Augmentation of Heat Transfer for Spiral Coil Heat Exchanger in Solar Energy Systems By Using Nano fluids
Engineering and Technology Journal,
2015, Volume 33, Issue 9, Pages 1619-1634
AbstractThis article presents an experimental study on pressure drop and enhancement of heat transfer of nanofluids flow in coil heat exchanger of solar energy system. In this study the method using to enhancement of heat transfer and pressure drop, by used the spiral coiled tube heat exchange in solar energy systemand the nanofluids instead of the distilled water. The weight concentrations of nanoparticles used are ranging from (15 – 35wt%). Two types of nanoparticles used in this articlecupper (Cu(30nm)) and titanium Oxide(TiO2 (50nm)) as well as the distilled water. The effects of different parameters such as nanofluid temperature, concentration, type of nanoparticle and flow Reynolds number, on pressure drop and heat transfer coefficient of the flow are studied. The results indicated that an increase in heat transfer coefficient of 55.45% for Cu+ Dw and 40.2% for TiO2 + Dw at concentration of 35wt%compared with base fluid. The pressure drop and heat transfer coefficientis increased by using nanofluids (Cu,TiO2 – Dw ) instead of the distilled water.As well as the results indicated that by using heat exchanger with helically coiled tube and shell, the heat transfer performance is improved moreover the pressure drop enhancement due to the curvature of the coil tube.The maximum increase of 44.32% (Cu + Dw) and 34.42% (TiO2+ Dw) in Nusselt number ratio for a range of Reynolds numbers between 200–800. This article decided that the nanofluid behaviors are close to typical Newtonian fluids through the relationship between shear rate and viscosity.Furthermore to performance index are used to present the corresponding heat transfer technique and flow. Thesize and type nanoparticles play an important role in enhancement of heat transfer rate.
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