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.

Preliminary Design of Small-Scale Supercritical CO2 Radial Inflow Turbines

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Tina Unglaube ◽  
Hsiao-Wei D. Chiang
Keyword(s):  
Optimum Design ◽  
Supercritical Co2 ◽  
Velocity Ratio ◽  
Design Procedure ◽  
Expansion Ratio ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Small Scale ◽  
Preliminary Design ◽  
Line Design

Abstract In recent years, supercritical CO2 (sCO2) Brayton cycles have drawn the attention of researchers due to their high cycle efficiencies, compact turbomachinery, and environmental friendliness. For small-scale cycles, radial inflow turbines (RIT) are the prevailing choice and one of the key components. A mean line design procedure for sCO2 RIT is developed and design space exploration conducted for a 100 kW-class turbine for a low-temperature waste-heat utilization sCO2 Brayton cycle. By varying the two design parameters, specific speed and velocity ratio, different turbine configurations are setup and compared numerically by means of computational fluid dynamics (CFD) simulations. Results are analyzed to conclude on optimum design parameters with regard to turbine efficiency and expansion ratio. Specific speeds between 0.2 and 0.5 are recommended for sCO2 RIT with small though flow (3 kg/s). The higher the velocity ratio, the bigger the turbine expansion ratio. Pairs of optimum design parameters that effectuate maximum efficiency are identified, with smaller velocity ratios prevailing for smaller specific speeds. The turbine simulation results for sCO2 are compared to well-established recommendations for the design of RIT from literature, such as the Balje diagram. It is concluded that for the design of sCO2 RITs, the same principles can be used as for those for air turbines. By achieving total-to-static stage and rotor efficiencies of 84% and 86%, respectively, the developed mean line design procedure has proven to be an effective and easily applicable tool for the preliminary design of small-scale sCO2 RIT.

Biomass combined cycles based on externally fired gas turbines and organic Rankine expanders

2011 ◽  
Vol 225 (8) ◽  
pp. 1066-1075 ◽  
Author(s):  
C M Invernizzi ◽  
P Iora ◽  
R Sandrini
Keyword(s):  
Gas Turbines ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Economic Feasibility ◽  
Maximum Efficiency ◽  
Working Fluid ◽  
Inlet Temperature ◽  
System A ◽  
Combined Cycles

This article investigates the possibility to enhance the performance of a biomass organic Rankine cycle (ORC) plant by adding an externally fired gas turbine (EFGT), yielding a combined EFGT + ORC system. A typical ORC configuration is first modelled and validated on data available from an existing unit 1.5 MW reference plant. Then, different working fluids belonging to the methyl-substituted benzene series and linear methylpolysiloxanes have been evaluated for the ORC section on the basis of both thermodynamics considerations and design issues of the regenerator and the turbine. Results of the simulations of the combined cycle (CC) referred to a furnace size of about unit 9 MW, assuming a maximum GT inlet temperature of 800 °C, show a maximum efficiency of 23 per cent, obtained in the case where toluene is adopted as a working fluid for the bottoming section. This value is about 4 points per cent higher than the efficiency of the corresponding simple ORC. Finally, to conclude, some preliminary considerations are given regarding the techno-economic feasibility of the combined configuration, suggesting the need of a further investigation on the possible technological solution for the furnace which represents the main uncertainty in the resulting costs of the CC.

Design Parameters Exploration for Supercritical CO2 Centrifugal Compressors Under Multiple Constraints

2016 ◽  
Author(s):  
Wenyang Shao ◽  
Xiaofang Wang ◽  
Jinguang Yang ◽  
Huimin Liu ◽  
Zhenjun Huang
Keyword(s):  
Cfd Simulation ◽  
Velocity Ratio ◽  
Tangential Velocity ◽  
Flow Coefficient ◽  
Low Flow ◽  
Design Parameters ◽  
Working Fluid ◽  
Rotating Speed ◽  
Thermodynamic Conditions ◽  
Velocity Coefficient

The Supercritical Carbon Dioxide (SCO2) Brayton cycle has been getting more and more attentions all over the world in recent years for its high cycle efficiency and compact components. The compressor is one of the most important components in the cycle. Different from traditional working fluid, SCO2 has a risk of condensation at the impeller inlet because of the particular properties near the critical point. In order to determine the possibility of the condensation, a concept called “Condensation Margin (CM)” suited for SCO2 is introduced. It is associated with the total and saturated thermodynamic conditions. A design parameter called velocity ratio at the impeller inlet (IVR) is defined to control the state of working fluid at impeller inlet based on CM. In terms of different constraints and design requirements, such as impeller efficiency, operating range and processing technic, especially in small size cases, the design parameters at the impeller outlet are explored by establishing a function of outlet width, the number of blades, rotating speed, outlet tangential velocity coefficient and outlet meridional velocity coefficient. A preliminary design result of a low-flow-coefficient SCO2 centrifugal compressor is presented as an example of the application of the design parameters exploration results; then CFD simulation is performed, and consistent results are obtained compared with exploration results.

