scholarly journals Experimental Characterization of an Adaptive Supersonic Micro Turbine for Waste Heat Recovery Applications

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 25
Author(s):  
Tobias Popp ◽  
Andreas P. Weiß ◽  
Florian Heberle ◽  
Julia Winkler ◽  
Rüdiger Scharf ◽  
...  
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Pressure Ratio ◽  
Micro Turbine ◽  
Swallowing Capacity

Micro turbines (<100 kWel) are commercially used as expansion machines in waste heat recovery (WHR) systems such as organic Rankine cycles (ORCs). These highly loaded turbines are generally designed for a specific parameter set, and their isentropic expansion efficiency significantly deteriorates when the mass flow rate of the WHR system deviates from the design point. However, in numerous industry processes that are potentially interesting for the implementation of a WHR process, the temperature, mass flow rate or both can fluctuate significantly, resulting in fluctuations in the WHR system as well. In such circumstances, the inlet pressure of the ORC turbine, and therefore the reversible cycle efficiency must be significantly reduced during these fluctuations. In this context, the authors developed an adaptive supersonic micro turbine for WHR applications. The variable geometry of the turbine nozzles enables an adjustment of the swallowing capacity in respect of the available mass flow rate in order to keep the upper cycle pressure constant. In this paper, an experimental test series of a WHR ORC test rig equipped with the developed adaptive supersonic micro turbine is analysed. The adaptive turbine is characterized concerning its off-design performance and the results are compared to a reference turbine with fixed geometry. To create a fair data basis for this comparison, a digital twin of the plant based on experimental data was built. In addition to the characterization of the turbine itself, the influence of the improved pressure ratio on the energy conversion chain of the entire ORC is analysed.

Optimization of Supercritical CO2 Brayton Cycle for Simple Cycle Gas Turbines Exhaust Heat Recovery Using Genetic Algorithm

2017 ◽  
Author(s):  
Akshay Khadse ◽  
Lauren Blanchette ◽  
Jayanta Kapat ◽  
Subith Vasu ◽  
Kareem Ahmed
Keyword(s):  
Genetic Algorithm ◽  
Mass Flow Rate ◽  
Flow Rate ◽  
Supercritical Co2 ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Brayton Cycle ◽  
Exhaust Heat ◽  
Exhaust Heat Recovery

For the application of waste heat recovery (WHR), supercritical CO2 (S-CO2) Brayton power cycles offer significant suitable advantages such as compactness, low capital cost and applicable to a broad range of heat source temperatures. The current study is focused on thermodynamic modelling and optimization of Recuperated (RC) and Recuperated Recompression (RRC) S-CO2 Brayton cycles for exhaust heat recovery from a next generation heavy duty simple cycle gas turbine using a genetic algorithm. The Genetic Algorithm (GA) is mainly based on bio-inspired operators such as crossover, mutation and selection. This non-gradient based algorithm yields a simultaneous optimization of key S-CO2 Brayton cycle decision variables such as turbine inlet temperature, pinch point temperature difference, compressor pressure ratio. It also outputs optimized mass flow rate of CO2 for the fixed mass flow rate and temperature of the exhaust gas. The main goal of the optimization is to maximize power out of the exhaust stream which makes it single objective optimization. The optimization is based on thermodynamic analysis with suitable practical assumptions which can be varied according to the need of user. Further the optimal cycle design points are presented for both RC and RRC configurations and comparison of net power output is established for waste heat recovery.

Design and Internal Flow Analysis of a Ducted Contra-Rotating Axial Flow Fan

2014 ◽  
Author(s):  
Ali Mohammadi ◽  
Masoud Boroomand
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Optimum Operating ◽  
Axial Flow Fan ◽  
Design Algorithm ◽  
Flow Solver ◽  
Operating Points

