Reaction Turbine Research Articles

A Review on Micro Hydropower in Indonesia

Abstract This paper presents a review of status of micro hydropower in Indonesia. A micro hydropower plant can use a reaction or impulse turbine depending on the available resource. Only way to reduce the dependency on fossil fuel is by increasing the renewable energy production capabilities. It is very important to consider short term economic feasibility of renewable energy resources for developing countries. Among all renewable energy sources, hydroelectricity is the most economical and reliable source. Due to environmental concerns and very large capital cost a large hydro power station has less attraction in the present world economy. Nonetheless micro hydropower has a quite large potential to develop. Many of small rivers have much energy to exploit by hydropower electrification, from pico-hydro to micro-hydro scale. Particularly in Indonesia, in many islands country they have huge potential for using micro-hydro on many river and high rainfall because many area of Indonesia lie in equator line.

EVOLUTION OF SIMPLE REACTION TYPE TURBINES FOR PICO-HYDRO APPLICATIONS

This paper aims to explore the history and development of eight types of reaction water turbines, namely Hero’s turbine, Barker’s mill, Pupil’s turbine, Whitlaw’s mill, Quek’s turbine, the cross pipe turbine, the split reaction turbine and the Z-Blade turbine. These water turbines are discussed in terms of the complexity of the designs, the manufacturing processes involved, and the applications. It has been observed that even though most reaction type water turbines, except for the split reaction turbine and Z-blade turbine, have undergone different levels of design-related modifications and manufacturing processes, they are considered as being unsuitable for low-head and low-flow water resources in pico-hydro systems.

Tiny bubbles challenge giant turbines: Three Gorges puzzle.

Since the birth of the first prototype of the modern reaction turbine, cavitation as conjectured by Euler in 1754 always presents as a challenge. Following his theory, the evolution of modern reaction (Francis and Kaplan) turbines has been completed by adding the final piece of the element 'draft-tube' that enables turbines to explore water energy at efficiencies of almost 100%. However, during the last two and a half centuries, with increasing unit capacity and specific speed, the problem of cavitation has been manifested and complicated by the draft-tube surges rather than being solved. Particularly, during the last 20 years, the fierce competition in the international market for extremely large turbines with compact design has encouraged the development of giant Francis turbines of 700-1000 MW. The first group (24 units) of such giant turbines of 700 MW each was installed in the Three Gorges project. Immediately after commission, a strange erosion phenomenon appeared on the guide vane of the machines that has puzzled professionals. From a multi-disciplinary analysis, this Three Gorges puzzle could reflect an unknown type of cavitation inception presumably triggered by turbulence production from the boundary-layer streak transitional process. It thus presents a fresh challenge not only to this old turbine industry, but also to the fundamental sciences.

Computational fluid dynamics simulation and geometric design of hydraulic turbine draft tube

Any hydraulic reaction turbine is installed with a draft tube that impacts widely the entire turbine performance, on which its functions are as follows: drive the flux in appropriate manner after it releases its energy to the runner; recover the suction head by a suction effect; and improve the dynamic energy in the runner outlet. All these functions are strongly linked to the geometric definition of the draft tube. This article proposes a geometric parametrization and analysis of a Francis turbine draft tube. Based on the parametric definition, geometric changes in the draft tube are proposed and the turbine performance is modeled by computational fluid dynamics; the boundary conditions are set by measurements performed in a hydroelectric power plant. This modeling allows us to see the influence of the draft tube shape on the entire turbine performance. The numerical analysis is based on the steady-state solution of the turbine component flows for different guide vanes opening and multiple modified draft tubes. The computational fluid dynamics predictions are validated using hydroelectric plant measurements. The prediction of the turbine performance is successful and it is linked to the draft tube geometric features; therefore, it is possible to obtain a draft tube parameter value that results in a desired turbine performance.

Novel Power Generation System for Low Temperature Heat Sources

Objectives: This research is about a novel power generation system for producing electricity from low temperature heat sources including renewable energy sources or waste heat from industrial process. Usage of renewable energy sources by current technologies has low efficiency and high investing costs. Methods/Analysis: Innovated system that is described in this paper consists of a reaction turbine as main part of the system, turbine shield, working fluid, heat exchanger, condenser, pump and electrical generator. Working fluid that gets energy from heat exchanger and increased its temperature enter to reaction turbine; exiting saturated working fluid from nozzles of turbine according to third law of newton cause rotation of turbine and thus produce electricity. Findings: In this research we could successfully design and test a novel power generation system with output power of around 1 KWe. Proving capability of application of a reaction turbine with an organic working fluid for use as power cycle to produce electricity from low temperature heat sources is the key finding of this research. This concept is simple and have low initial cost and less technical problems like corrosion and maintenance compared to thermodynamic cycle that use impulse turbines as expansion device. Novelty/Improvement: Power generation from low temperature heat sources such as solar and geothermal by means of a reaction turbine concept and an organic fluid as working fluid of the system is the main novelty of this work. This combination let us to generate power from low temperature heat sources simply and efficiently.

