Efficiency and Sensitivity Analysis of Cavern-Based CAES Systems During off-Design Operating Conditions

2021 ◽  
pp. 177-199
Author(s):  
Mehdi Ebrahimi ◽  
David S.-K. Ting ◽  
Rupp Carriveau ◽  
Andrew McGillis ◽  
David Brown
Keyword(s):  
Sensitivity Analysis ◽  
Operating Conditions

scholarly journals Sensitivity Analysis of OTEC-CC-MX-1 kWe Plant Prototype

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2585
Author(s):  
Jessica Guadalupe Tobal-Cupul ◽  
Estela Cerezo-Acevedo ◽  
Yair Yosias Arriola-Gil ◽  
Hector Fernando Gomez-Garcia ◽  
Victor Manuel Romero-Medina
Keyword(s):  
Sensitivity Analysis ◽  
Experimental Tests ◽  
Caribbean Sea ◽  
Ocean Model ◽  
Operating Conditions ◽  
Working Fluid ◽  
Ocean Energy ◽  
Mexican Caribbean ◽  
Water Temperature Data ◽  
Mass Flows

The Mexican Caribbean Sea has potential zones for Ocean Thermal Energy Conversion (OTEC) implementation. Universidad del Caribe and Instituto de Ciencias del Mar y Limnologia, with the support of the Mexican Centre of Innovation in Ocean Energy, designed and constructed a prototype OTEC plant (OTEC-CC-MX-1 kWe), which is the first initiative in Mexico for exploitation of this type of renewable energy. This paper presents a sensitivity analysis whose objective was to know, before carrying out the experimental tests, the behavior of OTEC-CC-MX-1 kWe regarding temperature differences, as well as the non-possible operating conditions, which allows us to assess possible modifications in the prototype installation. An algorithm was developed to obtain the inlet and outlet temperatures of the water and working fluid in the heat exchangers using the monthly surface and deep-water temperature data from the Hybrid Coordinate Ocean Model and Geographically Weighted Regression Temperature Model for the Mexican Caribbean Sea. With these temperatures, the following were analyzed: fluctuation of thermal efficiency, mass flows of R-152a and water and power production. By analyzing the results, we verified maximum and minimum mass flows of water and R-152a to produce 1 kWe during a typical year in the Mexican Caribbean Sea and the conditions when the production of electricity is not possible for OTEC-CC-MX-1 kWe.

Sensitivity Analysis to Flutter for Front Stages Compressor Blades

2015 ◽  
Author(s):  
Marcello Benvenuto ◽  
Andrea Silingardi ◽  
Pio Astrua ◽  
Stefano Cecchi
Keyword(s):  
Sensitivity Analysis ◽  
Travelling Wave ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Elastic Behavior ◽  
Modal Shape ◽  
Compressor Blades ◽  
Flexural Mode ◽  
Non Linear ◽  
Heavy Duty Gas Turbine

Heavy duty gas turbine front stages compressor blades aero-elastic behavior is deeply analyzed and investigated by means of an uncoupled, non-linear and time-accurate CFD URANS solver. The travelling-wave approach and the energy method have been applied in order to assess the aerodynamic damping (in terms of logarithmic decrement) for each inter blade phase angle (IBPA) and thus to localize the flutter stability region. The work is mainly focused on a sensitivity analysis with respect to blade operating conditions, eigen-mode shapes and frequency in order to improve the understanding of flutter mechanism and to identify the key parameters. Transonic, supercritical and subsonic blades are investigated at different operating conditions with their corresponding eigenmode and eigen-frequency (first and second flexural mode and first torsional). The results show that non-linear effects can be neglected for subsonic blades. Besides, the modal-shape and the shock structure, if any, are identified to play a key role for flutter stability.

Geometric accuracy allocation for multi-axis CNC machine tools based on sensitivity analysis and reliability theory

2014 ◽  
Vol 229 (6) ◽  
pp. 1134-1149 ◽  
Author(s):  
Qiang Cheng ◽  
Ziling Zhang ◽  
Guojun Zhang ◽  
Peihua Gu ◽  
Ligang Cai
Keyword(s):  
Sensitivity Analysis ◽  
Machine Tool ◽  
Operating Conditions ◽  
Numerical Control ◽  
Cnc Machine Tools ◽  
Machining Accuracy ◽  
Geometric Errors ◽  
Volumetric Error ◽  
The Cost ◽  
Five Axis

