Lessons from Rotor 37

INTanDUCTIONhi1992theturbomachinerycommittee0ftheIoter-nationalGasTurbineInstitute(IGTI)decidedtosetuPatestcaseforCFDcalculations.Aftersomedebateitwasdecidedthatthetestcasesh0uldbecalculated'blind',i.e.thattheexperimentalresultssh0uldn0tbemadeawilableulltilafterthesolutionshadbeensubndtted.NASA(LewisResearchCenter)offeredasuitabletestca-seintheformofahighlyloadedtransoniccompressorrot0rwhichwasthenbeingtestedwitheXtensiveuseoflaseranemometrytomeasuretheiliternalflow.Themeasurementsw…     

Effective ways to reduce CO2 emissions from China's heavy industry? Evidence from semiparametric regression models

Using China's province-level panel data from 2005 to 2017, this article uses a semiparametric regression model to investigate CO₂ emissions in China's heavy industry. Empirical results show that while economic growth exerted carbon reduction effects in the eastern region, it stimulated the growth of CO₂ emissions in the central and western regions. This is mainly due to regional differences in industrial structure and the high-tech industry. Energy efficiency has made a greater contribution to reducing CO₂ emissions in the central region because the R&D investment and patent rights granted in this region has grown faster. The energy consumption structure has a more complex impact. It exerts a “pulling first, then restricting” (Ո-shaped) nonlinear effect on CO₂ emissions in the eastern and western regions, but an inverted “N-shaped” effect in the central region. This is mainly due to the differences in the composition of energy consumption across regions. Environmental regulations have a positive “U-shaped” nonlinear impact on CO₂ emissions in the eastern and western regions. It means that environmental regulations help cut down CO₂ emissions in the early stage, and the facilitation effect gradually disappears at the later stage. Conversely, environmental regulations produce an inverted “U-shaped” impact in the central region.     

Ni catalysts derived from Mg–Al layered double hydroxides for hydrogen production from landfill gas conversion

A layered double hydroxide (LDH) precursor with a hydrotalcite-like structure containing Ni/Mg/Al cations was prepared. A series of Ni catalysts containing mixed-oxides and spinel phases were then obtained through thermal treatment of the LDH precursor. X-ray diffraction (XRD), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR) revealed that the LDH derived Ni catalysts have well-dispersed nickel phases upon reduction. The thermal treatment temperatures have noticeable effects on the specific surface area, pore volume, phase transformation, particle size, and reducibility of the catalysts. Thermal treatment temperatures up to 700 °C promote the generation of mesopores which facilitate an increase in specific area and pore volume. Beyond 700 °C sintering occurs, mesopores collapse, and specific area and pore volume decrease. High thermal treatment temperatures favor the phase transformation to spinel solid solutions and the particle size growth. Metal-support interaction is enhanced but reducibility is hindered due to the formation of spinel solid solution phases. The LDH derived Ni catalysts were tested for landfill gas conversion at 750 °C and have shown excellent activity and stability in terms of methane conversion. At gas hourly space velocity (GHSV) of 240,000 h⁻¹ and pressure of 1 atm, 81% methane conversion was achieved during a 48 h test period without apparent catalyst deactivation.     

Inverter manages high current from 6” PV cells

Inverter manufacturer Fronius has recently highlighted that its Fronius IG series is well suited for combination with 6’’ solar cells given that all of its devices work without current limitation. The company claims that inverters that work with a current limitation run the risk of being overloaded due to the higher current flow with larger cells which can cause component defects and in series lead to a breakdown of the inverter. The company highlights the importance of installing the appropriate inverter to eliminate this danger. Another relevant advantage of devices without current limitation is that they can be used with every type of module available on the market. This enables all kinds of configuration and offers a great flexibility to the planner. Fronius has also just announced a new feature in its FRONIUS IG product range. The “FRONIUS IG Datalogger easy” has been especially developed to manage and store the data of only one FRONIUS IG inverter. As the recommended price for this device is at about 50% of the normal Datalogger price, the Datalogger easy should attract and incite privates and owners of “smaller” PV-systems to install data communication components and supervise the system. With the integration of a modem in the DatCom system, the job of monitoring can also be easily done by the installer.This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news.     

Energy recovery from hydrogen combustion at elevated pressures

Hydrogen is assumed as one of the most environmentally benign fuels. By the combustion of hydrogen enormous amount of H₂O; and therefore, latent heat is produced. Because, there is not so much need to heat at low temperatures, methods are needed to recover latent heat at higher temperatures. One of the methods to upgrade the latent heat at higher temperatures is the method of combustion at elevated pressures. Increasing the pressure of the exhaust gas makes it possible to recover latent heat and higher extra exergy output from the system. In this work, both latent and sensible heat recoveries at elevated pressures are investigated using environmentally friendly fuel hydrogen. It is shown that coefficient of performance (COP) and exergy efficiency (${\eta }_{ex}$) is very satisfactory even at high pressures.     

