scholarly journals Performance of Multi Junction Photovoltaic Cells with High Concentration Ratio

2014 ◽  
Vol 61 ◽  
pp. 2258-2261 ◽  
Author(s):  
A. Aldossary ◽  
A. Algarue ◽  
S. Mahmoud ◽  
R.K. AL-Dadah
Keyword(s):  
Concentration Ratio ◽  
Photovoltaic Cells ◽  
High Concentration

scholarly journals GLOBAL PRODUCTION CONCENTRATION OF MEDIUM DENSITY FIBERBOARD (MDF) (1995 - 2016)

2018 ◽  
Vol 42 (5) ◽  
Author(s):  
Thaisa de Sousa Selvatti ◽  
Luis Antônio Coimbra Borges ◽  
Helena Cristina Carvalho Soares ◽  
Álvaro Nogueira de Souza ◽  
Luiz Moreira Coelho Junior
Keyword(s):  
Gini Index ◽  
Concentration Ratio ◽  
Concentration Index ◽  
Medium Density Fiberboard ◽  
Average Concentration ◽  
Medium Density ◽  
High Concentration ◽  
The World ◽  
Concentration Degree ◽  
Production Concentration

ABSTRACT This papaer analyzed the global MDF production and its concentration degree between 1995 and 2016. In order to measure and analyze this concentration, we used the Concentration Ratio [CR(k)], the Herfindahl-Hirschman Index (HHI), Theil Entropy Index (E), Hall and Tideman Index (HTI), the Comprehensive Concentration Index (CCI), and the Gini Index (G). Global MDF production grew 12.81% p.a. from 1995 to 2016, reaching 99 million m3 at the end of the time series. China took over the hegemony in 2001 and arrived in 2016 with about 60% of the world’s MDF supply. The CR(k) of the global MDF production inferred a high concentration, mainly in the CR(4) from 2009. The CR(8) remained with a moderately high average concentration. During this period more than 90% of the offer was retained in the CR(20). The HHI, E and HTI indices corroborate that there is high concentration in global MDF production, as well as the CCI in the studied period. The inequality indicated by G also presented increasing behavior and was classified as strong and very strong. The concentration indicators were efficient in evaluating the concentration degree of the world MDF supply.

scholarly journals Theoretical Investigation of the Temperature Limits of an Actively Cooled High Concentration Photovoltaic System

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1902 ◽  
Author(s):  
Asmaa Ahmed ◽  
Katie Shanks ◽  
Senthilarasu Sundaram ◽  
Tapas Kumar Mallick
Keyword(s):  
Solar Cell ◽  
Concentration Ratio ◽  
Photovoltaic System ◽  
Thermal System ◽  
Outlet Temperature ◽  
Water Mixture ◽  
High Concentration ◽  
Cell Temperature ◽  
Photovoltaic Thermal System ◽  
Different Types

Concentrator photovoltaics have several advantages over flat plate systems. However, the increase in solar concentration usually leads to an increase in the solar cell temperature, which decreases the performance of the system. Therefore, in this paper, we investigate the performance and temperature limits of a high concentration photovoltaic Thermal system (HCPVT) based on a 1 cm2 multi-junction solar cell subjected to a concentration ratio from 500× to 2000× by using three different types of cooling fluids (water, ethylene glycol and water mixture (60:40), and syltherm oil 800). The results show that, for this configuration, the maximum volumetric temperature of the solar cell did not exceed the manufacturer’s recommended limit for the tested fluids. At 2000× the lowest solar cell temperature obtained by using water was 93.5 °C, while it reached as high as 109 °C by using syltherm oil 800, which is almost equal to the maximum operating limit provided by the manufacturer (110 °C). Overall, the best performance in terms of temperature distribution, thermal, and electrical efficiency was achieved by using water, while the highest outlet temperature was obtained by using syltherm oil 800.

Computational Analysis of Nanofluid Cooling of High Concentration Photovoltaic Cells

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Z. Xu ◽  
C. Kleinstreuer
Keyword(s):  
Reynolds Number ◽  
Energy Use ◽  
Volume Fraction ◽  
Cooling System ◽  
Optimal Parameter ◽  
Photovoltaic Cells ◽  
System Efficiency ◽  
Operational Parameters ◽  
High Concentration ◽  
Temperature Range

High concentration photovoltaic devices require effective heat rejection to keep the solar cells within a suitable temperature range and to achieve acceptable system efficiencies. Various techniques have been developed to achieve these goals. For example, nanofluids as coolants have remarkable heat transfer characteristics with broad applications; but, little is known of its performance for concentration photovoltaic cooling. Generally, a cooling system should be designed to keep the system within a tolerable temperature range, to minimize energy waste, and to maximize system efficiency. In this paper, the thermal performance of an Al2O3-water cooling system for densely packed photovoltaic cells under high concentration has been computationally investigated. The model features a representative 2D cooling channel with photovoltaic cells, subject to heat conduction and turbulent nanofluid convection. Considering a semi-empirical nanofluid model for the thermal conductivity, the influence of different system design and operational parameters, including required pumping power, on cooling performance and improved system efficiency has been evaluated. Specifically, the varied system parameters include the nanoparticle volume fraction, the inlet Reynolds number, the inlet nanofluid temperature, and different channel heights. Optimal parameter values were found based on minimizing the system's entropy generation. Considering a typical 200-sun concentration, the best performance can be achieved with a channel of 10 mm height and an inlet Reynolds number of around 30,000, yielding a modest system efficiency of 20%. However, higher nanoparticle volume fractions and lower nanofluid inlet temperatures further improve the cell efficiency. For a more complete solar energy use, a combined concentration photovoltaic and thermal heating system are suggested.

scholarly journals Experimental study on a high concentration photovoltaic/thermal system with plane mirrors array

2018 ◽  
Vol 22 (Suppl. 2) ◽  
pp. 517-525
Author(s):  
Haifei Chen ◽  
Jie Yang ◽  
Jie Ji ◽  
Wenzhu Huang ◽  
Gang Pei ◽  
...  
Keyword(s):  
Concentration Ratio ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Photovoltaic Module ◽  
Thermal System ◽  
Uniform Illumination ◽  
High Concentration ◽  
Electrical Efficiency ◽  
Photovoltaic Thermal System ◽  
The Cost

A high concentration photovoltaic/thermal system based on plane mirrors array has been developed and analyzed. It is found that the system with plane mirrors array not only can reduce the cost but also achieve a uniform illumination and adjustable concentration ratios. The system produces both electrical and thermal energy, with the electrical efficiency above 22% and the thermal efficiency above 47%. The experimental results show that the temperature coefficient of open circuit voltage in this photovoltaic module is around ?0.12 V/?C. Moreover, when the concentration ratio varies between 200 and 450, the decrease of electrical efficiency with the temperature is 0.08% per?C.

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