Heating the air in buildings by evacuated tube solar collector used AL2O3/ water nanofluid at Cairo-Egypt climates

Abstract

The present paper investigates experimentally the performance of the evacuated tube heat pipe solar collector in Cairo-Egypt climate conditions. The experimental work conducts by using an evacuated solar collector with nanofluid in indirect building heating. The investigation parameters are tilt angle, AL2O3 nanoparticles concentrations, mass flow rates, water temperature difference, useful heat gain, collector thermal efficiency, air temperature difference, thermal optical efficiency and energy loss coefficients. The results show that the tilt angle 45o gives best performance characteristics of the collector. At tilt angle of 45o, 90 kg/h flow rate, 0.2% of nanofluid concentration and at 1:30 PM the air temperature difference increases by 16.4% than the reference fluid. The collector thermal efficiency increases by high concentrations of nanofluid, which reaches to 49%, 44.8%, 42.9% and 39% at a nanofluid concentration of 0.2%, 0.15%, 0.1% and 0% at 1:30 PM and 90kg/h, respectively. Also at low mass flow rate the air temperature difference increases by 9oC at 0.2% of nanofluid concentration.