scholarly journals Power Conversion and Its Efficiency in Thermoelectric Materials

Entropy ◽  
2020 ◽  
Vol 22 (8) ◽  
pp. 803 ◽  
Author(s):  
Armin Feldhoff
Keyword(s):  
Thermoelectric Material ◽  
Electric Charge ◽  
Power Factor ◽  
Short Circuit ◽  
Power Conversion ◽  
Electrical Power ◽  
Electrical Current ◽  
Open Circuit ◽  
Pump Mode ◽  
Current Curve

The basic principles of thermoelectrics rely on the coupling of entropy and electric charge. However, the long-standing dispute of energetics versus entropy has long paralysed the field. Herein, it is shown that treating entropy and electric charge in a symmetric manner enables a simple transport equation to be obtained and the power conversion and its efficiency to be deduced for a single thermoelectric material apart from a device. The material’s performance in both generator mode (thermo-electric) and entropy pump mode (electro-thermal) are discussed on a single voltage-electrical current curve, which is presented in a generalized manner by relating it to the electrically open-circuit voltage and the electrically closed-circuited electrical current. The electrical and thermal power in entropy pump mode are related to the maximum electrical power in generator mode, which depends on the material’s power factor. Particular working points on the material’s voltage-electrical current curve are deduced, namely, the electrical open circuit, electrical short circuit, maximum electrical power, maximum power conversion efficiency, and entropy conductivity inversion. Optimizing a thermoelectric material for different working points is discussed with respect to its figure-of-merit z T and power factor. The importance of the results to state-of-the-art and emerging materials is emphasized.

scholarly journals MLR institute of technology campus energy monitoring and controlling system with interconnection of grid and solar power

2020 ◽  
Vol 9 (2) ◽  
pp. 424
Author(s):  
M. Sreenivasa reddy ◽  
A. Shubhangi Rao ◽  
Ch. Sai Prakash
Keyword(s):  
Power Factor ◽  
Solar Power ◽  
Low Voltage ◽  
Short Circuit ◽  
Open Circuit ◽  
Power Generating Unit ◽  
Power Resources ◽  
Controlling System ◽  
Institute Of Technology ◽  
Campus Energy

This paper mainly deals with energy consumption and monitoring of each block after carefully observing where the losses occur and how to minimize these losses and how to reduce unit consumption of each block and units consumed by capacitor bank. Base loads and Peak loads can be observed and operated in such a way as to reduce unit consumption.MLR college has 315KVA power from the grid as well as 260KW solar power generating unit where 40 percent of the power from the grid is saved. Proper planning for operating the underground bore motors used for Hostels, Mess and College buildings also saves some amount of units consumed by these motors. Further if power factor is maintained 0.99 instead of 0.2 or 0.3 some amount of units consumed can be saved. Further if maximum demand is prevented from reaching beyond the transformer rating then some amount of units consumed can be saved. Installing copper earth pits of suitable numbers for each block and balancing the loads in each phase can also reduce the losses.Synchronizing panel is to be connected to the existing 4 generators of rating 200KVA,180KVA and two numbers of 125 KVA to utilize the power resources properly.The common electrical problems like short circuit, open circuit, over voltage, low voltage, frequent power cuts, low power factor, high electricity bills damage in the meters etc. The above electrical problems are identified, rectified and frequently monitored through modern technologies like IOT.  

Effect of temperature on organic Schottky barrier cells

1981 ◽  
Vol 59 (6) ◽  
pp. 727-732 ◽  
Author(s):  
Rafik O. Loutfy ◽  
Cheng-Kuo Hsiao
Keyword(s):  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Schottky Barrier ◽  
Conversion Efficiency ◽  
Organic Solar Cells ◽  
Short Circuit ◽  
Power Conversion ◽  
Open Circuit ◽  
Effect Of Temperature ◽  
Photovoltaic Properties

The effect of temperature on the photovoltaic properties of indium/metal-free phthalocyanine Schottky barrier solar cells was investigated in the range 260–350 K. In general, the short circuit photocurrent, Jsc, and fill factor, ff, increased with increasing temperature (in contrast to inorganic photocells). The device series resistance and open circuit photovoltage, Voc, decreased (similar to inorganic photocells) as temperature was raised. An increase in the overall power conversion efficiency, η, has been observed with increase of temperature. In the case of x-H2Pc, the power conversion efficiency increased by 2.5 times due to a temperature rise of 60 °C above ambient. Thus, for operation at temperatures above ambient, organic solar cells may offer a significant advantage over inorganic cells.Analysis of the variation of the photovoltage with temperature showed that the decrease in Voc is mainly due to variation injunction impedance, which is controlled by thermionic current at high temperature and ionized impurity at low temperature.

