scholarly journals Assessment of Deterministic Shape Optimizations Within a Stochastic Framework for Supersonic Organic Rankine Cycle Nozzle Cascades

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Alessandro Romei ◽  
Pietro Marco Congedo ◽  
Giacomo Persico
Keyword(s):  
Shape Optimization ◽  
Computational Cost ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Objective Functions ◽  
Flow Solver ◽  
Design Variables ◽  
Stochastic Framework ◽  
Constraint Problem ◽  
The Impact

The design of converging–diverging blades for organic Rankine cycle (ORC) applications widely relies on automated shape-optimization processes. As a result, the optimization produces an adapted-nozzle cascade at the design conditions. However, only few works account for the uncertainties in those conditions and their consequences on cascade performance. The proposed solution, i.e., including uncertainties within the optimization routine, demands an overall huge computational cost to estimate the target output statistic at each iteration of the optimization algorithm. With the aim of understanding if this computational cost is avoidable, we study the impact of uncertainties in the design conditions on the robustness of deterministically optimized profiles. Several optimized blades, obtained with different objective functions, constraints, and design variables, are considered in the present numerical analysis, which features a turbulent compressible flow solver and a state-of-the-art uncertainty-quantification (UQ) method. By including measured field variations in the formulation of the UQ problem, we show that a deterministic shape optimization already improves the robustness of the profile with respect to the baseline configuration. Guidelines about objective functions and blade parametrizations for deterministic optimizations are also provided. Finally, a novel methodology to estimate the mass-flow-rate probability density function (PDF) for choked supersonic turbines is proposed, along with a robust reformulation of the constraint problem without increasing the computational cost.

scholarly journals Sensitivity of Supersonic ORC Turbine Injector Designs to Fluctuating Operating Conditions

2015 ◽  
Author(s):  
Elio A. Bufi ◽  
Paola Cinnella ◽  
Xavier Merle
Keyword(s):  
Method Of Characteristics ◽  
Organic Rankine Cycle ◽  
Design Procedure ◽  
Rankine Cycle ◽  
Operating Conditions ◽  
Real Gas ◽  
Real Gas Effects ◽  
Nozzle Shape ◽  
Turbine Design ◽  
The Impact

The design of an efficient organic rankine cycle (ORC) expander needs to take properly into account strong real gas effects that may occur in given ranges of operating conditions, which can also be highly variable. In this work, we first design ORC turbine geometries by means of a fast 2-D design procedure based on the method of characteristics (MOC) for supersonic nozzles characterized by strong real gas effects. Thanks to a geometric post-processing procedure, the resulting nozzle shape is then adapted to generate an axial ORC blade vane geometry. Subsequently, the impact of uncertain operating conditions on turbine design is investigated by coupling the MOC algorithm with a Probabilistic Collocation Method (PCM) algorithm. Besides, the injector geometry generated at nominal operating conditions is simulated by means of an in-house CFD solver. The code is coupled to the PCM algorithm and a performance sensitivity analysis, in terms of adiabatic efficiency and power output, to variations of the operating conditions is carried out.

Parameter assessment for virtual Stackelberg game in aerodynamic shape optimization

2018 ◽  
Vol 32 (12n13) ◽  
pp. 1840044
Author(s):  
Jing Wang ◽  
Fangfang Xie ◽  
Yao Zheng ◽  
Jifa Zhang
Keyword(s):  
Shape Optimization ◽  
Stackelberg Game ◽  
Critical Parameters ◽  
Aerodynamic Shape Optimization ◽  
Aerodynamic Optimization ◽  
Aerodynamic Shape ◽  
Design Variables ◽  
Design Cycle ◽  
Parametric Studies ◽  
The Impact

In this paper, parametric studies of virtual Stackelberg game (VSG) are conducted to assess the impact of critical parameters on aerodynamic shape optimization, including design cycle, split of design variables and role assignment. Typical numerical cases, including the inverse design and drag reduction design of airfoil, have been carried out. The numerical results confirm the effectiveness and efficiency of VSG. Furthermore, the most significant parameters are identified, e.g. the increase of design cycle can improve the optimization results but it will also add computational burden. These studies will maximize the productivity of the effort in aerodynamic optimization for more complicated engineering problems, such as the multi-element airfoil and wing-body configurations.

