Search Results (34)

Cross-Flow Turbines (CFTs) are widely recognized for their adaptability and cost-effectiveness in micro-hydropower (MHP) systems. However, their hydraulic efficiency remains highly sensitive to geometric configurations, particularly the Blade Entry Angle (BEA) and Water Admission Angle (WAA). This study presents a high-fidelity computational fluid dynamics (CFDs) investigation of CFT performance across a wide range of BEA (5–40°) and WAA (45–105°) combinations at runner speeds from 150 to 1200 rpm, under constant head and flow conditions. The simulations were performed using a steady-state Reynolds-Averaged Navier–Stokes (RANS) model coupled with the volume of fluid (VOF) method and the SST k–ω turbulence closure. Benchmarking against the widely used industrial standard configuration (BEA = 30°, WAA = 90°), which achieved 79.1% efficiency at 900 rpm, this study identifies an optimized setup at BEA = 15° and WAA = 60° delivering a peak efficiency of 84.91% and shaft power output of 225.5 W—representing an efficiency gain of approximately 5.8%. The standard configuration was found to suffer from flow misalignment, jet dispersion, and increased internal energy loss, particularly at off-design speeds. In contrast, optimized geometries ensured stable pressure gradients, coherent jet–blade interaction, and enhanced momentum transfer. The results provide a validated performance map and establish a robust design reference for enhancing CFT efficiency and reliability in decentralized renewable energy systems. Full article

Micro-hydroelectric power plants play a fundamental role in microgrid systems and rural electrification projects based on non-conventional renewable energies, where the stability of the electricity supply and load variability are critical factors for efficient operation. This work focuses on analyzing the impact of electrical load variation on the performance of a 10 kW micro hydroelectric power plant equipped with a Pelton turbine coupled to an electric generator. The main objective is to characterize the behavior of the turbine–generator system under different operating conditions, evaluating the hydraulic performance of the turbine, the electrical performance of the generator, and the overall performance of the micro power plant. Key variables such as flow rate, pressure, shaft speed, mechanical torque, current, and electrical voltage are monitored, considering the effect of electrical consumption on each of them. The experimental methodology includes tests at different electrical loads connected to the generator, using the spear system, which allows the flow rate in the injector to be modulated. The results indicate that reducing the flow rate using the spear increases the torque on the shaft, as well as the electrical current and voltage, for the same energy demand. Likewise, it is observed that the electrical efficiency of the generator remains stable for shaft speeds above 400 rpm, while the overall efficiency of the turbine–generator improves by up to 25% at this same speed. However, a voltage drop of more than 8% is recorded when the electrical power consumption increases from 3 kW to 9 kW, which demonstrates the sensitivity of the system to load variations. This work provides a comprehensive view of the dynamic behavior of micro-hydraulic power plants under realistic operating conditions, proposing an experimental methodology that can be applied to the design, optimization, and control of small-scale hydroelectric systems. These results provide novel experimental evidence on how electrical load variations affect the global performance of P -based micro hydropower systems. Full article

Flood control infrastructure is essential for the development of cities and the population’s well-being. The goal is to protect human and economic resources by reducing the inundation area and controlling the flood level and peak discharges. Detention basins can do this by storing a large volume of water to be released after the peak discharge. By doing this, a large amount of energy is stored, which can be recovered via micro-hydropower. In addition, as the release flow is controlled and almost constant, Pumps as Turbines (PAT) could be a feasible and economic option in these cases. Thus, this study investigates the feasibility of micro-hydropower (MHP) in urban detention basins, using the Santa Lúcia detention basin in Belo Horizonte as a case study. The methodology involved hydrological modeling, hydraulic analysis, and economic and environmental assessment. The results demonstrated that PAT selection has a crucial role in the feasibility of the MHP, and exploiting rainfall with lower intensities but higher frequencies is more attractive. Using multiple PATs with different operating points also showed promising results in improving energy production. In addition to the economic benefits, the MHP in the detention basin produces minimal environmental impact and, as it exploits a wasted energy source, it also reduces the carbon footprint in the urban water cycle. Full article

This study presents a comprehensive numerical investigation into the influence of blade profile geometry on the internal flow dynamics and hydraulic performance of Cross-Flow Turbines (CFTs) under varying runner speeds. Four blade configurations, flat, round, sharp, and aerodynamic, were systematically evaluated using steady-state, two-dimensional Computational Fluid Dynamics (CFD) simulations. The Shear Stress Transport (SST) k–ω turbulence model was employed to resolve the flow separation, recirculation, and turbulence across both energy conversion stages of the turbine. The simulations were performed across runner speeds ranging from 270 to 940 rpm under a constant head of 10 m. The performance metrics, including the torque, hydraulic efficiency, water volume fraction, pressure distribution, and velocity field characteristics, were analyzed in detail. The aerodynamic blade consistently outperformed the other geometries, achieving a peak efficiency of 83.5% at 800 rpm, with improved flow attachment, reduced vortex shedding, and lower exit pressure. Sharp blades also demonstrated competitive efficiency within a narrower optimal speed range. In contrast, the flat and round blades exhibited higher turbulence and recirculation, particularly at off-optimal speeds. The results underscore the pivotal role of blade edge geometry in enhancing energy recovery, suppressing flow instabilities, and optimizing the stage-wise performance in CFTs. These findings offer valuable insights for the design of high-efficiency, site-adapted turbines suitable for micro-hydropower applications. Full article