This paper presents the design procedure of a ducted contra-rotating axial flow fan and investigates the flow behavior inside it using ANSYS CFX-15 flow solver. This study investigates parameters such as pressure ratio, inlet mass flow rate and efficiency in different operating points. This system consists of two rotors with an outer diameter of 434 mm and an inner diameter of 260 mm which rotate contrary to each other with independent nominal rotational speeds of 1300 rpm. Blades’ maximum thickness and rotational speeds of each rotor will be altered as well as the axial distance between the two rotors to investigate their effect on the overall performance of the system. Designed to deliver a total pressure ratio of 1.005 and a mass flow rate of 1.8 kg/s at nominal rotational speeds, this system proves to be much more efficient compared to the conventional rotor-stator fans. NACA-65 airfoils are used in this analysis with the necessary adjustments at each section. Inverse design method is used for the first rotor and geometrical constraints are employed for the second one to have an axial inlet and outlet flow without using any inlet or outlet guide vanes. Using free vortex swirl distribution method, characteristic parameters and the necessary data for 3D generation of this model are obtained. The appropriate grid is generated using ATM method in ANSYS TurboGrid and the model is simulated in CFX-15 flow solver by employing k-ε turbulence model in the steady state condition. Both design algorithm and simulation analysis confirm the high anticipated efficiency for this system. The accuracy of the design algorithm will be explored and the most optimum operating points in different rotational speed ratios and axial distances will be identified. By altering the outlet static pressure of the system, the characteristic map is obtained.

Numerical Performance and Flow Field Study of Centrifugal Compressor With Supercritical Carbon-Dioxide (SCO2)

2019 ◽  
Author(s):  
Hemant Kumar ◽  
Chetan S. Mistry
Keyword(s):  
Carbon Dioxide ◽  
Thermodynamic Properties ◽  
Critical Point ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Compressor Inlet

Abstract The Supercritical carbon-dioxide Brayton cycle main attraction is due to the Supercritical characteristic of the working fluid, carbon-dioxide (SCO2). Some of the advantages of using SCO2 are relatively low turbine inlet temperature, the compression work will be low, and the system will be compact due to the variation of thermodynamic properties (like density, and specific heat ratio) of SCO2 near the critical point. SCO2 behave more like liquid when its state is near the critical point (Total Pressure = 7.39 MPa, Total Temperature = 305 K), operating compressor inlet near critical point can minimize compression work. For present study the centrifugal compressor was designed to operate at 75,000 rpm with pressure ratio (P.R) = 1.8 and mass flow rate = 3.53 kg/s as available from Sandai report. Meanline design for centrifugal compressor with SCO2 properties was done. The blade geometry was developed using commercial CAD Ansys Bladegen. The flow domain was meshed using Ansys TurboGrid. ANSYS CFX was used as a solver for present numerical study. The thermodynamic properties of SCO2 were imported from the ANSYS flow material library using SCO2.RPG [NIST thermal physics properties of fluid system]. In order to ensure the change in flow physics the mesh independence study was also conducted. The present paper discuss about the performance and flow field study targeting different mass flow rates as exit boundary condition. The comparison of overall performance (Pressure Ratio, the Blade loading, Stage efficiency and Density variation) was done with three different mass flow rates. The designed and simulated centrifugal compressor meets the designed pressure rise requirement. The variation of mass flow rate on performance of centrifugal compressor was tend to be similar to conventional centrifugal compressor. The paper discusses about the effect of variation in density, specific heat ratio and pressure of SCO2 with different mass flow outlet condition. The performance map of numerical study were validated with experiment results and found in good agreement with experimental results. The change in flow properties within the rotor flow passage are found to be interesting and very informative for future such centrifugal compressor design for special application of SCO2 Brayton cycle. 80% mass flow rate has given better results in terms of aerodynamic performance. Abrupt change in thermodynamic properties was observed near impeller inlet region. Strong density variations are observed at compressor inlet.

Centrifugal Compressor Performance Prediction Using Gaussian Process Regression and Artificial Neural Networks

2019 ◽  
Author(s):  
Pau Cutrina Vilalta ◽  
Hui Wan ◽  
Soumya S. Patnaik
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Centrifugal Compressor ◽  
Rotational Speed ◽  
Data Augmentation ◽  
Pressure Ratio ◽  
Gaussian Process Regression ◽  
Compressor Performance ◽  
Artificial Neural

Abstract In this paper, we use various regression models and Artificial Neural Network (ANN) to predict the centrifugal compressor performance map. Particularly, we study the accuracy and efficiency of Gaussian Process Regression (GPR) and Artificial Neural Networks in modelling the pressure ratio, given the mass flow rate and rotational speed of a centrifugal compressor. Preliminary results show that both GPR and ANN can predict the compressor performance map well, for both interpolation and extrapolation. We also study the data augmentation and data minimzation effects using the GPR. Due to the inherent pressure ratio data distribution in mass-flow-rate and rotational-speed space, data augmentation in the rotational speed is more effective to improve the ANN performance than the mass flow rate data augmentation.

