• Energy Research
• Closed Access close
• GB close
• BE close

Abstract Since the discovery of electricity, the demand for effective energy storage methods has increased. Energy storage devices are efficient tools used to manage power supply and produce resilient and cost-effective energy frameworks. Advanced technologies in modern economy and society require the application and design of inexpensive, highly efficient, and various infrastructures for energy storage systems. For instance, fuel cells, batteries, electrochemical capacitors, and conventional capacitors are used as energy storage devices because they can enhance energy or power densities. They can also supply energy within short or long periods. Their performances have also been improved. This review emphasizes carbon nanotubes as electrode materials for lithium-ion batteries and electrochemical capacitors. Different types of substrates and thin films may yield various structural and electrochemical properties of carbon nanotubes. This review also discusses their electrochemical performance observed through cyclic voltammetry and charge-discharge.

Abstract In a trial, 10 cucumber plants ( Cucumis sativus , variety ‘Virgo’ F 1 hybrids) were exposed continuously to a concentration of negative air ions exceeding 50 000/c.c. for a period of 40 days. The yield and productivity of the treated plants were compared with those of a control group of 10 plants in a matched-pairs experiment. An Index of Initial Vigour was developed to allow the subsequent production of the previously nursery-grown young plants to be related to their condition at the beginning of the trial. No effect on the total production or productivity at the end of the 40-day period was discerned, but the interim results (e.g. for the 10th day) are consistent with a model of reaction to stress governed by a negative-feedback mechanism. No harmful effects of the use of negatively ionised air were detected.

Abstract The direct carbon fuel cells with solid oxide electrolyte (DC-SOFC) and anodes deposited by inject printing (EM/DCIJP) were studied. The cells were fed with carbon fuel obtained by the direct RF plasma splitting of methane. Since the (EM/DCIJP)M/DCIJP technology allows easy modification of electrode material, the effect of Cu addition to the Ni–YSZ anode was investigated. The significant improvement of the cell performance with the new anode was observed.

AbstractIn this manuscript we reply to the issues raised by G. Bagheri and C. Bonadonna in their comment 2019JB017697. We reiterate our definition of particle Reynolds number, which is appropriate for our data set of experimental measurements, and we show that the poor performance of Bagheri and Bonadonna (2016, https://doi.org/10.1016/j.powtec.2016.06.015) model discussed in Dioguardi et al. (2018, https://doi.org/10.1002/2017JB014926) was mainly due to the typos in the equations presented in their original manuscript. We believe that the iterative methodology for calculating the drag coefficient is not strictly necessary for our data set. In this reply, however, we also include results of the intercomparison study among different drag models using the iterative methodology. Results show that the performance of the different drag models considered in the intercomparison study is not significantly affected by the employed methodology (direct vs. iterative) and that, regardless the employed methodology and unlike what has been stated in the comment 2019JB017697, our model has the best performance in reproducing the experimentally measured terminal velocities.

Abstract Various assumptions are often made to model turbomachinery bladed assemblies. In particular, the cyclic symmetry of single rotor stages, and dynamically independence of isolated rotor stages are frequently used. The first assumption enables a drastic reduction of the required computational resources by considering only one sector instead of the entire assembly to model and analyze the dynamic behavior of the complete structure. However, small random blade-to-blade structural variations, known as mistuning, exist due to manufacturing tolerances, etc. and significantly affect the dynamic behavior of bladed disks. The second assumption also reduces the needed computational resources and time. However, ignore inter-stage coupling does not always describe accurately the disk or drum flexibility especially at the inter-stage boundaries. In this work, the component mode mistuning method is used for multi-stage assemblies to create a mistuning identification approach. An experimental modal analysis is performed on a two-stage monobloc academic bladed drum. The frequency response function is measured using a base excitation with an electrodynamic shaker and one measurement point per blade of each stage is used. The approach is used to identify mistuning in a multi-stage rotor. Numerical and experimental results are presented. Results show that the proposed approach is effective even for modes which are multi-stage.

