The Effect of the Temperature Difference on the Performance of Photovoltaic-Thermoelectric Hybrid Systems

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
M. El Mliles ◽  
Y. El Kouari ◽  
A. Hajjaji
Keyword(s):  
Critical Temperature ◽  
Hybrid System ◽  
Temperature Difference ◽  
Efficiency Enhancement ◽  
Cell Efficiency ◽  
High Power Factor ◽  
Pv Cell ◽  
Te Material ◽  
Increasing Temperature ◽  
Selection Of

The performance of the photovoltaic-thermoelectric (PV-TE) hybrid system was examined using three types of PV cells and a thermoelectric generator (TEG) based on bismuth telluride. The investigated PV cells are amorphous silicon (a-Si), monocrystalline silicon (mono-Si), and cadmium telluride (CdTe). The results showed that the TEG contribution can overcome the degradation of the PV cell efficiency with increasing temperature at the minimal working condition. This condition corresponds to the critical temperature difference across the TEG that guarantees the same efficiency of the hybrid system as that of the PV cell alone at 298 K. The obtained results showed that the critical temperature difference is 13.3 K, 44.1 K, and 105 K for the a-Si, CdTe, and mono-Si PV cell, respectively. In addition, the general expression of the temperature difference across the TEG needed for an efficiency enhancement by a ratio of r compared with a PV cell alone at 298 K was given. For an efficiency enhancement by 5 % (r = 1.05), the temperature difference required is 30.2 K, 61.3 K, and 116.1 K for the a-Si, CdTe, and mono-Si PV cells, respectively. These values cannot be achieved practically only in the case of the a-Si PV cell. Moreover, a TE material with a high power factor can reduce this temperature difference and improve the performance of the hybrid system. This work provides a tool that may be useful during the selection of the PV cell and the TE material for the hybrid system.

Forced Convection Heat Transfer From a Cylinder in Carbon Dioxide Near the Thermodynamic Critical Point

1971 ◽  
Vol 93 (3) ◽  
pp. 290-296 ◽  
Author(s):  
J. R. Green ◽  
E. G. Hauptmann
Keyword(s):  
Heat Transfer ◽  
Critical Temperature ◽  
Forced Convection ◽  
Temperature Difference ◽  
Forced Flow ◽  
Fluid Temperature ◽  
Bulk Fluid ◽  
Transfer Rates ◽  
Heated Cylinder ◽  
Increasing Temperature

In an attempt to determine the heat transfer rates in forced flow normal to a heated cylinder and to provide some insight into the mechanisms in heat transfer in the critical region, heat transfer rates have been measured for both free and forced flow of supercritical carbon dioxide normal to a horizontal heated cylinder. The 0.006-in-dia cylinder was held at various constant temperatures by a feedback circuit. The effects of bulk fluid temperature, bulk fluid pressure, and surface temperature were studied for a range of bulk fluid temperatures and pressures from 0.8 to 1.4 times the critical temperature and pressure, and free-stream velocities from 0 to 3 fps. The temperature difference between the heated cylinder and the bulk fluid was varied from 1 to 300 deg F. Several photographs of the flow field are presented. In a supercritical fluid the heat transfer rate increases smoothly and monotonically with increasing temperature difference, increasing velocity, and increasing pressure. In fluid with the bulk temperature below the pseudo-critical temperature the heat transfer coefficient shows large peaks when the cylinder temperature is near the pseudo-critical temperature. The heat transfer coefficient decreases with increasing temperature difference when the bulk fluid temperature is above the pseudo-critical temperature. Supercritical forced convection does not exhibit the characteristic maximum in heat transfer rate shown in forced-flow nucleate boiling. Heat transfer rates at larger temperature differences are very similar in forced-flow film boiling and supercritical forced-flow heat transfer. With this horizontal constant-temperature cylinder, no “bubble-like” or “boiling-like” mechanisms of heat transfer were observed in supercritical free or forced convection.

Multi‐stack fuel cell efficiency enhancement based on thermal management

2017 ◽  
Vol 7 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Haitham Saad Mohamed Ramadan ◽  
Quentin Bortoli ◽  
Mohamed Becherif ◽  
Frederic Claude
Keyword(s):  
Fuel Cell ◽  
Thermal Management ◽  
Efficiency Enhancement ◽  
Cell Efficiency

scholarly journals Effects of WMA Additive on the Rheological Properties of Asphalt Binder and High Temperature Performance Grade

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Jiupeng Zhang ◽  
Guoqiang Liu ◽  
Li Xu ◽  
Jianzhong Pei
Keyword(s):  
Critical Temperature ◽  
Rheological Properties ◽  
Asphalt Binder ◽  
Aging Effect ◽  
Asphalt Binders ◽  
Short Term ◽  
Performance Grade ◽  
Temperature Performance ◽  
Effects Of Temperature ◽  
Increasing Temperature

Sasobit additives with different dosages were added into 70# and 90# virgin asphalt binders to prepare WMA binders. The rheological properties, includingG∗andδ, were measured by using DSR at the temperature ranging from 46°C to 70°C, and the effects of temperature, additive dosage and aging onG∗/sin⁡δ, critical temperature, and H-T PG were investigated. The results indicate that WMA additive improvesG∗but reducesδ, and the improvement on 70# virgin binder is more significant.G∗/sin⁡δexponentially decreases with the increasing temperature but linearly increases with the increasing additive dosage. Aging effect weakens the interaction between binder and additive but significantly increases the binder’s viscosity; that is whyG∗/sin⁡δis higher after short-term aging. In addition, the critical temperature increases with the increasing additive dosage, and the additive dosage should be more than 3% and 5% to improve H-T PG by one grade for 70# and 90# virgin binder, respectively.