Evaluation of Axial Compressor Characteristics Under Overspray Condition

2013 ◽  
Author(s):  
Chihiro Myoren ◽  
Yasuo Takahashi ◽  
Manabu Yagi ◽  
Takanori Shibata ◽  
Tadaharu Kishibe
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Water Mass ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Test Facility ◽  
Compressor Performance ◽  
Water Mass Flow Rate

An axial compressor was developed for an industrial gas turbine equipped with a water atomization cooling (WAC) system, which is a kind of inlet fogging technique with overspray. The compressor performance was evaluated using a 40MW-class test facility for the advanced humid air turbine system. A prediction method to estimate the effect of WAC was developed for the design of the compressor. The method was based on a streamline curvature (SLC) method implementing a droplet evaporation model. Four test runs with WAC have been conducted since February 2012. The maximum water mass flow rate was 1.2% of the inlet mass flow rate at the 4th test run, while the design value was 2.0%. The results showed that the WAC decreased the inlet and outlet temperatures compared with the DRY (no fogging) case. These decreases changed the matching point of the gas turbine, and increased the mass flow rate and the pressure ratio by 1.8% and 1.1%, respectively. Since prediction results agreed with the results of the test run qualitatively, the compressor performance improvement by WAC was confirmed both experimentally and analytically. The test run with the design water mass flow rate is going to be conducted in the near future.

Numerical Simulation of Steady Air Injection Flow Control Effects on a Transonic Axial Flow Compressor

2012 ◽  
Vol 224 ◽  
pp. 352-357
Author(s):  
Islem Benhegouga ◽  
Ce Yang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Axial Flow ◽  
Leading Edge ◽  
Air Injection ◽  
Axial Flow Compressor ◽  
Blade Tip ◽  
Flow Compressor

In this work, steady air injection upstream of the blade leading edge was used in a transonic axial flow compressor, NASA rotor 37. The injectors were placed at 27 % upstream of the axial chord length at blade tip, the injection mass flow rate is 3% of the chock mass flow rate, and 3 yaw angles were used, respectively -20°, -30°, and -40°. Negative yaw angles were measured relative to the compressor face in opposite direction of rotational speeds. To reveal the mechanism, steady numerical simulations were performed using FINE/TURBO software package. The results show that the stall mass flow can be decreased about 2.5 %, and an increase in the total pressure ratio up to 0.5%.

scholarly journals Characterization of Particle Flow in a Free-Falling Solar Particle Receiver

2015 ◽  
Author(s):  
Clifford K. Ho ◽  
Joshua M. Christian ◽  
David Romano ◽  
Julius Yellowhair ◽  
Nathan Siegel
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Numerical Models ◽  
Particle Flow ◽  
Concentrating Solar Power ◽  
Power Cycles ◽  
Solar Particle ◽  
Free Falling

Falling particle receivers are being evaluated as an alternative to conventional fluid-based solar receivers to enable higher temperatures and higher efficiency power cycles with direct storage for concentrating solar power applications. This paper presents studies of the particle mass flow rate, velocity, particle-curtain opacity and density, and other characteristics of free-falling ceramic particles as a function of different discharge slot apertures. The methods to characterize the particle flow are described, and results are compared to theoretical and numerical models for unheated conditions.

Optimization of Supercritical CO2 Brayton Cycle for Simple Cycle Gas Turbines Exhaust Heat Recovery Using Genetic Algorithm

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Akshay Khadse ◽  
Lauren Blanchette ◽  
Jayanta Kapat ◽  
Subith Vasu ◽  
Jahed Hossain ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Supercritical Co2 ◽  
Heat Recovery ◽  
Brayton Cycle ◽  
Exhaust Gas ◽  
Exhaust Heat ◽  
Exhaust Heat Recovery

