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Global Energy Interconnection 2022年第2期5卷 226-235页

作者： Adriano Pamain P.V.Kanaka Rao Frank Nicodem Tilya Department of Physics The University of DodomaDodomaTanzania

Prediction of power output plays a vital role in the installation and operation of photovoltaic modules.In this paper,two photovoltaic module technologies,amorphous silicon and copper indium gallium selenide installed outdoors on the rooftop of the University of Dodoma,located at 6.5738°S and 36.2631°E in Tanzania,were used to record the power output during the winter season.The average data of ambient temperature,module temperature,solar irradiance,relative humidity,and wind speed recorded is used to predict the power output using a non-linear autoregressive artificial neural network.We consider the Levenberg-Marquardt optimization,Bayesian regularization,resilient propagation,and scaled conjugate gradient algorithms to understand their abilities in training,testing and validating the data.A comparison with reference to the performance indices:coefficient of determination,root mean square error,mean absolute percentage error,and mean absolute bias error is drawn for both modules.According to the findings of our investigation,the predicted results are in good agreement with the experimental results.All the algorithms performed better,and the predicted power out of both modules using the Bayesian regularization algorithm is observed to exhibit good processing capabilities compared to the other three algorithms that are evident from the measured performance indices.

关键词： Photovoltaic Artificial neural network Training algorithms Ambient parameters power output

Energetic and Entropic Changes in Volume Work and Chemical Reactions

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Advances in Chemical Engineering and Science 2024年第1期14卷 8-47页

作者： Frank Diederichs Independent Researcher Schwarmstedt Germany

In the present study, energetic and entropic changes are investigated on a comparative basis, as they occur in the volume changes of an ideal gas in the Carnot cycle and in the course of the chemical reaction in a lead-acid battery. Differences between reversible and irreversible processes have been worked out, in particular between reversibly exchanged entropy (∆eS) and irreversibly produced entropy (∆iS). In the partially irreversible case, ∆eS and ∆iS add up to the sum ∆S for the volume changes of a gas, and only this function has an exact differential. In a chemical reaction, however, ∆eS is independent on reversibility. It arises from the different intramolecular energy contents between products and reactants. Entropy production in a partially irreversible Carnot cycle is brought about through work-free expansions, whereas in the irreversible battery reaction entropy is produced via activated complexes, whereby a certain, variable fraction of the available chemical energy becomes transformed into electrical energy and the remaining fraction dissipated into heat. The irreversible reaction process via activated complexes has been explained phenomenologically. For a sufficiently high power output of coupled reactions, it is essential that the input energy is not completely reversibly transformed, but rather partially dissipated, because this can increase the process velocity and consequently its power output. A reduction of the counter potential is necessary for this purpose. This is not only important for man-made machines, but also for the viability of cells.

关键词： Exchanged Entropy Entropy Production Coupled Reactions Activated Complexes power output

Local topography-induced pressure gradient effects on the wake and power output of a model wind turbine

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Theoretical & Applied Mechanics Letters 2021年第5期11卷 304-311页

作者： Tengfei Cai Shyuan Cheng Antonio Segalini Leonardo P.Chamorro School of Mechanical Engineering University of Science and Technology BeijingBeijing100083 China Department of Mechanical Science and Engineering University of IllinoisUrbanaIL 61801USA Department of Earth Sciences Uppsala UniversityUppsalaSweden Department of Aerospace Engineering University of IllinoisUrbanaIL 61801USA Department of Civil and Environmental Engineering University of IllinoisUrbanaIL 61801USA Department of Geology University of IllinoisUrbanaIL 61801USA

Wind-tunnel experiments were performed to study the effect of favorable and adverse constant pressure gradients(PG)from local changes in the topography right downwind of a model wind turbine.Particle image velocimetry was used to characterize the near and intermediate wake regions.We explored five scenarios,two favorable,two adverse PG,and a case with negligible PG.Results show that the PGs induce a wake deflection and modulate the wake.They imposed a relatively small impact on the turbulence kinetic energy and kinematic shear stress but a comparatively dominant effect on the bulk flow on the flow recovery.Based on this,a simple formulation is used to describe the impact of PG on the wake.We modeled the base flow through a linearized perturbation method;the wake is obtained by solving a simplified,integrated streamwise momentum equation.This approach reasonably estimated the flow profile and PG-induced power output variations.

