Thermal Properties of Epoxy-Based Adhesive Reinforced With Nano And MicroParticles For In-Situ Timber Bonding
—CB10TSS thixotropic and room temperature cured epoxy based adhesive specially formulated for in-situ bonding of pultruded rod into timber for repair and strengthening of timber structures. The glass transition temperature for CB10TSS is 31.7ºC which considered low for outdoor exposure. Therefore CB10TSS was modified by reinforcing it with nano-and micro-particles and denoted as Nanopox (CB10TSS/nanosilica), Albipox (CB10TSS/liquid rubber) and Timberset (CB10TSS/ceramics). Thermal properties of epoxy adhesives were studied by using dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC). Albipox showed significant improvement in the glass transition temperature but Timberset has the highest Tg, due to high modulus of ceramic particles. A second scan for all the adhesives increased Tg which shows that the room temperature cured adhesives are not fully cross-linked. In DSC scan, typical graphs of heat flow versus temperature able to describe more characteristic of the curing behavior such as a sharp and deep endothermic dip at Tg which corresponds to a rearrangement of the molecules and the wide and shallow endothermic dip at around 100°C is associated with moisture in the adhesive.
An Investigation of Thermal, Physical, and Electrical Properties and Morphological Behavior on Nanoepoxy Composite Insulation
Epoxy nanocomposites prepared by casting epoxy reinforced with silica flour and stiff spherical alumina nanoparticles were investigated for its electrical, mechanical, and thermal properties as well as morphological behavior and the role of interfacial interaction between nanoparticles and the matrix on these properties. It was observed that the dielectric breakdown of the cast epoxy system is affected by interfacial interaction between nanoparticles and epoxy chains at room temperature. However, dielectric strength significantly changes at different temperatures. Also, it was realized that the interaction between nanoalumina and epoxy chains dominate the mechanical properties of the system such as tensile and flexural strength. However, thermal properties of the nanocomposite were mainly affected by the matrix and the degree of crosslink density between chains.
Heat Transfer Analysis in Cooling System of Hydropower’s Generator
Cooling process of power plant generator is handled via air-cooled radiators in which the cooling water is supplied from lake with its water temperature varies from season to season. In this study, the effect of temperature fluctuations of cooling water entering the cooling system has been examined via analysis of energy (NTU method) and exergy. The exergy analysis has been done by definition of efficiency coefficient for exergy of cooling media (water) and heating media (air). Besides, the effect of changing the cooling water temperature and flow rate entering the radiators on the cooling system performance has been studied. The results revealed the generator cooling system performance level held sufficient till the temperature of inlet water was kept under 293 k (20°C). On one hand, when the temperature of cooling water at the inlet rises to 12°C, the rate of heat exchange at radiators falls up to 34.3%. On the other hand, by water temperature passing the 12°C limit, the efficiency of cooling media exergy falls to 78% leading to efficiency rise in radiators’ heating media exergy level to 61%. According to the results of this study, changing flow rate of cooling media up to 40% gives rise to the efficiency coefficient of radiators’ cooling media exergy level to about 18.7%. While it does not affect the efficiency level of energy at radiators, the flow rate rise of cooling media may not be considered as a way to give rise to efficiency level of radiators.