Experimental and Numerical Investigation of Small-Scale Tesla Turbines

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Avinash Renuke ◽  
Alberto Vannoni ◽  
Matteo Pascenti ◽  
Alberto Traverso
Keyword(s):  
Power Generation ◽  
Modular Design ◽  
Design Parameters ◽  
Working Fluid ◽  
Small Scale ◽  
One Dimensional ◽  
Micro Power ◽  
1D Model ◽  
Overall Performance ◽  
Numerical Performance

Abstract Interest in small-scale turbines is growing mainly for small-scale power generation and energy harvesting. Conventional bladed turbines impose manufacturing limitations and higher cost, which hinder their implementation at small scale. This paper focuses on experimental and numerical performance investigation of Tesla type turbines for micro power generation. A flexible test rig for Tesla turbine fed with air as working fluid has been developed, of about 100 W net mechanical power, with modular design of two convergent-divergent nozzles to get subsonic as well as supersonic flow at the exit. Seals are incorporated at the end disks to minimize leakage flow. Extensive experiments are done by varying design parameters such as disk thickness, gap between disks, radius ratio, and outlet area of exhaust with speeds ranging from 10,000 rpm to 40,000 rpm. A quasi-one-dimensional (1D) model of the whole setup is created and tuned with experimental data to capture the overall performance. Major losses, ventilation losses at end disks, and nozzle and exhaust losses are evaluated experimentally and numerically. Effect of design parameters on the performance of Tesla turbines is discussed.

Experimental and Numerical Investigation of Small Scale Tesla Turbines

2019 ◽  
Author(s):  
Avinash Renuke ◽  
Alberto Vannoni ◽  
Matteo Pascenti ◽  
Alberto Traverso
Keyword(s):  
Power Generation ◽  
Modular Design ◽  
Design Parameters ◽  
Working Fluid ◽  
Small Scale ◽  
Test Rig ◽  
Micro Power ◽  
1D Model ◽  
Overall Performance ◽  
Numerical Performance

Abstract Interest in small scale turbines is growing mainly for small scale power generation and energy harvesting. Conventional bladed turbines impose manufacturing limitations and higher cost, which hinder their implementation at small scale. This paper focuses on experimental and numerical performance investigation of Tesla type turbines for micro power generation. A flexible test rig for Tesla turbine fed with air as working fluid has been developed, of about 100W net mechanical power, with modular design of two convergent-divergent nozzles to get subsonic as well as supersonic flow at the exit. Seals are incorporated at the end disks to minimize leakage flow. Extensive experiments are done by varying design parameters such as disk thickness, gap between disks, radius ratio and outlet area of exhaust with speeds ranging from 10000 rpm to 40000 rpm. A quasi-1D model of the whole setup is created and tuned with experimental data to capture the overall performance. Major losses, ventilation losses at end disks, nozzle and exhaust losses are evaluated experimentally and numerically. Effect of design parameters on the performance of Tesla turbines is discussed.

scholarly journals Fluid dynamics assessment of the Tesla turbine rotor

2019 ◽  
Vol 23 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Giampaolo Manfrida ◽  
Lorenzo Talluri
Keyword(s):  
Power Generation ◽  
Power Plants ◽  
Low Cost ◽  
Turbine Rotor ◽  
Optimal Configuration ◽  
Design Parameters ◽  
Small Scale ◽  
Market Place ◽  
Micro Power ◽  
The Mathematical Model

The Tesla turbine seems to offer several points of attractiveness when applied to low-power applications. Indeed, it is a simple, reliable, and low cost machine. The principle of operation of the turbine relies on the exchange of momentum due to the shear forces originated by the flow of the fluid through a tight gap among closely stacked disks. This turbine was firstly developed by Tesla at the beginning of the 20th century, but it did not stir up much attention due to the strong drive towards large centralized power plants, on the other hand, in recent years, as micro power generation gained attention on the energy market place, this original expander raised renewed interest. The mathematical model of the Tesla turbine rotor is revised, and adapted to real gas operation. The model is first validated by comparison with other assessed literature models. The optimal configuration of the rotor geometry is then investigated running a parametric analysis of the fundamental design parameters. High values of efficiency (isolated rotor) were obtained for the optimal configuration of the turbine, which appears interesting for small-scale power generation. The rotor efficiency depends on the configuration of the disks, particularly on the gap and on the outlet diameter, which determines largely the kinetic energy at discharge.

