A Code for the Preliminary Design of Cooled Supercritical CO2 Turbines and Application to the Allam Cycle

2021 ◽  
Author(s):  
Roberto Scaccabarozzi ◽  
Emanuele Martelli ◽  
Matteo Pini ◽  
Carlo De Servi ◽  
Paolo Chiesa ◽  
...  
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Supercritical Co2 ◽  
Fluid Dynamic ◽  
Thermal Design ◽  
Working Fluid ◽  
Preliminary Design ◽  
Turbine Efficiency ◽  
Multi Stage ◽  
Axial Turbines

Abstract This paper documents a thermo-fluid-dynamic mean-line model for the preliminary design of multi-stage axial turbines with blade cooling applicable to supercritical CO2 turbines. Given the working fluid and coolant inlet thermodynamic conditions, blade geometry, number of stages and load criterion, the model computes the stage-by-stage design along with the cooling requirement and ultimately provides an estimate of turbine efficiency via a semi-empirical loss model. Different cooling modes are available and can be selected by the user (stand-alone or combination): convective cooling, film cooling, thermal barrier coating. The model is applied to attain the preliminary aero-thermal design of the 600 MW cooled axial supercritical CO2 turbine of the Allam cycle. Results show that a load coefficient varying from 3 to 1 throughout the machine, and a reaction degree ranging from 0.1 to 0.5 lead to the maximum total-to-static turbine efficiency of about 85 %. Consequently, as opposed to uncooled CO2 turbines, a repeated stage configuration is an unsuited design choice for cooled sCO2 machines. Moreover, the study highlights that film cooling is considerably less effective compared to conventional gas turbines, while increasing the number of stages from 5 to 6 and adopting higher rotational speeds leads to an increased efficiency.

Aerodynamics of Centrifugal Turbine Cascades

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Giacomo Persico ◽  
Matteo Pini ◽  
Vincenzo Dossena ◽  
Paolo Gaetani
Keyword(s):  
Power Systems ◽  
Coriolis Force ◽  
Gas Turbines ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Secondary Flows ◽  
Preliminary Design ◽  
Axial Turbines

The centrifugal turbine architecture is a promising solution for small-to-medium organic Rankine cycle (ORC) power systems. The inherent compactness of the multistage arrangement makes this configuration very attractive for dealing with the high volumetric flow ratios typical of ORC turbines. In absence of experimental evidence, a thorough assessment of the technology can be uniquely based on sufficiently accurate computational fluid dynamic (CFD) simulations. In the present work, the aerodynamic performance of a fixed and a rotating cascade of centrifugal turbine are investigated by applying a three-dimensional CFD model. Precisely, the study is focused on the sixth stage of the transonic centrifugal turbine proposed in Pini et al. (2013, “Preliminary Design of a Centrifugal Turbine for ORC Applications,” ASME J. Eng. Gas Turbines Power, 135(4), p. 042312). After recalling the blade design methodology, the blade-to-blade and secondary flow patterns are carefully studied for both stator and rotor. Results show that the centrifugal configuration exhibits distinctive features if compared to axial turbine layouts. The diverging shape of the bladed channel and the centrifugal force alter significantly the pressure distribution on the profile. Moreover, the Coriolis force induces a slip effect that should be properly included in the preliminary design phase. Provided that the flaring angle is limited, the almost uniform spanwise blade loading greatly augments the three-dimensional performance of the cascades compared to axial rows. In the rotor, the low inlet endwall vorticity and the Coriolis force further weaken the secondary flows, resulting in even lower secondary losses with respect to those predicted by loss models developed for axial turbines. Ultimately, the efficiency of the stage is found to be two points higher than that estimated at preliminary design level, demonstrating the high potential of the centrifugal turbine for ORC applications.

Conjugate Heat Transfer and Film Cooling of a Multi-Stage Cooling Scheme

2008 ◽  
Author(s):  
M. Ghorab ◽  
S. I. Kim ◽  
I. Hassan
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Gas Turbines ◽  
Conjugate Heat Transfer ◽  
Density Ratio ◽  
Design Parameters ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Multi Stage ◽  
Internal Gap

