Small Turbine Research Articles

Development of Small-Scale Facilities for Initiating Studies into Sea Wave Energy Generation.

This paper describes the preliminary work carried out within the Civil and Electronics and Electrical Engineering Departments of The University of Glasgow. Two experimental pieces of equipment are described; the first is a piston-type of device suitable for testing small turbines in an oscillating water column system. The second is the conversion of a water flume into a wave tank for use in tests of small wave generator models and wave prediction systems.

Numerical simulation of a novel small water turbine generator for installation in a deep-flow hydroponics system

Hydroponics systems are crucial for providing sustainable and cost-effective choices when soils are unavailable for conventional farming. The application of water flow rates within hydroponics systems to generate electricity is another idea that can be used in the field of power generation. This paper presents the determination of the mechanical power efficiency of a novel small water turbine generator for use in a deep-flow hydroponics system (DFT). The system was designed, analysed, and calculated for the most suitable geometries of the water pipeline inlet, DFT system, main structure of the PVC Tee Pipe Fitting, and a water turbine wheel using computational fluid dynamics software. The diameter of the water turbine wheel in this research was 48 mm. A DFT hydroponic system was modelled for the purposes of this research. We conducted a numerical simulation with water flow rates of 6, 8, and 10 l/min to evaluate the turbulent kinetic energy distribution in the DFT hydroponic system. The numerical simulation employed the control volume methodology, and the k-epsilon turbulence model was applied to obtain the computational conclusions. The highest torque and power that a novel small water turbine for installation in a DFT system could generate at a maximum flow rate of 0.000167 m3/s were 0.082 N.m. and 1.9568 watts, respectively. The forces generated by the fluid's speed and pressure can then be transferred to the building process of a novel small water turbine wheel. The FEA numerical result shows that the maximum value of the total deformation at a wheel speed of 228 rpm is 7.0 x 10-5 mm. The numerical simulations used in this study could potentially be used to further develop prototypes for innovative miniature water turbines that generate commercial electricity.

Development of an Arduino-Based Monitoring System for Pico-Hydro Power Plants

One of the problems faced by people in remote areas is the unavailability of infrastructure for power distribution. The available rivers can be used to generate electrical energy. The developed systems must be inexpensive, easy to operate and reliable. It should be equipped with a monitoring system to display the output. This study aims to develop a pico-hydro power plant and its monitoring system to meet the power needs in remote areas. The power plant consists of a small turbine, a generator, a battery charger, and a battery while the monitoring system consists of a current sensor, voltage sensor, Arduino Nano, and a display. The system was tested in the laboratory and the river. The test of the DC voltage sensor, AC voltage sensor, and DC current sensor produces errors of 1.88%, 5.24%, and 1.25% respectively. The no-load test shows that the system generates a voltage of 12.77 - 16.6 VDC and 224 - 245 VAC when rotated at 696 - 1363 RPM. When loaded, the system generates voltages of 12 - 12.8 VDC and 225 - 247 VAC when rotated at 1332 - 1564 RPM. The developed system can be used by people in remote areas to meet their power needs.

Extensive design and aerodynamic performance investigation of diffuser augmented wind turbine (DAWT) guided by generalized actuator disc theory

Shrouding a turbine boosts power, lowers cut-in speed, but raises installation costs, and limits adaptability to wind shifts. A compact, wide-angle DAWT with competitive capacity is crucial for practical installations. Small turbines, often in fluctuating wind sites, necessitate thorough off-design performance analysis. A relatively short, wide-angle GOE431 diffuser is optimized by an efficient response surface method. Inverse blade element method, combined with actuator disc DAWT CFD considering wake swirl, shapes 90 cm-diameter rotor blade with minimal iterations. Implications of Generalized Actuator Disc Theory on DAWT design and performance are addressed with three-dimensional CFD for the first time. This approach unveiled substantial room for improving DAWT efficiency and uncovered key factors causing deviations from ideal performance. Tip leakage and diffuser losses constituted 9.5% of overall energy losses, with wake rotation, blade efficiency, and blade drag at 9.2%. Tip-hub losses, finite blade number, rotor-diffuser interaction, suboptimal rotor, and turbulence contributed to 12.1% in three-bladed DAWT, reaching CP,max = 0.746, with tip losses about one-third of bare turbine. Six-bladed DAWT raised CP by 93%, from 0.417 to 0.805, achieving 75% of ideal DAWT. Finite blade number led to reduced attack angles, higher tip losses, and limited flow expansion, contributing significantly to energy losses. As blade number and design tip-speed-ratio increased, blade Reynolds number decreased, suggesting an optimal combination to minimize energy losses. At off-design, a strong connection existed between thrust coefficient, diffuser efficiency, and Cp increase in wide-angle diffuser DAWTs. Maintaining CT near CT,opt (0.786) at high tip-speed-ratio led to significant Cp rise.