关键词： Topographic effects Pressure gradient Turbine wake power output

Numerical Study on Aerodynamic Performance of Floating Dual-Rotor Wind Turbines in Heave and Surge Motions

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China Ocean Engineering 2023年第6期37卷 1011-1021页

作者： WU Xiao-di LU Wen-hao WANG Kai HU Wei-fei FANG Jian-hao ZHA Ruo-si School of Ocean Engineering and Technology Sun Yat-sen University&Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519000China State Key Laboratory of Fluid power and Mechatronic Systems Zhejiang UniversityHangzhou 310058China School of Mechanical Engineering Zhejiang UniversityHangzhou 310058China

Compared with the traditional wind turbine of a single rotor,dual-rotor wind turbines(DRWTs)have higher wind energy capture efficiency and a more complex structure.Therefore,the aerodynamic performance of the DRWT installed on the floating platform will be greatly affected by the motion caused by wind and wave loads.In this paper,5 MW and 750 kW single rotor wind turbines(SRWTs)are combined into a 5 MW-5 MW DRWT and a 5 MW-750 kW DRWT,and their power output and wake field characteristics in different motions are studied.The flow field is obtained by solving the Reynolds-averaged Navier–Stokes equation(RANS).The overset grid technique is employed to achieve the large-amplitude multiple-degree-of-freedom motion of the DRWT.The overall performance of the 5 MW single rotor wind turbine is determined by a numerical method.For the DRWTs,numerical results show that the surge motion and heave motion both have a negative effect on the power output of the DRWT.The surge motion is a critical factor that causes the power output of the DRWT to periodically change with motion.The average power output of the DRWT influenced by motion is lower than that of a DRWT with a fixed bottom.The surge motion significantly disturbs the wake of the DRWT due to the mutual interference between the upstream and downstream rotors.Under the influence of heave motion,low-velocity regions downstream of the blade tip are enhanced.This study indicates that attenuating the surge and heave motion of offshore DRWT is very significant for improving its efficiency and should be taken into consideration during the design procedure.

关键词： DRWT surge motion heave motion wake field power output

Influence of Cathode Modification by Chitosan and Fe^(3+)on the Electrochemical Performance of Marine Sediment Microbial Fuel Cell

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Journal of Ocean University of China 2023年第3期22卷 709-716页

作者： ZAI Xuerong GUO Man HUANG Xiang ZHANG Huaijing CHEN Yan JI Hongwei FU Yubin School of Materials Science&Engineering Ocean University of ChinaQingdao 266100China College of Chemistry and Chemical Engineering Ocean University of ChinaQingdao 266100China College of Marine Geosciences Ocean University of ChinaQingdao 266100China

The electrochemical performances of cathode play a key role in the marine sediment microbial fuel cells(MSMFCs)as a long lasting power source to drive instruments,especially when the dissolved oxygen concentration is very low in seawater.A CTS-Fe^(3+)modified cathode is prepared here by grafting chitosan(CTS)on a carbon fiber surface and then chelating Fe^(3+)through the coordination process.The electrochemical performance in seawater and the output power of the assembled MSMFCs are both studied.The results show that the exchange current densities of CTS and the CTS-Fe^(3+)group are 5.5 and 6.2 times higher than that of the blank group,respectively.The potential of the CTS-Fe^(3+)modified cathode increases by 138 mV.The output power of the fuel cell(613.0 mW m^(-2))assembled with CTS-Fe^(3+)is 54 times larger than that of the blank group(11.4 mW m^(-2))and the current output corresponding with the maximum power output also increases by 56 times.Due to the valence conversion between Fe^(3+)and Fe^(2+)on the modified cathode,the kinetic activity of the dissolved oxygen reduction is accelerated and the depolarization capability of the cathode is enhanced,resulting higher cell power.On the basis of this study,the new cathode materials will be encouraged to design with the complex of iron ion in natural seawater as the catalysis for oxygen reduction to improve the cell power in deep sea.

