The Magnetohydrodynamic Finite Step Slider Bearing

1963 ◽  
Vol 85 (1) ◽  
pp. 129-135 ◽  
Author(s):  
W. F. Hughes
Keyword(s):  
Short Circuit ◽  
Electrical Power ◽  
Transverse Field ◽  
External Source ◽  
Open Circuit ◽  
Slider Bearing ◽  
Electrically Conducting ◽  
Load Carrying ◽  
Contour Plots ◽  
Finite Step

A theoretical analysis is made of the finite step slider bearing using an electrically conducting liquid metal lubricant in the presence of a magnetic field applied both tangentially and transversely to the fluid film. The electrical terminal characteristics are discussed. For the transverse field it is found that only a slight increase in pressurization can be effected on open circuit conditions and that the short circuit condition is adverse. For the tangential field the effect is adverse for both open and short circuit. By supplying electrical power from an external source, however, significant increases in load carrying capacity can be achieved for both field geometries. Various curves of normalized load versus Hartmann number and pressure contour plots are presented.

Magnetohydrodynamic Effects in Composite Bearings

1967 ◽  
Vol 89 (3) ◽  
pp. 323-328 ◽  
Author(s):  
J. Prakash
Keyword(s):  
Hartmann Number ◽  
Load Capacity ◽  
Short Circuit ◽  
Electrical Energy ◽  
Open Circuit ◽  
Slider Bearing ◽  
Frictional Drag ◽  
Electrically Conducting ◽  
Open Circuit Condition ◽  
Composite Bearing

A theoretical analysis is made of a composite slider bearing using an electrically conducting lubricant such as a liquid metal in the presence of a magnetic field applied perpendicular to the bearing surfaces. Two solutions are presented for large and small values of Hartmann number. It is found that for large Hartmann number significant increase in load capacity can be obtained even under open circuit condition. Short circuit condition results in zero load capacity, under the approximation considered. At small Hartmann number only a slight increase occurs under open circuit condition and external power must be supplied to get a significant increase. It is seen that a magnetohydrodynamic composite bearing does not always give an increase in load capacity as compared to an equivalent inclined slider bearing, as is the case with classical composite bearing. There is a critical Hartmann number depending on the parameters of the problem, above which MHD effects reduce the load capacity as compared to the case of an equivalent inclined slider bearing. It is also observed that the frictional drag on the bearing can be made zero by supplying electrical energy through the electrodes to the fluid.

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 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.

scholarly journals Optimization of Method and Components of Enzymatic Fuel Cells

2019 ◽  
pp. 143-146
Author(s):  
Ibukun Akinsola ◽  
Aderemi Babatunde Alabi ◽  
Muibat A Soliu ◽  
Taiye Akomolafe
Keyword(s):  
Fuel Cells ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Renewable Energy Sources ◽  
Electrical Power ◽  
Short Circuit Current ◽  
Electrical Energy ◽  
Open Circuit ◽  
Biofuel Cell ◽  
Carbon Electrodes

Enzymatic fuel cells produce electrical power by oxidation of renewable energy sources. An enzymatic glucose biofuel cell uses glucose as fuel and enzymes as biocatalyst, to convert biochemical energy into electrical energy. The applications which need low electrical voltages and low currents have much of the interest in developing enzymatic fuel cells. The cell was constructed using three different materials with different electrodes (Bitter leaf and Copper electrodes (BCu), Bitter leaf and Carbon electrodes (BC) and Water leaf and Carbon electrodes (WC)). The short circuit current and open circuit voltage were measured in micro-ampere (mu A) and milli-volt (mV) respectively at 30 minutes interval over the period of 12 hours (from dawn to dusk). The results which show that fuel cells constructed using bitter leaf with carbon electrode has the highest open circuit voltage, short circuit current and generated power of 162.8~mV, 1.65~ mu A and 268.62~nW respectively at 720~mins is obtained from the plots generated by the use of Microsoft Excel. The results show that all short circuit currents, voltages and powers generated increases with time and this is as a result of the exposure to solar radiation during the period of taking the measurement.

scholarly journals Characteristic comparison of photovoltaic module and photovoltaic thermal

