Experimental Analysis on Thermal Efficiency of Evacuated Tube Solar Collector by Using Nanofluids

Abstract

This research is to study performance of a evacuated tube solar collector when silver (Ag(30nm)) + distilled water and oxide titanium (ZrO2(50nm)) + distilled water nanofluids was taken as the working fluid. With higher thermal conductivity of the working fluid the solar collector performance could be enhanced compared with that of distilled water. The two types of nanoparticles are used to investigate at different concentration (i.e. 0, 1, 3 and 5 % vol), mass flow rate (30,60 and 90 lit/hr m2) and the based working fluid was distilled water. The effect of different nanoparticle concentrations of Ag and ZrO2 mixed with distilled water as base fluid was examined on solar collector efficiency for different mass flow rates (30, and 90 lit/hr m2). The area under the curve as an index was used for comparing the effects of mass flow rates and nanoparticle concentrations on the collector total efficiency. The experimental results indicated that the concentration at 1%vol showed insignificant results compared with distilled water. As well as The nanofluids (Ag + DW), at concentrations (1, and 5%vol) and mass flow rates (30, and 90 lit/hr m2), the thermal solar characteristics values of FR(τα), – F RUL were 0.488, 1.168 W/m2.k , 0.593 and 1.252 W/m2.k, while the nanofluid (ZrO2 + DW) 0.437,1.025 W/m2.k ,0.480 and 1.140 W/m2.k respectively. Whereas in the case of distilled water at mass flow rates 30 lit/hr m2 and 90 lit/hr m2 were 0.413,0.973 W/m2.k,0.442 and ,1.011 W/m2.k respectively. Moreover use of nanofluids (Ag(30nm) + + distilled water) and( ZrO2(50nm) + distilled water) as a working fluid could improve thermal performance of flat plate collector compared with distilled water, especially at high inlet temperature. The solar collector efficiency for nanofluid (Ag(30nm) + distilled water) was greater than nanofluid (ZrO2(50nm) + distilled water) due to small particle size for the silver compared with zirconium oxide as well as high thermal conductivity for silver. The type of nanofluid is a key factor for heat transfer enhancement, and improve performance of evacuated tube solar collector.