Machining accuracy of a machine tool is influenced by geometric errors produced by each part and component. Different errors have varying influence on the machining accuracy of a tool. The aim of this study is to optimize errors to get a desired performance for a numerical control machine tool. Applying multi-body system theory, a volumetric error model was constructed to track and compensate effects of errors during operation of the machine, and to relate the functional specifications on volumetric accuracy to the permissible errors on the joints and links of the machine. Error sensitivity analysis was used to identify the influence of different errors (especially the errors which have large influences) on volumetric error. Based on First Order and Second Moment theory, an error allocation approach was developed to optimize allocation of manufacturing and assembly tolerances along with specifying the operating conditions to determine the optimal level of these errors so that the cost of controlling them and the cost of failure to meet the specifications is minimized. The approach developed was implemented in software and an example of the geometric errors budgeting for a five-axis machine was discussed. It is identified that the different optimal standard deviations reflect the cost-weighted influences of the respective parameters in the equations of the functional requirements. This study suggests that it is possible to determine the coupling relationships between these errors and optimize the allowable error budgeting between these sources.

Homogeneous Sono-Fenton Process: Statistical Modeling and Global Sensitivity Analysis

2015 ◽  
Vol 16 (1) ◽  
pp. 11-21
Author(s):  
Daniela Căilean ◽  
Florina Ungureanu ◽  
Carmen Teodosiu
Keyword(s):  
Sensitivity Analysis ◽  
Statistical Modeling ◽  
Global Sensitivity Analysis ◽  
Operating Conditions ◽  
Pollutant Concentration ◽  
Sample Mean ◽  
Global Sensitivity ◽  
Aqueous Effluents ◽  
Kolmogorov Smirnov ◽  
Smirnov Test

AbstractThe main objective of this study is to obtain and validate a mathematical model to describe a complex homogeneous Sono-Fenton (HSF) process used for the removal of 4-chlorophenol model pollutant from aqueous effluents. The investigated process parameters (acoustic amplitude, power density depending on the surface of the tip, initial pollutant concentration and time) serve as input parameters for the statistical modeling, while the output parameters considered are the final pollutant concentration and energy delivered to the sample. The accuracy of the models is analyzed by the values of the determination coefficients and by graphical tools available in MATLAB software such as: the Kolmogorov–Smirnov test (KS test), the graphical sensitivity tools, e.g. contribution to the sample mean (CSM) and variance (CSV) plots. The robustness of the model is also analyzed by global sensitivity analysis. Furthermore, the optimum set of operating conditions are determined by using the nlintool function.

scholarly journals Verification Techniques for Sensitivity Analysis and Design of Controllers for Nonlinear Dynamic Systems with Uncertainties

2009 ◽  
Vol 19 (3) ◽  
pp. 425-439 ◽  
Author(s):  
Andreas Rauh ◽  
Johanna Minisini ◽  
Eberhard Hofer
Keyword(s):  
Sensitivity Analysis ◽  
Dynamic Systems ◽  
Interval Arithmetic ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamical Systems ◽  
Operating Conditions ◽  
Nonlinear Dynamic Systems ◽  
Parameter Uncertainties ◽  
Analysis And Design ◽  
Verification Techniques

Verification Techniques for Sensitivity Analysis and Design of Controllers for Nonlinear Dynamic Systems with UncertaintiesControl strategies for nonlinear dynamical systems often make use of special system properties, which are, for example, differential flatness or exact input-output as well as input-to-state linearizability. However, approaches using these properties are unavoidably limited to specific classes of mathematical models. To generalize design procedures and to account for parameter uncertainties as well as modeling errors, an interval arithmetic approach for verified simulation of continuoustime dynamical system models is extended. These extensions are the synthesis, sensitivity analysis, and optimization of open-loop and closed-loop controllers. In addition to the calculation of guaranteed enclosures of the sets of all reachable states, interval arithmetic routines have been developed which verify the controllability and observability of the states of uncertain dynamic systems. Furthermore, they assure asymptotic stability of controlled systems for all possible operating conditions. Based on these results, techniques for trajectory planning can be developed which determine reference signals for linear and nonlinear controllers. For that purpose, limitations of the control variables are taken into account as further constraints. Due to the use of interval techniques, issues of the functionality, robustness, and safety of dynamic systems can be treated in a unified design approach. The presented algorithms are demonstrated for a nonlinear uncertain model of biological wastewater treatment plants.

scholarly journals Enhancement of ultrafiltration of milk proteins by applying twisted tapes: A sensitivity analysis using a response surface methodology

