scholarly journals Thermofluid Analysis of the Magnetocaloric Refrigeration

2014 ◽  
Author(s):  
Ayyoub Mehdizadeh Momen ◽  
Omar Abdelaziz ◽  
Kyle Gluesenkamp ◽  
Edward Vineyard ◽  
Michael Benedict
Keyword(s):  
Parametric Study ◽  
High Performance ◽  
Cooling Capacity ◽  
Multi Objective Optimization ◽  
Computationally Efficient ◽  
Multi Objective ◽  
Optimization Study ◽  
Wide Range ◽  
Dimensional Parameters ◽  
Generic System

While there have been extensive studies on thermofluid characteristics of different magnetocaloric refrigeration systems, a conclusive optimization study using non-dimensional parameters which can be applied to a generic system has not been reported yet. In this study, a numerical model has been developed for optimization of active magnetic refrigerator (AMR). This model is computationally efficient and robust, making it appropriate for running the thousands of simulations required for parametric study and optimization. The governing equations have been non-dimensionalized and numerically solved using finite difference method. A parametric study on a wide range of non-dimensional numbers has been performed. While the goal of AMR systems is to improve the performance of competitive parameters including COP, cooling capacity and temperature span, new parameters called “AMR performance index-1” have been introduced in order to perform multi objective optimization and simultaneously exploit all these parameters. The multi-objective optimization is carried out for a wide range of the non-dimensional parameters. The results of this study will provide general guidelines for designing high performance AMR systems.

Integrated Design and Multi-Objective Optimization of a Single Stage Heat-Pump Turbocompressor

2013 ◽  
Author(s):  
J. Schiffmann
Keyword(s):  
Design Optimization ◽  
High Efficiency ◽  
Integrated Design ◽  
Heat Pumps ◽  
Small Scale ◽  
Multi Objective Optimization ◽  
Design Constraints ◽  
Multi Objective ◽  
Wide Range ◽  
Standard Design

Small scale turbomachines in domestic heat pumps reach high efficiency and provide oil-free solutions which improve heat-exchanger performance and offer major advantages in the design of advanced thermodynamic cycles. An appropriate turbocompressor for domestic air based heat pumps requires the ability to operate on a wide range of inlet pressure, pressure ratios and mass flows, confronting the designer with the necessity to compromise between range and efficiency. Further the design of small-scale direct driven turbomachines is a complex and interdisciplinary task. Textbook design procedures propose to split such systems into subcomponents and to design and optimize each element individually. This common procedure, however, tends to neglect the interactions between the different components leading to suboptimal solutions. The authors propose an approach based on the integrated philosophy for designing and optimizing gas bearing supported, direct driven turbocompressors for applications with challenging requirements with regards to operation range and efficiency. Using previously validated reduced order models for the different components an integrated model of the compressor is implemented and the optimum system found via multi-objective optimization. It is shown that compared to standard design procedure the integrated approach yields an increase of the seasonal compressor efficiency of more than 12 points. Further a design optimization based sensitivity analysis allows to investigate the influence of design constraints determined prior to optimization such as impeller surface roughness, rotor material and impeller force. A relaxation of these constrains yields additional room for improvement. Reduced impeller force improves efficiency due to a smaller thrust bearing mainly, whereas a lighter rotor material improves rotordynamic performance. A hydraulically smoother impeller surface improves the overall efficiency considerably by reducing aerodynamic losses. A combination of the relaxation of the 3 design constraints yields an additional improvement of 6 points compared to the original optimization process. The integrated design and optimization procedure implemented in the case of a complex design problem thus clearly shows its advantages compared to traditional design methods by allowing a truly exhaustive search for optimum solutions throughout the complete design space. It can be used for both design optimization and for design analysis.

scholarly journals A spam filtering multi-objective optimization study covering parsimony maximization and three-way classification

2016 ◽  
Vol 48 ◽  
pp. 111-123 ◽  
Author(s):  
Vitor Basto-Fernandes ◽  
Iryna Yevseyeva ◽  
José R. Méndez ◽  
Jiaqi Zhao ◽  
Florentino Fdez-Riverola ◽  
...  
Keyword(s):  
Spam Filtering ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Optimization Study

scholarly journals Correction: A multi-objective optimization-based layer-by-layer blade-coating approach for organic solar cells: rational control of vertical stratification for high performance

2020 ◽  
Vol 13 (1) ◽  
pp. 317-317
Author(s):  
Rui Sun ◽  
Jie Guo ◽  
Qiang Wu ◽  
Zhuohan Zhang ◽  
Wenyan Yang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Organic Solar Cells ◽  
High Performance ◽  
Vertical Stratification ◽  
Layer By Layer ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Rational Control ◽  
Blade Coating ◽  
Energy Environ

Correction for ‘A multi-objective optimization-based layer-by-layer blade-coating approach for organic solar cells: rational control of vertical stratification for high performance’ by Rui Sun et al., Energy Environ. Sci., 2019, 12, 3118–3132.

The Multi-Objective Optimization under Random Loads

2012 ◽  
Vol 166-169 ◽  
pp. 548-552
Author(s):  
Xian Jie Wang ◽  
Xun An Zhang ◽  
Yeda Lian
Keyword(s):  
High Performance ◽  
Low Cost ◽  
Structure Optimization ◽  
Extreme Value Distribution ◽  
Random Excitation ◽  
Probability Method ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Structure Reliability ◽  
Random Loads

Structure optimization seeks to achieve the best performance for a structure while satisfying various constrains such as a given probability. In the traditional mathematical model of structure optimization, the goal and the restraint functions are given without considering the randomness of the structural system. In this paper, the random loads and strength are described by probability method, the structure reliability is considered as objective function. Using the genetic algorithm, the mega-sub controlled structural systems is multi-objective optimization designed based on the structure reliability under random excitation, combined with the probability density evolution method for evaluation of extreme value distribution. A low-cost and high-performance structure is getting.

Use Multi-Objective Optimization for Designing Cloaks With Acoustic and Elastic Materials

2012 ◽  
Author(s):  
Chunyan Bao ◽  
Liang-Wu Cai
Keyword(s):  
Optimization Approach ◽  
Multi Objective Optimization ◽  
Frequency Range ◽  
Elastic Materials ◽  
Optimization Scheme ◽  
Multi Objective ◽  
Wide Range ◽  
Optimization Schemes ◽  
Elastic Layers

The various optimization schemes have been recently shown to be a capable tool for designing acoustic cloaks based on Cummer-Schurig prescription without requiring material singularity. However, when using an optimization scheme to optimize a cloak at one specified frequency, sometimes it is observed that the cloaking effect deteriorate at other frequencies. This paper explores the use of multi-objective optimization approach such that the cloaking performance is maintained over a wide range of frequencies. Two examples are presented. The first cloak is comprised of all aocustic layers, and the second cloak is comprised of a mixture of acoustic and elastic layers. The results show the effectiveness of the multi-objective optimization approach on maintaining cloaking performance over a specified frequency range.

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