关键词： marine sediments microbial fuel cell chitosan and iron chelation modified cathode electrochemical performance power output

Performance Analysis of an Organic Rankine Cycle with a Preheated Ejector

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Fluid Dynamics & Materials Processing 2022年第4期18卷 1183-1193页

作者： Kaiyong Hu Yumeng Zhang Tianrun Zhang Dequan Zhang Zhaoxian Yang Tianjin Key Lab of Refrigeration Technology Tianjin University of CommerceTianjin300134China Institute of Food Science and Technology Chinese Academy of Agricultural SciencesNational Risk Assessment Laboratory of Agro-Products Processing Quality and SafetyMinistry of Agriculture and Rural AffairsBeijing100193China Tianjin Tengsheng Technology Co. Ltd.Tianjin300380China

The so-called organic Rankine cycle(ORC)is an effective technology allowing heat recovery from lower temperature sources.In the present study,to improve its thermal efficiency,a preheated ejector using exhaust steam coming from the expander is integrated in the cycle(EPORC).Considering net power output,pump power,and thermal efficiency,the proposed system is compared with the basic ORC.The influence of the ejector ratio(ER)of the preheated ejector on the system performances is also investigated.Results show that the net power output of the EPORC is higher than that of the basic ORC due to the decreasing pump power.Under given working conditions,the average thermal efficiency of EPORC is 29%higher than that of ORC.The ER has a great impact on the performance of EPORC by adjusting the working fluid fed to the pump,leading to significant variations of the pump work Moreover,the ER has a remarkable effect on the working fluid temperature lift(TL)at the evaporator inlet,thus reducing the evaporator heat load.According to the results,the thermal efficiency of EPORC increases by 30%,when the ER increases from 0.05 to 0.4.

关键词： Ejector preheat organic Rankine cycle(EPORC) heat recovery ejector power output

power output and carrier dynamics studies of perovskite solar cells under working conditions

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Power output and carrier dynamics studies of perovskite sola...

Study on the Control Strategy of Free Piston Expander-Linear Generator Used for Organic Rankine Cycle Waste Heat Recovery

第五届新型太阳能电池学术研讨会

作者： Man Yu Hao-Yi Wang Jia-Shang Zhao Yujun Qin Li-Min Fu Jian-Ping Zhang Xi-Cheng Ai Department of Chemistry Renmin University of China

Perovskite solar cells have emerged as a promising photovoltaic system with superb power conversion efficiency. For the practical application of the perovskite device, the greatest concern is the power output density and the related dynamics under the working conditions. The working conditions of the planar and mesoscopic perovskite solar cells are simulated and the power output density evolutions upon the working voltage are highlighted. The planar device exhibits higher capability in outputting power than the mesoscopic one. The transient photoelectric conversion dynamics are investigated under the open circuit, short circuit and working conditions.It is found that the power output and the dynamics processes are correlated intrinsically, which suggests that the power output is the competitive result of the charge carrier recombination and transport. The present work offers a unique view to elucidate the relationship between the power output and the charge carrier dynamics for the perovskite solar cells in a comprehensive manner, which would be beneficial to their future practical applications.

关键词： power output working condition carrier dynamics

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Journal of Thermal Science 2021年第2期30卷 585-597页

作者： HOU Xiaochen ZHANG Hongguang ZHAO Tenglong SHI Xin XU Yonghong LI Jian GE Zhong ZHANG Jun WU Yuting School of Transportation and Vehicle Engineering Shandong University of TechnologyZibo 255000China College of Environmental and Energy Engineering Beijing University of TechnologyBeijing 100124China School of Architecture and Urban Planning Yunnan UniversityKunming 650500China

This study presents a free piston expander-linear generator (FPE-LG) for engine waste heat recovery.The control strategies based on displacement (control strategy A) and valve timings (control strategy B) are proposed.The operation and output characteristics with different control strategies are conducted.The results show that control strategy has significant effect on the FPE-LG performance.When FPE-LG operates with control strategy A,the operation frequency is determined by the intake pressure,advanced exhaust duration,fixed position point and external load resistance,whereas it is only related with the intake/exhaust time and advanced exhaust duration (ta) for control strategy B.The external load resistance has slight influence on the stroke length for these two control strategies.For control strategy A,when advanced exhaust duration is more than 40 ms,the stroke length rises with the intake pressure,whereas it first rises and then reduces when advanced exhaust duration is less than 40 ms.There exist the optimal external load resistance and advanced exhaust duration to achieve the maximum power output with control strategy A,whereas the average power output reduces with the increasing advanced exhaust duration when using control strategy B.Stable operation and high power output can be obtained by using different control strategies and adjusting relevant operation parameters.