2018 ◽  
Vol 204 ◽  
pp. 04010 ◽  
Author(s):  
Krismadinata ◽  
Remon Lapisa ◽  
Syahril ◽  
Asnil
Keyword(s):  
Short Circuit ◽  
Electrical Power ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Photovoltaic Module ◽  
Heat Absorption ◽  
Electrical Characteristics ◽  
Solar Module ◽  
Circulating Water ◽  
Lower Temperature

This paper discusses an attempt to compares the electrical characteristics of two solar modules of the same type and size in which one of the solar modules at the bottom is mounted a copper pipe for circulating water (as call photovoltaic thermal). The research was steered to observe water cooling effect to electrical characteristics of PV module. This system serves as a heat absorption on the bottom of the solar module. The experiment is conducted at the same time, place, and sunlight intensity conditions for both solar modules. The characteristics of short-circuit current, open circuit voltage, upper and lower temperature and the irradiation of sunlight from the two solar modules are observed. The test results show that photovoltaic thermal generate greater electrical power than solar modules not equipped with heat absorption

Performance Study of GaAs Photovoltaic Power Converter in Optically Powered Systems

2014 ◽  
Vol 556-562 ◽  
pp. 1894-1897
Author(s):  
Xin Wei Yuan ◽  
Jie Qin Shi
Keyword(s):  
Short Circuit ◽  
Electrical Power ◽  
Maximum Output Power ◽  
Optical Power ◽  
Short Circuit Current ◽  
Power Converter ◽  
Open Circuit ◽  
Maximum Output ◽  
Performance Study ◽  
Photovoltaic Power

Optically powered system is a revolutionary new power delivery system, in which optical power is delivered over fiber to photovoltaic power converter, where optical power is transformed into electrical power. Therefore the system is inherently immune to RF, EMI, high voltage and lighting effects. Capable of powering electronic circuitry by optical fiber, this technology has been validated in industries such as electric power, communications, remote sensing and aerospace. To a large extent, photovoltaic power converter is a key component that decides the performance of optically powered system. In this paper, the commonly used GaAs photovoltaic power converter is studied and tested. Parameter values like open circuit voltage, short circuit current, maximum output power, conversion efficiency and the optimum load resistance are obtained through experiment, which can be severed as important reference while choosing or designing DC-DC converter.

scholarly journals Experimental and Analytical Simulation Analyses on the Electrical Performance of Thermoelectric Generator Modules for Direct and Concentrated Quartz-Halogen Heat Harvesting

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3315 ◽  
Author(s):  
Saim Memon ◽  
Khawaja Tahir
Keyword(s):  
Heat Sink ◽  
Short Circuit ◽  
Electrical Power ◽  
Extreme Temperature ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Electrical Performance ◽  
Performance Parameters ◽  
Temperature Conditions ◽  
Analytical Simulation

The scope of thermoelectric generators (TEGs), in improving the electric vehicle battery performance and glass/steel manufacturing industries, could achieve wider significance by harnessing the unused radiative heat and light conversion to electrical power. This paper experimentally investigates the electrical performance correlated to concentrated quartz-halogen, with acrylic Fresnel lens and heat-light harvesting, coupled with heat sink. This study also experimentally examined the influence of extreme temperature variance on the open circuit generated voltage of the Peltier electrical failure mode, compared to the standard performance parameters of the commercial TEG module. The research results presented provide expedient perception into the testing (open circuit voltage, short circuit current, and full load power) of a commercial heat-stove TEG to understand its performance limitations. The analytical simulation and mathematical model developed in MATLAB compared the electrical performance parameters and its dependencies. The analytical simulation shows that increasing the heat-sink temperature increases the efficiency of not more than 2% at the Δ T of 360 K, due to the limitation of the Z T ¯ of 0.43 at Δ T of 390 K. The maximum Z T ¯ of 0.7 for Bi2Te3, with an achievable efficiency of 4.5% at the Seebeck coefficient of 250 µV/K, was predicted. The design of three experimental setups and results presented demonstrate the functioning of TEG in stable and unstable temperature conditions, confirming the theoretical study and stipulating a quantity of the electrical output power in relation to extreme temperature conditions.

