Global Change Abstracts The Swiss Contribution - SCNAT

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196 Global Change Abstracts – The Swiss Contribution | Mitigation and Adaptation Technologies identify improvements on the basis of accelerated combustion caused by the hydrogen as well as the reduced gas exchange losses due to EGR and associated less required throttling for a given engine output. The best combinations of EGR rate, hydrogen-fraction in the fuel and ST exhibited optimal in- cylinder pressure characteristics accompanied by moderate combustion peak temperatures and low expansion cylinder temperatures. (c) 2007 International Association for Hydrogen Energy. International Journal of Hydrogen Energy, 2007, V32, N14, SI, SEP, pp 3073-3083. 08.1-418 Multi-regional long-term electricity supply scenarios with fusion Gnansounou E, Bednyagin D Switzerland Energy & Fuels , Engineering This paper examines the global potential for deployment of fusion power through elaboration of multi-regional long-term electricity market scenarios for the time horizon 2100. The probabilistic simulation dynamic programming model PLANELEC-Pro was applied in order to determine the expansion plans of the power generation systems in different world regions that adequately meet the projected electricity demand at minimum cost given the quality-of-service and CO 2 emissions constraints. It was found that the deployment of total 330 - 950 GWe of fusion power world-wide could allow for reducing 1.8 - 4.3 % of global CO 2 emissions from electricity generation, while entailing a slight increase of levelized system electricity cost (by approx. 0.1 - 0.4 is an element of(cents)/ kWh). By the end of century, the estimated share of fusion in regional electricity mixes varies from 1.5 to 23% depending on the region. It is concluded that economic analysis of fusion technology should be complemented with the evaluation of the whole fusion RTD program in terms of social rate of return taking into account its external “spillover” benefits. Fusion Science and Technology, 2007, V52, N3, OCT, pp 388-392. 08.1-419 Carbothermal reduction of alumina: Thermochemical equilibrium calculations and experimental investigation Halmann M, Frei A, Steinfeld A Israel, Switzerland Engineering , Energy & Fuels The production of aluminum by the electrolytic Hall-Heroult process suffers from high energy requirements, the release of perfluorocarbons, and vast greenhouse gas emissions. The alternative carbothermic reduction of alumina, while significantly less energy- intensive, is complicated by the formation of aluminum carbide and oxycarbides. In the present work, the formation of Al, as well as Al 2OC, Al 4O 4C, and Al 4C 3 was proven by experiments on mixtures of Al 2O 3 and activated carbon in an Ar atmosphere submitted to heat pulses by an induction furnace. Thermochemical equilibrium calculations indicate that the Al 2O 3-reduction using carbon as reducing agent is favored in the presence of limited amounts of oxygen. The temperature threshold for the onset of aluminum production is lowered, the formation of Al 4C 3 is decreased, and the yield of aluminum is improved. Significant further enhancement in the carbothermic reduction of Al 2O 3 is predicted by using CH 4 as the reducing agent, again in the presence of limited amounts of oxygen. In this case, an important by-product is syngas, with a H-2/CO molar ratio of about 2, suitable for methanol or Fischer-Tropsch syntheses. Under appropriate temperature and stoichiometry of reactants, the process can be designed to be thermo-neutral. Using alumina, methane, and oxygen as reagents, the co-production of aluminum with syngas, to be converted to methanol, predicts fuel savings of about 68% and CO 2 emission avoidance of about 91%, vis-A-vis the conventional production of Al by electrolysis and of methanol by steam reforming of CH 4. When using carbon (such as coke or petcoke) as reducing agent, fuel savings of 66% and CO 2 emission avoidance of 15% are predicted. Preliminary evaluation for the proposed process indicates favorable economics, and the required high temperatures process heat is readily attainable using concentrated solar energy. Energy, 2007, V32, N12, DEC, pp 2420-2427. 08.1-420 Secondarv effects of catalytic diesel particulate filters: Copper- induced formation of PCDD/Fs Heeb N V, Zennegg M, Gujer E, Honegger P, Zeyer K, Gfeller U, Wichser A, Kohler M, Schmid P, Emmenegger L, Ulrich A, Wenger D, Petermann J L, Czerwinski J, Mosimann T, Kasper M, Mayer A Switzerland Engineering, Meteorology & Atmospheric Sciences, Human & Public Health Potential risks of a secondary formation of polychlorinated dibenzodioxins/furans (PCDD/Fs) were assessed for two cordierite- based, wall-through diesel particulate filters (DPFs) for which soot combustion was either catalyzed with an iron- or a copper-based fuel additive. A heavy duty diesel