Tubular axial turbines (TATs) play a crucial role in mini and micro hydropower setups that require simplified yet reliable solutions. In very low head scenarios, single regulation in TATs is common, due to economic impracticality of the sophisticated mechanisms involved in the conjugate distributor–rotor regulation typical of the Kaplan turbines. Distributor or rotor single regulation strategies offer operation flexibility, each with distinct advantages and disadvantages. Stator regulation is simpler, while rotor regulation is more complex but offers potential efficiency gains. The present paper analyzes energy losses associated with these regulation strategies using two approaches: 1D mean line turbomachinery equations and 3D Computational Fluid Dynamics (CFD). The 1D mean line approach is used for understanding the conceptual fluid dynamic aspects involved in the two different regulation approaches, thereby identifying the loss-generation mechanisms in off-design operation. Fully 3D CFD simulations allow for quantifying and deeply explaining the differences in the hydraulic efficiencies of the two regulation strategies. Attention is focused on the two main loss contributions: residual tangential kinetic energy at the rotor outlet and entropy generation. Rotor regulation, even if more complex, provides better results than distributor regulation in terms of both effectiveness (larger flow rate sensitivity to stagger angle variation) and turbine operating efficiency (lower off-design losses). Full article

Cavitation erosion poses a significant challenge in fluid systems like hydraulic turbines and ship propellers due to pulsed pressure from collapsing vapor bubbles. To combat this, various materials and surface engineering methods are employed. In this study, nano and micro scale particles of silicon carbide (SiC) or boron carbide (B₄C) were incorporated as reinforcement at 6% and 12% ratios, owing to their exceptional resistance to abrasive wear and high hardness. Microparticles were incorporated to assess the damage incurred during the tests in comparison to nanoparticles. Wear tests were conducted on both bulk samples and coated aluminum sheets with a 1mm of composite. Additionally, cavitation tests were performed on coated aluminum tips until stability of mass loss was achieved. The results indicated a distinct wear behavior between the coatings and the bulk samples. Overall, wear tended to be higher for the coated samples with nanocomposites than bulk, except for the nano-composite material containing 12% SiC and pure resin. With the coatings, higher percentages of nanometric particles correlated with increased wear. The coefficient of friction remained within the range of 0.4 to 0.5 for the coatings. Regarding the accumulated erosion in the cavitation tests for 100 min, it was observed that for all nanocomposite materials, it was lower than in pure resin. Particularly, the composite with 6% B₄C was slightly lower than the rest. In addition, the erosion rate was also lower for the composites. Full article

Using pumps operating as turbines (PATs) offers the possibility of increasing the sustainability of water and energy systems by recovering the excess energy that would be otherwise lost in pressure-reducing valves or head loss chambers. Regarding on-grid applications, there have been many research works, and PATs have been implemented in several ways. However, more research still needs to be done on optimizing the efficiency and stability of PATs operating in off-grid systems. This work contributes to the development of stable direct current (DC) off-grid electric systems based on PATs using a self-excited induction generator (SEIG). In this context, a methodology is proposed, based on the hydraulic, mechanical, and electric subsystems, to define the PAT-SEIG operational area to maximize energy conversion and system efficiency. These limits depend highly on the capacitor value, rotational speed, and electric load. In addition, an analytical model is proposed to estimate the PAT-SEIG operation under specific conditions. With this, water managers can design and optimize an off-grid PAT-SEIG system and define the best hydraulic machines, electronic equipment, and control elements to maximize energy conversion within the target of operational limits. Two micro PAT-SEIG setups were implemented in the hydraulic laboratory of IST/CERIS under typical operating conditions to validate the proposed methodology. The system’s maximum efficiency and operational limits can be adapted using different capacitor values for the excitation of the SEIG. Considering the nominal efficiencies of the system’s components, the maximum p.u. efficiency obtained for each PAT-SEIG system was between 0.7 and 0.8 p.u. Full article