Small Scale Supercritical CO2 Radial Inflow Turbine Meanline Design Considerations

2018 ◽  
Author(s):  
Tina Unglaube ◽  
Hsiao-Wei D. Chiang
Keyword(s):  
High Velocity ◽  
Gas Turbines ◽  
Velocity Ratio ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Working Fluid ◽  
Small Scale ◽  
Optimum Velocity ◽  
Set Up ◽  
Very High

In recent years closed loop supercritical carbon dioxide Brayton cycles have drawn the attention of many researchers as they are characterized by a higher theoretic efficiency and smaller turbomachinery size compared to the conventional steam Rankine cycle for power generation. Currently, first prototypes of this emerging technology are under development and thus small scale sCO2 turbomachinery needs to be developed. However, the design of sCO2 turbines faces several new challenges, such as the very high rotational speed and the high power density. Thus, the eligibility of well-established radial inflow gas turbine design principles has to be reviewed regarding their suitability for sCO2 turbines. Therefore, this work reviews different suggestion for optimum velocity ratios for gas turbines and aims to re-establish it for sCO2 turbines. A mean line design procedure is developed to obtain the geometric dimensions for small scale sCO2 radial inflow turbines. By varying the specific speed and the velocity ratio, different turbine configurations are set up. They are compared numerically by means of CFD analysis to conclude on optimum design parameters with regard to maximum total-to-static efficiency. Six sets of simulations with different specific speeds between 0.15 and 0.52 are set up. Higher specific speeds could not be analyzed, as they require very high rotational speeds (more than 140k RPM) for small scale sCO2 turbines (up to 150kWe). For each set of simulations, the velocity ratio that effectuates maximum efficiency is identified and compared to the optimum parameters recommended for radial inflow turbines using subcritical air as the working fluid. It is found that the values for optimum velocity ratios suggested by Rohlik (1968) are rather far away from the optimum values indicated by the conducted simulations. However, the optimum values suggested by Aungier (2005), although also established for subcritical gas turbines, show an approximate agreement with the simulation results for sCO2 turbines. Though, this agreement should be studied for a wider range of specific speeds and a finer resolution of velocity ratios. Furthermore, for high specific speeds in combination with high velocity ratios, the pressure drop of the designed turbines is too high, so that the outlet pressure is beyond the critical point. For low specific speeds in combination with low velocity ratios, the power output of the designed turbines becomes very small. Geometrically, turbines with low specific speeds and high velocity ratios are characterized by very small blade heights, turbines with high specific speeds and small velocity ratios by very small diameters.

scholarly journals Modeling Small Scale Solar Powered ORC Unit for Standalone Application

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Enrico Bocci ◽  
Mauro Villarini ◽  
Luca Bove ◽  
Stefano Esposto ◽  
Valerio Gasperini
Keyword(s):  
Power Generation ◽  
Ad Hoc ◽  
Rankine Cycle ◽  
External Support ◽  
Working Fluid ◽  
Small Scale ◽  
Technical Solution ◽  
Solar Panels ◽  
Under Construction ◽  
Photovoltaic Generators

When the electricity from the grid is not available, the generation of electricity in remote areas is an essential challenge to satisfy important needs. In many developing countries the power generation from Diesel engines is the applied technical solution. However the cost and supply of fuel make a strong dependency of the communities on the external support. Alternatives to fuel combustion can be found in photovoltaic generators, and, with suitable conditions, small wind turbines or microhydroplants. The aim of the paper is to simulate the power generation of a generating unit using the Rankine Cycle and using refrigerant R245fa as a working fluid. The generation unit has thermal solar panels as heat source and photovoltaic modules for the needs of the auxiliary items (pumps, electronics, etc.). The paper illustrates the modeling of the system using TRNSYS platform, highlighting standard and “ad hoc” developed components as well as the global system efficiency. In the future the results of the simulation will be compared with the data collected from the 3 kW prototype under construction in the Tuscia University in Italy.

