Energy Generation Applications Research Articles

Turbulent flow characteristics in an 84-pin rod bundle for typical and damaged spacer grids

Hexagonal rod bundles arranged in a tightly packed triangular lattice are extensively used for heat transfer and energy generation applications. Staggered spacer grids are used to maintain the structural integrity of gas-cooled fast reactor (GFR) fuel assemblies, while inducing localized turbulence in flow. Damage to these spacer grids results in a disruption of flow fields within these hexagonal fuel bundles. Experimental flow visualizations are critical to identify the differences in local flow properties that the structural damage may cause. This experimental research investigates the flow-field characteristics at a near-wall and center plane in a prototypical 84-pin GFR fuel assembly. Newly installed typical spacers and spacers subject to naturally occurring damage due to material degradation over prolonged experimentation were investigated. Velocity fields were acquired by utilizing the matched-index-of-refraction method to obtain time-resolved particle image velocimetry measurements for a Reynolds number of 12 000. Reynolds decomposition statistical results divulged differences in the time-averaged velocity, velocity fluctuations, flow anisotropy, and Reynolds stress distributions. Galilean decomposition demarcated the influence of spacer grid damage on the velocity fields. To extract turbulent structures and elucidate mechanisms of flow instabilities, proper orthogonal decomposition analysis was employed. Reduced order flow reconstructions enabled the application of vortex identification algorithms to determine the spatial and statistical characteristics of vortices generated. This research work provides unique experimental data on the spacer grid condition-dependent flow. The results offer a deeper understanding of fluid dynamics behavior to support GFR rod bundle design efforts and computational fluid dynamics model validation.

Fuel-cell power conversion system based on double dual topologies

This article describes (and demonstrates through experiments) the feasible implementation of a power conversion system designed for a Fuel Cell (FC) application in renewable energy generation. The system is designed to be powered by an FC stack, which output is a low (in amplitude) non-regulated dc voltage, with a relatively wide range of variation. The system must boost the voltage from the power source to an internal 200 V dc bus, while the final output voltage (after the inversion) must be provided at a level of 120 V ac. The main feature of the described system is that it is based on double-dual converters, a family of converters with several advantages such as automatic power balance and large voltage gain; this leads to a good performance and power quality. The system is based on a double dual boost converter to increase and regulate the dc-voltage, and a double dual buck converter, to invert the dc-voltage and provide an ac-voltage as output. The article shows the system's feasibility through theoretical analysis and provides experimental results with an FC stack. Experimental results are provided to demonstrate the feasibility of the proposed system.

Striking dual functionality of iron pyrite-graphene oxide nanocomposites in water treating and water splitting reactions

In this study, we report a simple one-pot solvothermal route of FeS2 (pyrite)/GO (graphene oxide) nanocomposites that exhibit outstanding physicochemical properties as efficient catalysts towards dual functionality of water treating and water-splitting applications. The FeS2/GO (FSG) nanocomposites of varying FeS2 to GO weight ratios were prepared and characterized for physicochemical properties. The introduction of GO mediated the morphology and structural properties to aligned FeS2 spherical nanoparticles within the GO network compared with pristine FeS2 cubical nanostructures. In water treatment applications, the synthesized FSG nanocomposite with FeS2 to GO ratio of 4:3 was highly effective for the complete degradation (∼99%), significant mineralization (>70%), and complete detoxification of antibiotic amoxicillin (AMCT) under the optimal solar-Fenton treatment when compared to bare FeS2, and other FSG nanocomposites. Radical scavenging experiments, leaching profile for iron (Fe) species (total Fe, Fe(II), and Fe(III)), decomposition profile of hydrogen peroxide, and HO• generation in the reaction medium helps to postulate the possible reaction mechanisms for AMCT degradation. The greatly enhanced catalytic performance of FeS2/GO was correlated with efficient recycling of Fe(II)/Fe(III), higher solar-light absorptivity due to the GO existence, and synergistic coupling of FeS2 and GO evidenced through the strong formation of Fe-O chemical bonds as confirmed by Fourier-transform infrared spectroscopy. Finally, the nanocomposites achieved enhanced apparent quantum efficiency for hydrogen generation through a water-splitting reaction. The reaction mechanism of FSG nanocomposite for water-splitting was proposed accordingly. Overall, this work could provide new insights for developing potential nanocomposite materials for widespread energy generation and environmental remediation applications.