scholarly journals Design Methodology for Supersonic Radial Vanes Operating in Nonideal Flow Conditions

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Nitish Anand ◽  
Salvatore Vitale ◽  
Matteo Pini ◽  
Gustavo J. Otero ◽  
Rene Pecnik
Keyword(s):  
Shock Wave ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Computational Cost ◽  
Organic Rankine Cycle ◽  
Suction Side ◽  
Rankine Cycle ◽  
Computational Effort ◽  
Design Guidelines ◽  
Boundary Layer Interaction

The stator vanes of high-temperature organic Rankine cycle (ORC) radial-inflow turbines (RIT) operate under severe expansion ratios and the associated fluid-dynamic losses account for nearly two-thirds of the total losses generated within the blading passages. The efficiency of the machine can strongly benefit from specialized high-fidelity design methods able to provide shapes attenuating shock wave formation, consequently reducing entropy generation across the shock-wave and mitigating shock-wave boundary layer interaction. Shape optimization is certainly a viable option to deal with supersonic ORC stator design, but it is computationally expensive. In this work, a robust method to approach the problem at reduced computational cost is documented. The method consists of a procedure encompassing the method of characteristics (MoC), extended to nonideal fluid flow, for profiling the diverging part of the nozzle. The subsonic section and semibladed suction side are retrieved using a simple conformal geometrical transformation. The method is applied to design a supersonic ORC stator working with Toluene vapor, for which two blade shapes were already available. The comparison of fluid-dynamic performance clearly indicates that the MoC-Based method is able to provide the best results with the lowest computational effort, and is therefore suitable to be used in a systematic manner for drawing general design guidelines.

Computationally Efficient Combined Plant Design and Controller Optimization Using a Coupling Measure

2012 ◽  
Vol 134 (7) ◽  
Author(s):  
Rakesh Patil ◽  
Zoran Filipi ◽  
Hosam Fathy
Keyword(s):  
Optimal Control ◽  
Computational Cost ◽  
Systems Design ◽  
Plant Design ◽  
Coupling Term ◽  
Control Optimization ◽  
Novel Approach ◽  
Design Variables ◽  
The Impact ◽  
Plant Control

This paper presents a novel approach to the optimization of a dynamic systems design and control. Traditionally, these problems have been solved either sequentially or in a combined manner. We propose a novel approach that uses a previously derived coupling measure to quantify the impact of plant design variables on optimal control cost. This proposed approach has two key advantages. First, because the coupling term quantifies the gradient of the control optimization objective with respect to plant design variables, the approach ensures combined plant/control optimality. Second, because the coupling term equals the integral of optimal control co-states multiplied by static gradient terms that can be computed a priori, the proposed approach is computationally attractive. We illustrate this approach using an example cantilever beam structural design and vibration control problem. The results show significant computational cost improvements compared to traditional combined plant/control optimization. This reduction in computational cost becomes more pronounced as the number of plant design variables increases.

scholarly journals Dynamic Modeling and Control System Definition for a Micro-CSP Plant Coupled With Thermal Storage Unit

2014 ◽  
Author(s):  
Melissa K. Ireland ◽  
Matthew S. Orosz ◽  
J. G. Brisson ◽  
Adriano Desideri ◽  
Sylvain Quoilin
Keyword(s):  
Rural Communities ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Thermal Storage ◽  
Energy Coupling ◽  
Operating Conditions ◽  
Small Scale ◽  
Storage Unit ◽  
Modeling And Control ◽  
The Impact

Organic Rankine cycle (ORC) systems are gaining ground as a means of effectively providing sustainable energy. Coupling small-scale ORCs powered by scroll expander-generators with solar thermal collectors and storage can provide combined heat and power to underserved rural communities. Simulation of such systems is instrumental in optimizing their control strategy. However, most models developed so far operate at steady-state or focus either on ORC or on storage dynamics. In this work, a model for the dynamics of the solar ORC system is developed to evaluate the impact of variable heat sources and sinks, thermal storage, and the variable loads associated with distributed generation. This model is then used to assess control schemes that adjust operating conditions for daily environmental variation.

