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Horizontal smooth and microfinned copper tubes with an approximate diameter of 9 mm were successively flattened in order to determine changes in flow field characteristics as a round tube is altered into a flattened tube profile. Refrigerants R134a and R410A were investigated over a mass flux range from 75 to 400 kg m−2 s−1 and a quality range from approximately 10–80%. For a given refrigerant mass flow rate, the results show that a significant reduction in refrigerant charge is possible. Pressure drop results show increases of pressure drop at a given mass flux and quality as a tube profile is flattened. Heat transfer results indicate enhancement of the condensation heat transfer coefficient as a tube is flattened. Flattened tubes with an 18° helix angle displayed the highest heat transfer coefficients. Smooth tubes and axial microfin tubes displayed similar levels of heat transfer enhancement. Heat transfer enhancement is dependent on the mass flux, quality and tube profile.

High Density Plasma (HDP) reactors are currently introduced for the deposition of SiO/sub 2/ and SiOF in submicron gaps between aluminium conductors in advanced integrated circuits. The main feature of HDP reactors is the ability to fill high aspect ratio spaces between aluminium conductors. This feature is achieved by employing a simultaneous deposition and sputtering process.

As a preliminary step to evaluating the acute neurobehavioral effects of hydrocarbon solvents and to establish a working model for extrapolating animal test data to humans, joint neurobehavioral/toxicokinetic studies were conducted which involved administering ethanol to rats and volunteers. The specific objectives of the present studies were to evaluate the acute central nervous system (CNS) effects of ethanol in rats and humans and to assess relationships between internal levels of exposure and behavioral effects. A more general objective was to validate a battery of neurobehavioral tests that could be used to carry out comparative studies in both species. Accordingly, a range of tests including standardized observational measures, spontaneous motor activity assessments and learned visual discrimination performance was utilized in rat studies to evaluate acute CNS effects. Groups of rats were given ethanol at levels of approximately 0.5, 1.0 or 2.0g/kg, with blood level measurements to verify internal doses. In a volunteer study, 12 healthy male subjects were given 0.65g/kg ethanol, a level approximating the limit for motor vehicle operation in The Netherlands, and neurobehavioral effects were measured prior to and 1 and 3h after ethanol administration, with a computerized neurobehavioral test battery. Blood and air measurements were made to quantify internal doses. Results of the behavioral tests in rats provided evidence of ethanol-induced changes in neuromuscular, sensori-motor, and activity domains. There were also significant changes in visual discrimination, particularly in the areas of general measures of responding and psychomotor speed. In humans there were small but statistically significant effects on learning and memory, psychomotor skills and attention. However, the effects were subtle and not all parameters within given domains were affected. These studies demonstrated a qualitative similarity in response between rats and humans.

This review highlights the challenges of fiscal system optimization considering both the host government and extraction company perspectives. Countries around the world face an arduous task in determining the optimal fiscal system to maximize the capture of economic rents of natural resource extraction activities. The extraction industry is equally challenged to meet global commodity demand because the capital investments required for developing new hydrocarbon fields and ore mines are on the rise, while tax takes on extraction activities tend to rise too in many frontier jurisdictions. Normal profit must remain for the extraction companies, and returns must be large enough to replace for resource depletion. Companies use the benefits of resources produced in one country to finance capital investments for future field development in another country. One viewpoint is that profits are expatriated to the detriment of the host country and to the benefit of another country or the world supply chain as a whole. Another viewpoint is that all resource holders benefit because a foreign entity always starts in a new resource holding nation by investing in the development of an oil field or solid mineral mine using the profits from previous projects in other countries. A key question is What is a fair taxation regime for natural resource extraction in a particular geological setting and a given geographical location, taking into account subsurface uncertainty about the quality and volume of the resource, infrastructure needs and proximity to the world’s major markets and trade centers? Tax distortion could go both ways: either incentivize, attract and stimulate or des-incentivize, repel and deter resource development. Additional factors to consider are external uncertainties such as political and fiscal stability, sovereign risk and even local weather conditions (mostly in offshore and Arctic petroleum operations). Governments must tax the upstream rents of petroleum and mineral resources, but not to the level that suppresses extraction activities. All stakeholders want at least an equitable share of the profits. Defining what is equitable is a matter of intensive negotiations, renegotiation of prior agreements and sometimes litigation and international arbitration. Several case studies, covering both petroleum and solid mineral extraction projects, are included to highlight the key points involved in fiscal policies designed to optimize the utility of geological resource endowments. For example, the offshore tax regime employed in the US pivots the trade-offs between fiscal incentives and long-term resource supply to ensure energy security. This review concludes with a call for further research.