Teaching Metal-Organic Frameworks to Conduct: Ion and Electron Transport in Metal-Organic Frameworks

Metal-organic frameworks (MOFs) are an expansive class of extended solids formed by coordination bonding between metal ions/clusters and organic ligands. Although MOFs are best known for their intrinsic porosity, they are now also emerging as an unusual set of porous, electrical, and ionic conductors that could address a number of applications in energy storage and generation. In this review, we focus on intrinsic ionic conductivity in MOFs and outline approaches for achieving high ionic conductivities. First, we highlight the use of noncoordinating acidic groups to integrate anions into MOF organic linkers. Next, we discuss the use of open metal sites to anchor anions and generate mobile ions. Then, we discuss the use of postsynthetic modifications to graft anions onto ligands and defect sites. Finally, we outline several unexplored approaches to improving ionic conductivity in MOFs and highlight several potential new applications.

Liquefied natural gas exports from Canada to China: An analysis of internationally transferred mitigation outcomes (ITMO)

The ever-increasing anthropogenic greenhouse gas (GHG) emissions worldwide make it quite challenging to meet country-specific Nationally Determined Contributions (NDC) targets. Therefore, it is evident that the existing emissions abatement measures need to be taken a step further. Internationally Transferred Mitigation Outcomes (ITMOs) are allowed in Article 6.2 of the Paris Agreement as a cooperative approach to achieving NDC goals. There is a potential to create ITMOs between Canada and China by replacing coal use in China with British Columbia (BC)'s liquefied natural gas (LNG) supply. Replacing coal with LNG in energy generation applications is a promising approach to mitigate emissions. With global and national pressures to reduce emissions, China has created a market for LNG imports to cater to its rising natural gas (NG) consumption due to the coal-to-gas source switching strategy. However, the terms under Article 6.2 requires generated ITMOs to ensure environmental integrity, support sustainable development goals, and have a robust accounting system. Therefore, the current study aims to quantify the life cycle environmental outcomes of generating ITMOs by exporting LNG from BC to Chinese end-users while integrating uncertainties and to provide policy recommendations in adherence with the requirements of Article 6.2. Different LNG export scenarios were generated in the study and environmental impacts of each scenario were assessed and compared using a life cycle assessment (LCA) framework developed by the authors. Sensitivity and uncertainty analyses were conducted to understand the impacts created by the data uncertainties in the final result. By replacing conventional coal with NG, approximately 40–45% and 26%–32% emissions reductions can be obtainable for Chinese textile and chemical industries, respectively. The highest emissions reduction of approximately 60% was observed when coal is replaced with NG for district heating. The life cycle emissions (LCE) quantification framework provided in the study provides stakeholders with a systematic approach to determine the total GHG emissions and emissions reduction potential of different LNG export scenarios.

Engineering the Defects and Microstructures in Ferroelectrics for Enhanced/Novel Properties: An Emerging Way to Cope with Energy Crisis and Environmental Pollution.