Cooling techniques play a key role in improving efficiency and power output of modern gas turbines. The conjugate technique of film and impingement cooling schemes is considered in this study. The Multi-Stage Cooling Scheme (MSCS) involves coolant passing from inside to outside turbine blade through two stages. The first stage; the coolant passes through first hole to internal gap where the impinging jet cools the external layer of the blade. Finally, the coolant passes through the internal gap to the second hole which has specific designed geometry for external film cooling. The effect of design parameters, such as, offset distance between two-stage holes, gap height, and inclination angle of the first hole, on upstream conjugate heat transfer rate and downstream film cooling effectiveness performance are investigated computationally. An Inconel 617 alloy with variable properties is selected for the solid material. The conjugate heat transfer and film cooling characteristics of MSCS are analyzed across blowing ratios of Br = 1 and 2 for density ratio, 2. This study presents upstream wall temperature distributions due to conjugate heat transfer for different gap design parameters. The maximum film cooling effectiveness with upstream conjugate heat transfer is less than adiabatic film cooling effectiveness by 24–34%. However, the full coverage of cooling effectiveness in spanwise direction can be obtained using internal cooling with conjugate heat transfer, whereas adiabatic film cooling effectiveness has narrow distribution.

scholarly journals Selected Issues of the Structures and Parameters of Supercritical CO2 Gas Turbine Cycles

2020 ◽  
Vol 22 (2) ◽  
pp. 565-584
Author(s):  
Jarosław Milewski ◽  
Kamil Futyma ◽  
Arkadiusz Szczęśniak ◽  
Marcin Wołowicz ◽  
Gabriel Ziembicki
Keyword(s):  
Carbon Dioxide ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Supercritical Co2 ◽  
Heat Supply ◽  
Operating Temperature ◽  
Working Fluid ◽  
Co2 Gas ◽  
Variant Analysis ◽  
Recompression Cycle

AbstractThe paper presents a variant analysis of the structures of closed gas turbines using supercritical carbon dioxide (super-CO2) as a working fluid. Several configurations covered in the available literature were collected, commented on and compared. The parameters of the cycles, such as operating temperature and heat supply are noted and commented on. There are three main configurations considered in the available literature: the precompression cycle, partial cooling cycle, and recompression cycle.

Evaluation for Scalability of a Combined Cycle Using Gas and Bottoming SCO2 Turbines

2015 ◽  
Author(s):  
Leonid Moroz ◽  
Petr Pagur ◽  
Oleksii Rudenko ◽  
Maksym Burlaka ◽  
Clement Joly
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Combined Cycle ◽  
Electricity Production ◽  
Working Fluid ◽  
Gas Temperature ◽  
Cycle System ◽  
Gas Turbine Exhaust

Bottoming cycles are drawing a real interest in a world where resources are becoming scarcer and the environmental footprint of power plants is becoming more controlled. Reduction of flue gas temperature, power generation boost without burning more fuel and even production of heat for cogeneration applications are very attractive and it becomes necessary to quantify how much can really be extracted from a simple cycle to be converted to a combined configuration. As supercritical CO2 is becoming an emerging working fluid [2, 3, 5, 7 and 8] due not only to the fact that turbomachines are being designed significantly more compact, but also because of the fluid’s high thermal efficiency in cycles, it raises an increased interest in its various applications. Evaluating the option of combined gas and supercritical CO2 cycles for different gas turbine sizes, gas turbine exhaust gas temperatures and configurations of bottoming cycle type becomes an essential step toward creating guidelines for the question, “how much more can I get with what I have?”. Using conceptual design tools for the cycle system generates fast and reliable results to draw this type of conclusion. This paper presents both the qualitative and quantitative advantages of combined cycles for scalability using machines ranging from small to several hundred MW gas turbines to determine which configurations of S-CO2 bottoming cycles are best for pure electricity production.

Computational Fluid Dynamics of a Radial Compressor Operating With Supercritical CO2

2012 ◽  
Author(s):  
Rene Pecnik ◽  
Enrico Rinaldi ◽  
Piero Colonna
Keyword(s):  
Critical Point ◽  
Gas Turbine ◽  
Supercritical Co2 ◽  
High Speed ◽  
Power Plants ◽  
Compressible Flows ◽  
High Efficiency ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Maximum Pressure