Performance of a rotating two-phase turbine for combined power generation and desalination

The main purpose of this study was to develop a simple design of a two-phase flow reaction turbine and experimentally estimate its performance characteristics with sub-cooled hot water as working fluid. Sub-cooled feed water at 96 °C and under local atmospheric pressure was supplied to the turbine while the pressure at the turbine exit was maintained at around 6 kPa absolute within an evacuated container. The turbine under investigation had an outer diameter of 412 mm, throat diameter of 2.5 mm and total nozzle exit area of 1320 mm2 for two curved nozzles. The best position of the throat was found to be around 34 mm from the centre of the turbine under investigation. Placement of a flat head pin downstream of the throat improved the turbine's performance.

Experimental performance of a rotating two-phase reaction turbine

This paper presents the experimental performance of a curved nozzle two-phase reaction turbine design for trilateral flash cycle heat engine. Results from two tests have been presented, for first test the average feed water temperature was maintained around 97 °C under local atmospheric pressure, while for the second test the average feed water temperature was maintained around 115 °C under 200 kPa absolute pressure. For both the tests the initial condenser pressure was maintained around 6 kPa absolute. The maximum power output of the turbine is estimated to be around 1330 W with an isentropic efficiency of around 25%.

Design and analysis of a compact solar-driven constant-torque reaction steam turbine

The design and performance analysis of a self-sustaining, solar-driven reaction steam turbine are presented. The reaction turbine, placed horizontally, consists of two concentric cylinders with the outer one rotating with respect to the stationery inner cylinder, providing a compact and agile design. The inner cylinder, constantly filled and replenished with water, hosts conically shaped holes to allow a constant stream of feed water into the clearance between the two cylinders. With means of the thermal energy provided by the solar collector, water in the clearance will produce superheated steam that will be released in the form of steam jets causing rotational velocity, through a set of pressure relief valves placed at the surface of the outer cylinder. The main advantage of this turbine unit is the production of constant torque that is independent of temperature, with an efficiency of around 3.7%.

Investigating the potential for using a simple water reaction turbine for power production from low head hydro resources

In this analysis the simple reaction water turbine known as Barker’s Mill is revisited. The major geometrical and operational parameters have been identified and, using principles of conservation of mass, momentum and energy, the governing equations have been developed for the ideal case of there being no frictional losses. The solutions of the resulting equations are offered in a non-dimensional form. It is shown that the maximum torque produced by the machine is developed when the turbine is stationary. At this point the net output power is zero. As the load torque is decreased the turbine rotates and power is produced. Furthermore, because of a centrifugal pumping effect, the mass flow rate of water through the turbine increases during acceleration. Further decrease in the load torque is accompanied by increases of speed, output power, water mass flow rate and efficiency. It is shown that when the load torque is reduced towards half the value of the torque at the stationary condition, water mass flow rate, rotational speed and output power tend towards infinity. Under this condition the efficiency of the machine approaches unity. The non-dimensional characteristics of the idealized turbine are used to investigate the general characteristics of the machine and to explore its application for production of power from water reservoirs with low heads. Theoretical analysis of a simple reaction turbine is presented including consideration of the fluid frictional losses for a practical situation. A practical turbine will never run away towards infinite speed and the maximum power and efficiency of such a turbine will depend on the fluid frictional losses. Here a new factor is defined, representing the overall fluid frictional losses within the turbine. Finally this paper presents briefly the experimental performance results for two simple reaction water turbine prototypes. The two turbine prototypes under investigation have rotor diameters Ø0.24m and Ø0.12m respectively. The two turbine models were tested under supply heads ranging from 1m to 4m. The simple reaction water turbine can operate under very low hydro-static head with high energy conversion efficiency. This type of turbine exhibits prominent self-pumping ability at high rotational speeds. Under low head to achieve high rotational speeds the turbine diameter should be very small and this limits the volumetric capacity and hence the power generation capacity of such a turbine. Consequently the practical applications of this turbine would be limited to micro-hydro power generation. The split pipe design of the reaction turbine tested is easy to manufacture and it has been shown to have overall energy conversion efficiency of approximately 50% even under low heads.