2020 ◽  
pp. 73-73
Author(s):  
Svetlana Popovic ◽  
Mirela Ilicic ◽  
Igor Gáspár
Keyword(s):  
Sensitivity Analysis ◽  
Aspect Ratio ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Milk Proteins ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Twisted Tape ◽  
Linear Effect ◽  
Twisted Tapes

This paper presents the intensification of the ultrafiltration of milk proteins by applying twisted tapes as turbulence promoters to minimize membrane fouling. The aim was to examine the influence of operating conditions and twisted tape dimension on the alleviation of flux and the consumption of specific energy. A twisted tape was inserted in the ultrafiltration membrane (50 nm pore size) to alleviate turbulence and minimize fouling. The response surface methodology was used for the sensitivity analysis of the effects of operating conditions on the responses. The analysis showed that the linear effect of the aspect ratio of a twisted tape has a dominant significant effect on flux improvement. The linear effect of cross-flow rate has a positive dominant effect on the specific energy consumption. The linear effect of concentration and the mutual effect of aspect ratio and transmembrane pressure are statistically significant for both responses. By adjusting the operating conditions properly, the high flux improvement of 300 % can be reached with specific energy consumption below 1.0 kWh m-3 using a twisted tape of the aspect ratio of 1.0 and imposing low transmembrane pressure.

scholarly journals Sensitivity analysis for operating loads in fatigue design of railway vehicles

2021 ◽  
pp. 095440972110454
Author(s):  
Sönke Kraft ◽  
Daniel Lüdicke
Keyword(s):  
Sensitivity Analysis ◽  
Regression Models ◽  
Operating Conditions ◽  
Linear Regression Models ◽  
Virtual Design ◽  
Railway Vehicles ◽  
Operation Conditions ◽  
Fatigue Design ◽  
Simulation Based ◽  
Multi Body

For the reliable simulation-based fatigue design of railway vehicles, the operation conditions and resulting loads over the lifespan of the vehicle have to be considered. After introducing the relevant fatigue loads on the vehicle and the methods for modelling the fatigue damage, this work aims at analysing the influence of the operating conditions and loads on the damage using sensitivity analysis. Two approaches are studied: the variance-based sensitivity analysis of the loads acting on the car body and the influence of different operating conditions using statistical values per track section. The loads are obtained from multi-body simulations and the damage is estimated using both physical FE-models and meta-models. The performances of linear regression models and polynomial chaos models are evaluated. The proposed sensitivity analysis is applied to the highspeed train being developed in the Next Generation Train (NGT) project at DLR and will serve as a basis for the virtual design and reliability analysis.

Uncertainty Quantification of NOx Emission Due to Operating Conditions and Chemical Kinetic Parameters in a Premixed Burner

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Sajjad Yousefian ◽  
Gilles Bourque ◽  
Rory F. D. Monaghan
Keyword(s):  
Sensitivity Analysis ◽  
Uncertainty Quantification ◽  
Gas Turbine ◽  
Flow Reactor ◽  
Epistemic Uncertainty ◽  
Plug Flow ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Nox Emission ◽  
Gas Turbine Combustion

Many sources of uncertainty exist when emissions are modeled for a gas turbine combustion system. They originate from uncertain inputs, boundary conditions, calibration, or lack of sufficient fidelity in a model. In this paper, a nonintrusive polynomial chaos expansion (NIPCE) method is coupled with a chemical reactor network (CRN) model using Python to quantify uncertainties of NOx emission in a premixed burner. The first objective of uncertainty quantification (UQ) in this study is development of a global sensitivity analysis method based on the NIPCE method to capture aleatory uncertainty on NOx emission due to variation of operating conditions. The second objective is uncertainty analysis (UA) of NOx emission due to uncertain Arrhenius parameters in a chemical kinetic mechanism to study epistemic uncertainty in emission modeling. A two-reactor CRN consisting of a perfectly stirred reactor (PSR) and a plug flow reactor (PFR) is constructed in this study using Cantera to model NOx emission in a benchmark premixed burner under gas turbine operating conditions. The results of uncertainty and sensitivity analysis (SA) using NIPCE based on point collocation method (PCM) are then compared with the results of advanced Monte Carlo simulation (MCS). A set of surrogate models is also developed based on the NIPCE approach and compared with the forward model in Cantera to predict NOx emissions. The results show the capability of NIPCE approach for UQ using a limited number of evaluations to develop a UQ-enabled emission prediction tool for gas turbine combustion systems.

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