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AbstractWe measured dissolved inorganic carbon (DIC) stable isotopes (813CDIC in ‰) of brine from an observation well within the first aquifer above the CO2 reservoir at the Ketzin pilot site, to test weather these can detect potential CO2 leakage. The monitoring revealed that DIC concentrations and 813CDIC values were masked by the used high alkaline drilling mud, even eight months after well development. However, subsequent changes in 813CDIC and DIC from of -27 ‰ and 165mg L−1 to -23.5 ‰ and 116mg L−1 reflect most likely a shift towards pristine values of the aquifer.

Abstract In present study, the concentrated photovoltaic thermal (PVT) has been proposed for higher thermal gain. The compound parabolic concentrator (CPC) has been also implemented with photovoltaic thermal (PVT) to increase higher input energy or solar radiation to get higher temperature. Here, water and dimethyl‐diphenyl silicone fluid (DMDP) have been considered as a fluid for proposed system. The comparative study of two fluids: water and DMDP has been presented. The maximum outlet fluid temperature of PVT (25% of collector area covered by PV module) - CPC collector have been optimized for 190 0C at mass flow rate=0.06 kg/s of this fluid. The area of receiver and aperture are 2 m2 and 4m2. The concentration ratio is 2. The area of semi-transparent (glass to glass) PV module is 0.5m2. The annual analysis has been carried out for a clear day condition for each month, New Delhi, India. Here, the net annual overall thermal energy and exergy have been found 304.46 kWh and 50.58 kWh, respectively. The electrical gain has also been found as 12.97 kWh. The proposed system has been designed for space heating or drying for many applications with self-sustainability feature.

9th International Renewable Energy Storage Conference, IRES 2015 / Edited by Peter Droege 9th International Renewable Energy Storage Conference, IRES 2015, Düsseldorf, Germany, 9 Mar 2015 - 11 Mar 2015; Engergy procedia, 73, 145-153 (2015). doi:10.1016/j.egypro.2015.07.662

AbstractThe paper is devoted to the identification of the metallic impurities in silicon wafers by using Temperature Dependent Lifetime Spectroscopy (TDLS). We consider the variation of all recombination mechanisms, intrinsic and extrinsic, to follow the variation of lifetime with the temperature. The extrinsic recombination mechanism is based on the standard Shockley-Read-Hall theory (SRH) [1], [2] and we simulated the variation of SRH lifetime for two impurities: gold and iron. The simulation results show that their SRH lifetime variations with the temperature are opposite and that the presence of a peak is characteristic of the impurity studied. Experimental measurements are displayed showing the identification of gold impurity by means of Phase-Shift TDLS (PS-TDLS) measurement. Thanks to these results, we demonstrate that PS-TDLS is an efficient method to identify gold and iron impurities at concentrations as low as 1.1010cm-3 for a doping level of 1.1015cm-3.

Abstract A state feedback nonlinear control design approach for the stabilization of chaotic phenomenon of Chua's circuit is presented in this paper. Following the feedback linearization based dynamic inversion method, the nonlinear dynamic behavior of the Chua's circuit is projected into an equivalent linearize dynamic error framework. Such design mechanism inherently suppresses the chaotic nature of Chua's circuit dynamics and enforces the system states (essentially capacitive voltage and inductive current) to asymptotically stabilize around equilibrium conditions. The stability of the controlled Chua's circuit is theoretically proven with Lyapunov theory. The simulation results show the effectiveness of the proposed method.

AbstractOne variation of exergy analysis, specific fuel consumption (SFC) analysis, was modified according the advanced exergy analysis, where exergy destructions within each component were split into endogenous/exogenous and avoidable/unavoidable parts, and by combining the energy-savings effects of each component. The modified analysis approach can help locate not only the weak points at the component level but also certain bottlenecks from the topology viewpoint, which may indicate adding or deleting some components, or enhancing the thermodynamic interactions between different process or subsystems. The modified approach was then applied to a conventional coal-fired power plant. The detailed spatial distribution of SFC within the current system at different partial-load conditions were deeply discussed at both component and process levels. Further splitting of SFC and the energy-saving effects of each process are also obtained and discussed. The results show that combustion and heat-and-mass transfer processes have the largest SFC. Heat-and-mass transfer process and the vent process have the greatest avoidable SFCs. The closer the component to the final product, the larger its influence on the overall performance, and, thus, a small improvement to these components may lead to a large reduction in the overall fuel consumption. More effective energy-saving measures of coal-fired power plants should focus on the match of heat transfer at intermediate-and-low temperature level and the breakage of the isolation of heat transfer subsystems, especially enhancing the interaction between the air preheating process and feedwater preheating process.

AbstractIn Rajasthan, the received solar irradiation is high, however, dry and dusty atmosphere are issues for harnessing of solar energy. The high speed wind characteristic of Rajasthan can initiate the saltation process, which in turn removes and carries dust from ground and deposit on collecting surfaces, such as, heliostats. This in turn reduces the collection and therefore the overall efficiency of concentrating solar thermal system. Dust deposition on flat mirror plates depends on various factors like heliostat field density, soil composition, atmospheric condition, mirror orientation, wind speed, plate material, height and structure of heliostat etc.In this article, experiments on dust deposition by wind onto a mirror simulating a heliostat model in wind tunnel are presented. Further, the performed analyses of dust deposition on single and multiple heliostats are described. These clearly indicate the influence of flow and position of heliostat. Furthermore, the obtained observations indicate a possible way of mitigating cleaning effort with localized deposition.

AbstractThe mineral fixation of CO2 has a significant but highly varying relevance in carbon capture and storage (CCS) models. One reason is the impact of the minerals’ concentrations, but the choice of the thermodynamic database on which the geochemical model calculations are based, has probably an equivalent or even more important impact on the model results.In this example, natural groundwater and a mineral assemblage consisting of calcite, dolomite, albite, and K-feldspar in two different concentrations were used to perform scenario simulations with the geochemical model PHREEQC. The four different thermodynamic datasets phreeqc.dat, wateq4f.dat, llnl.dat, and minteq.dat were used to calculate the amount of CO2 which could be fixed through the reactions with the described minerals.In the simulations using low reactive mineral concentrations (1–2.5 wt%), the range of the amount of fixed CO2 in the mineral and dissolved phases lies between 0.29 and 0.31 mol/kgw for the four chosen thermodynamic databases, which reflects the complete transformation of albite and K-feldspar to secondary minerals in all the simulations and only minor differences in the amounts of dissolved calcite and dolomite. On the other hand, the amount of fixed CO2 shows a variance of between 1.51 and 2.17 mol/kgw when using high reactive mineral concentrations (10–25 wt%). Especially the transformation of the K-feldspar depended significantly on the chosen thermodynamic database which affected the calculated product minerals of the reaction. Using the phreeqc.dat, the wateq4f.dat, and the minteq.dat databases, the amount of CO2 fixation due to its reaction with K-feldspar is up to six times larger than the amount calculated with the llnl.dat database.It is currently not clearly possible to decide which thermodynamic database should be used to receive the most realistic modeling results. Consequently, the uncertainty in the modeling results due to varying thermodynamic databases should be regarded in addition to the uncertainty resulting from factors like the heterogeneous distribution of mineral phases in the aquifers. It still has to be discussed whether a risk-based approach offers a secure way of modeling CCS related scenarios or whether worst-case scenarios have to be applied.