An investigation on asymmetric flow characteristics of asymmetric twin-scroll turbine

Asymmetry, as the most significant characteristic of asymmetric twin-scroll turbines, has a significant effect on the flow characteristics of asymmetric twin-scroll turbines. In this paper, the effect of asymmetry on flow parameters, efficiency, twin-scroll pressure ratio ( SPR), single admission twin-scroll flow parameters ratio ( SSMR) and twin-scroll divide wall of asymmetric twin-scroll turbines were investigated for the first time. First, several turbines with the same total critical section of twin scrolls and different asymmetries were designed, as well as several turbines with the same asymmetric twin scrolls and different heights of the divide wall. Subsequently, these asymmetric twin-scroll turbines were tested and studied on the turbine performance rig. Asymmetry had little influence on turbine flow characteristics under equal admission, but a great impact under partial and single admission. Meanwhile, SMR had a low slope linear relationship with the expansion ratio for every asymmetry turbine. Moreover, the asymmetry was approximately linear with the average single admission twin-scroll pressure ratio ( SSMR ave), which could be used to guide the early design of asymmetric twin-scroll turbines. Besides, divide wall schemes testing found that the length of divide wall had a certain effect on the SSMR ave, which is a control factor to maintain asymmetric property. Finally, the relation between the expansion ratio of small or large scroll turbines and lg(SPR) was approximately exponential function, and the exponential parameter was strongly correlated with SSMR and SSMR ave, which could be the key parameter reflecting the asymmetry.

Pumps as turbines for pumped hydro energy storage systems - A small-size case study

Pumped Hydro Energy Storage (PHES) technology has been used since early 1890s and is, nowadays, a consolidated and commercially mature technology. PHES systems allow energy to be stored by pumping water from a lower-to a higher-level reservoir. Subsequently, this energy can be released through a turbine placed in a penstock, which connects the two reservoirs, to produce energy. Although these plants have historically been employed at large power scales (in the order of hundreds of MW), in recent years, micro- and small-scale plants are becoming more interesting, due to their possibility of being integrated with renewable energy systems (RES) used in autonomous island grids. Capital costs associated with hydraulic machines used in PHES systems represent the most critical economic factor, which can be mitigated by using commercial centrifugal pumps in reverse mode (Pumps as Turbines, PATs) in place of small hydro turbines. These expected economic benefits must be weighed in each specific case study, with some drawbacks related to the use of PATs, mainly associated to a lower round-trip efficiency with respect to specifically designed pumps and turbines.In this work, a small-scale PHES plant has been studied coupled to an existent photovoltaic system for the integration in the electric grid of a small island in Southern Italy. Two different PHES outlines have been compared based on techno-economic considerations. The former is a typical PHES system composed of both pumps and a turbine, while the latter uses only an array of parallel pumps which work also in reverse mode. The analysis demonstrates the feasibility of integrating a photovoltaic and PHES plant, which results in a lower cost of electricity production, while PHES performance in the PAT-based outline results penalized by the lower efficiency of PATs with respect to the hydraulic turbine.

