OPTIMIZATION OF THE STACK IN A STANDING WAVE THERMOACOUSTIC REFRIGERATOR AT DIFFERENT DESIGN TEMPERATURES

2016 ◽  
Vol 78 (8-4) ◽  
Author(s):  
Normah Mohd-Ghazali ◽  
Mawahib Hassan El-Fawal
Keyword(s):  
Optimization Methods ◽  
Simultaneous Optimization ◽  
Coefficient Of Performance ◽  
Design Parameters ◽  
Vapor Compression ◽  
Upper Limit ◽  
Center Position ◽  
Discrete Variations ◽  
Parameters Of Interest ◽  
Thermoacoustic Refrigerator

Although numerous successful thermoacoustic refrigerators have been reported to date, the performance of these systems is still lower than their vapor compression counter parts. Optimization is imperative to identify the upper limit of the performance in order to be competitive and accepted by the general public. However, optimization methods adopted so far, experimentally and numerically, involved discrete variations of the selected parameters of interest. This paper presents the results of an optimization using the Lagrange Multiplier method, a mathematical approach never used before. The simultaneous optimization of the stack length and center position at various design temperatures is performed for a standard thermoacoustic refrigerator design. Results show similar pattern and trend with previous results with a 24.7% higher stack coefficient of performance achievable. This is promising considering that only two of the design parameters have been optimized.

Single-Objective Optimization of a Thermoacoustic Refrigerator

2016 ◽  
Vol 819 ◽  
pp. 88-93 ◽  
Author(s):  
Nor Atikah Zolpakar ◽  
Normah Mohd-Ghazali ◽  
Robiah Ahmad
Keyword(s):  
Genetic Algorithm ◽  
Uv Light ◽  
Coefficient Of Performance ◽  
Blockage Ratio ◽  
Optimization Scheme ◽  
Center Position ◽  
Negative Impacts ◽  
By Products ◽  
Single Objective ◽  
Thermoacoustic Refrigerator

Optimization of energy-related systems with by-products that involve environmental degradation has never been so crucial today with depleting resources and global concerns over negative impacts on our environment. This paper reports the results of an optimization scheme on the coefficient of performance (COP) of a standing wave thermoacoustic refrigerator based on genetic algorithm. The environmentally friendly refrigerator operates without any CFCs, which has been associated with the depletion of ozone, a substance that prevents uv light from reaching the earth’s atmosphere. A single-objective optimization to maximize the COP of a thermoacoustic refrigerator has been completed. The variables investigated include the length of the stack, Lsn, center position of the stack, xsn, blockage ratio, B and drive ratio, DR. The results show that a COP of up to 1.64 is achievable which provides promise for future improvements in the present systems.

Integration of an Automatic Optimizer Functionality Into the Design Process of Industrial Steam Turbines

2012 ◽  
Author(s):  
Dimitri Drapkin ◽  
Franz Kores ◽  
Thomas Polklas
Keyword(s):  
Design Process ◽  
Optimization Methods ◽  
Simultaneous Optimization ◽  
Design Parameters ◽  
Optimization Approach ◽  
Steam Turbines ◽  
Particle Swarm Optimizer ◽  
Optimization Task ◽  
Wide Range ◽  
Optimization Parameters

Industrial steam turbines are mostly tailor made machinery, varying in a wide range of specifications. This feature introduces high requirements on the design process which has to be flexible, efficient and fast at the same time. Given live steam and design parameters as input, the geometry corresponding to the valid design scheme can be calculated together with the required thermodynamic, aerodynamic and mechanical characteristics. By variation of design parameters a design may be achieved which optimizes both, efficiency and cost. The optimization task is formulated mathematically, e.g. crucial optimization parameters, criteria for evaluation of different designs and other required constraints are selected. The structure of the resulting optimization problem is analyzed. Based on this analysis a modular optimization system design is proposed. The choice of Genetic Algorithms and Adaptive Particle Swarm Optimizer as optimization methods is discussed, recommendations for their proper use are given. A bicriterial optimization approach for a simultaneous optimization of efficiency and cost is developed.