In the past century, ferroelectrics are well known in electroceramics and microelectronics for their unique ferroelectric, piezoelectric, pyroelectric, and photovoltaic effects. Nowadays, the advances in understanding and tuning of these properties have greatly promoted a broader application potential especially in energy and environmental fields, by harvesting solar, mechanical, and heat energies. For example, high piezoelectricity and high pyroelectricity can be designed by defect or microstructure engineering for piezo‐ and pyro‐catalyst, respectively. Moreover, highly piezoelectric and broadband (UV–Vis–NIR) light‐responsive ferroelectrics can be designed via defect engineering, giving rise to a new concept of photoferroelectrics for efficient photocatalysis, piezocatalysis, pyrocatalysis, and related cocatalysis. This article first summarizes the recent developments in ferroelectrics in terms of piezoelectricity, pyroelectricity, and photovoltaic effects based on defect and microstructure engineering. Then, the potential applications in energy generation (i.e., photovoltaic effect, H2 generation, and self‐powered multisource energy harvesting and signal sensing) and environmental protection (i.e., photo‐piezo‐pyro‐ cocatalytic dye degradation and CO2 reduction) are reviewed. Finally, the outlook and challenges are discussed. This article not only covers an overview of the state‐of‐art advances of ferroelectrics, but also prospects their applications in coping with energy crisis and environmental pollution.

A Single-Switch High Step-Up DC–DC Converter Based on Three-Winding Coupled Inductor and Pump Capacitor Unit

In this article, a novel single-switch, high step-up dc–dc converter based on three-winding coupled inductor and voltage multiplier circuit (VMC) is proposed. And on this basis, pump capacitor unit (PCU) is integrated to achieve a very high voltage gain. The converter makes full use of the advantages of three-winding coupled inductor, skillfully combines it with the VMC, and integrates the PCU that can be used in superposition to further improve the voltage gain. The voltage stress of the switch is reduced by using a passive clamping circuit to recycle the leakage energy of the coupled inductor. The operating principle and steady-state analysis of the presented converter in continuous conduction mode are introduced in detail. Moreover, the comparative analysis shows that under the same conditions, the proposed converter has higher voltage gain and lower voltage stress than others. Several advantages include high voltage gain, low voltage stress, low turns ratio of coupled inductor, and high conversion efficiency, make the proposed converter very suitable for new energy generation applications, such as photovoltaic systems. Finally, the feasibility of the proposed converter and the correctness of theoretical analysis are verified by a 500-W prototype at 50 kHz switching frequency.

Modification of optical emission in electrospun PVA nanofibers: effect of cerium oxalate crystals doped with neodymium and praseodymium

ABSTRACT Development of functional nanofibers from transparent polymer systems attracted attention of researchers recently. Doping of functional nanoparticles in a suitable polymer matrix in the nanofiber forms enables them as active materials for photonic, electronic and for energy generation applications. Cerium oxalate crystals in its pure and rare earth-doped form are found to be a potential system for such investigations. Cerium oxalate crystals and its praseodymium (Pr3+)- and neodymium (Nd3+)-doped forms were synthesized by single diffusion gel growth method. These crystals, in the powder form, were incorporated in PVA matrix to form nanofibers (NFs) by electrospinning technique. Morphological studies were done by scanning electron microscopy (SEM). From the X-ray powder diffraction analysis, monoclinic structure of Ce2(C2O4)3 was confirmed. The notable changes observed in the FTIR spectra revealed interactions between the cerium ions and polymer PVA. The optical absorption characteristics of pure and doped PVA NFs were done by UV–Visible absorption spectroscopy. The photoluminescence spectrum of the rare earth-doped cerium oxalate-PVA NFs showed that the fiber had strong emission in the blue-green region.

Steering response to roll control of a two-line disk kite

Kites are utilized in both professional sporting activities and potential new energy generation applications. Most of these use two or four-line steerable kites, but the steering response is not well understood. Previous work on kite behaviour has focused on single-line kites, and the dynamics of two-line kites has been limited to quasi-static analysis. The mathematical formulation of the few models that consider the dynamics have been based only on energy methods. Furthermore, existing work relies on not-validated generalised aerodynamic models unsuitable for design optimisation tasks. Understanding the dynamics of two-line steerable kites allows for innovative improvements for such applications. In this work we introduce a two-disk kite as a simplified generic model for analysis of steering response. We derive the fully non-linear governing dynamic equations of motion for a two-line four-attachment point disk kite using 4DOF with a Newton–Euler formulation. The aerodynamic model of the kite is taken from previous work of our group (CFD/wind-tunnel tested and validated). The analysis considers the stability regions for flight behaviour and the manoeuvrability of the kite. Kite design parameters are investigated to guide future designs.