Investigation of Enhanced Boiling Heat Transfer from Porous Surfaces

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Hydrogen from biomass – Present scenario and future prospects

Hydrogen is considered in many countries to be an important alternative energy vector and a bridge to a sustainable energy future. Hydrogen is not an energy source. It is not primary energy existing freely in nature. Hydrogen is a secondary form of energy that has to be manufactured like electricity. It is an energy carrier. Hydrogen can be produced from a wide variety of primary energy sources and different production technologies. About half of all the hydrogen as currently produced is obtained from thermo catalytic and gasification processes using natural gas as a starting material, heavy oils and naphtha make up the next largest source, followed by coal. Currently, much research has been focused on sustainable and environmental friendly energy from biomass to replace conventional fossil fuels. Biomass can be considered as the best option and has the largest potential, which meets energy requirements and could insure fuel supply in the future. Biomass and biomass-derived fuels can be used to produce hydrogen sustainably. Biomass gasification offers the earliest and most economical route for the production of renewable hydrogen.     

How certain are greenhouse gas reductions from bioenergy? Life cycle assessment and uncertainty analysis of wood pellet-to-electricity supply chains from forest residues

Climate change and energy policies often encourage bioenergy as a sustainable greenhouse gas (GHG) reduction option. Recent research has raised concerns about the climate change impacts of bioenergy as heterogeneous pathways of producing and converting biomass, indirect impacts, uncertainties within the bioenergy supply chains and evaluation methods generate large variation in emission profiles. This research examines the combustion of wood pellets from forest residues to generate electricity and considers uncertainties related to GHG emissions arising at different points within the supply chain. Different supply chain pathways were investigated by using life cycle assessment (LCA) to analyse the emissions and sensitivity analysis was used to identify the most significant factors influencing the overall GHG balance. The calculations showed in the best case results in GHG reductions of 83% compared to coal-fired electricity generation. When parameters such as different drying fuels, storage emission, dry matter losses and feedstock market changes were included the bioenergy emission profiles showed strong variation with up to 73% higher GHG emissions compared to coal. The impact of methane emissions during storage has shown to be particularly significant regarding uncertainty and increases in emissions. Investigation and management of losses and emissions during storage is therefore key to ensuring significant GHG reductions from biomass.     

Photocatalytic hydrogen generation from water—Organic solutions using polytungstates

Illumination of polytungstate (PT) solutions, containing organic compounds results in the formation of photoreduced tungsten species and the evolution of hydrogen. Photocatalytic hydrogen generation from water-ethanol solutions using PT was studied in detail. Prolonged irradiation of this solution leads to the formation of hydrogen and acetaldehyde in a stoichiometric ratio. Absorption and ESR spectra of the photolyte indicate the subsequent formation of one- and two-electron reduced decatungstates. The addition of colloidal platinum to the system results in the increase in rate of hydrogen evolution. The dependences of the rate of hydrogen generation on a number of parameters (pH, concentrations of reagents, amounts of colloidal Pt, temperature) were studied. A mechanism of the process was proposed involving the formation of two-electron reduced PT and its subsequent reoxidation yielding hydrogen in the presence of colloidal platinum.     

Computational analysis of geometrical factors affecting experimental data extracted from hydrogen permeation tests: III – Comparison with experimental results from the literature

The membrane thickness is one of the major parameters affecting hydrogen diffusion during electrochemical permeation tests. In this work, we study the effects of membrane thickness by comparing experimental results from the literature with a numerical analysis by finite element method (FEM). We consider the effects of a palladium coating or an oxide layer on the diffusion through α-iron, and we also studied the effects of an oxide layer on the diffusion through martensitic steels. Our model allows us to match the experimental data and determine the initial subsurface hydrogen concentration, trap densities, and the diffusivity of the layer. However, we had to consider the effects of the mechanical polishing on hydrogen trap densities and concentrations to ensure a reasonable correlation. The balance between the effects of trapping and the oxide layer are finally discussed; while hydrogen trapping increases the effective subsurface concentration, the oxide layer decreases its value.     

Local Convective Heat Transfer from Small Heaters to Impinging Submerged Axisymmetric Jets of Seven Coolants with Prandtl Number Ranging from 0.7 to 348

INTRODUCTIoNJetimpingementhasbeenextensivelyemployedintechnicalprocessestoproducerelativelyhighheat/massfluxes.Incomparisonwiththeheat/masstransferratesprovidedbyconventionaltechniqueswithfluidfiowsparalleltotheheat/masstransfersur-face,aremarkableincreaseintransfercoefficientscanbeobtainedinthisfashion.Inmostcasesairisusedastheworkingmedium.Examplesofairjetapp1icationsincludecoolingofturbinebladesandelectroniccom-ponents,annealingofmetallicandplasticsheets,dry-ingoftextilesandpaper,andtem…     

Kinetics of Iododeoxyuridine release from sodium alginate hydrogel in vitro

Objective To investigate the kinetics of Iododeoxyuridine (IUdR)release from sodium alginate hydrogel cross-linked with varying amounts of calcium chloride, and to optimize sustained release for further periadventitial I125-labeled IUdR     

42-V battery requirements from an automaker’s perspective

Present and future automotive electrical loads are surveyed relative to power and electrochemical storage requirements. It is concluded that existing power and energy needs are near the maximum capability of the existing 14-V system, and that future automotive loads may be 10 kW or more. The efficiency of the electrical distribution system at this power level requires a higher voltage and safety considerations dictate that a 42-V limit will be the most satisfactory standard. The higher-voltage systems will likely include advanced controls, thermal management, and more complex architectures.     

