Search results for "Efficient"
showing 10 items of 1603 documents
Polypropylene-based melt mixed composites with singlewalled carbon nanotubes for thermoelectric applications: Switching from p-type to n-type by the …
2017
Abstract The thermoelectric properties of melt processed conductive nanocomposites consisting of an insulating polypropylene (PP) matrix filled with singlewalled carbon nanotubes (CNTs) and copper oxide (CuO) were evaluated. An easy and cheap route to switch p-type composites into n-type was developed by adding polyethylene glycol (PEG) during melt mixing. At the investigated CNT concentrations of 0.8 wt% and 2 wt% (each above the electrical percolation threshold of ∼0.1 wt%), and a fixed CuO content of 5 wt%, the PEG addition converted p-type composites (positive Seebeck coefficient (S)) into n-type (negative S). PEG was also found to improve the filler dispersion inside the matrix. Two co…
Reduction of the interfacial tension between ‘immiscible’ polymers: to which phase one should add a compatibilizer
2001
Abstract The reduction of interfacial tension σ between polyethylene oxide (PEO) and polypropylene oxide (PPO) by either a triblock copolymer EO–PO–EO or a diblock copolymer styrene–EO was studied by means of the pendant drop method from 70 to 120°C. Time independent data correspond to stationary states and do not represent equilibrium information. The addition of the compatibilizer to the PPO phase is approximately twice as efficient as the addition to the PEO phase for both block copolymers. Knowing the concentration dependence of σ for one of the coexisting phases it is possible to forecast the effects resulting from the addition of the other phase by means of model considerations based …
(Liquid + liquid) equilibria of polymer-salt aqueous two-phase systems for laccase partitioning : UCON 50-HB-5100 with potassium citrate and (sodium …
2012
Aqueous two-phase systems (ATPS) are recognized as very suitable techniques for the recovery of target solutes in biological applications. Three new phase diagrams of (UCON 50-HB-5100 + potassium citrate + water), (UCON 50-HB-5100 + sodium formate + water), and (UCON 50-HB-5100 + potassium formate + water) systems were measured at 23 C. The binodal curves were successfully described using the empirical equation suggested by Merchuk and co-workers. The reliability of the tie-line data experimentally determined was evaluated using the equations reported by Othmer–Tobias and Bancroft and satisfactory linearity was obtained for all ATPS. Among the salts studied, potassium citrate proved to be t…
Smart grid-aware scheduling in data centres
2015
In several countries the expansion and establishment of renewable energies result in widely scattered and often weather-dependent energy production, decoupled from energy demand. Large, fossil-fuelled power plants are gradually replaced by many small power stations that transform wind, solar and water power into electrical power. This leads to changes in the historically evolved power grid that favours top-down energy distribution from a backbone of large power plants to widespread consumers. Now, with the increase of energy production in lower layers of the grid, there is also a bottom-up flow of the grid infrastructure compromising its stability. In order to locally adapt the energy deman…
Energy-Efficient Protocol Design
2015
Recent studies have shown that the total energy consumed by the Internet has followed an increasing trend over the years. A considerable part of this energy is wasted due to an inefficient utilization of edge devices , that is, Personal Computers (PCs) and other user equipment in homes and offices. PCs are often left on even when they are not used (e.g., overnight or during weekends), while other edge devices, such as printers, IP phones, and displays, are typically kept always on , especially in public buildings. A number of solutions have been proposed for eliminating, or reducing, energy wastes caused by edge devices. In this chapter, we propose a general taxonomy for their classificatio…
Numerical simulation of nanofluids for improved cooling efficiency in a 3D copper microchannel heat sink (MCHS)
2017
ABSTRACTIn this paper, laminar nanofluid flow in 3D copper microchannel heat sink (MCHS) with rectangular cross section, and a constant heat flux, has been treated numerically using the computational fluid dynamics software (FLUENT). Results for the temperature and velocity distributions in the investigated MCHS are presented. In addition, experimental and numerical values are compared in terms of friction factors, convective heat transfer coefficients, wall temperature and pressure drops, for various particle volume concentrations and Reynolds numbers. The numerical results show that enhancing the heat flux has a very weak effect on the heat transfer coefficient for pure water, but an appr…
Energy efficiency in the European Union: What can be learned from the joint application of directional distance functions and slacks-based measures?
2014
Abstract Over the last few years concerns have increased about the energy mix in many countries. These concerns have been of greater magnitude for countries with a common energy regulation such as European Union (EU) member states. An important aspect to take into account when choosing a given energy mix is the efficiency involved in its generation. In this context, the present study analyzes the efficiency with which electricity and derived heat was produced in 25 EU member states over the last decade. This analysis considers not only the inputs and outputs involved but, more importantly, which undesirable by-products were generated during the production process, a relevant issue for EU cl…
(In)Efficiencies in Latin American ETFs
2017
Este estudio evalúa empíricamente la eficiencia en la valoración de varios ETFs latinoamericanos, expresada en desviaciones de sus precios de mercado frente a los valores liquidativos subyacentes. Se cuantifican tales ineficiencias y se implementa una estrategia de negociación verificada por regresiones basadas en el CAPM y el Modelo Fama-French. Los resultados discrepan con la Hipótesis de los Mercados Eficientes y son mejor explicados por aspectos de las finanzas comportamentales. Finalmente, se examina cómo las desviaciones influyen sobre la decisión de creación o redención de ETFs, mediante un análisis de regresión logística. Los resultados evidencian que los participantes autorizados r…
The European Green Deal: New Challenges for the Economic Feasibility of Energy Retrofit at District Scale
2020
The European Green Deal proposes an epochal change in the European society by transforming environmental and climatic problems into opportunities and making sustainable and fair the European Union economic system. Radical changes will also concern urban redevelopment and energy efficiency measures in order to reduce global greenhouse gas emissions. To achieve these objectives, rules and standards, as well as financial resources and assessment tools, are needed to support both urban planning and public decision process. This paper aims to analyze the existing European programs that are applied in some European smart cities, as they constitute a valuable source of information for the developm…
Isobaric vapor-liquid equilibria for binary and ternary systems composed of water, 1-propanol, and 2-propanol at 100 kPa
1996
Isobaric vapor−liquid equilibria data were obtained for the 2-propanol + 1-propanol binary system and the water + 1-propanol + 2-propanol ternary system at 100 kPa. The data were found to be thermodynamically consistent according to the Van Ness−Byer−Gibbs method for the binary system and according to the McDermott−Ellis method for the ternary one. The binary system is well represented by assuming ideal behavior. The binary interaction parameters obtained from this and our previous work are used to predict the vapor−liquid equilibrium for the ternary system using the UNIQUAC, NRTL, and Wilson models. The ternary system is well predicted from binary data.