scholarly journals Donor-Acceptor Polymer Based on Planar Structure of Alkylidene-Fluorene Derivative: Correlation of Power Conversion Efficiency among Polymer and Various Acceptor Units

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2859
Author(s):  
Eui Jin Lee ◽  
Ho Jun Song
Keyword(s):  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Short Circuit ◽  
Power Conversion ◽  
Average Molecular Weight ◽  
Coupling Reaction ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Planar Structure ◽  
Quinoxaline Derivatives

This study synthesized a novel polymer, poly(alkylidene fluorene-alt-diphenylquinoxaline) (PAFDQ), based on a planar alkylidene-fluorene and a highly soluble quinoxaline derivative through the Suzuki coupling reaction. We designed a novel molecular structure based on alkylidene fluorene and quinoxaline derivatives due to compact packing property by the planar structure of alkyidene fluorene and efficient intra-molecular charge transfer by quinoxaline derivatives. The polymer was largely dissolved in organic solvents, with a number average molecular weight and polydispersity index of 13.2 kg/mol and 2.74, respectively. PAFDQ showed higher thermal stability compared with the general fluorene structure owing to its rigid alkylidene-fluorene structure. The highest occupied and lowest unoccupied molecular orbital levels of PAFDQ were −5.37 eV and −3.42 eV, respectively. According to X-ray diffraction measurements, PAFDQ exhibited the formation of an ordered lamellar structure and conventional edge-on π-stacking. The device based on PAFDQ/Y6-BO-4Cl showed the best performance in terms of short circuit current (9.86 mA/cm2), open-circuit voltage (0.76 V), fill factor (44.23%), and power conversion efficiency (3.32%). Moreover, in the PAFDQ/Y6-BO-4Cl-based film, the phase separation of donor-rich and acceptor-rich phases, and the connected dark domains, was observed.

scholarly journals Development of a New Class of Thiocyanate-Free Cyclometalated Ruthenium(II) Complex for Sensitizing Nanocrystalline TiO2Solar Cells

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Surya Prakash Singh ◽  
Ashraful Islam ◽  
Masatoshi Yanagida ◽  
Liyuan Han
Keyword(s):  
Fill Factor ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Power Conversion ◽  
Electrical Energy ◽  
Photocurrent Density ◽  
Open Circuit ◽  
Photoelectrochemical Cells ◽  
Broad Absorption ◽  
New Class

We designed and developed a new class of thiocyanate-free cyclometalated ruthenium sensitizers for sensitizing nanocrystalline TiO2solar cells. This complex shows appreciably broad absorption range. Anchoring to nanocrystalline TiO2films for light to electrical energy conversion in regenerative photoelectrochemical cells achieves efficient sensitization to TiO2electrode. With this new sensitizer, there were a power conversion efficiency of 4.76%, a short-circuit photocurrent density of 11.21 mA/cm2, an open-circuit voltage of 0.62 V, and a fill factor of 0.68 obtained under standard AM 1.5 sunlight.

Low-Temperature Processed Hybrid Organic/Silicon Solar Cells with Power Conversion Efficiency up to 6.5%

2015 ◽  
Vol 1771 ◽  
pp. 201-206 ◽  
Author(s):  
M. Weingarten ◽  
T. Zweipfennig ◽  
A. Vescan ◽  
H. Kalisch
Keyword(s):  
Solar Cells ◽  
Low Temperature ◽  
Schottky Diode ◽  
Current Density ◽  
Short Circuit ◽  
Power Conversion ◽  
Open Circuit ◽  
Silicon Solar Cells ◽  
Organic Silicon ◽  
Hybrid Devices