The merit of using supercritical CO2 (scCO2) as the working fluid of a closed Brayton cycle gas turbine is now widely recognized, and the development of this technology is now actively pursued. scCO2 gas turbine power plants are an attractive option for solar, geothermal and nuclear energy conversion. Among the challenges which must be overcome in order to successfully bring the technology to the market, the efficiency of the compressor and turbine operating with the supercritical fluid should be increased as much as possible. High efficiency can be reached by means of sophisticated aerodynamic design, which, compared to other overall efficiency improvements, like cycle maximum pressure and temperature increase, or increase of recuperator effectiveness, does not require an increase in equipment cost, but only an additional effort in research and development. This paper reports a three-dimensional CFD study of a high-speed centrifugal compressor operating with CO2 in the thermodynamic region slightly above the vapor-liquid critical point. The investigated geometry is the compressor impeller tested in the Sandia scCO2 compression loop facility [1]. The fluid dynamic simulations are performed with a fully implicit parallel Reynolds-averaged Navier-Stokes code based on a finite volume formulation on arbitrary polyhedral mesh elements. The CFD code has been validated on test cases which are relevant for this study, see Ref. [2,3]. In order to account for the strongly nonlinear variation of the thermophysical properties of supercritical CO2, the CFD code is coupled with an extensive library for the computation of properties of fluids and mixtures [4]. Among the available models, the one based on reference equations of state for CO2 [5,6] has been selected, as implemented in one of the sub-libraries [7]. A specialized look-up table approach and a meshing technique suited for turbomachinery geometries are also among the novelties introduced in the developed methodology. A detailed evaluation of the CFD results highlights the challenges of numerical studies aimed at the simulation of technically relevant compressible flows occurring close to the liquid-vapor critical point. The data of the obtained flow field are used for a comparison with experiments performed at the Sandia scCO2 compression-loop facility.

Nonlinear Harmonic Method Applied to Turbine Conjugate Heat Transfer Analysis for Efficient Simulation of Hot Streak Clocking and Unsteady Heat Transfer

2017 ◽  
Author(s):  
Omid Z. Mehdizadeh ◽  
Stéphane Vilmin ◽  
Benoît Tartinville ◽  
Charles Hirsch
Keyword(s):  
Heat Transfer ◽  
Conjugate Heat Transfer ◽  
Guide Vane ◽  
Computational Effort ◽  
Thermal Design ◽  
Metal Temperature ◽  
Heat Transfer Analysis ◽  
Turbine Efficiency ◽  
Multi Stage ◽  
Nozzle Guide

High pressure turbine (HPT) optimum thermal design is critical in further improving gas turbine efficiency. However, this is a challenging task as it requires accurate simulation of unsteady flows in conjunction with heat transfer simulation of the airfoil solid structure, which in turn requires large computational resources. In this work, the nonlinear harmonic (NLH) method is applied to conjugate heat transfer (CHT) simulation to provide an effective tool for turbine thermal design and analysis. The NLH method can be seen as a computationally affordable alternative to the traditional time-marching unsteady simulation particularly in turbomachinery applications, where the unsteadiness is mostly periodic. When applied to CHT simulations, it also addresses the difficulty of dealing with large time-scale mismatch between fluid and solid domains by casting the periodic perturbations into the frequency domain. Furthermore, it naturally allows for the study of hot streaks clocking effects by means of space harmonics. These capabilities are demonstrated on the HPT of the NASA/GE Energy Efficient Engine (E3), where hot streaks clocking effect on the metal temperature of the nozzle guide vane (NGV) is simulated. Also, the time variation of the rotor blade metal temperature as it crosses the hot streaks is simulated. The results confirm that, with only a single NLH solution, different aspects of the thermal design of a multi-stage turbine can be explored with little additional computational effort with respect to the standard steady approach.

scholarly journals Research on the influence of fuel gas on energy characteristics of a gas turbine

2019 ◽  
Vol 124 ◽  
pp. 05063 ◽  
Author(s):  
G.E. Marin ◽  
B.M. Osipov ◽  
D.I. Mendeleev
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Thermodynamic Cycle ◽  
Working Fluid ◽  
Fluid Composition ◽  
Fuel Gas ◽  
Turbine Engine ◽  
Equipment Operation ◽  
Turbine Efficiency ◽  
The Impact

The purpose of this paper is to study and analyze the gas turbine engine and the thermodynamic cycle of a gas turbine. The article describes the processes of influence of the working fluid composition on the parameters of the main energy gas turbines, depending on the composition of the fuel gas. The calculations of the thermal scheme of a gas turbine, which were made using mathematical modeling, are given. As a result of research on the operation of the GE PG1111 6FA gas turbine installation with various gas compositions, it was established that when the gas turbine is operating on different fuel gases, the engine efficiency changes. The gas turbine efficiency indicators were determined for various operating parameters and fuel composition. The impact of fuel components on the equipment operation is revealed.

scholarly journals Simulation of Supercritical CO2 Flow Through Circular and Annular Orifice