Reinforcement Learning-Based Wind Farm Control: Toward Large Farm Applications via Automatic Grouping and Transfer Learning

The high system complexity and strong wake effects bring significant challenges to wind farm operations. Conventional wind farm control methods may lead to degraded power generation efficiency. A reinforcement learning (RL)-based approach is proposed in this paper to handle these issues, which can increase the long-term farm-level power generation subject to strong wake effects while without requiring analytical wind farm models. The proposed method is significantly distinct from existing RL-based wind farm control approaches, whose computational complexities usually increase heavily with the increase of total turbine numbers. In contrast, our method can greatly reduce training loads and enhance learning efficiency via two novel designs: (1) automatic grouping and (2) multi-agent-based transfer learning (MATL). Automatic Grouping can divide a large wind farm into small turbine groups by analyzing the aerodynamic interactions between turbines and utilizing some key principles from the graph theory. It enables the separated conduction of RL algorithms on small turbine groups, avoiding the complex training process and high computational costs of applying RL on the entire farm. Based on Automatic Grouping, MATL can further reduce the computational complexity by allowing agents (i.e. wind turbines) to inherit control policies under potential group changes. Case studies with a dynamical simulator show that the proposed method achieves clear power generation increases than the benchmark. It also dramatically reduces computational costs compared with typical RL-based wind farm control methods, paving the way for the application of RL in general wind farms.

Performance analysis of small steam turbine in high back pressure heating unit

In view of the change of the operation mode of the small steam turbine of the high back pressure modified unit, the performance evaluation formula of the small steam turbine and the feed water pump is given. Through the performance test, the performance indexes of the small steam turbine and the feed water pump set are obtained, and the detailed data analysis is carried out. It is found that the modified small steam turbine and the feed water pump set do not meet the design requirements. The analysis of the test results, found the reasons for the performance is not up to the standard, and gave the next step.

Design and Thermodynamic Analysis of Waste Heat Recovery System of Sludge Hydrothermal Carbonization

This paper proposes a new type of sludge hydrothermal carbonization waste heat recovery system, which transfers the heat in the sludge hydrothermal carbonization to the combustion air of the boiler through total heat exchange to achieve waste heat recovery. The waste heat recovery system makes full use of the heat in the steam and improves the calorific value of the sludge entering the incinerator. With the increase of combustible matter content in sludge, the exergy efficiency of waste heat recovery system increases. Due to the improved steam quality and the use of small turbines to do work, the operating economy is improved.

FED evaluation in a small double-suction reversible pump turbine considering sediment erosion

Double-suction pump-turbines are a special type of reversible pump-turbine which serves the pumped storage hydro power plant. Enhancing the energy conversion efficiency of the power station can be effectively achieved by reducing the internal Flow Energy Dissipation (FED) within the pump-turbine. The key to addressing this challenge lies in the identification of high FED regions and conducting visualized analyses. In this study, computational fluid dynamics (CFD), thermodynamic calculation methods and the Finnie erosion model are combined to perform two-phase flow numerical simulations of a specific double-suction pump-turbine model under both pump and turbine operating modes. We analyzed the FED in different regions off wall. The energy loss distribution is provided within these five regions for the volute casing, suction chamber, and impeller separately, and conducted an analysis of component wear. The research findings revealed that, in the pump mode, FED primarily concentrates within the volute casing, while in the turbine mode, it is concentrated within the suction chamber, with both regions accounting for over 70 % of the total energy dissipation. The proportion of internal FED in five regions at varying distances from the wall for each component showed significant disparities under different operating conditions, closely related to the internal flow characteristics of the components. In pump mode, wear primarily occurs in the volute casing, while the wear in the suction chamber and impeller can be considered negligible. In turbine mode, each component experiences some level of wear. This provides a foundation for reducing flow energy losses and preventing sediment erosion.

Numerical simulation and low speed experiment of a low partially admitted rate axial turbine for small scale organic Rankine cycle

High rotating speed is a prominent feature of turbine used for small-scale organic Rankine cycle (ORC) system, which can bring the problems of safety, reliability, sealing, vibration, economics, etc. Partial admission method has potential to reduce the rotating speed of small turbine. In this study, an axial turbine with low partially admitted rate of 0.033 was tested in ORC loop using R1233zde as working fluid, and numerically researched using Ansys CFX software with k-omega turbulence model. Results showed that the specific powers of turbine resulting from CFD should be corrected with losses to match well with the experimental results. Losses could reduce the optimal rotating speed of turbine. The optimal rotating speed, mass flow rate, power and efficiency of turbine under rated condition were 8000 RPM, 115.8 g/s, 611.8 W and 35.8 %, respectively. The corresponding power and thermal efficiency of ORC were 551.0 W and 2.15 %. The influences of inlet and back pressures on the performance of turbine were different. With constant inlet pressure and temperature, the mass flow rate kept almost unchanged after chocking, but the power continued to increase. Under allowable conditions, reducing back pressure of turbine played an important role in improving turbine performance.

