This paper presents a detailed review of the numerical studies carried out by various researchers in order to obtain enhanced heat transfer in free, forced, and mixed convection, under laminar, transition, and turbulent flow regimes, by using nanofluids in different solar collector geometries. Recently, nanofluids have been increasingly used in various solar collector configurations. Nano-sized metallic or non-metallic particles such as Cu, Au, Al2O3, SiO2, TiO2, CuO, etc, were used in the heat transfer fluid for various solid volume fractions. The average size of the particles was less than 100 nm. The higher conductivity of nanoparticles even at low particle concentration results in higher thermal conductivity of the base fluid and improves the thermal characteristics of the system. Nanoparticle size, type and shape are important factors for the thermal conductivity enhancement of the nanofluid with nanoparticles.
This paper presents a numerical analysis on turbulent flow and forced-convection characteristics of rectangular solar air heater tube fitted with staggered, transverse, V-shape, modern obstacles on the heated walls. Air, whose Prandtl number is 0.71, is the working fluid used, and the Reynolds number considered equal to 6 × 10 3 . The governing flow equations are solved using a finite volume approach and the semi-implicit pressure linked equation (SIMPLE) algorithm. With regard to the flow characteristics, the quadratic upstream interpolation for convective kinetics differencing scheme (QUICK) was applied, and a second-order upwind scheme (SOU) was used for the pressure terms. The dynamic thermo-energy behavior of the V-shaped baffles with various flow attack angles, i.e., 50 • , 60 • , 70 • , and 80 • are simulated, analyzed, and compared with those of the conventional flat rectangular baffles with attack value of 90 • . In all situations, the thermal transfer rate was found to be much larger than unity; its maximum value was around 3.143 for the flow attack angle of 90 • and y = H/2.
This research is based on an experimental investigation of four different types of heatsinks, which was backed up by a simulation analysis. The goal of this study is to determine the relevance of various heatsink forms and sizes, as well as to enhance the best situation. The cooling strength of these heatsinks was next investigated experimentally and then numerically, while adjusting in the same initial conditions, finding in principle that the experimental and numerical results agree, with a contrast ratio of less than 10.24%. As a consequence, we concluded that the coolant D3, which is circular and has a heat resistance of 0.582 K. W-1, is stronger than the D2 compact circular cooler, which has a resistance of 0.590 K. W-1. These two varieties were far superior to the regular D1 heatsink, which first debuted in the early days of computers and had a resistance of 0.595 K. W-1, but the best was the mixed engineering D4 heatsink, which had a heat resistance of 0.50 K. W-1. Changes were also made to the geometry of the best heatsink D4, by varying its heights (28, 23, 19, and 15 mm). The heat resistors were arranged in sequence (0.50, 0.560, 0.568, 0.586 kg/s), and the weights were arranger in order (3.12N, 2.56N, 2.11N and 1.67N).
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