Solar Thermal Energy: Use of Volumetric Absorption in Domestic Applications

Solar thermal systems are one of the renewable energy systems used in the residential buildings for the heating purpose, and with these systems, the usage of non-renewable energy resources decreases. To improve the performance of solar collectors, engineers and scientists are regularly working on it. Direct absorption-based solar thermal collectors (DASTC) are kind of solar collectors in which the fluid can be heated directly (without any absorption surface). The present study deals with numerical model of direct absorption-based solar collector which can be used for residential purposes. The absorbed energy fraction, effect of the height, length of collector, and mass flow rate on the collector efficiency have been determined. The analysis shows that collector efficiency increases with the increase of mass flow rate when the height of the fluid in the collector is same and the efficiency of the collector deceases with the increase of channel length. Further, it has been observed that it is beneficial to use an optimum volume fraction of the nanoparticles in DASTC because at an optimum volume fraction, the collector achieved maximum efficiency.