scholarly journals Performance Analysis and Four-Objective Optimization of an Irreversible Rectangular Cycle

Entropy ◽  
2021 ◽  
Vol 23 (9) ◽  
pp. 1203
Author(s):  
Qirui Gong ◽  
Yanlin Ge ◽  
Lingen Chen ◽  
Shuangshaung Shi ◽  
Huijun Feng
Keyword(s):  
Decision Making ◽  
Power Density ◽  
Power Output ◽  
Expansion Ratio ◽  
Maximum Power ◽  
Maximum Power Density ◽  
Density Point ◽  
Nsga Ii ◽  
Effective Power ◽  
Maximum Power Output

Based on the established model of the irreversible rectangular cycle in the previous literature, in this paper, finite time thermodynamics theory is applied to analyze the performance characteristics of an irreversible rectangular cycle by firstly taking power density and effective power as the objective functions. Then, four performance indicators of the cycle, that is, the thermal efficiency, dimensionless power output, dimensionless effective power, and dimensionless power density, are optimized with the cycle expansion ratio as the optimization variable by applying the nondominated sorting genetic algorithm II (NSGA-II) and considering four-objective, three-objective, and two-objective optimization combinations. Finally, optimal results are selected through three decision-making methods. The results show that although the efficiency of the irreversible rectangular cycle under the maximum power density point is less than that at the maximum power output point, the cycle under the maximum power density point can acquire a smaller size parameter. The efficiency at the maximum effective power point is always larger than that at the maximum power output point. When multi-objective optimization is performed on dimensionless power output, dimensionless effective power, and dimensionless power density, the deviation index obtained from the technique for order preference by similarity to an ideal solution (TOPSIS) decision-making method is the smallest value, which means the result is the best.

A single-liquid miniature biofuel cell with boosting power density via gas diffusion bioelectrodes

2020 ◽  
Vol 8 (16) ◽  
pp. 3550-3556 ◽  
Author(s):  
Jing Wan ◽  
Li Mi ◽  
Zhaoyan Tian ◽  
Quan Li ◽  
Songqin Liu
Keyword(s):  
Power Density ◽  
Power Output ◽  
Active Sites ◽  
Reaction Rate ◽  
Enzymatic Reaction ◽  
Gas Diffusion ◽  
Gas Diffusion Electrode ◽  
Maximum Power ◽  
Biofuel Cell ◽  
Maximum Power Output

A single-liquid glucose–O2 cell is constructed by gas diffusion electrode. O2 diffusion directly from air to active sites of enzyme enhances the enzymatic reaction rate. The maximum power output density of the cell is 53 μW cm−2.

scholarly journals Performance Optimizations with Single-, Bi-, Tri-, and Quadru-Objective for Irreversible Atkinson Cycle with Nonlinear Variation of Working Fluid’s Specific Heat

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4175
Author(s):  
Shuangshuang Shi ◽  
Yanlin Ge ◽  
Lingen Chen ◽  
Huijun Feng
Keyword(s):  
Specific Heat ◽  
Power Density ◽  
Compression Ratio ◽  
Power Output ◽  
Thermal Efficiency ◽  
Maximum Power ◽  
Maximum Power Density ◽  
Multi Objective Optimization ◽  
Nonlinear Variation ◽  
Atkinson Cycle

Considering nonlinear variation of working fluid’s specific heat with its temperature, finite-time thermodynamic theory is applied to analyze and optimize the characteristics of an irreversible Atkinson cycle. Through numerical calculations, performance relationships between cycle dimensionless power density versus compression ratio and dimensionless power density versus thermal efficiency are obtained, respectively. When the design parameters take certain specific values, the performance differences of reversible, endoreversible and irreversible Atkinson cycles are compared. The maximum specific volume ratio, maximum pressure ratio, and thermal efficiency under the conditions of the maximum power output and maximum power density are compared. Based on NSGA-II, the single-, bi-, tri-, and quadru-objective optimizations are performed when the compression ratio is used as the optimization variable, and the cycle dimensionless power output, thermal efficiency, dimensionless ecological function, and dimensionless power density are used as the optimization objectives. The deviation indexes are obtained based on LINMAP, TOPSIS, and Shannon entropy solutions under different combinations of optimization objectives. By comparing the deviation indexes of bi-, tri- and quadru-objective optimization and the deviation indexes of single-objective optimizations based on maximum power output, maximum thermal efficiency, maximum ecological function and maximum power density, it is found that the deviation indexes of multi-objective optimization are smaller, and the solution of multi-objective optimization is desirable. The comparison results show that when the LINMAP solution is optimized with the dimensionless power output, thermal efficiency, and dimensionless power density as the objective functions, the deviation index is 0.1247, and this optimization objective combination is the most ideal.

scholarly journals Performance Optimizations with Single-, Bi-, Tri-, and Quadru-Objective for Irreversible Diesel Cycle

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 826
Author(s):  
Shuangshuang Shi ◽  
Lingen Chen ◽  
Yanlin Ge ◽  
Huijun Feng
Keyword(s):  
Objective Function ◽  
Power Density ◽  
Power Output ◽  
Thermal Efficiency ◽  
Maximum Power ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Multi Objective ◽  
Deviation Index ◽  
Diesel Cycle

