Method to Design a Hydro Tesla Turbine for Sensitivity to Varying Laminar Reynolds Number Modulated by Changing Working Fluid Viscosity

2017 ◽  
Author(s):  
Mubarak S. Alrabie ◽  
Faisal N. Altamimi ◽  
Muhammad H. Altarrgemy ◽  
Fatemeh Hadi ◽  
Muhammad K. Akbar ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Design Process ◽  
Power Output ◽  
Working Fluid ◽  
Biomass Combustion ◽  
Fluid Viscosity ◽  
Corn Syrup ◽  
Power Extraction ◽  
Physical Scale ◽  
Disk Spacing

There has been a recent surge in interest for Tesla turbines used in renewable energy applications such as power extraction from low-quality steam generated from geothermal or concentrated solar sources as well as unfiltered particle-laden biomass combustion products. High interest in these bladeless turbines motives renewed theoretical and experimental study. Despite this renewed interest, no systematic Tesla turbine design process based in foundational theory has been published in the peer reviewed engineering literature. A design process is thus presented which is flexible, allowing an engineering designer to select and address goals beyond simply maximizing turbine output power. This process is demonstrated by designing a Tesla turbine where Reynolds number can be easily varied while holding all other parameters fixed. Tesla turbines are extremely sensitive to inter-disk spacing. It is therefore desirable to design the experiment to avoid turbine disassembly/reassembly between tests; this assures identical disk spacing and other parameters for all tests. It is also desirable to maintain similar working fluid mass flow rate through the turbine in all tests to minimize influence of losses at the nozzle impacting shaft power output differently across experiments. Variation in Reynolds number over more than two orders of magnitude is achieved by creating a set of two-component working fluid mixtures of water and corn syrup. Increasing mixture mass fraction of corn syrup achieves increased working fluid viscosity but only small increase in density with a corresponding decrease in working fluid Reynolds number. The overall design goal is to create a turbine that allows modulating Reynolds number impact on Tesla turbine performance to be evaluated experimentally. The secondary goal is to size the turbine to maximize sensitivity to changes in Reynolds number to make experimental measurement easier. The presented example design process results in a Tesla turbine with 8-cm-outer-diameter and 4-cm-inner-diameter disks. The turbine will be able to access a range of Reynolds numbers from 0.49 < Rem < 99.50. This range represents a Reynolds number ratio of Rem,max/Rem,min = 202.8, more than two orders of magnitude and spanning the lower part of the laminar range. The turbine’s expected power output will be Ẇ = 0.47 Watts with a delivered torque of 0.024 mN-m at a rotation rate of ωmax = 1197 rev/min. Combining the analytical equations underpinning the design process with similarity arguments, it is shown that shrinking the Tesla turbine’s physical scale drives the Reynolds number toward 0. The resulting velocity difference between the working fluid and the turbine disks gets driven toward infinity, which makes momentum transfer and the resulting turbine efficiency extremely high. In other words, unlike conventional turbines whose efficiency drops as they are scaled down, the performance of Tesla turbines will increase as they are made smaller. Finally, it is shown through similarity scaling arguments that the 8-cm-diameter turbine resulting from the design process of this paper and running liquid Ethylene Glycol working fluid can be used to evaluate and approximate the performance of a 3-mm-diameter Tesla turbine powered by products of combustion in air.

Extending “Assessment of Tesla Turbine Performance” Model for Sensitivity-Focused Experimental Design

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Matthew J. Traum ◽  
Fatemeh Hadi ◽  
Muhammad K. Akbar
Keyword(s):  
Reynolds Number ◽  
Power Output ◽  
Performance Model ◽  
Nozzle Geometry ◽  
Design Parameters ◽  
Working Fluid ◽  
Extended Model ◽  
Number Range ◽  
Nozzle Height ◽  
Turbine Performance

The analytical model of Carey is extended and clarified for modeling Tesla turbine performance. The extended model retains differentiability, making it useful for rapid evaluation of engineering design decisions. Several clarifications are provided including a quantitative limitation on the model’s Reynolds number range; a derivation for output shaft torque and power that shows a match to the axial Euler Turbine Equation; eliminating the possibility of tangential disk velocity exceeding inlet working fluid velocity; and introducing a geometric nozzle height parameter. While nozzle geometry is limited to a slot providing identical flow velocity to each channel, variable nozzle height enables this velocity to be controlled by the turbine designer as the flow need not be choked. To illustrate the utility of this improvement, a numerical study of turbine performance with respect to variable nozzle height is provided. Since the extended model is differentiable, power sensitivity to design parameters can be quickly evaluated—a feature important when the main design goal is maximizing measurement sensitivity. The derivatives indicate two important results. First, the derivative of power with respect to Reynolds number for a turbine in the practical design range remains nearly constant over the whole laminar operating range. So, for a given working fluid mass flow rate, Tesla turbine power output is equally sensitive to variation in working fluid physical properties. Second, turbine power sensitivity increases as wetted disk area decreases; there is a design trade-off here between maximizing power output and maximizing power sensitivity.

