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Abstract Energy storage has the potential to reduce the fuel consumption of ships by loading the engine(s) more efficiently. The exact effect of on-board energy storage depends on the ship functions, the configuration of the on-board power system and the energy management strategy. Previous research in this area consists of detailed modelling, design, and comparisons of specific on-board power systems for explicitly defined operational profiles. The necessary inputs for these studies are rarely known initially however, since the effect of energy storage on the fuel consumption is not necessarily always positive, it is essential to know the limitations of fuel savings obtained by an on-board energy storage early in the design stage. To that effect, the paper proposes a set of algebraic formulas for the equivalent specific fuel consumption of on-board power systems equipped with electrical energy storage, which give a quick estimation of the maximum fuel savings obtainable. Depending on the specific fuel consumption of the prime mover, the loading point of the system and the use scenario of the battery, relative efficiency improvements can vary between −48% and 57%. A set of design guidelines is also proposed based on the obtained results.

This research was performed to study the anode reaction in a molten carbonate fuel cell. Chronoamperometry experiments and impedance measurements were carried out at gold and nickel flag-type electrodes in a 62 mole percent (m/o) Li{sub 2}CO{sub 3}/38 m/o K{sub 2}CO{sub 3} eutectic carbonate mixture at 923 K as a function of gas composition (H{sub 2}/CO{sub 2}/H{sub 2}O), and as a function of temperature between 823 and 1073 K. The i {minus} {radical}t extrapolation technique, generally applied to evaluate chronoamperometry results, is shown to yield systematic errors for the hydrogen oxidation studies in molten carbonates. A direct fit of the Gerischer-Vielstich relation yields more reliable results for gold. The current responses on Ni cannot be described by the Gerischer-Vielstich relation. The high reaction orders for hydrogen (0.7 to 1.0), medium for carbon dioxide (order 0.5), and the low or even negative reaction order for water (0 to {minus}0.25), indicate the hydrogen oxidation follows a Volmer-Heyrovsky-type mechanism on gold flag electrodes. The reaction rate at a nickel electrodes was found to be too high to be studied accurately using impedance measurements and chronoamperometry on flag electrodes. In spite of the poor accuracy reaction orders indicate that a final chemical reaction ismore » the rate-determining step in the reaction mechanism on nickel. The activation energy for the exchange current density was found to be in the order of 80 kJ/mol with a tendency to be higher for the gases richer in hydrogen. The activation energy for the Warburg coefficient (diffusion) was found to be about {minus}15 kJ/mol.« less

The EU Project AquaTerra generates knowledge about the river-soil-sediment-groundwater system and delivers scientific information of value for river basin management. In this article, the use and ignorance of scientific knowledge in decision making is explored by a theoretical review. We elaborate on the 'two-communities theory', which explains the problems of the policy-science interface by relating and comparing the different cultures, contexts, and languages of researchers and policy makers. Within AquaTerra, the EUPOL subproject examines the policy-science interface with the aim of achieving a good connection between the scientific output of the project and EU policies. We have found two major barriers, namely language and resources, as well as two types of relevant relationships: those between different research communities and those between researchers and policy makers. © 2007 Elsevier Ltd. All rights reserved.

Abstract Poor reconstitution of food powders is a defect that hampers the development of novel dehydrated food products. In order to improve the quality of a powdered food during the development stages, a better understanding of how the powder behaves upon rehydration is vital. However, common methods to follow powder reconstitution, e.g. conductimetry, can yield uninterpretable results, especially if a powder does not completely wet, sink, disperse and dissolve. To circumvent this problem, a mapping approach was developed to describe the powder behavior depending on the combinations of variables. To construct such a map, powders are reconstituted using a transparent vessel, and an optical recording of each trial is utilized to describe if the process was ‘normal’, i.e. if wetting/sinking, dispersing, and dissolving of the particles occur readily and more or less sequentially, or if it was limited by poor powder sinking, by sedimentation, slow material dissolution, or lump formation. By mapping the behaviors at different combinations of temperatures and agitation speeds, various regimes of limiting reconstitution behavior can be identified. In the current study, rate-limiting regime maps of four types of maltodextrin (Glucidex DE21, IT21, DE6, and IT6) are constructed and compared in order to investigate the influence of molecular weight, particle size, water temperature, and agitation speed on the rehydration of a water-soluble amorphous food powder. Such a study would not have been possible using conventional techniques, as powder reconstitution is not always complete.