Jet Engine Turbine Mechanical Properties Prediction by Using Progressive Numerical Methods

The propulsion system for an aircraft is one of its most crucial systems; therefore, its reliable work must be ensured during all operational conditions and regimes. Modern materials, techniques and methods are used to ensure this goal; however, there is still room for improvement of this complex system. The proposed manuscript describes a progressive approach for the mechanical properties prediction of the turbine section during jet engine operation using an artificial neural network, and it illustrates its application on a small experimental jet engine. The mechanical properties are predicted based on the measured temperature, pressure and rpm during the jet engine operation, and targets for the artificial neural network are finite element analyses results. The artificial neural network (ANN) is trained using training data from the experimental measurements (temperatures, pressure and rpm) and the results from finite element analyses of the small experimental engine turbine section proposed in the paper. The predicted mechanical stress by ANN achieved high accuracy in comparison to the finite element analyses results, with an error of 1.38% for predicted mechanical stress and correlation coefficients higher than 0.99. Mechanical stress and deformation prediction of the turbine section is a time-consuming process when the finite element method is employed; however, the method with artificial neural network application presented in this paper decreased the solving time significantly. Mechanical structural analyses performed in ANSYS software using finite element modeling take around 30–40 min for one load step. In contrast, the artificial neural network presented in this paper predicts the stress and deformation for one load step in less than 0.00000044 s.

Is Hydraulic Fracturing the Next Big Breakthrough in Battery Tech?

Drill a well. Induce a fracture. Pump water. Start flowback. This sounds like the steps used to bring to life tens of thousands of tight-oil and gas wells over the past quarter century. But what it really describes is the emerging approach that a pair of Houston-based companies are using to turn rock formations into giant batteries. Differences aside, the respective processes developed by Quidnet Energy and Sage Geosystems involve hydraulically fracturing vertical wells, injecting water into fractures, and flowing that water back to surface under high pressure to drive a small industrial turbine. Founded in 2013, Quidnet was the first to try to commercialize this concept which represents a new twist on a very old technology known as pumped storage hydropower. Introduced in the 1890s, the technique works chiefly by sending water uphill—e.g., a mountain or a fjord—to create a gravity-assisted energy system. And despite its geographical limitations, this pumped storage represents more than 90% of the world’s energy storage today, an estimated 9,000 GWh. Of course, what both Quidnet and Sage want to do instead is to have subsurface rock formations do the heavy lifting and force the water uphole like it was shooting out of a geyser. To highlight this distinction, Quidnet refers to its version as “geomechanical” pumped storage while Sage so far prefers to call it “mechanical” pumped storage. Each firm claimed this year to have shown through respective field tests that all this is not merely theoretical. Most of this work has involved existing wells but both companies have plans for dedicated new-drill wells. Quidnet and Sage say the electric outputs they’ve achieved so far are promising enough to start considering pumped storage in rocks as a way to solve grid shortages and the intermittency issues that hamper wind farms and solar arrays. During periods of low grid demand, the proposal is to run water pumps on surplus electricity. Hours or days later when demand rises, that water is released to the surface and most of the electricity required to pump it down can now flow back into the grid. Sage shared figures at a geothermal conference in September boasting its nascent approach as already cost competitive with traditional pumped storage and commercial-scale lithium-ion batteries. That optimism is built upon the company’s first and only test well in Starr County, Texas, which bested expectations. “The output just blew us away,” Cindy Taff, CEO of Sage, said at the PIVOT conference last month. “We literally had to repipe the surface equipment three times because we were getting more force and pressure than what we had anticipated.” Taff, who previously spent 35 years working in the oil and gas business for Shell, said the well produced a flow stream that was converted into 200 kW for 18 hours. This adds up to 3,600 kWh, which is roughly four times the electricity consumed each month in the average US household.