关键词： free piston expander-linear generator advanced exhaust duration control strategy operation frequency power output

Effect of Temperature on Photovoltaic Solar Cell Cadmium Telluride Thin Film

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Advances in Materials Physics and Chemistry 2023年第1期13卷 1-15页

作者： Kishan C. Rathod Vishalkumar R. More Jayashree S. Kshirsagar Santosh R. Sonwane Kallapa R. Sanadi Pradip D. Kamble Ganesh S. Kamble Sandip V. Mahamuni Muddsar L. Gaur Yong-Chein Ling Department of Chemistry The New College Kolhapur Department of Chemistry Doodhsakhar Mahavidyalaya Kolhapur Department of Physics The New College Kolhapur Department of Engineering Chemistry KIT Engineering College Kolhapur Department of Chemistry Sadguru Gadage Maharaj College Karad Department of Chemistry C. B. Khedgi’s Basaveshwar Science Raja Vijaysinh Commerce and Raja Jaysinh Arts College Ak-kalkot Department of Chemistry National Tsing Hua University Hsinchu City

Solar cell technology comes with unique temperature coefficients. These temperature coefficients are important and temperature of the solar cell has direct influence on the power output of a photovoltaic cells. CdTe is a very robust and chemically stable material and for this reason its related solar cell. Thin film photovoltaic technology is now the only thin film technology in the first top 10 producers in the world. The strong improvement in efficiency in the last 7 years was obtained by a new redesign of the CdTe solar cell device reaching a single solar cell. In this paper, we describe the fabrication process following the history of the solar cell as it was developed in the early years up to the latest development and changes. The configuration of fabricated cell is n-CdTe/NaOH (0.15 M) + S (0.15 M) + Na2S (0.15 M)/C(graphite). The junction ideality factor was found to be 2.63, 2.13, and 1.89. The flat band potential is found to be -0.400, -0.450, -0.501 V. The barrier height value was found to be 0.523, 0.487, and 0.436 eV. The study of power output characteristic shows open circuit voltage, short circuit current, fill factor and efficiency were found to be 120 mV, 24.2 μA, 32.68%, 26.18%, and 19.73% and 0.63%, 0.37%, and 0.23%, respectively. The lighted ideality factor was calculated and found to be 3.26, 1.87, and 1.17. Spectra attain maximum value of current at λ = 580 nm and decrease with increase in wavelength. The photovoltaic cell characterization of the thin films is carried out by studying current-voltage characteristics in dark, capacitance-voltage in dark, barrier height measurements, power output characteristics.

关键词： CBD power output Barrier Height Photo Response Spectral Response

Optimizing Grids Demand Reduction through Enhanced Heat Transfer in Low-Temperature Waste Heat Driven ORC Systems

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Energy and power Engineering 2023年第12期15卷 457-467页

作者： Cheng Wang Zizeng Gao Shanghai Leadership Refrigeration Technology Company Shanghai China Institute of Refrigeration and Cryogenic Shanghai Jiao Tong University Shanghai China

With increasing awareness of energy conservation and environmental protection, the Organic Rankine Cycle (ORC) system has gained significant attention. This technology enables the recovery of industrial waste heat, waste incineration heat, and renewable energy sources such as geothermal heat, biomass energy, and solar energy at lower temperatures. However, the low-grade heat source utilized in ORC systems faces a challenge to achieving high power generation efficiency and output power. Therefore, enhancing the power generation capacity of ORC systems is a key research focus in this field. An entranced heat exchanger ORC system with the screw expander driven by the low-temperature heat source is established to investigate the relevant performance. Hot water temperature from 77°C to 132°C is adopted for performance analysis, while the environmental temperature is approximately 25°C. Refrigerant R245fa is selected as the working fluid, and the screw expander is employed for power generation. It is worth noting that the entranced heat exchanger ORC system has significant potential for low-temperature heat recovery. Experimental results indicate that the maximum power output is 12.83 kW, which is obtained at around 105°C hot water inlet temperature. Correspondingly, the average power output remains 11.75 kW, revealing the system’s high stability for power generation. The implementation of a plate heat exchanger for enhanced heat transfer has enabled a 50% reduction in system size compared to traditional shell-tube type ORC systems. Besides, economic calculations demonstrate substantial benefits associated with the ORC system. The calculations indicate an internal benefit of 560,000 RMB/year, accompanied by notable external benefits such as an energy saving and emission reduction potential of up to 784 t CO2 per year. Moreover, the payback period is 2.23 years. It shows a remarkable improvement in terms of performance and excellent economic benefits. As a result, the novel ORC presents a promising alternative for low-g

关键词： ORC (Organic Rankine Cycle) Plate Heat Exchanger Screw Expander power output Economic Analyse Energy Saving