Co3O4/Zn–Co–Mo Nanomaterials and Their Applications in Supercapacitors and Electrocatalysis Hydrogen Evolution Reaction

Mixed transition metal compounds with abundant more active sites are attractive to supercapacitors and electrochemical water splitting. In this work, the Co3O4/Zn–Co–Mo/NF composite is prepared by a hydrothermal method and thermal annealing. The Zn–Co–Mo nanosheet arrays are synthesized on nickel foam (NF) to form a three-dimensional (3D) network to take advantage of the electrical conductivity and viscosity of NF. Co3O4 is produced directly in the 3D microchannels to achieve a large energy density and robust stability. In the test of the supercapacitor performance, the specific capacitance of Co3O4/Zn–Co–Mo/NF is 2169 F g−1 at a current density of 1 A g−1. In addition, excellent long-term cycling stability is observed as manifested by specific capacitance retention of 85% after 4,000 cycles at a current density of 25 A g−1. As a catalyst in the hydrogen evolution reaction (HER), Co3O4/Zn–Co–Mo/NF shows an overpotential of 128 mV at 10 mA cm−2. Our results confirm the dual functionality of the materials which have promising potential in energy storage and generation applications.

Highly Active Biphasic Anatase-Rutile Ni-Pd/TNPs Nanocatalyst for the Reforming and Cracking Reactions of Microplastic Waste Dissolved in Phenol.

Solvent-based recycling of plastic can offer the main improvement when it is employed for pyrolysis-catalytic steam reforming. In this research, plastic waste dissolved in phenol was used as a feed for catalytic cracking and steam reforming reactions for valuable liquid fuels and hydrogen production, which is gaining the attention of researchers globally. Microplastic wastes (MPWs) are tiny plastic particles that arise due to product creation and breakdown of larger plastics. They can be found mainly in several habitats, including seas and freshwater ecosystems. MPWs harm aquatic species, turtles, and birds and were chosen to recover in this study that can be reacted on the catalyst surface. Biphasic anatase-rutile TiO2 with spherical-shaped support for Ni and Pd metals with nanosized particles was synthesized via the hydrothermal treatment method, and its chemical and physical properties were characterized accordingly. According to temperature-programmed desorption of carbon dioxide (CO2-TPD) and temperature-programmed reduction of hydrogen (H2-TPR) results, the incorporation of Pd into Ni/TNPs enhanced the basicity of the support surface and the redox properties of catalysts, which were strongly linked to the improved hydrogen yield (71%) and phenol conversion (79%) at 600 °C. The Ni-Pd/TNPs nanocatalyst, with remarkable stability for 72 h of time on stream, is a promising catalyst for the MPW-phenol cracking and steam reforming reactions toward H2 production for clean energy generation and other environmental applications. Besides, this study has also highlighted the opportunities of overcoming the risk of microplastic waste and converting it into valuable fuels such as decamethyltetrasiloxane, phenanthrene, methyl palmitate, benzenepropanoic acid, benzoic acid, azulene, xanthene, anisole, biphenyl, phthalic acid, diisooctyl phthalate, etc.