ABSTRACTHybrid organic/silicon heterostructures have become of great interest for photovoltaic application due to their promising features (e.g. easy fabrication in a low-temperature process) for cost-effective photovoltaics. This work is focused on solar cells with a hybrid heterojunction between the polymer poly(3-hexylthiophene-2,5-diyl) (P3HT) and n-doped monocrystalline silicon. As semi-transparent top contact, a thin (15 nm) Au layer was employed. Devices with different P3HT thicknesses were processed by spin-casting and compared with a reference Au/n-Si Schottky diode solar cell.The current density-voltage (J-V) measurements of the hybrid devices show a significant increase in open-circuit voltage (VOC) from 0.29 V up to 0.50 V for the best performing hybrid devices compared to the Schottky diode reference, while the short-circuit current density (JSC) does not change significantly. The increased VOC indicates that P3HT effectively reduces the reverse electron current into the gold contact. The wavelength-dependent JSC measurements show a decreased JSC in the wavelength range of P3HT absorption. This is related to the reduced JSC generation in silicon not being compensated by JSC generation in P3HT. It is concluded that the charge generation in P3HT is less efficient than in silicon.After a thermal annealing of the hybrid P3HT/silicon solar cells, we achieved power conversion efficiencies (PCE) (AM1.5 illumination) up to 6.5% with VOC of 0.52 V, JSC of 18.6 mA/cm² and a fill factor (FF) of 67%. This is more than twice the efficiency of the reference Schottky diode.

Thermoelectric Module of P-Type Ca-Co-O/N-Type ZnO Thin Films

2012 ◽  
Vol 622-623 ◽  
pp. 726-733 ◽  
Author(s):  
Weerasak Somkhunthot ◽  
Nuwat Pimpabute ◽  
Tosawat Seetawan
Keyword(s):  
Thin Films ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Power Factor ◽  
Electrical Power ◽  
Thermoelectric Module ◽  
Preliminary Test ◽  
Internal Resistance ◽  
Open Circuit ◽  
P Type

Thin films thermoelectric module fabricated by pulsed-dc magnetron sputtering system using Ca3Co4O9(p-type) and ZnO (n-type) targets of 60 mm diameter and 2.5 mm thickness, which were made from powder precursor, and obtained by solid state reaction. Thin films of p-Ca-Co-O (Seebeck coefficient = 143.85 µV/K, electrical resistivity = 4.80 mΩm, power factor = 4.31 µW/m K2) and n-ZnO (Seebeck coefficient =229.24 µV/K, electrical resistivity = 5.93 mΩm, power factor = 8.86 µW/m K2) were used to make a thermoelectric module, which consist of four pairs of legs connected by copper electrodes (0.5 mm thickness, 3.0 mm width, and 3.0-8.0 mm length). Each leg is 3.0 mm width, 20.0 mm length, and 0.44 µm thickness on a glass substrate of 1.0 mm thickness in dimension 25.0x50.0 mm2. For preliminary test, a module was used to thermoelectric power generation. It was found that the open circuit voltage increased with increasing temperature difference from 3 mV at 5 K up to 20 mV at 78 K. The internal resistance of a module reached a value of 14.52 MΩ. This test indicated that a module can be generated the electrical power. Therefore, it can be used as an important platform for further thin films thermoelectric module research.

Novel Linear and Hyperbranched Polythiophene Derivatives Containing Diketopyrrolopyrroles as Linking Groups

2015 ◽  
Vol 1771 ◽  
pp. 213-219
Author(s):  
Sheng-Hsiung Yang ◽  
Chia-Hao Hsieh
Keyword(s):  
Fill Factor ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Power Conversion ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Photovoltaic Properties ◽  
Molecular Weights ◽  
Active Layers ◽  
Film State

ABSTRACTThe goal of this research is to synthesize novel linear and hyperbranched polythiophene derivatives containing diketopyrrolopyrrole (DPP) as linking groups, and to investigate thermal, optical, electrochemical, and photovoltaic properties of those derivatives. Polymers with high regioregularity were synthesized via the Universal Grignard metathesis polymerization. Those linear or hyperbranched polythiophenes containing DPP bridging moieties showed higher molecular weights and better thermal stability compared with normal P3HT. The UV-vis absorption spectra of the DPP-containing polymers are similar to that of P3HT in film state, while they show distinct attenuation in fluorescent emission. Finally, all polymers were blended with PC61BM and used as active layers for fabrication of inverted solar devices. The devices based on those DPP-containing polythiophenes revealed the open-circuit voltage (VOC) of 0.55–0.58 V, the short-circuit current (JSC) of 8.62–16.21 mA/cm2, the fill factor (FF) of 36–41%, and the power conversion efficiency (PCE) of 1.73–3.74%.