Stirling Power Unit: Impact of a Controlled Displacer Piston on Efficiency and Power Output

2015 ◽  
Author(s):  
Anna Winkelmann ◽  
Eric J. Barth
Keyword(s):  
Dynamic Model ◽  
Power Unit ◽  
Power Output ◽  
Dynamic Models ◽  
Thermodynamic Cycle ◽  
Working Fluid ◽  
Electric Generator ◽  
Power Extraction ◽  
Extraction Unit ◽  
Pressure Dynamics

This paper presents the design and dynamic model of a novel “controlled Stirling power unit” with an independently controlled displacer piston. Breaking the coupling traditionally seen in Stirling devices between the power piston and the displacer piston, realized either kinematically or dynamically, allows an additional control degree of freedom that can be used to shape the thermodynamic cycle independent of the load. The device presented combines such a controlled Stirling engine (called a pressurizer) with a power extraction unit. The dynamic models of three different power extraction units are presented. The dynamic model builds on a previous experimentally validated first-principles model of a Stirling pressurizer. The model is a lumped parameter compressible fluid power dynamic model that captures the pressure dynamics of the high pressure helium working fluid as it is affected in time by volume, mass and heat flux changes. The dynamic model of a pressurizer combined with a linear electric generator is used to study different displacer motion profiles with regard to the shape of the thermodynamic cycle, and the effect on the power output and efficiency of the device.

Characteristics of the Diffuser/Nozzle Valve-Less Micro-Pump

2007 ◽  
Author(s):  
Seiichi Tanaka ◽  
Hiroshi Tsukamoto ◽  
Koji Miyazaki
Keyword(s):  
Reynolds Number ◽  
Flow Rate ◽  
Volumetric Flow Rate ◽  
Simplified Model ◽  
Working Fluid ◽  
Oscillating Flow ◽  
Fluid Viscosity ◽  
Pump Performance ◽  
Micro Pump ◽  
Pump Head

In this study we have developed a valve-less micro-pump with one diffuser shaped element and a chamber with a diaphragm; the vibration of which produces an oscillating flow. The pressure-loss in a nozzle is lower than that in a diffuser, and therefore one-way flow is realized in the nozzle direction. The frequency characteristics and the pump characteristics are measured. The maximum total pump head and volumetric flow rate are 0.8 kPa and 2.4 ml/min respectively. The effect of working-fluid viscosity on pump characteristics is also discussed using water and glycerin-water solutions. As a result, the pump performances were found to decrease with increasing fluid viscosity and the pump performance depended on the Reynolds number of oscillating flow. The experimental results are discussed using a simplified model based on the Bernoulli’s theory for unsteady flow in pump.

Influence of viscosity temperature dependence on the spectral characteristics of the thermoviscous liquids flow stability equation

2019 ◽  
Vol 14 (1) ◽  
pp. 52-58 ◽  
Author(s):  
A.D. Nizamova ◽  
V.N. Kireev ◽  
S.F. Urmancheev
Keyword(s):  
Reynolds Number ◽  
Spectral Characteristics ◽  
Wave Number ◽  
Critical Parameters ◽  
Fluid Viscosity ◽  
Flat Channel ◽  
Stability Equation ◽  
The Stability ◽  
Thermoviscous Fluid ◽  
Sommerfeld Equation

The flow of a viscous model fluid in a flat channel with a non-uniform temperature field is considered. The problem of the stability of a thermoviscous fluid is solved on the basis of the derived generalized Orr-Sommerfeld equation by the spectral decomposition method in Chebyshev polynomials. The effect of taking into account the linear and exponential dependences of the fluid viscosity on temperature on the spectral characteristics of the hydrodynamic stability equation for an incompressible fluid in a flat channel with given different wall temperatures is investigated. Analytically obtained profiles of the flow rate of a thermovisible fluid. The spectral pictures of the eigenvalues of the generalized Orr-Sommerfeld equation are constructed. It is shown that the structure of the spectra largely depends on the properties of the liquid, which are determined by the viscosity functional dependence index. It has been established that for small values of the thermoviscosity parameter the spectrum compares the spectrum for isothermal fluid flow, however, as it increases, the number of eigenvalues and their density increase, that is, there are more points at which the problem has a nontrivial solution. The stability of the flow of a thermoviscous fluid depends on the presence of an eigenvalue with a positive imaginary part among the entire set of eigenvalues found with fixed Reynolds number and wavenumber parameters. It is shown that with a fixed Reynolds number and a wave number with an increase in the thermoviscosity parameter, the flow becomes unstable. The spectral characteristics determine the structure of the eigenfunctions and the critical parameters of the flow of a thermally viscous fluid. The eigenfunctions constructed in the subsequent works show the behavior of transverse-velocity perturbations, their possible growth or decay over time.