Investigation on Solar-Powered Turbines Using Refrigerant R-134A

2014 ◽  
Author(s):  
Jihad Rishmany ◽  
Michel Daaboul ◽  
Issam Tawk ◽  
Nicolas Saba
Keyword(s):  
Power Generation ◽  
Solar Energy ◽  
Fossil Fuels ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Small Scale ◽  
Combustion Gases ◽  
Water Heaters ◽  
Wide Range ◽  
R 134A

Renewable energy has become a promising solution to substitute fossil fuels in power generation. In particular, the use of solar energy is stretched to a wide range of applications, e.g. photovoltaic cells, solar water heaters, solar space heating, solar thermal plants. However, the combination of solar energy with the Rankine cycle is limited to few applications only. In this context, this study aims in investigating the practicality of employing solar heaters to operate a Rankine cycle for small scale power generation. The working fluid in this study is refrigerant R-134a. Sizing and calculations of the various components of the system are carried out based on a net output power of 1 kW. In comparison with available electricity sources in Lebanon, it was found that the proposed system is currently more expensive than public electricity. However, it can compete with private generators that currently fill the gap in electricity shortage. The main advantage herein lies in the friendly environmental load due to the absence of combustion gases.

A Preliminary Turbine Design for an Organic Rankine Cycle

2013 ◽  
Author(s):  
T. Efstathiadis ◽  
M. Rivarolo ◽  
A. I. Kalfas ◽  
A. Traverso ◽  
P. Seferlis
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Energy Sources ◽  
Small Scale ◽  
Choked Flow ◽  
Turbine Speed ◽  
Turbine Design

An increasing trend in exploiting low enthalpy content energy sources, has led to a renewed interest in small-scale turbines for Organic Rankine Cycle applications. The design concept for such turbines can be quite different from either standard gas or steam turbine designs. The limited enthalpic content of many energy sources enforces the use of organic working media, with unusual properties for the turbine. A versatile cycle design and optimization requires the parameterization of the prime turbine design. In order to address the major challenges involved in this process, the present study discusses the preliminary design of an electricity-producing turbine, in the range of 100 kWel, for a low enthalpy organic Rankine cycle. There are many potential applications of this power generating turbine including geothermal and solar thermal fields or waste heat of PEM type fuel cells. An integrated model of equations has been developed, accordingly. The model aims to assess the performance of an organic cycle for various working fluids, including NH3, R600a and R-134a. The most appropriate working fluid has been chosen, taking into consideration its influence on both cycle efficiency and the specific volume ratio. The influence of this choice is of particular importance at turbine extreme operating conditions, which are strongly related to the turbine size. In order to assess the influence of various design parameters, a turbine design tool has been developed and applied to preliminarily define the blading geometry. Finally, a couple of competitive turbine designs have been developed. In one approach, the turbine speed is restricted to subsonic domain, while in the other approach the turbine speed is transonic, resulting to choked flow at the turbine throat. The two approaches have been evaluated in terms of turbine compactness and machine modularity. Results show that keeping the crucial parameters of the geometrical formation of the blade constant, turbine size could become significantly smaller decreasing up to 90% compared its original value.

Influence of Design Parameters on the Performance of a Multistage Centrifugal Compressor for Supercritical Carbon Dioxide Applications

2015 ◽  
Author(s):  
B. Monge ◽  
D. Sánchez ◽  
M. Savill ◽  
P. Pilidis ◽  
T. Sánchez
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Centrifugal Compressor ◽  
Design Space ◽  
Operating Conditions ◽  
Design Parameters ◽  
Working Fluid ◽  
Small Scale ◽  
Main Design ◽  
Supercritical Carbon

The development of the supercritical Carbon Dioxide power cycle has relied on parallel tracks along which theoretical and experimental works have successfully complemented each other in the last few years. Following this approach, intensive work on the development of critical components has enabled the demonstration of the technology in small-scale test loops. The next step in the roadmap is scaling-up the technology in order to bridge the gap to commercialisation. To this aim, not only is it necessary to demonstrate that the cycle works, but it is also mandatory to rise component (and system) efficiencies to levels comparable with competing technologies. In this process, assessing the impact of the main design parameters on the efficiency of turbomachinery is deemed crucial. The present work is a follow-up to others presented by the authors in previous years where preliminary analysis on centrifugal compressor design combining tools of different levels of fidelity were used. Nevertheless, whilst these presented guidelines to design the main compressor successfully, this new piece of research presents how the design space of the unit is affected by the characteristics of the working fluid. A review of past research is first presented to evidence that the design space is largely influenced by the particular behaviour of the working fluid close to the critical point. Then, design maps are presented for different operating conditions (cycle heat balance), showing that their shapes change substantially depending on compressor inlet pressure and temperature. Also, a comparison of these maps confirms that the design regions enabling high efficiency can be substantially reduced depending on the inlet/outlet thermodynamic states. Finally, conclusions are drawn regarding optimal intervals for the main design parameters involved in the process.