Nedstack manufactures and commercialises PEM fuel cell stacks for a wide variety of applications, from backup power to transportation, with more than 1000 PEM fuel cell stacks sold. The company also has extensive system integration experience, including the installation and operation of a 70 kW power plant at a chlor-alkali factory in the Netherlands, and a 1 MW unit in operation at a Solvay chemical plant in Belgium.

Intrinsic stresses in bondpads may lead to early failure of IC's. In order to determine the intrinsic stresses in semiconductor structures, a new procedure is set up. This procedure is a combined experimental/numerical approach which consists of the following steps: First, a conductive gold layer (20 nm thickness) is deposited on the power line surface; subsequently markers (small holes) for Digital Image Correlation (DIC) purposes are added using a focused ion beam (FIB). Next, a scanning electron microscope (SEM) is used to image the original ('before') surface. The FIB is then used to mill a slot into the surface to release the intrinsic stresses, which results in contraction of the surface. Finally, a SEM image is made of the contracted ('after') surface. DIC is used to determine in-plane displacements due to FIB milling. DIC performance was verified by the traditional strain gauge approach. An inverse Finite Element (FE) modelling approach is used to determine the before mentioned stresses. The slot displacements found with DIC are inserted into an FE model of the product. Stresses which now emerge from closing the (virtual) FIB slot correspond to the intrinsic stresses which were originally present in the product. Favorable positions for FIB milling are near the edge of the structure and displacements are determined to be in the nanometer range. This indicates a presence of substantial (50-250 MPa) compressive stresses. Displacements near the center of the structure appear to be smaller than DIC resolution. ©2010 IEEE.

Abstract A particle velocity meter is described for the measurement of local solids velocities. Depending on the impact of the particles, individual particle momentums or local mass flow rates can be measured. In the latter case the meter has to be calibrated as a function of the porosity. The particle velocity meter has been used successfully in gas-solids fluidized beds.

Abstract Knowledge of flame responses to acoustic perturbations is of utmost importance to predict thermoacoustic instabilities in gas turbine combustors. However, measuring transfer functions linking acoustic quantities upstream and downstream of flames is very challenging in practical systems and these measurements can significantly deviate from state-of-the-art models. Moreover, there is a lack of studies investigating the effect of hydrogen enrichment on the response of natural gas (NG) flames. In this work, measurements of flame transfer matrices (FTM) of turbulent H2/NG flames in an atmospheric combustor featuring an axial swirler burner have been performed, allowing us to unravel the transition between FTM in fully premixed (FP) and in technically premixed (TP) conditions. Furthermore, imaging of OH* chemiluminescence and OH-Planar Laser Induced Fluorescence are obtained for characterizing the topology of the flame for varying H2 fraction and mixing conditions. Transfer matrices are measured using the multi-microphone method for H2 fractions ranging from 12% to 43% in power. Afterwards, the flame transfer functions (FTF), which linearly relate the coherent fluctuations of the heat release rate to the acoustic velocity oscillations, are obtained from the FTM by using the Rankine-Hugoniot jump conditions across the flame. Using the OH* chemiluminescence intensity as a surrogate for the heat release rate, the FTF based on this optical measurement is also extracted and compared to the one exclusively obtained with the multi-microphone method. As expected, the two different methods are in very good agreement for the FP case and significantly differ for the TP case. Indeed, chemiluminescence fluctuations cannot be directly linked to heat release rate fluctuations when the acoustic forcing induces equivalence ratio fluctuations at the flame, making the optical method unusable for TP configurations. We also show that the two methods agree in the high end of the explored excitation frequency range and we provide an explanation to this intriguing finding. Moreover, we investigate the sensitivity of the FTM measurement to the estimate of the speed of sound in the rig in FP conditions. Finally, the measured FTFs are fitted with FTF models based on multiple distributed time delays. This allows us to explain the frequency dependence and the hydrogen fraction dependence of the gain and the phase in FP and TP conditions.