For the application of waste heat recovery (WHR), supercritical CO2 (S-CO2) Brayton power cycles offer significant suitable advantages such as compactness, low capital cost, and applicability to a broad range of heat source temperatures. The current study is focused on thermodynamic modeling and optimization of recuperated (RC) and recuperated recompression (RRC) configurations of S-CO2 Brayton cycles for exhaust heat recovery from a next generation heavy duty simple cycle gas turbine using genetic algorithm (GA). This nongradient based algorithm yields a simultaneous optimization of key S-CO2 Brayton cycle decision variables such as turbine inlet temperature, pinch point temperature difference, compressor pressure ratio, and mass flow rate of CO2. The main goal of the optimization is to maximize power out of the exhaust stream which makes it single objective optimization. The optimization is based on thermodynamic analysis with suitable practical assumptions which can be varied according to the need of user. The optimal cycle design points are presented for both RC and RRC configurations and comparison of net power output is established for WHR. For the chosen exhaust gas mass flow rate, RRC cycle yields more power output than RC cycle. The main conclusion drawn from the current study is that the choice of best cycle for WHR actually depends heavily on mass flow rate of the exhaust gas. Further, the economic analysis of the more power producing RRC cycle is performed and cost comparison between the optimized RRC cycle and steam Rankine bottoming cycle is presented.

Design of a Highly Efficient Low-Noise Fan for Ultra-High Bypass Engines

2006 ◽  
Author(s):  
Burak Kaplan ◽  
Eberhard Nicke ◽  
Christian Voss
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Low Noise ◽  
Test Rig ◽  
Noise Emission ◽  
Rotor Stator Interaction ◽  
Funded Project ◽  
Bypass Ratio

In order to achieve an environmental-friendly engine i.e. with more efficiency and less noise emission, a geared ultra-high bypass ratio fan test rig has been designed within the EU-funded project SILENCE®. Engine cycle requirements were untypical in terms of mass flow rate, pressure ratio and BPR. In order to reach the desired mass flow rate and simultaneously to avoid a strong interaction of the shocks with the boundary layer an S-shape leading edged rotor with forward sweep close to casing has been designed. Specific blade numbers for rotor and stator has been used to minimize the rotor-stator interaction noise. For the same purpose a backward swept bypass stator has been designed. There are two stators in the core duct in order to bring the flow to zero swirl which is a necessity for test rig measurements. The main design loop includes blade shape and the flow path optimization as well as the computation of stress distribution in all blades and the rotor disc. The fan is being manufactured from titanium because of its specific aeroelastic properties and stators are made of steel. The rig is scheduled to be tested in 2006 for its aerodynamic and aeroacoustic performance.

2D Parametric Study Using CFD of a Circulation Control Inlet Guide Vane

2007 ◽  
Author(s):  
H. E. Hill ◽  
W. F. Ng ◽  
P. P. Vlachos ◽  
S. A. Guillot ◽  
D. Car
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Pressure Ratio ◽  
Operating Conditions ◽  
Circulation Control ◽  
Trailing Edge ◽  
Pressure Losses ◽  
Supply Pressure ◽  
Edge Radius

Circulation control inlet guide vanes (IGVs) may provide significant benefits over current IGVs that employ mechanical means for flow turning. This paper presents the results of a two-dimensional computational study on a circulation control IGV that takes advantage of the Coanda effect for flow vectoring. The IGV in this study is an uncambered airfoil that alters circulation around itself by means of a Coanda jet that exhausts along the IGV’s trailing edge surface. The IGV is designed for an axial inlet flow at a Mach number of 0.54 and an exit flow angle of 11 degrees. These conditions were selected to match the operating conditions of the 90% span section of the IGV of the TESCOM compressor rig at the Compressor Aero Research Laboratory (CARL) located at Wright-Patterson AFB, the hardware that is being used as the baseline in this study. The goal of the optimization was to determine the optimal jet height, trailing edge radius, and supply pressure that would meet the design criteria while minimizing the mass flow rate and pressure losses. The optimal geometry that was able to meet the design requirements had a jet height of h/Cn = 0.0057 and a trailing edge Radius R/Cn = 0.16. This geometry needed a jet to inflow total pressure ratio of 1.8 to meet the exit turning angle requirement. At this supply pressure ratio the mass flow rate required by the flow control system was 0.71 percent of the total mass flow rate through the engine. The optimal circulation control IGV had slightly lower pressure losses when compared with a reference cambered IGV.

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