جستجوی مقالات مرتبط با کلیدواژه « CuO » در نشریات گروه « مکانیک »

This paper presents the catalytic effect of Al/CuO nanothermite on thermal decomposition of RDX. Currently, synthesizing a green alternative for primary explosives has become a new challenge for researchers. Therefore, feasibility of nanothermite-based nanocomposite Al/CuO/RDX was studied in this work. To this end, the CuO nanoparticles (NPs) are synthesized by the sol-gel method and applied as a nanocatalyst in thermal decomposition of RDX, as well as an oxidant in an Al-based nanothermite. The CuO NPs were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and Brunauer-Emmett-Teller (BET). The XRD, FE-SEM, HRTEM, and BET images showed the excellent synthesis of spherical morphology of the CuO NPs with a mean size of 40.50 nm, and with surface area of approximately 25.98 m2/g. The reactivity was evaluated using thermogravimetry (TG) and differential scanning calorimetry (DSC), and the results show that the heat release of Al/CuO/RDX nanocomposite is 0.42 kJ/g more than that of pure RDX. It is shown, for the first time, that the electron transfer from Al/CuO nanothermite to –N–NO2 of RDX might play an important role in determining the catalytic properties of Al/CuO nanothermite.

In this research, the thermal performance of Perkins A4.248 engine radiator by CuO + Water nanofluid was studied under the defined environmental conditions on a laboratory model. The results showed that with increasing volume fraction of nanoparticles, density and thermal conductivity increased; Specific heat and dynamic viscosity decreased. The coefficient of friction increased with increasing volume fraction of nanoparticles in the base fluid, and decreased with increasing Reynolds number. Also, with increasing flow and volume fraction, the radiator efficiency coefficient showed an increase. At the maximum value of air flow velocity and cooling fluid, by adding 4% by volume of nanoparticles to the base fluid, the heat transfer rate can be increased by an average of 39% compared to the base fluid. Also, by increasing the electromotor speed from 20 Hz to 40 Hz, the heat transfer coefficient of pure water increased by an average of 28% and nanofluid by 32%. The pressure drop of the radiator with a volume fraction of 1 and 2% compared to the base fluid at the maximum speed of the electric motor was calculated to be 15.7% and 38.2%, respectively.

In this work, the effect of using the mixture of a phase change material (PCM) and CuO nanoparticles as a cooling agent on the performance of a photovoltaic module have been investigated experimentally. The phase change material that located in a chamber at the backside of module is cooled with spiral cooper tubes. Results show that using pure PCM significantly causes to decrease in the surface temperature of module from 58.34 ºC to 51.7 ºC. In addition, data depicted that adding CuO nanoparticles to the pure PCM results in increasing the cooling efficiency and the produced power. Increasing the weight of pure PCM and the mixture of PCM-4% CuO from 1 kg to 2.25 kg results in decrease in the surface temperature of PV module from 51.7 ºC to 48.1 ºC and 45 ºC to 42.9 ºC, respectively. In addition, by increasing the nanoparticles in PCM, cooling efficiency and the produced power are increased and the highest values are 22.87% and 3.46 W attributed to the layout of using 2.25 kg PCM and 4% CuO.