Although pressure reducing valves (PRVs) have traditionally been employed to regulate pressure and reducer water leakage, researchers have been increasingly investigating the strategy of micro-hydropower generation using pumps as turbines (PATs) to enable both pressure reduction and energy production as an alternative strategy in water distribution networks (WDNs). However, due to the continuous variability of flow discharge during the day, selecting the optimal PAT remains a challenging issue. To address this, the authors have developed HYPER, a freely available software app that implements an innovative approach for selecting the most suitable PAT in systems that involve both hydraulic and/or electrical regulation. In enabling the identification of the PAT parameters that maximize energy production, HYPER thus provides a fast and effective PAT selection tool. The effectiveness of the proposed approach was further demonstrated with application to a real WDN. Four operational patterns varying in terms of available flow and head drop were considered, showing that the most efficient pumps consistently tended to be located in close proximity to the maximum produced energy. Furthermore, the results confirmed that hydraulic regulation and coupled hydraulic/electric regulation-based installation layouts represent the best solutions in terms of energy produced. The solely electrical regulation option, given its poor flexibility, returns in all cases lower energy production with the lower adaptability of commercial pumps. Full article

The high price of purpose-made turbines always represents an active challenge when utilizing pico- and micro-hydropower resources. Pumps as turbines (PATs) are a promising option to solve the problem. However, the selection of a suitable pump for a specific site and estimating its performance in the reverse mode are both major problems in the field. Therefore, this paper aims to develop generic mathematical correlations between the site and the pump hydraulic data, which can be used to select the optimal operation of the pump as a turbine. A statistical model and the Pearson correlation coefficient formula were employed to generate correlations between the flow rate and the head of the pumps with the sites. Then, Ansys CFX, coupled with SST k-ω and standard k-ε turbulence models, was used to analyze the performance of the PAT. The analysis was conducted in terms of flow rate, pressure head, efficiency, and power output. The numerical results were validated using an experimental test rig. The deviations of the proposed correlations from the statistical model were found to be in the range of −0.2% and 1.5% for the flow rate and ±3.3% for the pressure head. The obtained numerical outputs using the standard k-ε turbulence model strongly agreed with the experimental results, with variations of −1.82%, 2.94%, 2.88%, and 1.76% for the flow rate, head, power, and efficiency, respectively. The shear stress transport (SST) k-ω turbulence model showed relatively higher deviations when compared to standard k-ε. From the results, it can be concluded that the developed mathematical correlations significantly contribute to selecting the optimal operation of the pump for power-generating applications. The adopted numerical procedure, selected mesh type, turbulence model, and physics setup provided good agreement with the test result. Among the two turbulence models, the standard k-ε performs better in estimating the pressure head, output power, and efficiency of the PAT with less than 3% errors when compared to experimental results. Full article

Renewable energy sources are rapidly increasing in demand and importance as governments and countries around the globe begin to understand their vital role in reducing climate change. This project aimed to design and create an optimised micro-hydro turbine system for downpipes to harness the currently untapped potential energy from rainwater. Experimental methods were used to determine the magnitude of voltage output available at different rainfall intensities by simulating such flow rates on a hydraulic bench. The viability of this energy to power household appliances was then evaluated, and methods of increasing the voltage output were assessed, such as layering the turbines in a single downpipe or placing multiple downpipes around the building. The study determined that, during average rainfall in the UK, a single turbine could produce a maximum of 7.21 V of DC voltage, or 50.49 V during heavy rainfall—enough energy to power a mobile device charger or a vacuum cleaner, respectively. Therefore, this proves a high potential in rainwater energy harvesting as a renewable energy source. It was also concluded that a positive correlation occurred for both the number of turbines in a downpipe and the number of pipes around the building with the voltage output of the whole system. Full article

The present work numerically investigates the flow behavior of Newtonian fluid between rotating disk systems. Rotating disk flow is an embranchment of fundamental flow research, which forms the theoretical basis for the flow media in many disk-type hydraulic machinery, and has been widely applied in energy, aerospace, vehicles, medical, and chemical areas. The Reynolds equation model of the rotating disk flow is established based on a series of assumptions, and considers the characteristics of hexahedral surface textures on the friction disk, and the control equation is dimensionless. The velocity, pressure, and pressure coefficient in oil film are solved by finite difference algorithm, and the shear cavitation incipient position is predicted. Graphical visualization and numerical data about cavitation characteristics are also presented. Furthermore, the cavitation process is researched in CFX and the experiment, eventually verifying the correctness of the numerical analysis. The pressure perturbation caused by texture boundaries and the low pressure at the vortex center induce the initial generation of cavitation, and cavitation effect can obviously enhance lubricating performance. The cavitation region extends from micro-dimples towards non-textured region when texture rate increases. This study can guide design of surface structures such as mechanical seals, wet clutches, and disk turbines. Full article