Organic Sensitizers Containing Julolidine Moiety for Dye-Sensitized Solar Cells

2008 ◽  
Vol 8 (9) ◽  
pp. 4761-4766 ◽  
Author(s):  
Dong Wook Kim ◽  
Jin Joo Choi ◽  
Man Ku Kang ◽  
Yongku Kang ◽  
Changjin Lee
Keyword(s):  
Solar Cells ◽  
Power Conversion Efficiency ◽  
Conversion Efficiency ◽  
Short Circuit ◽  
Power Conversion ◽  
Dye Sensitized Solar Cells ◽  
Open Circuit ◽  
Dye Sensitized ◽  
Sensitized Solar Cells ◽  
Organic Sensitizers

We prepared organic sensitizers (S1 and S2) containing julolidine moiety as a donor, phenyl or phenylene thiophene units as a conjugation bridge, and cyano acetic acid as an acceptor for dye sensitized solar cells. S1 exhibited two absorption maxima at 441 nm (ε = 26 200) and 317 nm (ε = 15 500) due to the π–π* transition of the dye molecule. S2 dyes with an additional thiophene unit showed the absorption maximum extended by 18 nm. DSSCs based on S1 dye achieved 2.66% of power conversion efficiency with 8.3 mA cm−2 of short circuit current, 576 mV of open circuit voltage, and 0.56 of fill factor. DSSCs using S2 dye with a longer conjugation attained only 1.48% of power conversion efficiency. The 0.21 V lower driving force for regeneration of the S2 dye compared to the S1 dye is one of the reasons for low conversion efficiency of the S2 dye.

Photovoltaic Effects of Bismuth Ferrite and Nd-Doped Barium Titanate Thin Films Prepared by Sol-Gel Method

2014 ◽  
Vol 787 ◽  
pp. 347-351 ◽  
Author(s):  
Chun Lin Fu ◽  
Wei Cai ◽  
Ze Bin Lin ◽  
Wei Hai Jiang
Keyword(s):  
Thin Films ◽  
Barium Titanate ◽  
Short Circuit ◽  
Bismuth Ferrite ◽  
Power Conversion ◽  
Sol Gel ◽  
Photocurrent Density ◽  
Open Circuit ◽  
Doped Barium Titanate ◽  
Open Circuit Photovoltage

Ferroelectric is a great potential material as new solar cells, light driver and optical sensor because of its anomalous photovoltaic effect. Bismuth ferrite and Nd-doped barium titanate thin films were prepared via sol–gel spin-coating method in the present study. The experimental results show that substitution of Nd3+ ions for Ba2+ on A sites leads to the decrease of band gap, and the short circuit photocurrent density, open circuit photovoltage and power conversion efficiency of Nd-doped barium titanate thin films begin to increase and reach the maximum and then decrease as Nd content increases. It has been found that the band gap of bismuth ferrite thin films annealed at 550–650oC was between 2.306 eV and 2.453 eV. The short circuit photocurrent density decreased with the rise of annealing temperature, and the open circuit photovoltage and the power conversion efficiency of bismuth ferrite thin films annealed at 550oC were higher than the thin films annealed at higher temperature.

scholarly journals Determine the Optimum Efficiency of Transformer Cores Using Comparative Study Method

2021 ◽  
Vol 12 (1) ◽  
pp. 35
Author(s):  
Nabeel Zahoor ◽  
Abid Ali Dogar ◽  
Akhtar Hussain
Keyword(s):  
Power Systems ◽  
Short Circuit ◽  
Electrical Power ◽  
Operating Cost ◽  
Open Circuit ◽  
Core Material ◽  
Local Market ◽  
Electrical Power Systems ◽  
Research Perspective ◽  
Core Losses

The transformer is one of the most discussed and important components of electrical power systems because of its reliability, durability and energy conversion capability. It is also useful in load sharing, which reduces system burden, but is also responsible for a sufficient number of losses, as it is used in different types of electric appliances that require voltage conversion. The no-load losses of transformers have gained much attention from research perspective because of its operating cost throughout its lifetime. Many studies were carried out to achieve the highest possible efficiency, decreasing certain losses by using different methods and materials. However, the local market in Pakistan is far behind in the field of efficient core material manufacturing of transformers, which is why consumers are unable to obtain efficient electric appliances. Due to these loss-making appliances, the overall residential load increases and the consumers are charged with heavy electricity bills. This proposed study discusses core losses, different core comparisons, T/F efficiency and advancement in the core material. To accomplish a core comparison, two locally available core materials are used to fabricate two different T/F, and some tests such as open-circuit and short-circuit tests are performed to discover their losses, thermal degradation, and output efficiencies.

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