Combinatorial and geometric optimization of a parabolic trough solar collector

The current investigation reveals the need for combinatorial and geometric optimization for parabolic trough solar collectors (PTSCs) and proposes methods to perform them. An analytical model of PTSC was drafted, which emerged to be quite accurate when exhaustively validated using experimental results. The analysis reveals that superior properties of design components (solar selective absorber coatings (SSACs), heat transfer fluids (HTFs), etc.) cannot guarantee better performance, as there are many interacting factors. Also, a particular combination of components can perform better at a certain temperature while lagging at another. To acquire an optimal combination of components, combinatorial optimization is introduced and carried out for PTSCs, using genetic algorithm (GA). Six SSACs, three absorber materials, and five HTFs are considered, significant efficiency improvements of 8% at 150 °C and 6% at 300 °C are observed. This study discloses that geometrical parameters (length and width of collector, focal length, etc.) possess positive as well negative impacts on efficiency. By varying these in a reasonable range, optimal values that lead to improved efficiency can be obtained. Particle swarm optimization (PSO) is used to attain this geometric optimization, and improvement of ≥3% in efficiency is noticed by only ±5% variation in dimensions.