Network analysis of nanoscale energy conversion processes

Abstract Energy conversion in nanosized devices is studied in the framework of state-space models. We use a network representation of the underlying master equation to describe the dynamics by a graph. Particular segments of this network represent input and output processes that provide a way to introduce a coupling to several heat reservoirs and particle reservoirs. In addition, the network representation scheme allows one to decompose the stationary dynamics as cycles. The cycle analysis is a convenient tool for analyse models of machine operations, which are characterized by different nanoscale energy conversion processes. By introducing the cycle affinity, we are able to calculate the zero-current limit. The zero-current limit can be mapped to the zero-affinity limit in a network representation scheme. For example, for systems with competing external driving forces the open-circuit voltage can be determined by setting the cycle affinity zero. This framework is used to derive open-circuit voltage with respect to microscopic material energetics and different coupling to particle and temperature reservoirs.

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Enhancement of Thermal to Electrical Energy Conversion with Thermal Diodes

MRS Proceedings ◽

10.1557/proc-691-g8.37 ◽

2001 ◽

Vol 691 ◽

Cited By ~ 2

Author(s):

P. L. Hagelstein ◽

Y. Kucherov

Keyword(s):

Energy Conversion ◽

Figure Of Merit ◽

Open Circuit Voltage ◽

Electrical Energy ◽

Open Circuit ◽

Return Current ◽

Physical Mechanisms ◽

Zero Current ◽

Single Side ◽

Current Leads

ABSTRACTExperiments demonstrating thermal to electrical energy conversion using thermal diodes have shown an enhancement of the open circuit voltage over the thermoelectric open circuit voltage. Two different physical mechanisms are proposed to be responsible for the effects seen: (1) Thermionic injection from the emitter can occur when a temperature gradient is present, which induces an increased ohmic return current under zero-current conditions. (2) Blockage of the ohmic return current leads to a voltage increase for both thermoelectric and thermionic forward currents. Both effects increase the efficiency of energy conversion. Experiments show enhancements of the figure of merit in the range of 5-8 over the thermoelectric values. The best results are consistent with a single-side conversion efficiency in excess of 30% of the Carnot limit.

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Improvement of Photovoltaic Module for Increasing Energy Conversion Efficiency

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.448-453.1428 ◽

2013 ◽

Vol 448-453 ◽

pp. 1428-1432 ◽

Cited By ~ 3

Author(s):

Warachit Phayom

Keyword(s):

Energy Conversion ◽

Conversion Efficiency ◽

Tilt Angle ◽

Horizontal Plane ◽

Open Circuit Voltage ◽

Cooling System ◽

Energy Conversion Efficiency ◽

Open Circuit ◽

Back Side ◽

Pv Module

For increasing energy conversion efficiency of PV module, this study was divided to two experiments. The first experiment was to investigate optimal tilt angle of PV module from 0-35° from horizontal plane in facing south for using in Udon thani Province and neighbouring in Thailand. The second experiment was to decrease PV module temperature and to determine appropriate cooling system by using water and small spray nozzles between front and back PV module. The results found, conversion efficiency was high during 15°-25° from horizontal plane for tilt angle in facing south, especially at 25° in whole year. Using thin film by spray nozzles at the front side was higher open circuit voltage and energy conversion efficiency than back side, with 6.06% of increasing open circuit voltage and 1.93% of increasing energy conversion efficiency when compared with no cooling system, due to can thoroughly distribute water on surface area and easily install.

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Fine Tuning of Open-Circuit Voltage by Chlorination in Thieno[3,4-b]thiophene–Benzodithiophene Terpolymers toward Enhanced Solar Energy Conversion

Macromolecules ◽

10.1021/acs.macromol.7b00785 ◽

2017 ◽

Vol 50 (13) ◽

pp. 4962-4971 ◽

Cited By ~ 43

Author(s):

Shiwei Qu ◽

Huan Wang ◽

Daize Mo ◽

Pengjie Chao ◽

Zhen Yang ◽

...

Keyword(s):

Solar Energy ◽

Energy Conversion ◽

Open Circuit Voltage ◽

Solar Energy Conversion ◽

Open Circuit ◽

Fine Tuning

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Study on Piezoelectric Stacked Generator

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.267.1005 ◽

2011 ◽

Vol 267 ◽

pp. 1005-1009 ◽

Cited By ~ 1

Author(s):

Wei Lin ◽

Zhe Li ◽

Wen Chen ◽

Jing Zhou

Keyword(s):

Energy Harvesting ◽

Energy Conversion ◽

Electrical Characteristic ◽

Driving Forces ◽

Mechanical Energy ◽

Electrical Power ◽

Characteristic Parameters ◽

Piezoelectric Generator ◽

Theoretical Predictions ◽

External Driving

A piezoelectric generator based on the piezoelectric stacked elements is applied to realize electro- mechanical energy conversion in this paper. The piezoelectric stacked generator is constructed. The relational expression about output electrical characteristic parameters, the constructional dimension parameters of piezoelectric stack elements and external driving forces is discussed here. Theoretical predictions confirmed by experimental results show that the piezoelectric generator produces electrical power with higher efficiency, and energy harvesting circuit can harvest energy from the piezoelectric generator effectively.

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Microcrystalline (Si,Ge):H Solar Cells

MRS Proceedings ◽

10.1557/proc-762-a7.6 ◽

2003 ◽

Vol 762 ◽

Cited By ~ 1

Author(s):

Jianhua Zhu ◽

Vikram L. Dalal

Keyword(s):

Solar Cells ◽

Buffer Layer ◽

Quantum Efficiency ◽

Fill Factor ◽

Open Circuit Voltage ◽

Defect Density ◽

Cell Structure ◽

Open Circuit ◽

Base Layer ◽

Ecr Plasma

AbstractWe report on the growth and properties of microcrystalline Si:H and (Si,Ge):H solar cells on stainless steel substrates. The solar cells were grown using a remote, low pressure ECR plasma system. In order to crystallize (Si,Ge), much higher hydrogen dilution (∼40:1) had to be used compared to the case for mc-Si:H, where a dilution of 10:1 was adequate for crystallization. The solar cell structure was of the p+nn+ type, with light entering the p+ layer. It was found that it was advantageous to use a thin a-Si:H buffer layer at the back of the cells in order to reduce shunt density and improve the performance of the cells. A graded gap buffer layer was used at the p+n interface so as to improve the open-circuit voltage and fill factor. The open circuit voltage and fill factor decreased as the Ge content increased. Quantum efficiency measurements indicated that the device was indeed microcrystalline and followed the absorption characteristics of crystalline ( Si,Ge). As the Ge content increased, quantum efficiency in the infrared increased. X-ray measurements of films indicated grain sizes of ∼ 10nm. EDAX measurements were used to measure the Ge content in the films and devices. Capacitance measurements at low frequencies ( ~100 Hz and 1 kHz) indicated that the base layer was indeed behaving as a crystalline material, with classical C(V) curves. The defect density varied between 1x1016 to 2x1017/cm3, with higher defects indicated as the Ge concentration increased.

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