The Magnetohydrodynamic Slider Bearing

1962 ◽  
Vol 84 (1) ◽  
pp. 197-202 ◽  
Author(s):  
William T. Snyder
Keyword(s):  
Magnetic Field ◽  
Liquid Metal ◽  
Boundary Conditions ◽  
Carrying Capacity ◽  
Load Capacity ◽  
Numerical Data ◽  
Load Carrying Capacity ◽  
Slider Bearing ◽  
Electrically Conducting ◽  
Load Carrying

An analysis is presented of the slider bearing using an electrically conducting lubricant, such as a liquid metal, in the presence of a magnetic field. The solution permits the calculation of the load-carrying capacity of the bearing. A comparison is made with the classical slider bearing solution. It is shown that the load capacity of the bearing depends on the electromagnetic boundary conditions entering through the conductivity of the bearing surfaces. Numerical data are presented for nonconducting surfaces with the emphasis on a comparison between the classical bearing and the magnetohydrodynamic bearing characteristics. It is shown that a significant increase in load capacity is possible with liquid metal lubricants in the presence of a magnetic field.

Nanostructure Control of Si and Ge Quantum Dots Based Solar Cells Using Plasma Processes

2014 ◽  
Vol 783-786 ◽  
pp. 2022-2027 ◽  
Author(s):  
Masaharu Shiratani ◽  
Giichiro Uchida ◽  
Hyun Woong Seo ◽  
Daiki Ichida ◽  
Kazunori Koga ◽  
...  
Keyword(s):  
Solar Cells ◽  
Fill Factor ◽  
Open Circuit Voltage ◽  
Short Circuit ◽  
Electrical Power ◽  
Chemical Vapor ◽  
Short Circuit Current ◽  
Open Circuit ◽  
Si Nanoparticles ◽  
Sensitized Solar Cells

We report characteristics of quantum dot (QD) sensitized solar cells using Si nanoparticles and Ge nanoparticles. Si nanoparticles were synthesized by multi-hollow discharge plasma chemical vapor deposition, whereas Ge nanoparticles were done by a radio frequency magnetron sputtering using Ar+H2under high pressure conditions. The electrical power generation from Si QDs and Ge QDs was confirmed. Si QD sensitized solar cells show an efficiency of 0.024%, fill factor of 0.32, short-circuit current of 0.75 mA/cm2and open-circuit voltage of 0.10 V, while Ge QD sensitized solar cells show an efficiency of 0.036%, fill factor of 0.38, short-circuit current of 0.64 mA/cm2and open-circuit voltage of 0.15 V.

scholarly journals On Field Infrared Thermography Sensing for PV System Efficiency Assessment: Results and Comparison with Electrical Models

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1055 ◽  
Author(s):  
Mirco Muttillo ◽  
Iole Nardi ◽  
Vincenzo Stornelli ◽  
Tullio de Rubeis ◽  
Giovanni Pasqualoni ◽  
...  
Keyword(s):  
Infrared Thermography ◽  
Short Circuit ◽  
Electrical Power ◽  
Electrical Characterization ◽  
Relative Difference ◽  
Open Circuit ◽  
Reference Points ◽  
Pv System ◽  
Efficiency Loss ◽  
Thermal Signature

The evaluation of photovoltaic (PV) system’s efficiency loss, due to the onset of faults that reduce the output power, is crucial. The challenge is to speed up the evaluation of electric efficiency by coupling the electric characterization of panels with information gathered from module diagnosis, amongst which the most commonly employed technique is thermographic inspection. The aim of this work is to correlate panels’ thermal images with their efficiency: a “thermal signature” of panels can be of help in identifying the fault typology and, moreover, for assessing efficiency loss. This allows to identify electrical power output losses without interrupting the PV system operation thanks to an advanced PV thermography characterization. In this paper, 12 faulted working panels were investigated. Their electrical models were implemented in MATLAB environment and developed to retrieve the ideal I-V characteristic (from ratings), the actual (operative) I-V characteristics and electric efficiency. Given the curves shape and relative difference, based on three reference points (namely, open circuit, short circuit, and maximum power points), faults’ typology has been evidenced. Information gathered from infrared thermography imaging, simultaneously carried out on panels during operation, were matched with those from electrical characterization. Panels’ “thermal signature” has been coupled with the “electrical signature”, to obtain an overall depiction of panels’ health status.

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