scholarly journals Regulation of Temperature on Multitrays in an Indirect Solar Dryer (ISD) with Energy Storage and Three Airflow Modes

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
G. B. Tchaya ◽  
E. Tchoffo Houdji ◽  
J. H Tchami ◽  
C. Kapseu ◽  
M. Kamta
Keyword(s):  
Energy Storage ◽  
Negative Temperature Coefficient ◽  
Variable Parameter ◽  
Negative Temperature ◽  
Regulation System ◽  
Outlet Temperature ◽  
Temperature Regulator ◽  
Average Temperature ◽  
Solar Dryer ◽  
Transfer Equations

This work presents the regulation of temperature in an indirect multitrays solar dryer with oriented flux under the irradiance fluctuation. The temperature regulator using a negative temperature coefficient (NTC) as a sensor and fans is designed, and a similar device is also used to measure humidity through a sensor. Inlet and outlet dryer temperature and temperature on the three trays have been recorded with the regulation system according to different airflow modes. Irradiance and humidity have also been recorded. The model of outlet temperature with energy storage was given by using heat transfer equations. The results have shown that in the linking airflow mode, the average temperature on the three trays is 51.3 ± 1.5a°C, 52.18 ± 1.4a°C, and 51.9 ± 1.2a°C, respectively, with 52°C as setpoint temperature and NTC fixed on tray number 2. With temperature sensor in the same tray and 51°C as setpoint temperature, the average temperatures on the three trays are 51.86 ± 1.54°C, 51.60 ± 1.16°C, and 50.42 ± 1.13°C, respectively, in mixed mode, whereas in crossing airflow mode, the temperature gradient does not allow regulation on all trays. The regulation is possible when the temperature in the dryer chamber exceeds the set point temperature by more than 5%. The proportional type corrector is suitable for the temperature controller in indirect solar dryers. When the energy source is unstable, humidity which is a variable parameter is used to mark the end of drying instead of time.

Structural, optical and electrical properties of thermal evaporated nano sized In2Te3 thin films

2018 ◽  
Vol 1 (1) ◽  
pp. 21-25
Author(s):  
R Revathi ◽  
R Karunathan
Keyword(s):  
Thin Films ◽  
Negative Temperature Coefficient ◽  
Thermal Evaporation ◽  
Structural Parameters ◽  
Negative Temperature ◽  
Resistivity Measurements ◽  
Allowed Transition ◽  
Evaporation Technique ◽  
Indium Telluride ◽  
Made In

Indium Telluride thin films were prepared by thermal evaporation technique. Films were annealed at 573K under vacuum for an hour. Both as-deposited and annealed films were used for characterization. The structural parameters were discussed on the basis of annealing effect for a film of thickness 1500 Å. Optical analysis was carried out on films of different thicknesses for both as - deposited and annealed samples. Both the as- deposited and annealed films exhibit direct and allowed transition. Electrical resistivity measurements were made in the temperature range of 303-473 K using Four-probe method. The calculated resistivity value is of the order of 10-6 ohm meter. The activation energy value decreases with increasing film thickness. The negative temperature coefficient indicates the semiconducting nature of the film.

scholarly journals Temperature Dependence of G and D’ Phonons in Monolayer to Few-Layer Graphene with Vacancies

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Mingming Yang ◽  
Longlong Wang ◽  
Xiaofen Qiao ◽  
Yi Liu ◽  
Yufan Liu ◽  
...  
Keyword(s):  
Negative Temperature Coefficient ◽  
Negative Temperature ◽  
Intrinsic Properties ◽  
Temperature Dependent ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Layer Graphene ◽  
A Value ◽  
Few Layer Graphene

Abstract The defects into the hexagonal network of a sp2-hybridized carbon atom have been demonstrated to have a significant influence on intrinsic properties of graphene systems. In this paper, we presented a study of temperature-dependent Raman spectra of G peak and D’ band at low temperatures from 78 to 318 K in defective monolayer to few-layer graphene induced by ion C+ bombardment under the determination of vacancy uniformity. Defects lead to the increase of the negative temperature coefficient of G peak, with a value almost identical to that of D’ band. However, the variation of frequency and linewidth of G peak with layer number is contrary to D’ band. It derives from the related electron-phonon interaction in G and D’ phonon in the disorder-induced Raman scattering process. Our results are helpful to understand the mechanism of temperature-dependent phonons in graphene-based materials and provide valuable information on thermal properties of defects for the application of graphene-based devices.

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