Miniaturized Traveling-Wave Thermoacoustic Refrigerator Driven by Loudspeaker: Numerical Design

2020 ◽  
Vol 28 (04) ◽  
pp. 2050035
Author(s):  
Oday S. Mahmood ◽  
Abdul Mun’em A. Karim ◽  
Samir Gh. Yahya ◽  
Itimad D. J. Azzawi
Keyword(s):  
Traveling Wave ◽  
New Technology ◽  
Acoustic Power ◽  
Inert Gases ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Vapor Compression ◽  
Sound Waves ◽  
Numerical Design ◽  
Thermoacoustic Refrigerator

Ordinary refrigeration systems such as vapor-compression refrigerators are the commonly used devices in industry, mostly for their high efficiencies. However, they make a significant contribution to the depletion of Ozone and global warming due to their operational refrigerants. Hence, thermoacoustic refrigeration can be a great alternative candidate which uses inert gases such as air, helium and nitrogen as the primary refrigerant. Thermoacoustic refrigerators convert the acoustic power (sound waves) into a thermal effect (cooling power). Thermoacoustics can be counted as a new technology that has a strong potential toward the development of the thermal applications. This study aims to design and fabricate miniaturized traveling wave thermoacoustic refrigerator which can be driven by an ordinary loudspeaker. The optimized numerical design of the refrigerator shows an overall efficiency (cooling power over input electricity) of nearly 66% at a temperature difference of 25[Formula: see text]K (between cold and ambient heat exchangers). The maximum estimated cooling power is 65[Formula: see text]W at coefficient of performance (COP) of 2.65.

OPTIMIZATION OF A THERMOACOUSTIC REFRIGERATOR WITH AN EVOLUTIONARY ALGORITHM APPROACH

2016 ◽  
Vol 78 (9-2) ◽  
Author(s):  
Nor Atiqah Zolpakar ◽  
Normah Mohd-Ghazali
Keyword(s):  
Environmentally Friendly ◽  
Optimization Procedure ◽  
Coefficient Of Performance ◽  
Blockage Ratio ◽  
Efficient Energy ◽  
Alternative Technologies ◽  
Design Variables ◽  
Center Position ◽  
Ratio Optimization ◽  
Thermoacoustic Refrigerator

Current non-environmentally friendly refrigerants released into our environment have caused serious concern over reports of the depleting of the ozone layer and global warming. Alternative technologies and efficient energy-related systems are being investigated to perhaps reduce if not stop the environmental degradation. This paper reports the outcomes of an optimization procedure performed on an environmentally friendly standing wave thermoacoustic refrigerator. A typical system to date has a low coefficient of performance (COP) and thus is not attractive to the general public. Optimization is completed using genetic algorithm over four design variables; the stack length and center position within a thermoacoustic resonator, the blockage ratio, and drive ratio. Optimization results show a maximum COP obtainable at 1.64. The outcomes indicate a potential for better thermoacoustic refrigerators in future.

SIMULTANEOUS OPTIMIZATION OF FOUR PARAMETERS IN THE STACK UNIT OF A THERMOACOUSTIC REFRIGERATOR

2014 ◽  
Vol 22 (02) ◽  
pp. 1450011 ◽  
Author(s):  
NOR ATIQAH ZOLPAKAR ◽  
NORMAH MOHD-GHAZALI ◽  
ROBIAH AHMAD
Keyword(s):  
Cooling System ◽  
Acoustic Power ◽  
Optimization Techniques ◽  
Simultaneous Optimization ◽  
Coefficient Of Performance ◽  
Cooling Power ◽  
Multi Objective Genetic Algorithm ◽  
Parametric Studies ◽  
Discrete Values ◽  
Thermoacoustic Refrigerator

Thermoacoustic refrigerators are environmentally friendly cooling systems that use no refrigerants. Optimization of the performance of any cooling system is crucial for an efficient energy management. Most of the optimization techniques in thermoacoustic systems utilized to date involved experimental and numerical parametric studies which are generally limited to the variations of the parameters to be optimized at discrete values. This study reports on the optimization of a thermoacoustic refrigerator using multi-objective genetic algorithm (MOGA). The study introduces the ability of MOGA to optimize four different variables which are length of stack, center position of stack, blockage ratio and drive ratio simultaneously. The four variables are optimized to achieve the two objectives; a maximum cooling and minimum acoustic power required at the stack and provide the optimum coefficient of performance, COP. The results show that the optimum COP = 1.35 with a cooling power of Qc = 6.57 W, acoustic power of Wn = 4.86 W and with the resonator diameter of D = 3.8 cm.

