Advantage of superconducting bearing in a commercial flywheel system

The use of a superconducting magnetic bearing in an Urenco Power Technologies (UPT) 100kW flywheel is being studied. The dynamics of a conventional flywheel energy storage system have been studied at low frequencies. We show that the main design consideration is overcoming drag friction losses and parasitic resonances. We propose an original superconducting magnetic bearing design and improved cryogenic motor cooling to increase stability and decrease energy losses in the system. © 2008 IOP Publishing Ltd.

Towards productivity indicators for performance-based façade design in commercial buildings

Decision-making in the façade design process has a significant influence on several aspects of indoor environment, thereby making it a complex and multi-objective optimisation process. There are two principal barriers in the process of indentifying an optimal façade solution. Firstly, most existing indoor environmental evaluation methods do not account for all the indoor environmental quality (IEQ) aspects relevant to façade design. Secondly, the relationship between the physical properties of a particular façade design option and the resulting economic benefits accrued during its service-life is unknown. In this paper, we introduce the bases for establishing relationships between occupant productivity and the combinatorial effects of four key façade-related IEQ aspects, namely, thermal comfort, aural comfort, visual comfort and air quality, on occupant productivity. The proposed framework's potential is tested against seven existing experimental investigations and its applicability is illustrated by a simple façade design example. The proposed approach ultimately aims to provide a quantitative economic measure of alternative façade design options that would be applicable to early design stage. Aspects of the work that require further experimental validation are identified. © 2012 Elsevier Ltd.

A validation of commercial flow solver performance on hybridised octree meshes

In recent years we have been developing a meshing system which is aimed at eliminating the bottleneck represented by building meshes for real-world, complex turbomachinery configurations. This system is based on a rapid octree meshing technology which is then made conformal to the bodies present. The objective of this paper is to demonstrate that this class of mesh is not only very fast to produce but also fit-for-purpose in the sense that simulations generated with third-party commercial flow solvers like Fluent have the same accuracy as those performed on more conventional meshes. A range of standard examples and test cases will be presented. Copyright © 2011 by ASME.

Carbon nanotubes: Present and future commercial applications

Worldwide commercial interest in carbon nanotubes (CNTs) is reflected in a production capacity that presently exceeds several thousand tons per year. Currently, bulk CNT powders are incorporated in diverse commercial products ranging from rechargeable batteries, automotive parts, and sporting goods to boat hulls and water filters. Advances in CNT synthesis, purification, and chemical modification are enabling integration of CNTs in thin-film electronics and large-area coatings. Although not yet providing compelling mechanical strength or electrical or thermal conductivities for many applications, CNT yarns and sheets already have promising performance for applications including supercapacitors, actuators, and lightweight electromagnetic shields.

Life cycle assessments of biodegradable, commercial biopolymers - A critical review

Biopolymers are generally considered an eco-friendly alternative to petrochemical polymers due to the renewable feedstock used to produce them and their biodegradability. However, the farming practices used to grow these feedstocks often carry significant environmental burdens, and the production energy can be higher than for petrochemical polymers. Life cycle assessments (LCAs) are available in the literature, which make comparisons between biopolymers and various petrochemical polymers, however the results can be very disparate. This review has therefore been undertaken, focusing on three biodegradable biopolymers, poly(lactic acid) (PLA), poly(hydroxyalkanoates) (PHAs), and starch-based polymers, in an attempt to determine the environmental impact of each in comparison to petrochemical polymers. Reasons are explored for the discrepancies between these published LCAs. The majority of studies focused only on the consumption of non-renewable energy and global warming potential and often found these biopolymers to be superior to petrochemically derived polymers. In contrast, studies which considered other environmental impact categories as well as those which were regional or product specific often found that this conclusion could not be drawn. Despite some unfavorable results for these biopolymers, the immature nature of these technologies needs to be taken into account as future optimization and improvements in process efficiencies are expected. © 2013 Elsevier B.V. All rights reserved.