Evaluation of small hydropower turbines installed downstream of Nile River branches (Egypt)

The current study proposes a new strategy for using small hydroelectric turbines in downstream river branches with the least amount of construction and the lowest cost by comparing two different methods of installing the turbines, the first by installing the turbines at the river's bottom and the second by installing the turbines on floating boats. The methodology of this article is based on predicting the distribution of velocities through the watercourse using experimental data collected at various points in the river's depth, and then predicting the resulting electrical power for different sizes of turbines, as well as estimating the number of turbines for each row and the number of rows along the river. Therefore, Investigate the proposed systems. The proposed small hydropower system's economic viability and environmental impact are investigated in this article. According to the nature of the waterway, the best diameter of a turbine that can be used is 1.5 m based on water velocities and river depths. The proposed power plant generated 25.8 kW per single turbine row, with an estimated cost of produced power (0.035 USD/kWh) of approximately 20 turbines installed per row. Compared to other renewable energy sources, the proposed hydropower system is cost-effective and environmentally friendly, as generating electricity with the proposed small hydropower plant could reduce annual carbon dioxide emissions by 368 tones of CO2 per single turbine row.

Critical Feature and Seawater Testing of Cross-Flow Rotor Components Fabricated with Additive Manufacturing

Cross-flow tidal turbines are an attractive option for powering remote or off-grid applications because of their simplicity as compared to axial-flow turbines. For instance, when oriented vertically, they harvest power from any current direction with a single degree of freedom and no yaw mechanism. Additive manufacturing (AM) offers an opportunity to print parts out of a wide variety of materials that can result in components that are lighter, stronger and/or less expensive to produce than with traditional manufacturing techniques. When coupled with cross-flow turbine rotors, which require critical features (blade-strut, strut-shaft connections) to be both structurally stiff and hydrodynamically shaped, which can be challenging for typical fabrication processes, AM offers the ability to do both well. This paper describes work on the feasibility of using advanced AM techniques to fabricate small cross-flow turbine rotors for applications at sea and near remote coastal communities.
 AM materials were categorized into 3 classes – plastics, metals, and ceramics – and reviewed for suitability based on a set of engineering requirements and criteria related to turbine characteristics, material properties, and AM process capabilities. Two plastics and two metals were selected to undergo further testing: Essentium CF25, CarbonX Ult 9085, Titanium Ti-6Al-4V, and Inconel 718. Testing is conducted in three phases: the first is a long-term, 5-month submersion test in the seawater tanks at PNNL-Sequim to study corrosion, water uptake, and biofouling potential; in the second, materials are tensile tested on a load frame to find their failure parameters to compare to material standards; the third test is a fatigue test consisting of cyclically loading test parts with a known force on the order of that exerted on rotor blades in a 1.5 m/s current flow. These tests are designed to discern the suitability of AM materials since their properties from 3D printing processes are known to vary from published parameters. The test samples undergoing submersion testing will be tension tested and compared to control samples not subjected to extended seawater immersion. For fatigue life testing, a small rotor is expected to complete 100 million cycles over the course of a year-long lifespan, but for the case herein is restricted to 1 million for a preliminary performance evaluation. The first 10k cycles are run on an MTS 312.21 load frame at a rate of 0.2 Hz, with the remaining on a custom-built cyclic-deflection test rig at 0.8 Hz.

Development of an Unmanned Mobile Current Turbine Platform

A prototype low-flow (~0.5 m/s) marine current turbine for deployment from a small unmanned mobile floating platform has been developed at Florida Atlantic University for autonomously seeking and harnessing tidal/coastal currents. The support platform is an unmanned surface vehicle (USV) in the form of a catamaran with two electric outboard motors and with capabilities for autonomous navigation. An undershot water wheel (USWW), aided by a custom flow concentrator, has been selected as the basic design for the marine current turbine, which is mounted on the stern of the USV. The concept of operation is that the unmanned surface vehicle would navigate to a designated marine current resource, autonomously anchor at the location, align itself in the current, and deploy the USWW turbine using a custom cable-lift deployment mechanism. As the USWW harnesses the local current, an onboard power-take-off (PTO) device converts the harnessed mechanical energy to electricity which is stored in onboard batteries. The selected PTO utilizes a spur drivetrain/gearbox coupled with a NuVinci Ball-continuously variable transmission (CVT). It is estimated that the small prototype turbine system will produce over 12W power for currents over 0.5 m/s. The automated anchoring system consists of an electric winch, a Rocna anchor, anchor chain/rode and a line locking mechanism designed to aid in taking tension off the winch. Preparations have been made to test and demonstrate the application of the platform in harnessing tidal currents in the Intracoastal Waterway in South Florida and coastal currents at locations off Fort Lauderdale, Florida. The preparations include obtaining the necessary environmental permits for conducting in-water testing; developing required mitigation measures in protecting local wildlife and their habitats; and identifying potential in-water test sites and surveying them for their suitability in terms of current resource, bottom type, water depth and local boat traffic. Application of the marine current turbine platform to serve as an unmanned mobile floating recharge station for small aerial drones will be demonstrated. For this purpose, the USV includes a flight deck for landing and takeoff of small aerial drones whose batteries would be recharged via a wireless direct-contact recharging pad powered by the onboard batteries. Modeling in support of turbine design and parametric studies in support of optimization of the performance of the system will be discussed. Scaling of the prototype system in terms of size and capacity will be discussed.