A Micro-Scale Membrane-Actuated Condenser/Evaporator for Enhanced Thermal Management

2000 ◽  
Author(s):  
Marianne M. Francois ◽  
Wei Shyy ◽  
Jacob N. Chung
Keyword(s):  
Thermal Management ◽  
High Energy ◽  
Coefficient Of Performance ◽  
Design Parameters ◽  
Present System ◽  
Vapor Compression ◽  
Thermodynamic Consideration ◽  
Micro Scale ◽  
Modular Concept ◽  
Droplet Sizes

Abstract There is a strong need to improve our current capabilities in thermal management and electronic cooling. The present study investigates the feasibility of a micro-scale membrane-actuated dropwise condenser/evaporator. An actuated membrane is adopted as the droplet condensing and ejecting device. Droplets with appropriate dimensions and frequencies are formed and ejected for efficient cooling. The present system requires no mechanical moving parts, and hence is reliable. In addition, it needs little maintenance due to closed recirculation, exhibits favorable packaging scalability in view of the modular concept, and offers high energy transfer effectiveness. In this work, we outline the thermodynamic consideration based on a vapor-compression cycle to assess the performance of such a device. The coefficient of performance of the cycle is estimated for four different fluids: water, R12, R134a and FC-72. The system design parameters and operating performances are estimated for droplet sizes ranging from 10 to 500 micrometers. It is demonstrated that in this operating range, the gravity effect is small, making this device ideal for both earth-bound and spacecraft applications.

Life Augmentation of Turbine Exhaust System Compensators Through Integrated MADM Optimization Approach of Stress Based Fatigue Cycles

2021 ◽  
Author(s):  
Nitin D. Pagar ◽  
Amit R. Patil
Keyword(s):  
Exhaust System ◽  
Optimization Methods ◽  
Fractional Factorial ◽  
Design Parameters ◽  
Optimization Approach ◽  
Auxiliary Equipment ◽  
Maximum Expansion ◽  
Optimal Configurations ◽  
Selection Of ◽  
Turbine Exhaust

Abstract Exhaust expansion joints, also known as compensators, are found in a variety of applications such as gas turbine exhaust pipes, generators, marine propulsion systems, OEM engines, power units, and auxiliary equipment. The motion compensators employed must have accomplished the maximum expansion-contraction cycle life while imposing the least amount of stress. Discrepancies in the selecting of bellows expansion joint design parameters are corrected by evaluating stress-based fatigue life, which is challenging owing to the complicated form of convolutions. Meridional and circumferential convolution stress equations that influencing fatigue cycles are evaluated and verified with FEA. Fractional factorial Taguchi L25 matrix is used for finding the optimal configurations. The discrete design parameters for the selection of the suitable configuration of the compensators are analysed with the help of the MADM decision making techniques. The multi-response optimization methods GRA, AHP, and TOPSIS are used to determine the parametric selection on a priority basis. It is seen that weighing distribution among the responses plays an important role in these methods and GRA method integrated with principal components shows best optimal configurations. Multiple regression technique applied to these methods also shows that PCA-GRA gives better alternate solutions for the designer unlike the AHP and TOPSIS method. However, higher ranked Taguchi run obtained in these methods may enhance the suitable selection of different design configurations. Obtained PCA-GRG values by Taguchi, Regression and DOE are well matched and verified for the all alternate solutions. Further, it also shows that stress based fatigue cycles obtained in this analysis for the L25 run indicates the range varying from 1.13 × 104 cycles to 9.08 × 105 cycles, which is within 106 cycles. This work will assist the design engineer for selecting the discrete parameters of stiff compensators utilized in power plant thermal appliances.

