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Oscillating water column (OWC) devices, either fixed or floating, are the most common wave energy converter (WEC) devices. In this work, the fluid dynamic interaction between waves and a U-shaped OWC breakwater embedding a Wells turbine has been investigated through unsteady Computational Fluid Dynamic (CFD) simulations. The full-scale plant installed in the harbor of Civitavecchia (Italy) was numerically modeled. A two-dimensional domain was adopted to simulate the unsteady flow, both outside and inside the U-OWC device, including the air chamber and the oscillating flow inside the conduit hosting the Wells turbine. For the numerical simulation of the damping effect induced by the Wells turbine connected to the air chamber, a porous medium was placed in the computational domain, representing the conduit hosting the turbine. Several simulations were carried out considering periodic waves with different periods and amplitudes, getting a deep insight into the energy conversion process from wave to the turbine power output. For this purpose, the three main steps of the overall energy conversion process have been examined. Firstly, from the wave power to the power of the water oscillating flow inside the U-duct. Secondly, from the power of the oscillating water flow to the air pneumatic power. Finally, from the air pneumatic power to the Wells turbine power output. Results show that the U-OWC can capture up to 66% of the incoming wave power, in the case of a wave period close to the eigenperiod of the plant. However, only two-thirds of the captured energy flux is available to the turbine, being partially dissipated due to the losses in the U-duct and the air chamber. Finally, the overall time-average turbine power output is evaluated showing that it is strongly influenced by a suitable choice of the turbine characteristics (mainly geometry and rotational speed).

Environmental pollution damages public health and affects economic development. Environmental regulation is the main way for the government to solve environmental pollution. So what type of environmental regulation works better for public health and economic development? Can environmental regulation have an influence on economic development through public health? To solve these problems, this research uses China’s provincial panel data from 2013 to 2017 to divide environmental regulation into command-control policy tools and economic incentive policy tools and uses the mediating effect model to examine the relationship among environmental regulation, public health and economic development. The results show that: (1) There is a positive correlation between economic incentive policy tools and economic development; while no significant relationship between command-control policy tools and economic development is founded; (2) The relationship between command-control policy tools and public health is not significant, while the relationship between economic incentive policy tools and public health is positive; (3) Public health does not play a mediating role between command-control policy tools and economic development but plays a partial mediating role between economic incentive policy tools and economic development. Therefore, the government should strengthen the use of economic incentive policy tools to promote public health and sustainable economic development.

Islands are a constrained environment due to their geographical peculiarities and their land use accounting for, especially in the touristic locations, strong variability during the year. Consequently, the variation of energy demand to be met by variable renewable energy leads to a complex issue. This study aims at investigating the PRISMI Plus approach applied to the Island of Procida to drive the transition towards low-carbon and high-renewable energy system. The toolkit involves the analysis of local renewable energy potential, their potential matching of the energy demand, and the prioritization of the technological solutions to achieve the decarbonization targets set by the energy planning strategies. Three scenarios are designed for 2030 considering low, middle, and high penetration of renewable energy in the systems, results indicate that the amount of power production in low, middle, and high penetration of renewable energy scenarios are 0.18, 14.5, 34.57 GWh/year, respectively. The environmental and landscape constraints lead to a restricted set of available solutions. The decarbonization of the electricity supply is foreseen thanks to the available local solar resources plus the electrification of other sectors, i.e. heating by using Heat Pumps and transport by using Electric Vehicles.

A high-speed centrifugal pump is the key facility to deliver oil in an aero-engine. The stable operation is quite important to the safety of the engine. High-speed pump stability is essentially caused by the transient pressure pulsations excited by the complex flow within the pump, which needs to be clarified, especially for the pump under a rotating stall condition. In the current research, unsteady pressure pulsation and the corresponding flow distribution of the high-speed centrifugal pump are analyzed using the delayed detached-eddy simulation (DDES) method. Pressure signals within the pump are extracted by monitoring points. Results show that the dominant components in the pressure spectrum exhibit a significant difference at various flow rates, which locates at the blade passing frequency fBPF under the rated working condition and deviates to five times the shaft frequency (5fn) at the stalled condition. Such phenomenon is not observed in the normal centrifugal pump with low speed when using numerical and experiment methods, and usually the amplitude at fBPF reaches the maximum. Under the stalled condition, the component at 0.2fn is generated and considered as the rotating stall frequency, which is the same at different stalled flow rates. From velocity distribution, it is found that several blade channels are stalled as characterized by the large-scale separation bubbles, which are induced and triggered by the volute tongue.