Numerical Study on Performance Characteristics of Draft Tube of Mixed Flow Hydraulic Turbine

Draft tube is an important component of the hydraulic reaction turbine and affects the overall performance of turbine to a large extent. The flow inside the draft tube is complex because of the whirling flow coming out of runner and its diffusion along the draft tube. The kinetic energy coming out of runner is recovered in draft tube and part of recovery meets the losses. In the present work, the computational fluid dynamics (CFD) has been used for flow simulation in complete mixed flow Francis turbine for performance analysis for energy recovery, losses and flow pattern in an elbow draft tube used in Francis turbine at different operating conditions. The overall performance of the turbine at some typical operating regimes is validated with the experimental results and found to be in close comparison.DOI: http://dx.doi.org/10.3126/hn.v10i0.7103 Hydro Nepal Vol.10 January 2012 48-52

Expander Modelling in Binary Cycle Utilizing Geothermal Resources for Generating Green Energy in Victoria, Australia

This paper investigates the computational modeling of a binary organic Rankine power cycle. The computer model has been generated to aid the design and manufacture of apparatus that will be utilized during experimentation on the geothermal resources in Victoria, Australia. A review of Australia's geothermal prospects is also presented here. Suitable technology to utilize the low grade heat from the available geo-fluids has been explained to connect the recent technology with the new approached design. The paper involves the design of the heat engine with the reaction turbine. In addition, theoretical analysis and performance predictions have been presented briefly in the paper to compare between different diameters for the reaction turbine in the organic Rankine cycle engine with power and efficiency. In this paper, realistic recommendations will be discussed to the best of the geothermal energy as sustainable energy resources to be useful for achieving the Australian target.The binary cycle is modeled to evaluate the output power and the efficiency. A computer model for binary cycle is presented in this paper. Thermal-mechanical energy conversion efficiency is predicted using the computer modeling and presented in the analysis.

Performance Investigation of a Simple Reaction Water Turbine for Power Generation from Low Head Micro Hydro Resources

Theoretical investigation has shown a simple reaction water turbine would perform better when it spins faster. And for the simple reaction turbine water turbine to spin faster under constant water head, its diameter should be smaller. This paper reports on a performance analysis based on the experimental data collected from different performance tests carried on two simple reaction water turbine prototypes. Two new designs of simple reaction water turbines and their manufacturing methods are reported. The two turbines under investigation have different rotor diameters Φ 0.243 m and Φ 0.122 m. In case of the simple reaction water turbine the water enters into the turbine axially and exits tangentially through nozzles located on the outer periphery of the turbine. Further this paper will discuss the performance characteristics of stationary turbine i.e. zero power produced and performance characteristics of turbine producing power. It was found that rotor diameter affects the maximum rotational speed of the simple reaction turbine for constant supply head. It was also found that faster the turbine spins its performance improves. The two turbines were tested between supply head range of 1 m to 4 m.

Research on the Relationships between Blade Angles and External Characteristics of a Centimeter Scale Pneumatic Turbine

A pneumatic motor based on the principle of reaction micro turbine has been developed with a rotor diameter of 24 mm. The turbine motor includes a planet-gear reducer with gear ratio of 6.5, generates a maximum mechanical power of 248W with total efficiency 60%. It has been tested to speeds up to 10,000rpm on shaft end. Based on the developed cm-scale micro reaction turbine motors prototype, the mathematical models about the blade angles and its external characteristic parameters were built and carried out, and then their relationships are researched and obtained when the blade angles change within possible ranges.

Design and analysis of a split reaction water turbine

This paper explores the performance characteristics of a split reaction water turbine. The governing equations are derived by using the principles of conservation of mass, momentum and energy for a practical case, which includes consideration of frictional losses. The optimum diameter for a simple reaction turbine is defined and an equation for the optimum diameter is derived. Design and building procedures for a split reaction turbine are described. Using the equation for optimum diameter and assuming a loss factor ( k-factor) of 0.05, optimum rotor diameters for different operating heads and rotational speeds are plotted and discussed. Measured performance of a 122 mm diameter split reaction water turbine rotor is presented. The relationship between k-factor and relative velocity for a split reaction turbine model is discussed with reference to experimental data.

Performance analysis of an enhanced thermosyphon Rankine cycle using impulse turbine

Thermosyphon Rankine cycle (TRC) is an environmentally friendly system for direct extraction of electrical power using low enthalpy heat sources. An enhanced design of the TRC system using impulse turbine was recommended, in this paper. Energy and exergy analysis of the TRC was formulated in order to estimate its optimum operating conditions. Also the data available in open literature were used to validate the TRC mathematical model. The results showed that the highest efficiency happens for the reaction turbine model at the turbine infinite speed; and for the impulse turbine at the turbine limited speed. The simulation results indicated that the present model can be able to increase the efficiency of the TRC system.