Correlative investigation of the corrosion susceptibility of C70600 and C26000 copper based alloys for application in seawater environment

Appropriate selection of Cu based alloys for petrochemical, energy generation, desalination and piping applications in marine operating conditions is of utmost importance. Correlative investigation of the corrosion susceptibility of two Cu based alloys (C70600 CuNi and C26000 CuZn) was done with potentiodynamic polarization technique and open circuit potential analysis in 0.05 M H2SO4 solution at 0.5%, 1.5%, 2.5%, 3.5% and 4.5% NaCl concentration. The corrosion susceptibility of both alloys were generally similar at 0.5% (0.05 mm/y and 0.06 mm/y), and 1.5% (0.11 mm/y and 0.10 mm/y) Cl- ion concentration. Beyond 1.5% concentration C70600 proves to be substantially more corrosion resistant with optimal corrosion rate value of 0.74 mm/y compared to 2.68 mm/y for C26000 at 4.5% NaCl concentration due to variation in the constituent of the oxide layer precipitated on C70600 alloy which differs from C26000. C70600 exhibited dominant cathodic passivation and subsequent corrosion deterioration resulting in visible cathodic potential displacement. C26000, despite its relatively higher corrosion susceptibility underwent metastable pitting activity proportional to the Cl- ion concentration. Anodic passivation and selective dissolution of C26000 occurred following anodic polarization due to the presence of Zn in its outer matrix. Open circuit potential measurement shows Cl- ion concentration significantly influences the thermodynamic stability, passivation and corrosion resistance of the Cu alloys. However plot characteristics and potential readings showed C70600 to be more corrosion resistant and thermodynamically stable coupled with significantly lower tendency to corrode.

Investigation of the effect of the injection pressure on the direct-ignition diesel engine performance

<abstract> <p>Internal combustion engines (ICE) play a major role in converting the energy with its different types in order to benefit from it for various applications such as transportation, energy generation, and many others applications. Internal combustion engines use two main types of operation cycles, namely the Otto and Diesel cycles. Many development processes are carried out to improve the efficiency of the ICE nowadays such as working on the design of the combustion engine and the material selections and others. One of the main parameters which play an important role in improving the diesel engine is the fuel pressure. By increasing the fuel pressure injected into the engine, the efficiency, in consequence, will increase. This work investigates the injection pressure of the fuel (Diesel) and studies the effect of these changes on engine efficiency. It was found that the increase in injection pressure significantly affected the improvement in engine performance. Such improved engine subsystems will have a great impact on the energy extracted and used for various engineering applications.</p> </abstract>

One-step hydrothermal synthesis of MoS2 nano-flowers CoS2 square composites electrode materials for supercapacitor application

Developing efficient materials for generating and storing renewable energy is now a pressing test for future energy demand. The advent of (2D) two-dimensional materials has attracted much research interest as electrode materials for supercapacitors due to their intriguing mechanical and electrochemical properties. This report used a facile one-step hydrothermal process to synthesize MoS2@CoS2 Composite as electrode materials for supercapacitors with good energy storage performance and explore energy generation and storage applications. The structure and morphology were investigated by X-ray diffraction pattern, field emission scanning electron microscope consisting of square-shaped CoS2 and flower-like MoS2, and characterization; meanwhile, their electrochemical properties were evaluated by CV, GCD, and EIS measurements. The electrochemical performance of symmetric MoS2@CoS2 binary Composite was examined in 1 M H2SO4 in a two-electrode assembly. The as-prepared MoS2@CoS2 electrode exhibited a specific capacitance of 199F/g at a current density of 2A/g, while its counterpart MoS2 electrode exhibited only 127F/g at 2 A/g current density. The MoS2@CoS2 composite attains specific energy and power densities of 27.74 WhKg−1 and 494.46 Wkg−1, respectively, due to the unique morphology of the MoS2-flowery shape and CoS2 square. CoS2 squares effectively prevent the agglomeration and restacking of MoS2 sheets, facilitating smother ion dynamics. Technological demonstration of MoS2@CoS2 cell is presented by illuminating commercially available light-emitting diode for more than 3 min.