EXPERIMENTAL STUDY ON THERMAL TRANSPORT PHENOMENON OF NANOFLUIDS AS WORKING FLUID IN HEAT EXCHANGER

2014 ◽  
Vol 22 (01) ◽  
pp. 1450005 ◽  
Author(s):  
SHUICHI TORII
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Pure Water ◽  
Horizontal Tube ◽  
Constant Heat Flux ◽  
Working Fluid ◽  
Transfer Performance ◽  
Nanoparticles Concentration ◽  
Transfer Behavior

This paper aims to study the convective heat transfer behavior of aqueous suspensions of nanoparticles flowing through a horizontal tube heated under constant heat flux condition. Consideration is given to the effects of particle concentration and Reynolds number on heat transfer enhancement and the possibility of nanofluids as the working fluid in various heat exchangers. It is found that (i) significant enhancement of heat transfer performance due to suspension of nanoparticles in the circular tube flow is observed in comparison with pure water as the working fluid, (ii) enhancement is intensified with an increase in the Reynolds number and the nanoparticles concentration, and (iii) substantial amplification of heat transfer performance is not attributed purely to the enhancement of thermal conductivity due to suspension of nanoparticles.

Non-Isothermal Peristaltic Flow of Newtonian Fluids in a Circular Tube

2009 ◽  
Author(s):  
M. S. Yun ◽  
B. P. Huynh
Keyword(s):  
Reynolds Number ◽  
Flow Pattern ◽  
Circular Tube ◽  
Pressure Change ◽  
Peristaltic Flow ◽  
Isothermal Flow ◽  
Newtonian Fluids ◽  
Fluid Viscosity ◽  
Fluid Properties ◽  
Isothermal Case

Non-isothermal peristaltic flow of Newtonian fluids in a circular tube is investigated numerically, using a commercial Computational Fluid Dynamics (CFD) software package. Simulation is performed over a range of Reynolds-number values, up to 1000. Temperature affects the flow field via fluid viscosity, which is assumed to decrease exponentially with temperature. Other fluid properties are assumed to be constant, and are similar to those of an oil. Allowing for temperature effects alters significantly the flow pattern and reduces pressure change. In the crest region, recirculation appears in non-isothermal flow at a much smaller Reynolds number Re than in isothermal flow. Influence of the Reynolds number itself is also reduced significantly, such that the flow pattern changes very little with increasing Re, in contrast to the isothermal case. Similarly, in non-isothermal flow, flow pattern is unchanged at different flow rate. This is also in contrast to the isothermal situation.

Hybrid Solar-Geothermal Power Generation to Increase the Energy Production From a Binary Geothermal Plant

2011 ◽  
Author(s):  
Giovanni Manente ◽  
Randall Field ◽  
Ronald DiPippo ◽  
Jefferson W. Tester ◽  
Marco Paci ◽  
...  
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Energy Production ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Working Fluid ◽  
Solar Thermal Energy ◽  
Geothermal Fluid ◽  
Industrial Grade ◽  
Design Values

This article examines how hybridization using solar thermal energy can increase the power output of a geothermal binary power plant that is operating on geothermal fluid conditions that fall short of design values in temperature and flow rate. The power cycle consists of a subcritical organic Rankine cycle using industrial grade isobutane as the working fluid. Each of the power plant units includes two expanders, a vaporizer, a preheater and air-cooled condensers. Aspen Plus was used to model the plant; the model was validated and adjusted by comparing its predictions to data collected during the first year of operation. The model was then run to determine the best strategy for distributing the available geothermal fluid between the two units to optimize the plant for the existing degraded geofluid conditions. Two solar-geothermal hybrid designs were evaluated to assess their ability to increase the power output and the annual energy production relative to the geothermal-only case.

Renewable Hydrogen Production Using Sailing Ships

2011 ◽  
Author(s):  
Max F. Platzer ◽  
Nesrin Sarigul-Klijn ◽  
J. Young ◽  
M. A. Ashraf ◽  
J. C. S. Lai
Keyword(s):  
Electric Power ◽  
Wind Power ◽  
Power Output ◽  
Power Plants ◽  
Sea Water ◽  
Water Electrolysis ◽  
Strong Wind ◽  
Hydro Power ◽  
Power Extraction ◽  
Wind Currents

