Life cycle assessment of fuels for district heating: A comparison of waste incineration,biomass- and natural gas combustion

The aim of this consequential life cycle assessment (LCA) is to compare district heating based on waste incineration with combustion of biomass or natural gas. The study comprises two options for energy recovery (combined heat and power (CHP) or heat only), two alternatives for external, marginal electricity generation (fossil lean or intense), and two alternatives for the alternative waste management (landfill disposal or material recovery). A secondary objective was to test a combination of dynamic energy system modelling and LCA by combining the concept of complex marginal electricity production in a static, environmental systems analysis. Furthermore, we wanted to increase the methodological knowledge about how waste can be environmentally compared to other fuels in district-heat production. The results indicate that combustion of biofuel in a CHP is environmentally favourable and robust with respect to the avoided type of electricity and waste management. Waste incineration is often (but not always) the preferable choice when incineration substitutes landfill disposal of waste. It is however, never the best choice (and often the worst) when incineration substitutes recycling. A natural gas fired CHP is an alternative of interest if marginal electricity has a high fossil content. However, if the marginal electricity is mainly based on non-fossil sources, natural gas is in general worse than biofuels.     

Refractive index sensor based on the diamond like carbon diffraction grating

In this work we present an optical refractive index (RI) sensor based on the spectral analysis of anomalies in the optical response from the diffraction grating employing polarized polychromatic light. The sensor consists of holographic diffraction grating (period 423.5 nm) coated with a thin (110 nm) SiO_x doped diamond like carbon film (DLC) that defines sensitivity of the sensor as well as the range of the spectral analysis. The deposition of the DLC film (synthesized by the direct ion beam deposition from the hydrocarbon source) has influence on the shape but not on the position of the anomalies observed in the specular reflection spectrum. From the reflection spectra the RI dispersion curve of liquid analyte-water was obtained.     

Contribution of biomass burning to atmospheric polycyclic aromatic hydrocarbons at three European background sites

Radiocarbon analysis of atmospheric polycyclic aromatic hydrocarbons (PAHs) from three background areas in Sweden, Croatia, and Greece was performed to apportion their origin between fossil and biomass combustion. Diagnostic ratios of PAHs implied that wood and coal combustion was relatively more important in the northern European site, while combustion of fossil fuels was the dominant source of PAHs to the two central-southern European background sites. The radiocarbon content (delta14C) of atmospheric PAHs in Sweden ranged between -388 per thousand and -381 per thousand, while more depleted values were observed for Greece (-914 per thousand) and Croatia (-888 per thousand). Using a 14C isotopic mass balance model it was calculated that biomass burning contributes nearly 10% of the total PAH burden in the studied southern European atmosphere with fossil fuel combustion making up the 90% balance. In contrast, biomass burning contributes about 50% of total PAHs in the atmosphere at the Swedish site. Our results suggest that the relative contributions of biomass burning and fossil fuels to atmospheric PAHs may differ considerably between countries, and therefore, different national control strategies might be needed if a further reduction of these pollutants is to be achieved on a continental-global scale.     

Life margin assessment with Physics of Failure Tools application to BGA packages

Designers of electronic equipment are faced with the contractual obligation of guaranteeing that their products will fulfil the specifications on life duration. Classically, empirical methods based on databases and handbooks are used and features such as Mean Time Between Failure (MTBF) are provided. This paper presents how to use Physics of Failure (PoF) tools and results in order to provide the customer with a reliability feature, called life margin, based on Cycles To Failure (CTF) figures. The method defines and computes a life margin for 99% of the population in the given environmental life conditions. This feature is used to evaluate the different technological possibilities and decide the best trade-off to satisfy the customer’s requirement on life duration. The method has been applied to a given board and a given application, where the component, which limits reliability, has been identified as being packaged in a Ball Grid Array (BGA) package.     

Efficient collision detection for models deformed by morphing

Published online: 5 February 2003     

Indentation Thermal Shock Test for Ceramics

This paper presents an indentation-quench method to determine the resistance of ceramics to thermal cycling. The method defines a critical quench temperature difference, Δ T _c, based on a criterion which includes a minimum amount of crack growth and a minimum fraction of growing cracks. The method is applied to three different materials, which are ranked according to the individual values of Δ T _c. The variation of ΔT_c with different indentation loads and indentation positions is investigated. This technique uses a small number of specimens, avoids subsequent mechanical testing, and provides information about the ΔT C of the materials. The effect of repeated cycling on crack extension is also discussed.     

Discrete Element Method Simulation of Effect of Aggregate Shape on Fragmentation of Particle Composite

How primary particles affect the fragmentation of particle composites using discrete element method simulation is described. Disk‐shaped composite particles consisting of large aggregate particles embedded in a matrix of smaller sand particles have been impacted against a solid surface at range of collision velocities. The results have been analyzed to determine whether the shapes of the aggregates in the mixture have an influence on the fragmentation of particle composites. It has been identified that the fracture depends on the aggregate shapes of the particle composites. Liberation degrees and particle size distributions have also been found to be controlled by the shape of the primary particles. Particle shapes have a remarkable influence on the fragmentation behavior of the specimen, especially at lower velocities.