One of the hardest challenges in irrigation systems is to reduce the use of water resources. The goal “more crop per drop“ has fostered the improvement of hydraulic infrastructure by replacing old open channel networks with pressurized systems (e.g., drip and sprinkler irrigation). This has resulted in reduced water losses, as well as the possibility for farmers to benefit from on-demand water. On the other hand, this improvement in water efficiency has controversially resulted in a large increase in energy consumption, since pressurized systems demand large flows with high pressures. The high energy requirements, along with the investment and operational costs, may compromise the viability of such irrigation systems. Several strategies to save both water and energy resources have, therefore, been proposed in the recent literature. Among these, the exploitation of excess pressure to produce energy by means of energy production devices (EPDs) has been proven to be a very effective strategy. Pumps-as-turbines (PATs) are, by far, preferred over traditional EPDs, such as pico- or micro-turbines, being very cost-effective solutions. In this study, the optimal location of PATs within an irrigation system is investigated with reference to a whole irrigation season. A case study network, the Zújar Canal irrigation district, is considered, for which accurate records of hourly water demands are available due to a diffuse telemetry system over the irrigation area. The aim of the optimization is to search for the best number and location of PATs within the irrigation network in order to maximize the energy production and minimize the investment costs. The hydraulic resolution of the network is coupled with the optimal location problem in one single mathematical model and the optimization procedure is performed via the use of a global optimization solver. The promising results in terms of the hydropower potential prove the effectiveness of the PAT installation within the case study network. Full article

In this work, a discontinuous airfoil fin printed circuit heat exchanger (PCHE) was used as a recuperator in a micro gas turbine system. The effects of the airfoil fin geometry parameters (arc height, maximum arc height position, and airfoil thickness) and the airfoil fin arrangements (horizontal and vertical spacings) on the PCHE channel’s thermo-hydraulic performance were extensively examined by a numerical parametric study. The flow features, local heat transfer coefficient, and wall shear stress were examined in detail to obtain an enhanced heat transfer mechanism for a better PCHE design. The results show that the heat transfer and flow resistance were mainly increased at the airfoil leading edge owing to a flow jet, whereas the airfoil trailing edge had little effect on the thermo-hydraulic performance. The airfoil thickness was the most significant while the arc height and the vertical spacing were moderately significant to the performance. Moreover, only the airfoil thickness had a significant effect on the PCHE compactness. Based on a comprehensive investigation, two solutions NACA-6230 and -3220 were selected owing to their better thermal performance and smaller pressure drop, respectively, with horizontal spacings of 2 mm and vertical spacings of 2 or 3 mm. Full article

In order to adapt to the development of the green power certificate trading (GPCT) and carbon emissions trading (CET) market, reduce the carbon emissions of the distribution network and increase the investment income, this paper proposes a new distribution network (NDN) planning and simulation operation bi-layer model with new energy (NE) as the main body, considering the GPCT and CET mechanisms. First, the upper layer determines the capacity and location of wind turbine (WT), photovoltaic (PV), hydraulic turbine (HT), micro turbine (MT), and energy storage (ES), while the lower simulation operation considers the operation costs of WT, PV, HT, MT, ES, load demand response (DR) and carbon emissions. The planning objective was to minimize the total cost of investment, operation and carbon emissions in the planning period. Then, on the basis of a traditional distribution network (TDN), security constraints, carbon emissions intensity, GPCT volume and CET volume were added. Finally, the cases study of the improved IEEE33 node and PG&E69 node NDN planning were provided. The results of NDN planning and TDN planning are compared and analyzed, and a sensitivity analysis was carried out to study the impact of GPCT and CET mechanisms with different price levels on investment planning. The results verify the applicability and rationality of the model. Full article

Sustainability and energy prices make the use of energy obtained from renewable sources on an urban scale and for isolated local facilities necessary for municipal authorities. Moreover, when the demand of energy is at night, as for street lighting installations, the use of accumulative systems is necessary, which means a major drawback due to a short lifetime expectancy and high cost. The use of batteries can require more than 70% of the budget of these lighting systems and has a critical impact in the project. The problem to solve is finding different renewable energy sources that can produce energy throughout the day, especially during the night, at the same time at which it is consumed. As one of the competences of municipal authorities is water supply networks, this paper analyzes the use of energy recovery turbines within these installations as an alternative to photovoltaic generators. To study the viability and effectiveness of this alternative, the water flows available in the network of a medium-size municipality were monitored and analyzed in depth to assess the amount of recoverable energy. In addition, an energy recovery turbine (ERT) station was set up, installing a bypass around one of the pressure-reducing valves (PRV) of the installation where energy is dissipated without practical use. The results obtained imply that the system proposed has economical and technical viability, is reliable and guarantees full service in all the seasons’ conditions. Moreover, the needs of the energy storage capacity are much lower (~8%) than with solar panels. Full article