Thermal Analysis of Novel Pebble Absorber Based Solar Thermal Collector

Abstract

The fluid flow rate of the heat absorbing medium plays a crucial role in the performance of the collector. Studies were carried out with varying fluid flow rates of 0.01 kg/s, 0.013 kg/sec and 0.016 kg/sec respectively for different days from 8:00 hour to 18:00 hour. The input parameters considered for the computational modeling are i) Solar radiation (I) ii) Ambient temperature (Ta) iii) Inlet water temperature (T_i) and iv) Mass flow rate (m_f). Experiments carried out using coated and uncoated pebbles as absorber along with a conventional flat plate collector.   The efficiency of the solar thermal collector increases with flow rate and incident radiation. The coated pebble absorber collector is more efficient than the uncoated pebble absorber collector and less efficient than the conventional metal absorber         collector at above mentioned flow rates. The total average efficiency of coated absorber collector was 67.036%, 51.35% for the uncoated absorber collector and 72.857% for the conventional copper absorber collector.