Vast ocean areas of planet Earth are exposed year-round to strong wind currents. We suggest that this untapped ocean wind power be exploited by the use of sailing ships. The availability of constantly updated meteorological information makes it possible to operate the ships in ocean areas with optimum wind power so that the propulsive ship power can be converted into electric power by means of ship-mounted hydro-power generators. Their electric power output then is fed into ship-mounted electrolyzers to convert sea water into hydrogen and oxygen. In this paper we estimate the ship size, sail area and generator size to produce a 1.5 MW electrical power output. We describe a new oscillating-wing hydro-power generator and present results of model tests obtained in a towing tank. Navier-Stokes computations are presented to provide an estimate of the power extraction efficiency and drag coefficient of such a generator which depends on a range of parameters such as foil maximum pitch angles, plunge amplitude, phase between pitch and plunge and load. Also, we present a discussion of the feasibility of sea water electrolysis and of the re-conversion of hydrogen and oxygen into electricity by means of shore-based hydrogen-oxygen power plants.

Waste Heat Recovery in a Cruise Vessel in the Baltic Sea by Using an Organic Rankine Cycle: A Case Study

2015 ◽  
Author(s):  
Fredrik Ahlgren ◽  
Maria E. Mondejar ◽  
Magnus Genrup ◽  
Marcus Thern
Keyword(s):  
Power Output ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Maritime Transportation ◽  
Working Fluid ◽  
Net Power Output

Maritime transportation is a significant contributor to SOx, NOx and particle matter emissions, even though it has a quite low CO2 impact. New regulations are being enforced in special areas that limit the amount of emissions from the ships. This fact, together with the high fuel prices, is driving the marine industry towards the improvement of the energy efficiency of current ship engines and the reduction of their energy demand. Although more sophisticated and complex engine designs can improve significantly the efficiency of the energy systems in ships, waste heat recovery arises as the most influent technique for the reduction of the energy consumption. In this sense, it is estimated that around 50% of the total energy from the fuel consumed in a ship is wasted and rejected in fluid and exhaust gas streams. The primary heat sources for waste heat recovery are the engine exhaust and the engine coolant. In this work, we present a study on the integration of an organic Rankine cycle (ORC) in an existing ship, for the recovery of the main and auxiliary engines exhaust heat. Experimental data from the operating conditions of the engines on the M/S Birka Stockholm cruise ship were logged during a port-to-port cruise from Stockholm to Mariehamn over a period of time close to one month. The ship has four main engines Wärtsilä 5850 kW for propulsion, and four auxiliary engines 2760 kW used for electrical consumers. A number of six load conditions were identified depending on the vessel speed. The speed range from 12–14 knots was considered as the design condition, as it was present during more than 34% of the time. In this study, the average values of the engines exhaust temperatures and mass flow rates, for each load case, were used as inputs for a model of an ORC. The main parameters of the ORC, including working fluid and turbine configuration, were optimized based on the criteria of maximum net power output and compactness of the installation components. Results from the study showed that an ORC with internal regeneration using benzene would yield the greatest average net power output over the operating time. For this situation, the power production of the ORC would represent about 22% of the total electricity consumption on board. These data confirmed the ORC as a feasible and promising technology for the reduction of fuel consumption and CO2 emissions of existing ships.

scholarly journals Estimation and Mitigation of Unknown Airplane Installation Effects on GPA Diagnostics

Machines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 36
Author(s):  
Mikael Stenfelt ◽  
Konstantinos Kyprianidis
Keyword(s):  
Design Process ◽  
Gas Turbines ◽  
Diagnostic System ◽  
Power Extraction ◽  
Installation Effects ◽  
Degradation Pattern ◽  
Shaft Power ◽  
Air Intake ◽  
Intake Pressure ◽  
Diagnostic Framework

In gas turbines used for airplane propulsion, the number of sensors are kept at a minimum for accurate control and safe operation. Additionally, when data are communicated between the airplane main computer and the various subsystems, different systems may have different constraints and requirements regarding what data transmit. Early in the design process, these parameters are relatively easy to change, compared to a mature product. If the gas turbine diagnostic system is not considered early in the design process, it may lead to diagnostic functions having to operate with reduced amount of data. In this paper, a scenario where the diagnostic function cannot obtain airplane installation effects is considered. The installation effects in question is air intake pressure loss (pressure recovery), bleed flow and shaft power extraction. A framework is presented where the unknown installation effects are estimated based on available data through surrogate models, which is incorporated into the diagnostic framework. The method has been evaluated for a low-bypass turbofan with two different sensor suites. It has also been evaluated for two different diagnostic schemes, both determined and underdetermined. Results show that, compared to assuming a best-guess constant-bleed and shaft power, the proposed method reduce the RMS in health parameter estimation from 26% up to 80% for the selected health parameters. At the same time, the proposed method show the same degradation pattern as if the installation effects were known.

Sign in / Sign up

Export Citation Format

Share Document