Widespread commercialization of PCM-based latent heat storage systems is limited by the low melting and solidification rates during the phase transition process. In this study, fins are used to enhance the phase change process. A parametric study is conducted to understand the effect of fins on the thermal performance of vertically- and horizontally-oriented rectangular storage tanks. Throughout simulations, the fin volume, and thereby the mass of PCM in the tank, were kept constant. It was observed that the horizontal enclosures can take advantage of the development of strong natural convection flow until near the end of the melting process, whereas with vertical counterparts the strength of the convection currents was diminished during the shrinkage stage. The results suggest that longer and thinner fins are more beneficial for enhancing the melting rate than shorter and thicker fins. It was concluded that for horizontal enclosures with fin lengths of 25 and 35 mm, increasing the number of fins does not necessarily shorten the melting time. The maximum melting time reduction compared to the 3-fin vertical enclosure with a fin length of 25 mm (chosen as our benchmark case) was 75.1% when nine 45-mm-long fins are used in a horizontal enclosure. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public. Process and Energy

This paper presents the extension of the open source SU2 software suite to perform turbulent Non-Ideal Compressible Fluid-Dynamics (NICFD) simulations. A new built-in thermodynamic library has been developed and tightly coupled with the existing structure of the code, properly re-organized for accommodating arbitrary thermophysical models. The library implements simple models and interfaces to an external software for a more accurate estimation of thermophysical properties of NICFD pure fluids and mixtures. Moreover, the Reynolds-averaged Navier-Stokes (RANS) equations are spatially discretized by resorting to suitably defined convective and viscous numerical schemes for general fluids. The capabilities of the code are finally verified on twoand three-dimensional inviscid and turbulent flow problems against solutions obtained with different NICFD solvers, and known analytical ones. The results prove that SU2 is comparatively accurate and computational efficient with respect to existing codes. Definitively, SU2 can be considered as a trustworthy tool for NICFD-based simulations and the future pillar of advanced automated design techniques involving complex fluid laws.

This chapter focuses on the application of passive flow control technologies to wind turbine blades. The motivation of using these technologies is always an enhancement of the wind turbine performance (increase of power production, load reduction, noise reduction, etc.) in comparison to the standard blade. Passive flow control solutions can be limited to static add-ons or involve more significant modifications of the blade for dynamic approaches. Furthermore, these technologies can be included in the initial design of the blade or included later as add-ons to improve the performance of an existing blade design. A large number of passive technologies have been proposed for wind turbine applications, although the level of maturity is not the same for all of them ranging from conceptual studies in some cases to commercial products in others. Some representative examples of specific technologies are included in this chapter: vortex generators, static miniflaps, root spoilers, serrations, winglets, passive flaps, and aeroelastic coupling. For each technology, some aspects related to the state of the art, main concept, impact on the wind turbine performance, application, and design have been described. Finally, passive flow control technologies have to be integrated into the design process of wind turbines. To select and properly apply the most suitable technology for each specific problem, the chapter highlights the importance of modeling tools, design methodologies, objectives and restrictions, design parameters, and scale of impact of each passive flow control solution. In addition, from a general point of view, some design guidelines have been mentioned.

This research presents an integrated optimal controller to maximize the fuel efficiency of a Hybrid Electric Vehicle (HEV) traveling on rolling terrain. The controller optimizes both the vehicle acceleration and the hybrid powertrain operation. It takes advantage of the emerging Connected Vehicle (CV) technology and utilizes present and future information as optimization input, which includes road topography, and dynamic speed limit. The optimal control problem was solved using Pontryagin’s Minimum Principle (PMP). Efforts were made to reduce the computational burden of the optimization process. The evaluation shows that the benefit of the proposed optimal controller is significant compared to regular HEV cruising at the speed limit on rolling terrain. The benefit ranges from 5.0% to 8.9% on mild slopes and from 15.7% to 16.9% on steep slopes. The variation is caused by the change of hilly road density.