چكيده به لاتين
Abstract:
Flat plate solar thermal collector is the most common technology for solar energy conversion at the building scale. In this study, the effects of pure water, Al2O3/water nanofluid and microencapsulated phase change slurry (a mixture of water and microencapsulated phase change material), as working fluids, on the efficiency and temperature difference of a flat-plate solar collector are numerically investigated. The governing equations are discretized and solved using the pressure-based finite volume method by the ANSYS Fluent 16.2 software. At first, the 3D numerical model is validated by comparing the simulation results of pure water as working fluid with an Experimental study on the same collector which has done by some other investigator. In the next step, nanofluid with 2% and 4% volumetric fractions is investigated. In genral, the results show that, in comparison with water as absorption medium using the nanofluids as working fluid increases the efficiency. Also, the tempreture difference of inlet and outlet nanofluid increases by increasing nanofluid's concenteration. In comparison with water, the tempreture difference of 4% nanofluid in best case, increases 8.653˚C. Also the results show that, there is an optimum concenteration for collector's efficiency. Despite it's lower tempreture difference, the 2% nanofluid has higher efficiency and in comparison with water, the increased efficiency is 4.5% in best case. In the next step, the 5% microencapsulated phase change slurry (mPCS) compares with 2% nanofluid as the best nanofluid in efficiency. The results show that, for Microencapsulated Phase Change Slurry 5%, the collector has approximately equal efficiency with nanofluid 2% and it can also save thermal energy for night time. However, nanofluid shows highest temperature difference. In the end, a combined of Microencapsulated Phase Change Slurry 5% and nanofluid 2% propose to have thermal energy saving advantage, compared to nanofluid 2% and higher temperature difference, compared to Microencapsulated Phase Change Slurry 5%.
Keywords: Solar collector, Nanofluid, Microencapsulated Phase Change Material (mPCM), Microencapsulated Phase Change Slurry, Thermophysical properties (mPCS)