Applying finite time thermodynamics theory and the non-dominated sorting genetic algorithm-II (NSGA-II), thermodynamic analysis and multi-objective optimization of an irreversible Diesel cycle are performed. Through numerical calculations, the impact of the cycle temperature ratio on the power density of the cycle is analyzed. The characteristic relationships among the cycle power density versus the compression ratio and thermal efficiency are obtained with three different loss issues. The thermal efficiency, the maximum specific volume (the size of the total volume of the cylinder), and the maximum pressure ratio are compared under the maximum power output and the maximum power density criteria. Using NSGA-II, single-, bi-, tri-, and quadru-objective optimizations are performed for an irreversible Diesel cycle by introducing dimensionless power output, thermal efficiency, dimensionless ecological function, and dimensionless power density as objectives, respectively. The optimal design plan is obtained by using three solution methods, that is, the linear programming technique for multidimensional analysis of preference (LINMAP), the technique for order preferences by similarity to ideal solution (TOPSIS), and Shannon entropy, to compare the results under different objective function combinations. The comparison results indicate that the deviation index of multi-objective optimization is small. When taking the dimensionless power output, dimensionless ecological function, and dimensionless power density as the objective function to perform tri-objective optimization, the LINMAP solution is used to obtain the minimum deviation index. The deviation index at this time is 0.1333, and the design scheme is closer to the ideal scheme.

scholarly journals Performance optimization of an air-breathing PEM fuel cell

2019 ◽  
Vol 25 (3) ◽  
pp. 289-298
Author(s):  
Levent Akyalçın
Keyword(s):  
Fuel Cell ◽  
Power Density ◽  
Power Output ◽  
Performance Optimization ◽  
Current Collector ◽  
Maximum Power ◽  
Design Parameters ◽  
Membrane Electrode ◽  
Maximum Power Density ◽  
Cathode Current

In this study, Taguchi?s experimental design is used to determine the optimum component combination of a membrane electrode assembly and cathode current collector opening geometry to obtain maximum power density of an airbreathing polymer electrolyte membrane fuel cell at 0.5 V. An analysis of variance was conducted to figure out the optimum levels and significant differences of the effect of the combinations, followed by a performance measurement analysis. Experimental investigations of the effecting parameters enabled the determination of the optimum configuration of the MEA and cathode current collector opening geometry design parameters for maximum power density at a certain cell potential. Effective parameters which enable withdrawal of a maximum power output from an ABPEMFC at 0.5 V are, in order of effectiveness: the amount of platinum on the cathode, the thickness of the Nafion membrane, the cathode current collector opening geometry, and the amount of platinum on the anode. Optimum component combinations are: 0.45 mgPt cm?2 for the platinum loading on the cathode, Nafion 112 for membrane, a vertical cathode opening geometry and 1.78 mg cm?2 for the amount of platinum on the anode. For these component combinations, a 98.5 mW cm?2 power output was obtained from an ABPEMFC at 0.5 V cell voltage.

Oxidation of combined ingestion of glucose and fructose during exercise

2004 ◽  
Vol 96 (4) ◽  
pp. 1277-1284 ◽  
Author(s):  
Roy L. P. G. Jentjens ◽  
Luke Moseley ◽  
Rosemary H. Waring ◽  
Leslie K. Harding ◽  
Asker E. Jeukendrup
Keyword(s):  
Power Output ◽  
Statistical Significance ◽  
Random Order ◽  
Carbohydrate Oxidation ◽  
Maximum Power ◽  
The Other ◽  
Cycling Exercise ◽  
Oxidation Rates ◽  
Maximum Power Output ◽  
Exercise Period

The purpose of the present study was to examine whether combined ingestion of a large amount of fructose and glucose during cycling exercise would lead to exogenous carbohydrate oxidation rates >1 g/min. Eight trained cyclists (maximal O2consumption: 62 ± 3 ml·kg-1·min-1) performed four exercise trials in random order. Each trial consisted of 120 min of cycling at 50% maximum power output (63 ± 2% maximal O2consumption), while subjects received a solution providing either 1.2 g/min of glucose (Med-Glu), 1.8 g/min of glucose (High-Glu), 0.6 g/min of fructose + 1.2 g/min of glucose (Fruc+Glu), or water. The ingested fructose was labeled with [U-13C]fructose, and the ingested glucose was labeled with [U-14C]glucose. Peak exogenous carbohydrate oxidation rates were ∼55% higher ( P < 0.001) in Fruc+Glu (1.26 ± 0.07 g/min) compared with Med-Glu and High-Glu (0.80 ± 0.04 and 0.83 ± 0.05 g/min, respectively). Furthermore, the average exogenous carbohydrate oxidation rates over the 60- to 120-min exercise period were higher ( P < 0.001) in Fruc+Glu compared with Med-Glu and High-Glu (1.16 ± 0.06, 0.75 ± 0.04, and 0.75 ± 0.04 g/min, respectively). There was a trend toward a lower endogenous carbohydrate oxidation in Fruc+Glu compared with the other two carbohydrate trials, but this failed to reach statistical significance ( P = 0.075). The present results demonstrate that, when fructose and glucose are ingested simultaneously at high rates during cycling exercise, exogenous carbohydrate oxidation rates can reach peak values of ∼1.3 g/min.