Global Change Abstracts – The Swiss Contribution | Mitigation and Adaptation Technologies engine was used as test platform, applying the eightstage ISO 8178/4 C1 cycle. DPF applications neither affected the engine performance, nor did they increase NO, NO 2, CO, and CO 2 emissions. The latter is a metric for fuel consumption. THC emissions decreased by about 40% when deploying DPFs. PCDD/F emissions, with a focus on tetra- to octachlorinated congeners, were compared under standard and worst case conditions (enhanced chlorine uptake). The iron-catalyzed DPF neither increased PCDD/F emissions, nor did it change the congener pattern, even when traces of chlorine became available. In case of copper, PCDD/F emissions increased by up to 3 orders of magnitude from 22 to 200 to 12 700 pg I-TEO./L with fuels of < 2, 14, and 110 µg/g chlorine, respectively. Mainly lower chlorinated DD/Fs were formed. Based on these substantial effects on PCDD/F emissions, the copper-catalyzed DPF system was not approved for workplace applications, whereas the iron system fulfilled all the specifications of the Swiss procedures for DPF approval (VERT). Environmental Science Technology, 2007, V41, N16, AUG 15, pp 5789-5794. 08.1-421 Towards multi-source multi-product energy systems Hemmes K, Zachariah Wolff J L, Geidl M, Andersson G Netherlands, Switzerland Energy & Fuels , Engineering , Modelling Historically, energy conversion was seen as a onedimensional system, in the sense that one form of energy was converted into another form. Byproducts of the conversions such as heat were disregarded and/or treated as waste. Cogeneration is a first step towards system improvement since the ‘waste heat’ is recovered and used as a valuable product. Trigeneration systems, which take the concept even further, are proposed for the simultaneous production of chemicals, power, and heat, and are integrated into larger systems, such as chemical plants, to achieve increased overall performance. In these systems electricity may just be a by-product. However, co- and trigeneration systems are still characterized by a single input. In this paper we further extend this concept and explore the potential role of multi-source multiproduct (MSMP) systems. International Journal of Hydrogen Energy, 2007, V32, N10-11, JUL-AUG, pp 1332-1338. 197 08.1-422 An energy management method for the food industry Müller D C A, Marechal F M A, Wolewinski T, Roux P J Switzerland Economics , Energy & Fuels , Engineering This article presents a method aimed at tracking energy saving opportunities in the food-processing industry through a combination of top-down and bottom-up approaches. On the one hand, the top-down modelling method aims at correlating the measured energy consumptions with the final products and auxiliaries as well as at allocating the energy bills among major consumers. This approach will, therefore, set priorities for energy saving actions. On the other hand, the bottom-up approach, which is based on the thermodynamic requirements of the process operations, is used to define the energy requirements of these consumers. A comparison of the measured consumptions and the energy requirements enables the identification of energy saving opportunities. In the case study presented in this article, these opportunities have been evaluated using thermo-economic modelling tools and range from good housekeeping measures and optimised process operations to energy saving investments. Applied Thermal Engineering, 2007, V27, N16, NOV, pp 2677-2686. 08.1-423 H 2O-splitting thermochemical cycle based on ZnO/Zn-redox: Quenching the effluents from the ZnO dissociation Müller R, Steinfeld A Switzerland Geochemistry & Geophysics , Engineering The production of zinc by thermal dissociation of zinc oxide has been experimentally investigated in the range of 1700-1950 K using a 10 kW solar chemical reactor directly exposed to concentrated solar radiation. The gaseous products Zn(g) and O-2 exiting the reactor underwent rapid cooling by flowing through an annular water-cooled quench unit and by injection of Ar. XRD analysis along with SEM and TEM images of the solid products deposited at the quenching zone revealed the formation of spherical particles of sizes in the 0.1-30 µm range, with their surface covered with smaller edged structures, which are characteristic of Zn(g) undergoing condensation followed by Zn(l)/Zn(s) oxidation and coalescence. Chemical Engineering Science, 2008, V63, N1, JAN, pp 217-227.
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