This study is to our knowledge the first to describe the effect of a Gas-Gas Heater (GGH) of a coal fired power plant's has on (i) the H2SO4 concentration and (ii) the particle/aerosol number concentration and particle size distribution present in the flue gas. In the absence of a GGH, homogenous nucleation takes places inside the Wet Flue Gas Desulphurisation (WFGD) converting the gaseous H2SO4 into aerosol H2SO4. This leads to a high aerosol number concentration behind the WFGD with 80% of the aerosols being smaller than 0.02 μm. This implies that an amine based carbon capture (CC) installation treating this flue gas can suffer from amine mist formation due to the high amount of available nuclei (i.e., H2SO4 aerosols) resulting in high amine emissions. In contrast, in the presence of a GGH not only 70% of the H2SO4 is removed from the flue gas (measured at the Nijmegen powerplant), but also homogenous nucleation in the WFGD is prevented resulting in low particle number concentrations. The flue gas leaving the GGH will not create any mist formation issues in an amine based CC installation due to the low amount of nuclei present in the flue gas. It is not the reduction in H2SO4 concentration by 70% inside the GGH as such that prevents mist formation but absence of H2SO4 in its aerosol form. These results are most likely quite widely transformable to other power plants that burn low sulfur coal i.e., around 0.7 weight%. This information will serve future pilot and demo CC installation around the world; in particular when retrofitted on power plants that have a GGH.

Use of a pilot-scale fixed-film bioreactor was investigated for remediation of bromate contamination within groundwater. Bromate reduction with stoichiometric production of bromide was observed, providing supporting evidence for complete reduction of bromate with no production of stable intermediates. Reduction of 87-90% bromate from an influent concentration of 1.1 mg L(-1) was observed with retention times of 40-80 h. Lower retention times led to decreases in bromate reduction capability, with 11.5% removal at a 10 h retention time. Nitrate reduction of 76-99% from a 30.7 mg L(-1) as NO(3)(-) influent was observed at retention times of 10-80 h, although an increase in nitrite production to 2.7 mg L(-1) occurred with a 10 h retention time. Backwashing was not required, with the large plastic packing media able to accommodate biomass accumulation without decreases in operational efficiency. This study has provided proof of concept and demonstrated the potential of biological bromate reduction by fixed-film processes for remediation of a bromate contaminated groundwater source.

Abstract The almost two-dimensional steady-state rates of heat loss from arrays of uniformly-spaced vertical rectangular fins, extending upwards—in otherwise stagnant air—from horizontal heated bases, have been measured. (The vertical air gaps between the fins were closed at their sides, by insulated vertical end-barriers.) The effects of various combinations of height, thickness and spacing of the fins, for different base temperatures (in the range 40 to 100°C), have been studied. For the configuration considered, in a normal ambient environment (∼ 20°C), there is an optimal fin spacing (⋍ 16 mm) corresponding to the greatest steady-state rate of free convective/conductive heat loss through the air from the finned system, and this is almost independent of the temperature of the heat exchanger base (in the range 40–100°C). At this optimal spacing for base temperatures not greater than 50°C, the convective/conductive heat transfer rate from the array increases with the fin height up to about 60 mm, so that it would be uneconomic to employ taller fins if convection/conduction is dominant compared with radiation. If the radiation contribution is also considered, then the optimal spacing corresponding to the maximum total steady-state rate of heat loss through the air is somewhat less than the optimal spacing for which, under the same temperature conditions, the maximum steady-state rate of convective/conductive heat leak occurs. The greater the emissivity of the heat exchanger surfaces, the narrower the optimal uniform gaps between the fins. A two-dimensional finite-difference computer program has been composed to predict the temperature distribution throughout the heat exchanger for a stipulated ambient environmental temperature and experimentally-determined distribution of the heat transfer coefficient over the surfaces of the exchanger. This enables, for instance, any hot spots to be located prior to a proposed design being built.