M.Sc. Tezi Görüntüleme

      There has been an increase in the technological application of non-Newtonian fluids (NNF) in recent years. NNFs are chosen over Newtonian fluids (NF) because of their superior hydrodynamic and thermal properties. It is particularly used as damping fluid in shock absorbers, the making of armours in defence industry and as insulator in thermal systems. This study applies a numerical analysis for the natural convection in a two dimensional trapezoidal (isosceles trapezoid) enclosure filled with power-law NNF. The use of NNF in Concentrated Photovoltaics (CPV) in order to prevent over-heating problem which affects the efficiency has become widespread. This study investigates the effects of various parameters on heat transfer over the bottom wall by developing a two dimensional model of such a cell. The bottom edge of the trapezoidal enclosure is considered as hot, top edge as cold while the side walls are considered as adiabatic. The study investigates how various changes in power-law index values and Rayleigh numbers affect the heat transfer on the bottom wall by altering the trapezoid side wall angles in the range of 0^o≤  ≤ 〖20〗^o. The power-law index values have been changed in the range of 0.6 ≤ n ≤ 1.8 and Rayleigh number (Ra) in the range of 〖10〗^3≤Ra ≤ 〖10〗^5 while Prandtl number has been kept as Pr=1000. The results indicate that the heat transfer rate in trapezoid bottom wall increases with an increase in trapezoid angle and decreasing power-law index (n). According to this evidence, it can be suggested that the use of power-law NNFs can contribute to increase efficiency by averting the over-heating problems in CPVs which have been regarded as a significant application field in green and renewable energy systems.