scholarly journals Heating Performance of MWCNT Module according to Size Effect

2021 ◽  
Vol 21 (5) ◽  
pp. 175-182
Author(s):  
Sohyeon Park ◽  
Sungju An ◽  
Heeyoung Lee ◽  
Donghwi Kim ◽  
Wonseok Chung

Black ice is a road-freezing phenomenon that occurs on the surfaces of roads and is caused by sub-zero temperatures. Black ice is dangerous to vehicular traffic because it is difficult for a driver to detect its presence on roads. Further, it causes vehicles to lose traction on roads, thus causing accidents. Therefore, this study aims to solve this problem by utilizing a heating module with multi-walled carbon nanotubes (MWCNTs) and analyzing the heating efficiency according to the size effect of the heating module. The heating modules were divided into cubes (50 × 50 × 50 mm3) and cuboids (100 × 300 × 60 mm3). The parameters considered were the size of the heating module, number of curing days, and supply voltage. The maximum temperature change of the cubes was 75.7 ℃, and the maximum temperature change of the cuboids was 78% of the cube. The thermal images demonstrated that the cuboids exhibited better thermal dispersibility than that exhibited by the cubes. Therefore, the heating efficiency of the cuboids was inferred to be excellent. Thus, the cuboid heating module can be used to reduce the risk of accidents occurring caused by black ice.

Author(s):  
V. S. Yagubov ◽  
A. V. Shchegolkov

The review of modern approaches to the development of electric heating materials makes it possible to conclude that the studies of electrically conductive composites are based on using elastomers modified with nanoscale carbon materials. In the manufacturing of electric heaters, temperature self-regulation is the main property that increases their characteristics. However, researchers engaged in studying such heaters, face difficulties associated with the magnitude of supply voltage and power. In this regard, the tasks of the present work were as follows: to study the modifier characteristics for nanomodified heaters, and to select a modifier that is best dispersed in the elastomer, which will ensure the maximum magnitude of the supply voltage and the high value of the specific power of the heater. To develop an electric heater, silicone rubber modified with carbon nanotubes was used as an elastomer. The method for manufacturing the heating element nanomodified material was described. Multi-walled carbon nanotubes synthesized through the CVD method were employed as an electrically conductive modifier. Before modifying the elastomer, the carbon nanotubes were processed in a mill at a rotational speed of working blades of 25,000 rpm. Then, the nanotubes were thermally treated in a furnace until the temperature of 110 °C was reached. After that, the nanotubes and the elastomer were mixed using a BRABENDER mixer, followed by pressing and obtaining plates of the electric heating material. To ensure contact between the heater and the power source, aluminum foil, inserted into the punches before pressing, was used. The electrical conductivity of the elastic heater nanomodified material was studied using a setup (facility) constructed especially for that purpose. Based on the results obtained, a conclusion can be made on the expediency of using different multi-walled carbon nanotubes as elastomer modifiers, which form electrically conductive networks inside the elastomer and are capable of releasing heat when connected to an electrical voltage source. Employing a non-contact method of measuring the temperature field on the electric heater surface, thermograms were recorded. It was found that the temperature field is uniformly distributed on the heater surface and is stabilized at a certain time after achieving a thermal balance with the environment. From the data obtained, it can be concluded that the heating element connected to an alternating current network with a voltage of 220 V is efficient.


Author(s):  
Mariano Martin Escobar ◽  
Adrián Di Paolo ◽  
Analía Vazquez

CO2 emission from fossil fuel fired power plants contributed 30% of global emissions in 1990. In the same year, the cement industry contributed about 5% of the total. According to Kyoto Protocol, a tremendous effort is required to reduce the carbon dioxide emission. One potential technology in CO2 mitigation responses is the use of concrete products as carbon sink through the early age fast curing. The cement compounds C3S and C2S are instantaneously carbonized into calcium carbonate and silica gel, once cement is mixed with water and exposed to the carbon dioxide gas. The objective of this work is to evaluate the effect of adding carbon nanotubes in cement paste matrix on the capacity as CO2 sink. Adiabatic temperature was determined for different carbon nanotubos content on the cement paste. The microstructure was studied by scanning electronic microscopy. The calcium carbonate and calcium hydroxide content were determined by a thermogravimetric analysis. The storage modulus was measured for the specimens of cement paste before and after the immersion in CO2. Carbon nanotubes act as nuclear agent of the calcium carbonate and increase the maximum temperature and decrease the time of hydration. The incorporation of carbon nanotubes to Portland cement paste could modify the transport properties of the matrix. In fact, it was shown that interfacial interactions between the hydration products and multi-walled carbon nanotubes occur; and it was observed the insertion of multi-walled carbon nanotubes between the hydration products.


Nanoscale ◽  
2013 ◽  
Vol 5 (17) ◽  
pp. 7882 ◽  
Author(s):  
Laura Martínez Maestro ◽  
Patricia Haro-González ◽  
Blanca del Rosal ◽  
Julio Ramiro ◽  
A. J. Caamaño ◽  
...  

Acta Naturae ◽  
2011 ◽  
Vol 3 (1) ◽  
pp. 99-106 ◽  
Author(s):  
E A Smirnova ◽  
A A Gusev ◽  
O N Zaitseva ◽  
E M Lazareva ◽  
G E Onishchenko ◽  
...  

2003 ◽  
Vol 772 ◽  
Author(s):  
T. Seeger ◽  
G. de la Fuente ◽  
W.K. Maser ◽  
A.M. Benito ◽  
A. Righi ◽  
...  

AbstractCarbon nanotubes (CNT) are interesting candidates for the reinforcement in robust composites and for conducting fillers in polymers due to their fascinating electronic and mechanical properties. For the first time, we report the incorporation of multi walled carbon nanotubes (MWNTs) into silica-glass surfaces by means of partial surface-melting caused by a continuous wave Nd:YAG laser. MWNTs were detected being well incorporated in the silica-surface. The composites are characterized using scanning electron microscopy (SEM) and Raman-spectroscopy. A model for the composite-formation is proposed based on heatabsorption by MWNTs and a partial melting of the silica-surface.


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