Carbon Nano Tube-Polymer Hybrid Nanocomposite Electrodes for Porous Polydimethylsiloxane Sponge-Based Flexible Triboelectric Nanogenerators

2021 ◽  
Vol 21 (9) ◽  
pp. 4680-4684
Author(s):  
Dae-Hyeon Kwon ◽  
Jaebum Jeong ◽  
Yongju Lee ◽  
Jun-Kyu Park ◽  
Suwoong Lee ◽  
...  
Keyword(s):  
Power Density ◽  
Output Voltage ◽  
Maximum Power ◽  
Maximum Power Density ◽  
Flexible Electrodes ◽  
Flexible Devices ◽  
Copper Electrodes ◽  
Polymer Hybrid ◽  
Triboelectric Nanogenerators ◽  
Carbon Nano Tube

Flexible triboelectric nanogenerators (TENGs) have attracted much attention because of its environmentally friendly, practical, and cost-producing advantages. In flexible TENGs, it is important to study the flexible electrodes in order to fabricate the fully flexible devices. Here, we compared electrical characteristics of the sponge porous polydimethylsiloxane (PDMS)-based flexible TENGs with two types of flexible electrodes, copper and carbon nanotube (CNT)-PDMS electrodes. The output voltage and maximum power density of sponge PDMS-based flexible TENGs with copper and CNTPDMS electrodes were compared. The voltage and power density of sponge PDMS-based flexible TENGs with CNT-PDMS electrodes were improved compare to those with copper electrodes. The output voltage and the maximum power density of sponge PDMS-based flexible TENGs with copper and CNT-PDMS electrodes increased 4 times and 7 times, respectively. It is attributed to higher electrical conductivity and stably flow electricity of CNT than those of copper.

Influence of Composition of Gd-Doped Ceria Electrolyte on Performance of Solid Oxide Fuel Cell

2012 ◽  
Vol 724 ◽  
pp. 389-392 ◽  
Author(s):  
Yuta Ibusuki ◽  
Yoshihiro Hirata ◽  
Soichiro Sameshima ◽  
Naoki Matsunaga
Keyword(s):  
Power Density ◽  
Open Circuit ◽  
Solid Oxide ◽  
Maximum Power ◽  
Cell Performance ◽  
Excess Oxygen ◽  
Doped Ceria ◽  
Oxide Fuel ◽  
Maximum Power Density ◽  
Oxide Ion Conductivity

Cell performance was measured for four types of Ni (40 vol%)-Gd-doped ceria (GDC) anode-supported solid oxide fuel cells with GDC electrolyte (40-120 μm thickness) of Ce1-xGdxO2-x/2 compositions (x = 0.05, 0.1, 0.15 and 0.2) at 773-1073 K using a H2 fuel. (La0.8Sr0.2)(Co0.8Fe0.2)O3 cathode was printed on the GDC films. The open circuit voltage and maximum power density at 873-1073 K showed a maximum at x = 0.1. The maximum power density at x = 0.1 was 166 and 506 mW/cm2 at 873 and 1073 K, respectively. The excess oxygen vacancy at x = 0.1-0.2, which does not contribute to the oxide ion conductivity, reacts with a H2 fuel to form electrons (H2 + VO 2H+ + VO×, VO× VO + 2e-). This reaction reduces the cell performance.

Performance comparison of an irreversible closed variable-temperature heat reservoir brayton cycle under maximum power density and maximum power conditions

2005 ◽  
Vol 219 (7) ◽  
pp. 559-565 ◽  
Author(s):  
L Chen ◽  
J Zheng ◽  
F Sun ◽  
C Wu
Keyword(s):  
Power Density ◽  
Heat Exchangers ◽  
Variable Temperature ◽  
Thermal Capacity ◽  
Maximum Power ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Maximum Power Density ◽  
Temperature Ratio ◽  
Temperature Heat

The power density is taken as an objective for performance analysis of an irreversible closed Brayton cycle coupled to variable-temperature heat reservoirs. The analytical formulas about the relationship between power density and working fluid temperature ratio (pressure ratio) are derived with the heat resistance losses in the hot- and cold-side heat exchangers, the irreversible compression and expansion losses in the compressor and turbine, and the effect of the finite thermal capacity rate of the heat reservoirs. The obtained results are compared with those results obtained by using the maximum power criterion. The influences of some design parameters, including the temperature ratio of the heat reservoirs, the effectivenesses of the heat exchangers between the working fluid and the heat reservoirs, and the efficiencies of the compressor and the turbine, on the maximum power density are provided by numerical examples, and the advantages and disadvantages of maximum power density design are analysed. The power plant design with maximum power density leads to a higher efficiency and smaller size. When the heat transfers between the working fluid and the heat reservoirs are carried out ideally and the thermal capacity rates of the heat reservoirs are infinite, the results of this article become similar to those obtained in the recent literature.

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