Optimization of Looped Airfoil Wind Turbine (LAWT™) Design Parameters for Maximum Power Generation

2016 ◽  
Author(s):  
Binhe Song ◽  
Subhodeep Banerjee ◽  
George Syrovy ◽  
Ramesh K. Agarwal
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Rural Areas ◽  
Analytical Formula ◽  
Maximum Power ◽  
Total Power ◽  
Design Parameters ◽  
Small Scale ◽  
Drag Coefficients ◽  
Lift And Drag

The looped airfoil wind turbine (LAWT™) is a patented new technology by EverLift Wind Tecnology, Inc. for generating power from wind. It takes advantage of the superior lift force of a linearly traveling wing compared to the rotating blades in conventional wind turbine configurations. Compared to horizontal and vertical axis wind turbines, the LAWT™ can be manufactured with minimal cost because it does not require complex gear systems and its blades have a constant profile along their length [1]. These considerations make the LAWT™ economically attractive for small-scale and decentralized power generation in rural areas. Each LAWT™ is estimated to generate power in the range of 10 kW to 1 MW. Due to various advantages, it is meaningful to determine the maximum power generation of a LAWT™ by optimizing the structural layout. In this study, CFD simulations were conducted using ANSYS Fluent to determine the total lift and drag coefficient for a cascade of airfoils. The k-kl-ω turbulence model was used to account for flow in the laminar-turbulent transition region. Given the lift and drag coefficients and the kinematics of the system, an analytical formula for the power generation of the LAWT™ was developed. General formulas were obtained for the average lift and drag coefficients so that the total power could be predicted for any number of airfoils in LAWT™. The spacing between airfoils was identified as the key design parameter that affected the power generation of the LAWT™. The results show that a marked increase in total power can be achieved if the optimum spacing between the airfoils is used.

scholarly journals Assessment of a District Trigeneration Biomass Powered Double Organic Rankine Cycle as Primed Mover and Supported Cooling

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1030
Author(s):  
Muhammad Tauseef Nasir ◽  
Michael Chukwuemeka Ekwonu ◽  
Yoonseong Park ◽  
Javad Abolfazli Esfahani ◽  
Kyung Chun Kim
Keyword(s):  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Hot Water ◽  
Design Parameters ◽  
Working Fluid ◽  
Small Scale ◽  
Vapor Compression ◽  
Medium Temperature ◽  
Exergetic Analysis ◽  
The Impact

This study presents a combined cooling, heating, and power system powered by biogas, suitable for small scale communities in remote locations. To run such a system, in order to obtain the daily life essentials of electricity, hot water, and cooling, municipal waste can be considered as an option. Furthermore, the organic Rankine cycle part of the organic Rankine cycle powered vapor compression chiller can be used in times of need for additional electric production. The system comprises a medium temperature organic Rankine cycle utilizing M-xylene as its working fluid, and the cooling was covered by an Isobutane vapor compression cycle powered by an R245fa employing organic Rankine cycle. The system analyzed was designated to provide 250 kW of electricity. The energetic and exergetic analysis was performed, considering several system design parameters. The impact of the design parameters in the prime mover has a much greater effect on the whole system. The system proposed can deliver cooling values at the rate between 9.19 and 22 kW and heating values ranging from 879 up to 1255 kW, depending on the design parameter. Furthermore, the second law efficiency of the system was found to be approximately 56% at the baseline conditions and can be increased to 64.5%.

scholarly journals Dynamic exergetic and environmental assessments of the small scale LNG cold utilized micro power generation systems

2017 ◽  
Vol 143 ◽  
pp. 680-685 ◽  
Author(s):  
Baris Burak Kanbur ◽  
Xiang Liming ◽  
Swapnil Dubey ◽  
Choo Fook Hoong ◽  
Fei Duan
Keyword(s):  
Power Generation ◽  
Small Scale ◽  
Environmental Assessments ◽  
Micro Power ◽  
Power Generation Systems
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