TiO2 NTAs decorated with thin CuBi2O4 nanosheets for efficient photocatalytic dye degradation and hydrogen generation

Photocatalytic technology is the recent investigation focus because of the wide applications in sewage disposal and new energy generation. In this paper, the optical and photocatalytic properties of TiO2 NTAs were enhanced by the hydrothermal deposition of CuBi2O4 by regulating the precursor concentration. The results indicated that the precursor concentration played remarkable influences on the morphology and photocatalytic ability. The mild reagent concentration was in favor of super-thin CuBi2O4 nanosheet formation. CuBi2O4/TiO2 NTAs with high reagent concentration exhibited high photocurrent and hydrogen production, and showed outstanding performance in the removal of organic dyes and heavy metal ions. The free radical production and the photocatalytic progress were introduced in detail. The high photocatalytic activity exhibits prospective foreground in industrial waste water treatment and novel energy resource development.

Facile synthesis and application of CdS/Bi20TiO32/Bi4Ti3O12 ternary heterostructure: A synergistic multi-heterojunction photocatalyst for enhanced endosulfan degradation and hydrogen evolution reaction

Facile fabrication of visible light responsive multicomponent heterostructure photocatalysts with synergistic photoelectron migration is an effective approach with potential application in water remediation and renewable energy generation. In this study, a series of ternary multi-heterojunction CdS/Bi20TiO32/Bi4Ti3O12 (CdSxBTC) photocatalysts were prepared by hydrothermal deposition of CdS nanoparticles (15–25 nm) over one pot combustion synthesized Bi20TiO32/Bi4Ti3O12 (BTC) nanostructures. Comprehensive characterization of the ternary composites revealed enhanced optical absorption, high interfacial contact, fast electron channelization and a prolonged excited state life time. The CdSxBTC composite materials displayed enhanced photocatalytic activity for endosulfan degradation (kapp value 6–12 times greater than pure semiconductors) and water splitting reaction (H2 production rate 1890 μmolg−1h−1 and apparent conversion efficiency 19%). The cell viability -study disclosed non-cytotoxic nature of the treated endosulfan solution. A synergistic Type-I bridged coupled Z-scheme electron migration process accounted for robust radical generation ability (•O2− and •OH) and photocatalytic activity of the ternary composites.

Harnessing Slow Light in Optoelectronically Engineered Nanoporous Photonic Crystals for Visible Light-Enhanced Photocatalysis

Spectrally tunable nanoporous anodic alumina distributed Bragg reflectors (NAA-DBRs) are modified with titanium dioxide (TiO2) coatings via atomic layer deposition and used as model optoelectronic platforms to harness slow light for photocatalysis under visible–NIR illumination. Photocatalytic breakdown of methylene blue (MB) with a visible absorbance band is used as a benchmark reaction to unveil the mechanism of slow light-enhanced photocatalysis in TiO2–NAA-DBRs with a tunable photonic stop band (PSB) and thickness of TiO2. Assessment of the optical arrangement between MB’s absorbance band and the PSB of TiO2–NAA-DBRs is used to identify and quantify slow light contributions in driving this model photocatalytic breakdown reaction. Our findings reveal that photodegradation rates rely on both the spectral position of PSB and thickness of the semiconductor. The performance of these photocatalysts is the maximum when the red edge of the PSB is spectrally close to the red or blue boundary of the MB’s absorbance band and to dramatically decrease within the absorbance maximum of MB due to light screening by dye molecules. It is also demonstrated that TiO2–NAA-DBRs featuring thicker photoactive TiO2 layers can harvest more efficiently incident slow light by generating extra pairs of charge carriers on the semiconductor coating’s surface. The crystallographic phase of TiO2 in the functional coatings is found to be critical in determining the performance of these model photocatalyst platforms, where the anatase phase provides ∼69% higher performance over its amorphous TiO2 form. This study provides opportunities toward the development of energy-efficient photocatalysts for environmental remediation and energy generation and other optoelectronic applications.