Dynamic Modeling of Magnetostrictive Hydraulic Pump

Aerospace ◽  
2006 ◽  
Author(s):  
A. Chaudhuri ◽  
J.-H. Yoo ◽  
N. M. Wereley
Keyword(s):  
Heat Generation ◽  
Smart Materials ◽  
Degrees Of Freedom ◽  
Simulated Data ◽  
Maximum Efficiency ◽  
Design Parameters ◽  
Working Fluid ◽  
Hydraulic Pump ◽  
Magnetostrictive Material ◽  
Operational Conditions

Recently, there has been substantial research on the development of a hybrid hydraulic pump driven by various smart materials. Piezo-hydraulic actuators have already been developed for potential use in smart rotor applications. However, at high actuation frequencies, piezo-stacks generate significant heat mainly due to the hysteresis losses that can deteriorate their performance and permanently damage the piezo material. In contrast, magnetostrictive materials are more robust than piezostacks, especially at high temperatures, while offering almost the same bandwidth and higher maximum induced strain when compared with piezoelectric stacks. Also, the magnetostrictive material usually has a particular frequency range where the hysteretic losses taking place are minimum and consequently the operation results in least heat generation. As a result, to operate the pump with higher flow rate with minimum heat generation and maximum efficiency, we need to know the system resonance. Moreover, the hybrid pump with smart material is mechanically more complex than a single rod actuator; consequently, it can have more than one resonant frequency depending on the number of degrees of freedom of the system. A hybrid pump using the magnetostrictive material Terfenol-D has been developed in our laboratory with hydraulic oil as the working fluid. Several key design parameters, which include output cylinder size, diaphragm thickness, reed valve thickness and tubing diameter, along with operational conditions, like input current and bias pressure within the fluid, have been varied to identify a set of optimum driving conditions. Tests at no-load have been carried out for unidirectional motion of the output piston. In this paper, we develop a dynamic model of the hydraulic hybrid actuator to show the basic operational principle and compare the simulated data with test results. The final target of this study is to find optimal operational frequency to get highest performance and also to predict the pump sizing for a desired output velocity and load lifting capability.

scholarly journals Evaluation of Bleed Flow Precooling Influence on the Efficiency of the E-MATIANT Cycle

2020 ◽  
Vol 22 (2) ◽  
pp. 593-602 ◽  
Author(s):  
Andrey Rogalev ◽  
Vladimir Kindra ◽  
Alexey Zonov ◽  
Nikolay Rogalev ◽  
Levon Agamirov
Keyword(s):  
Gas Turbines ◽  
Pressure Ratio ◽  
Water Injection ◽  
Design Parameters ◽  
Inlet Temperature ◽  
Combustion Chambers ◽  
Turbine Inlet ◽  
Performance Penalty ◽  
Set Up ◽  
Cycle Efficiency

AbstractThis study aims to present a method for precooling bleed flow by water injection in the E-MATIANT cycle and to estimate its impact on the overall efficiency. The design parameters of the cycle are set up on the basis of the component technologies of today's state-of-the-art gas turbines with a turbine inlet temperature between 1100 and 1700°C. Several schemes of the E-MATIANT cycle are considered: with one, two and three combustion chambers. The optimal pressure ratio ranges for the considered turbine inlet temperatures are identified and a comparison with existing evaluations is made. For the optimal initial parameters, cycle net efficiency varies from 42.0 to 49.8%. A significant influence of turbine stage cooling model on optimal thermodynamic parameters and cycle efficiency is established. The maximum cycle efficiency is 44.0% considering cooling losses. The performance penalty due to the oxygen production and carbon dioxide capture is 20–22%.

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.

Gas Turbine Intake Systems: High Velocity Filtration for Marine GT Installations — Part 2

2003 ◽  
Author(s):  
S. D. Hiner ◽  
R. K. Mudge
Keyword(s):  
Gas Turbine ◽  
High Velocity ◽  
Gas Turbines ◽  
Design Parameters ◽  
Royal Navy ◽  
Sea Trial ◽  
Conventional Design ◽  
Engine Design ◽  
Potential Benefits

Following the development of a high velocity spray eliminator system for marine gas turbines, a sea trial has been completed on board a Royal Navy vessel, for back to back comparison with a unit of conventional design. This paper, will give a brief overview of the trial fit to HMS Coventry. It will then continue by presenting in detail the data obtained throughout the trial and showing the resulting comparisons between the new high velocity and conventional designs. The initial and final inspections of both engines will be presented and the appraisal by Rolls Royce, the engine design authority, will be discussed. Conclusions will be drawn detailing the suitability of the new high velocity design for use onboard RN vessels, to protect their gas turbine intakes. Design parameters for the intakes of the WR21 will be proposed to demonstrate the system’s potential benefits.

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.

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%.

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