Performance Assessment of a Multi-Rotor Floating Tidal Energy System

Performance assessments of full-scale tidal turbines have been carried out for multiple machines deployed globally and reported in literature. The rotor number and diameter of the demonstrated tidal energy converters differs from single rotor devices in the MW class to scalable arrays of comparably small turbines. For multi-rotor systems (MRS), potential interaction, positive or negative, remains a key research question. Previous studies at Sustainable Marine prototype system (PLAT-I 4.63) have implied that variations in the incoming flow field are highly likely to cause deviations in rotor performance.
 Sustainable Marine has developed and built the pre-commercial PLAT-I 6.40 platform. PLAT-I 6.40 has been connected to the Canadian grid in May 2022. Between May and end of September 2022 the system has been undergone comprehensive commissioning and performance trials. PLAT-I 6.40, carries six 4m diameter SCHOTTEL Instream Turbines (SIT), each rated at 70 kW. This work presents the results of full-scale field tests that focussed on the assessment of differences in the performance between the individual turbines during summer 2022.
 To evaluate the variances in the flow field across all rotors, a specific test campaign has been conducted, where a flow speed sensor was sequentially positioned upstream of each turbine while a second flow measurement device was stationary as reference. For all test configurations the power curves have been determined following the guidance of the IEC TS 62600-200 based on the flow speeds measured with both devices.
 This paper presents the experimentally obtained power curves for each test configuration and compares it against the reference values. The results show that there are steady differences in the flow field resulting in varying power outputs across the different rotors (Figure 1). However, a comparison of the individual rotor power curves with the design predictions shows good agreement.

Improvement in Power Quality of Grid Connected PV & Wind Power Generation Systems

Abstract: The small turbine shows the connection of the source. This system, also used by remote and off-network systems, is known as a crossover power system. It uses wind energy from wind turbines to provide the mechanical ability to convert to electrical force. Regarding cost, efficiency, and dependability, combining at least two sustainable power sources is preferable to using just one. n terms of cost, efficiency, and dependability, a combination of at least two sustainable power sources is superior to one. The most important component for every country's contemporary and agricultural progress is energy

Design, fabrication, and evaluation of a small turbine blade manufactured by rotational molding

Design, fabrication, and evaluation of a small turbine blade manufactured by rotational molding

Effect of the von Karman Shedding Frequency on the Hydrodynamics of a Francis Turbine Operating at Nominal Load

This paper presents a numerical analysis of the influence of the von Karman vortex shedding at the blade trailing edge on the hydrodynamics of a recently installed small hydro Francis turbine manifesting very loud and high-frequency acoustic pulsations when operating close to the nominal load. A reduced single-passage numerical model is developed to reduce the computational effort of the simulation while ensuring high accuracy in the assessment of fluid flow. The accuracy of the proposed numerical approach is investigated by comparing the frequency spectrum of the experimentally acquired acoustic frequency and the numerical pressure signals, confirming the nature of the machine’s vibrations. The validated numerical model represents a useful tool for an in-depth analysis of the machine’s hydrodynamics in the preliminary design phases. The proposed approach represents a valid alternative to the traditional correlation-based approach for the evaluation of the von Karman shedding frequency with less computational effort compared with a transient simulation of the entire machine.