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 Development and Experimental Validation of Real Fluid Models for CFD Calculation of ORC and Steam Turbine Flows

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6879
Author(s):  
Andrii Rusanov ◽  
Roman Rusanov ◽  
Piotr Klonowicz ◽  
Piotr Lampart ◽  
Grzegorz Żywica ◽  
...  
Keyword(s):  
Experimental Data ◽  
Equation Of State ◽  
Steam Turbine ◽  
Thermodynamic Parameters ◽  
Equations Of State ◽  
Computational Cost ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Large Power ◽  
Wide Range

The article describes an interpolation–analytical method of reconstruction of the IAPWS-95 equations of state and the modified Benedict–Webb–Rubin equations of state with 32 terms (mBWR32). The method enables us to provide the thermodynamic closure in 3D computational fluid dynamics (CFD) calculations of turbomachinery flows with real working media, such as steam and Organic Rankine Cycle (ORC) fluids. The described approach allows for the sufficient accuracy of 3D flow calculations and does not require a significant increase in computational cost over perfect gas calculations. The method is validated against experimental data from measurements and compared with computational results from the model using the Tammann equation of state. Three turbine blading systems are considered—a multi-stage configuration from a low-pressure cylinder of a large-power steam turbine and two ORC microturbines working with organic media HFE7100 and R227ea. The calculation results obtained using the described method of approximation of the IAPWS-95 and mBWR32 equations exhibit satisfactory agreement with the experimental data, considering pressures, temperatures and enthalpies in key sections, as well as turbine power and efficiency in a wide range of changing thermodynamic parameters. In contrast, the Tammann equation of state provides acceptable results only for relatively small changes of thermodynamic parameters.

Application of a Decomposition Technique for Treating a Shape Optimization Problem

1989 ◽  
Author(s):  
M. Bremicker ◽  
H. Eschenauer
Keyword(s):  
Sensitivity Analysis ◽  
Shape Optimization ◽  
Optimization Problem ◽  
Optimization Methods ◽  
Objective Functions ◽  
Shape Optimization Problem ◽  
Boundary State ◽  
Design Variables ◽  
Dimensional Shape ◽  
Suitable Approximation

Abstract The range of application of structural optimization methods can be considerably enlarged by using decomposition techniques. In this paper a novel procedure is introduced to deal with such problems more efficiently. The mechanical structure resp. system is divided into several subsystems splitting up the design variables, objective functions, and constraints accordingly. The boundary state quantities of the subsystems and the global (i.e. subsystem overlapping) functions are approximated by a sensitivity analysis of the entire system using suitable approximation concepts. It is thus possible to optimize the subsystems independently. Variables, objective functions and constraints can be chosen arbitrarily; all coupling information is obtained from the sensitivity analysis by means of global information. The application of this technique is demonstrated by a two-dimensional shape optimization problem.

Design Optimization of Ship Hulls via CFD Techniques

2001 ◽  
Vol 45 (02) ◽  
pp. 140-149
Author(s):  
Daniele Peri ◽  
Michele Rossetti ◽  
Emilio F. Campana
Keyword(s):  
Wave Pattern ◽  
Optimization Process ◽  
Objective Functions ◽  
Original Design ◽  
Flow Solver ◽  
Ship Hulls ◽  
Design Variables ◽  
Specific Objective ◽  
Geometrical Constraints ◽  
Computational Fluid Dynamics Cfd

Numerical shape optimization of a tanker ship hull has been carried out with the aid of computational fluid dynamics (CFD) techniques and experimentally verified. The choice of a specific objective function is based on the needs of the user. In the present study, total resistance and wave pattern have been used either separately or linearly combined. In the optimization process, three different algorithms have been tested, coupled together with a CFD flow solver. A perturbation surface has been used to modify the shape of the hull, allowing for a sharp reduction of the number of design variables. Accordingly, with different objective functions and geometrical constraints, several new optimized shapes of the bulb of a tanker ship have been automatically obtained. Among them, two optimized models have been built and tested, in the INSEAN towing tank, against the original design. In both cases the measured data have confirmed the success of the optimization process.

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