Global assessment for reduction of solar photovoltaic potential due to meteorological and geomorphological limiting factors

2021 ◽  
Author(s):  
Mustajab Ali ◽  
Hyungjun Kim
Keyword(s):  
Northern Hemisphere ◽  
Clean Energy ◽  
Global Scale ◽  
Limiting Factors ◽  
Solar Photovoltaic ◽  
Solar Pv ◽  
Temperature Changes ◽  
Cell Efficiency ◽  
Maximum Reduction ◽  
Pv Cell

<p>Solar Photovoltaic (PV) has the potential to fulfill a considerable amount of growing electricity demands worldwide.  In addition, being neat and clean, it can help to keep the greenhouse gases emission within safe limits. This resource needs a substantial amount of area for its sitting to supply the required amount of electricity. Such an area mainly depends on the available solar resource which is mainly the function of the local environment where PV is installed. Although some previous studies exist at the global scale, however, they have not comprehensively considered environmental (e.g., temperature, dust deposition, and snow) limiting factors that affect the actual solar PV yield. This study addresses such shortcomings and deals with all limiting factors simultaneously to provide a reliable assessment of potential PV performance at a global scale. PV cell efficiency is reduced due to an increase in resistance between cells at a temperature above a certain limit. Meanwhile, the accumulation of soil (dust) and snow on PV modules are also proven to limit the solar PV resources as it tends to block the incoming solar radiation. Lastly, the geomorphological parameter, which is an arrangement of a PV module to face the sun, is also shown to change its power output.</p><p>PV cell efficiency corrections for temperature changes, soil, and snow covers are applied using the biased corrected data from Global Soil Wetness Project 3 (GWSP3), CanSISE Observation-Based Ensemble of Northern Hemisphere Terrestrial Snow Water Equivalent, Version 2 from National Snow and Ice Data Center (nsidc), and TERRA/MODIS Aerosol Optical Thickness data available from NASA Earth Observations (NEO). The daily mean solar climatological values near the Earth’s surface for the last 14 years (2001–2014) with global coverage of 0.5º x0.5º are used in the analysis. The results have demonstrated that PV performance is affected by temperature increase, soil, snow, and varying tilt-angles. An annual maximum reduction of 5.7% in the total solar PV resource is seen in the Middle East due to the temperature changes. Likewise, a maximum loss of 6.45% in the total solar PV resource is witnessed for soil deposition for Sub-Saharan Africa. A higher reduction (~20%) is shown by snow covers for Russia and Canada in the upper Northern Hemisphere. In addition, a decline of 5–7% is observed for variation in the solar PV tilt-angles in comparison to optimum ones. As a whole, a maximum reduction of 19.45% in the total solar PV resource is found, which leads to a higher coefficient of determination (R<sup>2</sup>= 0.78) than uncorrected estimation (R<sup>2</sup>=0.67). This study will be helpful for household as well as large scale solar schemes and may contribute particularly to achieving the UN SDG No. 07 — Affordable and Clean Energy — and No. 13 — Climate Action — quantitatively.</p>

Eu (III), Tb (III) activated/ co-activated K2NaAlF6 host array: Simultaneous approach for improving photovoltaic efficiency and tricolour emission

2021 ◽  
Author(s):  
A.R. KADAM ◽  
Ramkumar B. Kamble ◽  
Meenal Joshi ◽  
Abhay Deshmukh ◽  
S. J. Dhoble
Keyword(s):  
Rare Earth ◽  
Solar Cell ◽  
Solid State ◽  
Solid State Lighting ◽  
Efficiency Enhancement ◽  
Solar Cell Efficiency ◽  
Simultaneous Approach ◽  
Cell Efficiency ◽  
Photovoltaic Efficiency

Rare earth activated fluoride phosphors have attention in recent years in the field of solid state lighting and solar cell efficiency enhancement. In the present study, RE (RE = Eu3+,...

scholarly journals Fabrication of a novel magnetic topological heterostructure and temperature evolution of its massive Dirac cone

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
T. Hirahara ◽  
M. M. Otrokov ◽  
T. T. Sasaki ◽  
K. Sumida ◽  
Y. Tomohiro ◽  
...  
Keyword(s):  
Critical Temperature ◽  
Magnetic Measurements ◽  
Anomalous Hall Effect ◽  
Temperature Evolution ◽  
Dirac Cone ◽  
Magnetic Layers ◽  
Device Applications ◽  
Quantum Phenomena ◽  
Increasing Temperature ◽  
Nontrivial Topology

Abstract Materials that possess nontrivial topology and magnetism is known to exhibit exotic quantum phenomena such as the quantum anomalous Hall effect. Here, we fabricate a novel magnetic topological heterostructure Mn4Bi2Te7/Bi2Te3 where multiple magnetic layers are inserted into the topmost quintuple layer of the original topological insulator Bi2Te3. A massive Dirac cone (DC) with a gap of 40–75 meV at 16 K is observed. By tracing the temperature evolution, this gap is shown to gradually decrease with increasing temperature and a blunt transition from a massive to a massless DC occurs around 200–250 K. Structural analysis shows that the samples also contain MnBi2Te4/Bi2Te3. Magnetic measurements show that there are two distinct Mn components in the system that corresponds to the two heterostructures; MnBi2Te4/Bi2Te3 is paramagnetic at 6 K while Mn4Bi2Te7/Bi2Te3 is ferromagnetic with a negative hysteresis (critical temperature  ~20 K). This novel heterostructure is potentially important for future device applications.

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