Facile in situ fabrication of rGO/MoS2 heterostructure decorated with gold nanoparticles with enhanced photoelectrochemical performance

Two-dimensional materials offer a promising visible light-driven photoelectrochemical (PEC) application thanks to their high electrical conductivity and tunable bandgap. However, the high recombination rate of photogenerated carriers significantly limits their photoelectrochemical efficiency. Here, a reduced graphene oxide/molybdenum disulfide/gold nanoparticles (rGO/MoS2/Au NPs) heterostructure is introduced based on a simple and high-throughput method to efficiently convert light into electricity. For this purpose, MoS2 dispersion is cast on GO few layers followed by sputtering 5 nm thin film of gold. With a thermal-assisted method not only GO is reduced to rGO but also Au is converted into Au NPs. The introduced heterostructure is thoroughly studied by SEM, TEM, Raman, UV–Visible, and AFM analyses. The rGO/MoS2/Au NPs heterostructure demonstrates about 240% improvement in photocurrent density compared with GO/MoS2 hybrid which is due to the efficient transfer of electrons to Au NPs and a significant reduction in the recombination rate of photogenerated carriers. Straightforward fabrication of such a high-performance PEC heterostructure is very promising for photoelectrochemical and energy generation applications. Finally, using numerical simulations, the mechanism of the photogenerated carriers is well elucidated in the suggested heterostructure, which shows complete agreement with the experimental results.

Highly Active Mo2C@WS2 Hybrid Electrode for Enhanced Hydrogen Evolution Reaction

Transition metal dichalcogenides (TMDs) are the auspicious inexpensive electrocatalysts for the hydrogen evolution reaction (HER) which has been broadly studied owing to their remarkable enactment, however the drought of factors understanding were highly influenced to hinder their electrocatalytic behavior. Recently, transition metal carbide (TMC) has also emerged as an attractive electrode material due to their excellent ionic and electronic transport behavior. In this work, Mo2C@WS2 hybrids have been fabricated through a simple chemical reaction method. Constructed heterostructure electrocatalyts presented the small Tafel slope of 59 and 95 mV per decade and low overpotential of 93 mV and 98 @10 mA·cm−2 for HER in acidic and alkaline solution, respectively. In addition, 24-h robust stability with the improved interfacial interaction demonstrated the suitability of hybrid electrocatalyst for HER than their pure form of Mo2C and WS2 structures. The derived outcomes describe the generated abundant active sites and conductivity enhancement in TMC/TMD heterostructure along with the weaken ion/electron diffusion resistance for efficient energy generation applications.

Effect of pitch angle on power and hydrodynamics of a vertical axis turbine

The use of vertical-axis turbines in marine-current applications for electric energy generation is still in early developments, and one of the key factors for assessing the applicability of such technology is the power coefficient. To contribute towards the highly competitive market of renewable energy conversions, the turbine system requires good outcomes in terms of energy yield. In this scenario, one of the main challenges regarding the design process to improve the blade performance is to find the best trade-off between the maximization of the power output and the minimization of the structural loadings.In the current work, the influence of blade pitch angles on the hydrodynamics of a vertical-axis five-blade water turbine has been studied. The pitch angles from −5° to +5° were investigated using Computational Fluid Dynamics (CFD). The simulations were validated against experimental data for the power coefficient collected in a river. Overall, a good agreement was found in terms of computed power between simulations and experiments for a wide range of tip speed ratios. The CFD model was proven to be suitable for exploratory analyses and an optimized design was found, providing a 2.3% higher power coefficient by adopting a pitch angle of +2° compared to the zero-referenced pitch angle. Besides validating with the experiment, the CFD simulations were compared with the results of a vortex model. The effect of different pitch angles on the performance prediction and on the blade and turbine loadings was also discussed. It is becoming vital to develop an understanding of the complex interaction of vertical-axis turbines, especially in tidal-current areas where there is a lack of detailed experimental data.