis accidents

Jacopo Buongiorno

Papers

Nanoparticle thin-film coatings for enhancement of boiling heat transfer

Design of an Actinide Burning, Lead or Lead-Bismuth Cooled Reactor that Produces Low Cost Electricity FY-01 Annual Report, October 2001

A Large Assembly with Small Pins Concept for High-Power-Density BWRs

Towards an Explanation of the Mechanism of Boiling Critical Heat Flux Enhancement in Nanofluids

Can corrosion and CRUD actually improve safety margins in LWRs