Simultaneous desalination and power generation using solar energy

Using solar energy to produce fresh water and electricity simultaneously is a prospective way to solve the problems combining fresh water shortage, energy crisis and farm land degradation in Northern Victoria. This paper records the process of calculating the performance of the nozzle applying homogenous equilibrium model, designing and testing the prototype of such system using three different types of the nozzles in static and rotary systems. The research on the project is divided into two steps: first is about static system in which the spray nozzle is proved to be the best in both production of fresh water and power generation; while on the second stage, the convergent–divergent (C–D) nozzles are the best in rotary system. Some data were analyzed theoretically based on the test and the results found that the percentage of fresh water measured by experiment is consistent with the calculation using homogenous equilibrium expansion model (HEM), however, there is big difference in power generation between theory and experiments. Based on our experimental figures and analysis, the reasons for low power generation are found and a new model is proposed. According to the new model, a different reaction turbine using curve length C–D nozzles is designed to overcome the problems which were encountered in the previous prototype. After analyzing the efficiency of the cycle by T– s diagram, the evacuated tube solar collector integrated heat pipe is suggested to be applied on this system.

Non-axisymmetric flow field in an axial impulse turbine

Phenomena such as hard landings or geometric flaws can cause non-axisymmetric tip clearance in turbines. Such geometric imperfections induce flow distortions which can, in turn, cause self-excited vibration of the rotor, or rotordynamic instability. Flow field perturbations in a single-stage, unshrouded impulse turbine caused by non-axisymmetric tip clearance have been investigated experimentally. Steady velocity and pressure data have been acquired at the design point with and without static turbine casing offset. Perturbations in tangential velocity and casing wall pressure have been obtained, and rotordynamic forces along and perpendicular to the axis of offset have been inferred. Compared to an unshrouded 20% reaction turbine, the forces due to tangential force asymmetry are much smaller, but the forces due to pressure asymmetry are comparable.

Hydraulic turbine efficiency

A set of empirical equations has been developed which defines the peak efficiency and shape of the efficiency curve for hydraulic turbines as a function of the commissioning date for the unit, rated head, rated flow, runner speed, and runner throat or impulse turbine jet diameter. The equations are based on an analysis of peak efficiency data from 56 Francis, 33 axial-flow, and eight impulse runners dating from 1908 to the present, with runner diameters ranging from just under 0.6 m to almost 9.5 m. The metric specific speeds (nq) ranged from 5.3 to 294. The root mean square error of the calculated peak efficiency for Francis and axial-flow runners was found to be 0.65%. The shape of the efficiency curves was derived from eight Francis, five Kaplan, three propeller, and four impulse turbines. Charts showing the relationship between calculated and actual efficiency curves for these 20 runners are provided. A good match between calculated and measured or guaranteed efficiency was obtained. The equations were also used to determine the relative increase in peak efficiency for new reaction runners installed in existing casings at 22 powerplants, with a root mean square accuracy of 1.0%. The equations can be used to (i) develop efficiency curves for new and old runners; (ii) compare the energy output of alternative types of turbines, where this choice is available; and (iii) calculate the approximate incremental energy benefit from installing a new runner in an existing reaction turbine casing, or onto the shaft of an impulse unit.Key words: hydraulic turbines, turbine renovation, turbine efficiency.

A Robust Control for Engine and Transmission Systems: Enhancement of Shift Quality.

In this paper, a robust integrated control for engine and automatic transmission systems is investigated. The modeling of powertrain system is split into five subparts including an engine, a torque converter, an automatic transmission, clutch torque generation, and a drivetrain. For improving the ride quality, a two-stage control strategy, torque phase and inertia phase, is proposed. During the torque phase, the slip in first gear is maintained to near zero, while the reaction carrier speed and turbine speed during the inertia phase are controlled to track their desired speeds. The reaction carrier speed is adjusted by the second clutch torque, and the turbine speed is controlled by engine throttle angle and spark advance. Due to the uncertainty and unmodelled dynamics of the system, the uniform ultimate boundedness of the error signals is assured by applying the Lyapunov stability analysis. Simulation results are provided.

Analysis of flow in the plate-spiral of a reaction turbine using a streamline upwind Petrov-Galerkin method

The prediction of the flow field in a novel spiral casing has been accomplished. Hydraulic turbine manufacturers are considering the potential of using a special type of spiral casing because of the easier manufacturing process involved in its fabrication. These special spiral casings are known as plate-spirals. Numerical simulation of complex three-dimensional flow through such spiral casings has been accomplished using a finite element method (FEM). An explicit Eulerian velocity correction scheme has been deployed to solve the Reynolds-average Navier–Stokes equations. The simulation has been performed to describe the flow in high Reynolds number (106) regimes. For spatial discretization, a streamline upwind Petrov–Galerkin (SUPG) technique has been used. The velocity field and the pressure distribution inside the spiral casing reveal meaningful results. Copyright © 2000 John Wiley & Sons, Ltd.