Comparative optical and thermal analysis of compound parabolic solar collector with fixed and variable concentration ratio

Solar thermal collectors such as flat plate and evacuated tube collectors are used for maximum of 60-80 degrees C temperature and parabolic trough collectors are used for 700-900 degrees C temperature ranges. It is needed to develop and analyse solar collector, such as compound parabolic collectors (CPC) which can operate for intermediate temperature range from 50-300 degrees C for industrial and domestic applications. However, optical and thermal performance of CPC is strongly influenced by concentration ratio. The current study presents a comparative optical and thermal analysis of CPC with fixed (4.58) and variable (4.58 to 5.87) concentration ratio by using model-based transient simulation approach. Two profiles of compound parabolic collector are analysed with fixed and variable concentration ratio for the subtropical climate of Taxila, Pakistan. 2D profiles of both collectors are modelled and designed in MATLAB and are then analysed optically by using Monte Carlo ray tracing technique through TracePro. In addition, thermal analysis of both profiles is also performed through ANSYS. The resulted optical efficiency with fixed and variable concentration is 91 % and 96 %, respectively at a given tilt angle. Whereas maximum temperature achieved with both profiles is 5 degrees C and 7 degrees C, respectively. Thus, it is concluded that performance of CPC with variable concentration ratio is much better compared to fixed value.