High reactivity coke is beneficial for achieving low carbon emission blast furnace ironmaking. Therefore, the preparation of highly reactive ferro-coke has aroused widespread attention. However, the effects of the particle size of iron ore on the pyrolysis behaviour of a coal-iron ore briquette are still unclear. In this study, the effect of three particle sizes (0.50–1.00 mm, 0.25–0.50 mm and <0.74 mm) of iron ore on the thermal and kinetic behaviours of coal-iron ore briquettes were investigated by non-isothermal kinetic analysis. The results showed that the synergistic effect of iron ore and coal during coking mainly occurred during the later reaction stage (850–1100 °C) and smaller particle sizes of iron ore have a stronger synergistic effect. The addition of iron ore had little effect on T0 (the initial temperature) and Tp (the temperature at the maximum conversion rate) of briquette pyrolysis, however itgreatly affected the conversion rate and Tf (the final temperature) of the briquettes. T0 decreased with the decrease of iron ore particle sizes, while Tp and Tf showed opposite trends. After adding iron ore into the coal briquette, the reaction kinetics at all stages of the coal-iron ore briquettes changed. The weighted apparent activation energy of the caking coal (JM) briquette was 35.532 kJ/mol, which is lower than that of the coal-iron ore briquettes (38.703–55.627 kJ/mol). In addition, the weighted apparent activation energy gradually increased with decreasing iron ore particle sizes.

Considering the ice shedding phenomena on ice-covered outdoor insulators, this paper conducted the artificial experiments by using a five-unit suspension ceramic insulator string covered with wet-grown ice to investigate the effects of ice shedding on the icing discharge characteristics. According to IEEE Standard 1783/2009, the minimum flashover voltage (VMF), propagation of discharges to flashover and related leakage current (LC) were measured. It was found that VMF after ice shedding can be increased by about 17% as compared with that before ice shedding. The initiation and formation of discharge arcs across ice-free regions caused by ice shedding become difficult, showing an unstable propagating path, indeterminate arc shape and longer arc column. Although VMF under ice shedding conditions is higher than that without ice shedding, the fundamental component, and harmonics show lower amplitudes for the latter case. The ratios of harmonics to the fundamental are well in accordance with discharge characteristics during the flashover for which the ratios show a relatively stable varying tendency in the absence of ice shedding, but show changeable and indeterminate variation under ice shedding conditions. The obtained results are helpful to understand the icing state and its influence on surface discharges for preventing the icing flashovers.

Nuclear graphite plays a crucial role in thermal-spectrum thorium molten salt reactors (TMSRs) as both the neutron moderator and the construct for the coolant flowing channel. When subjected to irradiation and elevated temperatures, graphite components experience considerable deformation due to a combination of dimensional changes, thermal expansion, irradiation creep, elastic deformation, and changes in thermomechanical characteristics. The lifespan of the graphite component is a limiting factor in TMSR designs as it strongly correlates with the dimensional changes of the graphite. To evaluate the thermal and mechanical reactions of graphite component under TMSR core conditions, it is necessary to couple models of thermal-hydraulics, neutronics, and thermal-mechanics. This paper presents an enhanced methodology for analyzing the deformation of graphite components using the finite element method. Then, this method was applied to analyze a 10-year deformation history of a hexagonal prism assembly (HPA) and it was compared with the traditional hexagonal round channel assembly (RCA). The results demonstrate that the stress–strain field of both types of graphite components undergo significant variations with the increasing neutron fluence from irradiation. HPA graphite exhibits a slower deformation as compared to RCA graphite when subjected to identical operating conditions. In this case, HPA graphite has a lifespan of approximately 10 years, while RCA graphite lasts only 8.8 years.

Electricity transmission in a grid-connected system provides an effective solution to promoting clean energy accommodation. However, with arbitrary determination in current operation models, the clean energy utilization ratio (CEUR) is not satisfactory largely due to the lack of electricity curtailment (the electricity equivalent of clean energy curtailment) cost-dependent optimization. In this study, a curtailment cost-dependent multi-objective operation (CCMO) model was proposed to complementarily operate a grid-connected hybrid energy system, identify optimal CEUR, and thus maximally reduce electricity curtailment. The CCMO model centers on coupling the punishment cost of electricity curtailment with the multi-objective function defined as the total cost of each grid component. The CCMO model was solved to derive the optimal equilibrium solution determined based on multiple non-dominated solutions. A grid-connected hybrid energy system including the Yunnan, Guangdong, and Guangxi Power Grids was used to test the model performance. The results showed that the CCMO model’s CEUR was up to 100% at hourly scale and 96.9% on daily average, which were both significantly higher than those in the current operation models. Furthermore, the CCMO’s optimal equilibrium solution, i.e., respective minimum total cost of each grid component, can also identify optimal transmission schemes of the daily channel utilization to make the peak utilization hours largest.