2015 ◽  
Vol 1 (2) ◽  
Author(s):  
Haomin Yuan ◽  
John Edlebeck ◽  
Mathew Wolf ◽  
Mark Anderson ◽  
Michael Corradini ◽  
...  
Keyword(s):  
Supercritical Co2 ◽  
High Efficiency ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Working Fluid ◽  
Operating Pressure ◽  
Two Phase ◽  
Choked Flow ◽  
Wide Range ◽  
Co2 Flow

Supercritical CO2 (sCO2) is a promising working fluid for future high-efficiency power conversion cycles. In order to develop these cycles, it is necessary to understand supercritical and two-phase CO2 flow. This paper presents a methodology for the computational fluid dynamic (CFD) simulation of sCO2 flowing through a restriction under a wide range of flow conditions. Under an accidental situation, such as a pipe break, the inventory of sCO2 leaks out through a small restriction. In this research, we use circular and annular orifices to mimic the behavior of restrictions. As the atmospheric pressure is much smaller than the operating pressure in the pipe, a two-phase choked flow will happen. Such behavior is considered in the simulation. The homogeneous equilibrium model (HEM) is employed to model the two-phase state. To correctly simulate the behavior of the power cycle under this accidental scenario, the inventory leakage rate should be calculated precisely. Therefore, at the current state, this study only focuses on the prediction of mass flow rate through orifices.

Experimental and Computational Evaluation of Flow Characteristics for Advanced Film Cooling Hole Geometries

2013 ◽  
Author(s):  
David Gomez-Ramirez ◽  
Shreyas Srinivasan ◽  
Sridharan Ramesh ◽  
Marco Miranda ◽  
Srinath V. Ekkad ◽  
...  
Keyword(s):  
Flat Plate ◽  
Film Cooling ◽  
Gas Turbines ◽  
Structural Integrity ◽  
Fluid Dynamic ◽  
Vortex Formation ◽  
Flow Characteristics ◽  
Cooling Effectiveness ◽  
Computational Evaluation ◽  
Cylindrical Holes

Film cooling is crucial in the field of gas turbines to protect the blade surfaces from the hot combustion gases. Several hole geometries have been studied in the past in an effort to optimize the cooling effectiveness of the holes while maintaining the structural integrity of the blade and low manufacturing costs. To understand the cooling effectiveness of the various hole geometries, the flow structures that develop as the coolant jet interacts with the hot mainstream must be understood. The present paper compares the results obtained from 2D Particle Image Velocimetry (PIV) measurements with CFD predictions using standard Reynolds-Averaged Navier Stokes (RANS) models with a commercially available code. The study is conducted for flat plate film cooling via conventional cylindrical holes, shaped holes (10° flare/laidback), and a tripod anti-vortex hole (AV) design. A constant blowing ratio (BR) of 0.5 was used for all the experiments, except for an additional measurement for the AV design at a BR of 1.0. Computational fluid dynamic (CFD) calculations were made with a standard k-epsilon model and compared to PIV results. The results show the counter-rotating vortices developing for cylindrical and shaped holes up to 5D and 3D respectively from the hole exit. AV holes showed no vortex formation, further supporting its higher cooling performance. Moreover, the present results indicate no separation of the coolant jet for AV or shaped holes as expected, while cylindrical holes displayed a small separation with a vertical extent of ∼0.1D. The CFD model was able to capture the main structures of the flow, but further efforts will concentrate in improving the representation of the flow normal to the flat plate surface.

Optimization of a Closed-Cycle OTEC System

1990 ◽  
Vol 112 (4) ◽  
pp. 247-256 ◽  
Author(s):  
Haruo Uehara ◽  
Yasuyuki Ikegami
Keyword(s):  
Heat Exchangers ◽  
Sea Water ◽  
Working Fluid ◽  
Turbine Efficiency ◽  
Thermal Energy Conversion ◽  
Calculation Results ◽  
Change Temperature ◽  
Ocean Thermal Energy ◽  
Powell Method ◽  
Method Of Steepest Descent

Optimization of an Ocean Thermal Energy Conversion (OTEC) system is carried out by the Powell Method (the method of steepest descent). The parameters in the objective function consist of the velocities of cold sea water and warm sea water passing through the heat exchangers, the phase change temperature, and turbine configuration (specific speed, specific diameter, ratio of blade to diameter). Numerical results are shown for a 100-MW OTEC plant with plate-type heat exchangers using ammonia as working fluid, and are compared with calculation results for the case when the turbine efficiency is fixed.

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