Optimization of profile and damping layer of plates embedded with acoustic black hole indentations for broadband energy dissipation

2022 ◽  
pp. 1045389X2110721
Author(s):  
Wei Huang ◽  
Chongcong Tao ◽  
Hongli Ji ◽  
Jinhao Qiu
Keyword(s):  
Black Hole ◽  
Energy Dissipation ◽  
Vibration Suppression ◽  
Optimal Solution ◽  
Simultaneous Optimization ◽  
Optimal Arrangement ◽  
Focusing Effect ◽  
Upper Limit ◽  
And Topology ◽  
Design Variables

Acoustic Black Hole (ABH) plate structure has shown promising potentials of vibration suppression above a cut on frequency. For energy dissipation below the cut on frequency, however, the ABH is less effective due to the absence of wave focusing effect. This work reports a simultaneous optimization of ABH plates for broadband energy dissipation. Two sets of design variables of ABH plates, that is, geometry of the profile and topology of the damping layer, are optimized in an alternatively nested procedure. A novel objective function, namely the upper limit of kinetic energy, is proposed. Modeling of ABH structures is implemented and dynamic characteristic is solved using finite element method. A rectangular plate embedded with two ABH indentations is presented as a numerical example. Influence of frequency ranges in the calculation and mass ratios of the damping layer on results are discussed. The achieved optimal arrangement of the damping layer is found to cover equally, if not more, above the non-ABH (uniform) part of the plate than the ABH area. This is inconsistent with the conventional believe that damping layers should cover as much of the ABH area as possible. Mechanism of the broadband energy dissipation by the optimal solution is demonstrated.

scholarly journals KAJI PERFORMANSI REFRIGERAN R-290, R-32, DAN R-410A SEBAGAI ALTERNATIF PENGGANTI R-22

2021 ◽  
Vol 4 ◽  
pp. 133-139
Author(s):  
Rikhard Ufie ◽  
Cendy S. Tupamahu ◽  
Sefnath J. E. Sarwuna ◽  
Jufraet Frans
Keyword(s):  
Air Conditioning ◽  
Cooling Capacity ◽  
Coefficient Of Performance ◽  
Condensation Temperature ◽  
Vapor Compression ◽  
Know How ◽  
Evaporation Temperature ◽  
Vapor Compression Cycle ◽  
Compression Cycle ◽  
Refrigeration Capacity

Refrigerant R-22 is a substance that destroys the ozone layer, so that in the field of air conditioning it has begun to be replaced, among others with refrigerants R-32 and R-410a, and also R-290. Through this research, we want to know how much Coefficient of Performance (COP) and Refrigeration Capacity (Qe) can be produced for the four types of refrigerants. The study was carried out theoretically for the working conditions of the vapor compression cycle with an evaporation temperature (Tevap) of 0, -5, and -10oC, a further heated refrigerant temperature (ΔTSH) of 5 oC, a condensation temperature (Tkond) of 45 oC and a low-cold refrigerant temperature. (ΔTSC) 10 oC and compression power of 1 PK . The results of the study show that the Coefficient of Performance (COP) in the use of R-22 and R-290 is higher than the use of R-32 and R-410a, which are 4,920 respectively; 4,891; 4.690 and 4.409 when working at an evaporation temperature of 0 oC; 4.260; 4,234; 4.060 and 3.812 when working at an evaporation temperature of -5 oC; and amounted to 3,730; 3,685; 3,550 and 3,324 if working at an evaporation temperature of -10 oC. Based on the size of the COP, if this installation works with a compression power of 1 PK, then the cooling capacity of the R-22 and R-290 is higher than the R-32 and R-410a, which are 3,617 respectively. kW; 3,597 kW; 3,449 kW and 3,243 kW. If working at an evaporation temperature of 0 oC; 3.133 kW; 3.114 kW; 2,986 kW and 2,804 kW if working at an evaporation temperature of -5 oC; and 2,741 kW; 2,710 kW; 2,611 kW and 2,445 kW if working at an evaporation temperature of -10oC.

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