Can China benefit from adopting a binding emissions target?

In the run-up to the Copenhagen climate summit, the USA announced an emissions reduction target of 17% by 2020 (relative to 2005), and the EU of 20–30% (relative to 1990). For the same time horizon, China offered to reduce the CO₂-intensity of its economy by 40–45% (relative to 2005), but rejects a legally binding commitment. We use the targets announced by the EU and the USA to analyze the potential gain for China if it were to adopt a binding emissions target and join an international emissions trading scheme. We show that China would likely benefit from choosing a binding target well below its projected baseline emissions for 2020.     

Formation of flammable hydrogen–air clouds from hydrogen leakage

The possibilities of the formation of a flammable cloud over the ground in an open atmosphere from the leakage of hydrogen stored at different temperatures are studied. The dispersion of hydrogen in the stable and unstable atmospheric conditions is determined using the Gaussian dispersion model. The efflux of hydrogen from the storage vessel is considered at velocities between 1 m/s and 1500 m/s, the latter corresponding to the upper limit of velocities arising from the choked flow. The dispersion analysis shows that flammable hydrogen–air clouds would not be formed over the ground under unstable atmospheric conditions for all efflux velocities and leakage areas and for the different temperatures of the hydrogen leak. However, under strongly stable atmospheric conditions, such as those associated with clear sky winter nights with low winds and temperature inversion in the planetary boundary layer, a flammable cloud is seen to be formed. This is particularly true for low temperature hydrogen efflux and very low velocities of the efflux.     

MgFe and Mg–Co–Fe mixed oxides derived from hydrotalcites: Highly efficient catalysts for COx free hydrogen production from NH3

Mg–Fe Layered Double Hydroxide (LDH) with M²⁺: M³⁺ 3:1 stoichiometric ratio was synthesized and employed as catalyst precursor for CO_x-free hydrogen production from ammonia. The resulting catalyst showed good catalytic activity. A series of Mg/Co–Fe layered double hydroxides were synthesized by replacing Mg²⁺ with Co²⁺ without disturbing M²⁺:M³⁺ ratio. The influence of nature and extent of Co(II) substitution on structure, morphology and surface properties were studied. A systematic study was carried out using these materials as catalyst precursors for ammonia decomposition. BET, XRD, TPR, XPS, CO₂-TPD and TEM techniques were used to characterize the synthesized catalysts. These Fe-based catalysts are highly active, highly stable and not promoting any stable surface nitridation during the ammonia decomposition reaction. Among all catalysts, the Mg₃Co₃Fe₂ catalyst showed the highest activity i.e. 100% conversion at 6,000 h⁻¹ and 60% at 50,000 h⁻¹ space velocities at 550 °C. The registered superior catalytic activity was result of the formed specific catalyst's properties like high surface area, high surface Co and Fe atomic concentration and suitable basicity. These Fe-based materials are, cost-effective, easily synthesize and highly stable, thus attractive for large-scale operation.     

Advances in Centrifugal Separators for Particulate Matter Control from Stationary Sources

This paper summarized recent developments in centrifugal separators for particulate matter (PM) emission control. Airborne particulate matter, which is responsible for many health and environmental problems, is generated mostly from combustion processes in stationary sources such as house burners and power plants and other production facilities, except field dust. Reverse flow cyclones are centrifugal separators having been widely used for industrial particulate matter removal. Typical pressure drops of these cyclones for air cleaning are 500 Pa or higher, and were believed to be only able to separate particles larger than 10 μm. An aerodynamic deduster that could separate particles as small as 1μm at a pressure drop of 200 Pa was recently developed. Field evaluation showed that the deduster can be effectively used in reducing particulate matter emission from stationary sources.     

What drives public acceptance of second-generation biofuels? Evidence from Canada

North American publics are currently much more supportive of second-generation biofuels than of conventional biofuels like corn-based ethanol. But what is the likely future trajectory of consumer acceptance of advanced biofuels? This study considers whether increased awareness of the potential unintended consequences of increasing the production of advanced biofuels could lead to a decline in public support for the technology. Using an experiment embedded in an original survey of Canadian adults, we test for the effect of two anti-biofuels arguments on Canadians' support for policies meant to encourage the production of biofuels. We find that support for biofuels policies was reduced in our experiment when respondents were exposed to an argument about the potential impact of biofuels production on food prices and when they were told that the use of woody biomass as a feedstock for the production of cellulosic biofuels might lead to an increase in commercial logging. In both cases, however, support was reduced only among respondents who did not perceive climate change to pose a significant risk. Overall, our results suggest that public support for advanced biofuels is potentially vulnerable to arguments that focus on the unintended consequences of producing biofuels from non-food feedstocks.     

Forced Convective Air Cooling from Electronic Component Arrays in a Parallel

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