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Hydrogenated microcrystalline silicon (μc-Si:H) is an important material for high-efficiency multijunction solar cells. Due to its complex microstructural properties, it is difficult to describe the electronic behavior clearly. In this study, we measure opto-electronic properties including the mobility gap of μc-Si:H films in solar cells, as well as physical properties such as the crystalline fraction profile. The height distribution function of the ZnO substrates is obtained by AFM scans, which is used for optical simulation. All the parameters that we obtained from measurements were used as input parameters of a model in the ASA simulator. We obtained a good fit between measurements and simulations.

Abstract In this paper, steady segregation and slugging experiments are presented which have been carried out with a binary large-particle system representing the ash—coal/sorbent mixture in a fluidized-bed coal combustor. The slugging beds are characterized by dimensionless slug parameters which are obtained from visual bed-height measurements. The influence of the superficial gas velocity and the bed diameter on the extent of particle segregation is investigated. It is shown that a critical bed diameter exists above which segregation is nil. A simple segregation model is introduced proceeding with a proposed mechanism of segregation in slugging gas fluidized beds, which is based upon the visual observed flow of particles. The segregating particle distribution is characterized by one ‘Peclet-like’ dimensionless number, which is the ratio between the net particle convective and segregating flows and the dispersive solids flow in the bed.

To properly simulate the highly anisotropic turbulent engine flows, higher order turbulence model should be used to correctly reproduce flow physics inside the engine. The popular KIVA computer code has been modified to include the Reynolds-stress turbulence model (RSTM) for this purpose. The objective of this paper is to present our recent research on the use of RSTM and the KIVA code for engine flow simulation, which include gas turbine combustors and IC engines.

Gasification is considered to be a promising way to use biomass with high efficiency in combined heatand power production, for the production of second generation biofuels and in the chemical industry.Especially allothermal fluidized bed steam gasification produces a medium calorific, nitrogen free gassuitable for a variety of downstream processes. In general the raw product gas has to be cleaned fromcondensable hydrocarbons (tar) and conditioned (e.g. adjustment of the H2/CO-ratio) before downstreamuse. The operating conditions of the gasification reactor have a large impact on the quality of the productgas. Hence first steps to a product gas low in tar content can be undertaken directly in the reactor. In thisstudy the capability of influencing the tar content and gas composition by changing temperature (750?840 C), steam to biomass (S/B) ratio (0.8?1.2) and pressure (0.1?0.25 MPa) in an allothermal bubblingfluidized bed steam gasifier is investigated. It is found that rising temperature reduces the total tar contentand affects especially heterocyclic and light aromatic compounds. At atmospheric pressure the naphthalenecontent increases slightly with increasing temperature in contrary to pressurized gasificationwhere naphthalene decreases significantly with increasing temperature. An increase in the S/B ratio leadsto a decreasing total tar content, this tar reduction according to a higher steam content is higher at highertemperatures. Increasing pressure leads to increasing total tar content mainly due to naphthalene, theeffect is most distinct for low S/B ratios.

Abstract A simple way to improve its power coefficient (cp) of a Savonius turbine is by its installation above a cuboidal building as the building will redirect the wind and increase its speed significantly. To determine the gain, a turbine was constructed and installed above a bluff body and tow tested. Detailed measurements of vehicle speed and turbine power were made. Tow test speeds were 8, 10 and 12 m/s, while TSR range was 0.6–1.1. Most importantly, wind speed at the position beside and slightly above the turbine was measured during test runs. The cp calculated using this measured wind speed was used to validate CFD simulation results. Simulation results were also used to obtain the relationships between the wind speed of the free stream and at the anemometer position. Typically, wind speed at the anemometer position is about 9% higher than those of the free stream. These relationships were used to derive the free stream wind speed of each experimental run. The cp calculated using these derived free stream wind speeds showed an increase of 25% at 12 m/s wind speed, compared to the cp reported by previous researchers for a similar turbine operating in unmodified air flow.

Unsustainable production and consumption patterns in China's metropolitan areas have resulted in an increase in the production of waste materials for which local governments have to find solutions, one of which is the construction of waste incineration power plants. These plans often meet resistance from residents who fear negative environmental impacts. This paper presents an in-depth study of how Chinese local governments responded to an environmental conflict regarding the construction of an incineration power plant in Panyu district, Guangzhou City, PRC, using a typology to identify and categorize these government responses. The empirical analysis shows that local governments engage in various new ways of dealing with these conflicts. The article aims to enhance insight into the response of Chinese local governments to these conflicts and provide building block for further research.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Abstract The storage of heat in aquifers, also referred to as Aquifer Thermal Energy Storage (ATES), bears a high potential to bridge the seasonal gap between periods of highest thermal energy demand and supply. With storage temperatures higher than 50 °C, High-Temperature (HT) ATES is capable to facilitate the integration of (non-)renewable heat sources into complex energy systems. While the complexity of ATES technology is positively correlated to the required storage temperature, HT-ATES faces multidisciplinary challenges and risks impeding a rapid market uptake worldwide. Therefore, the aim of this study is to provide an overview and analysis of these risks of HT-ATES to facilitate global technology adoption. Risk are identified considering experiences of past HT-ATES projects and analyzed by ATES and geothermal energy experts. An online survey among 38 international experts revealed that technical risks are expected to be less critical than legal, social and organizational risks. This is confirmed by the lessons learned from past HT-ATES projects, where high heat recovery values were achieved, and technical feasibility was demonstrated. Although HT-ATES is less flexible than competing technologies such as pits or buffer tanks, the main problems encountered are attributed to a loss of the heat source and fluctuating or decreasing heating demands. Considering that a HT-ATES system has a lifetime of more than 30 years, it is crucial to develop energy concepts which take into account the conditions both for heat sources and heat sinks. Finally, a site-specific risk analysis for HT-ATES in the city of Hamburg revealed that some risks strongly depend on local boundary conditions. A project-specific risk management is therefore indispensable and should be addressed in future research and project developments.