Fossil fuels demonstrate pollution effects and significant emissions on the atmosphere, which made the use of clean, renewable sources of energy a necessity. Renewable energy has many sources, but the most promising and cheapest energy source is solar energy, which has led to a focus on efficient solar energy harvesting to be cheaper for public use. Stationary solar collectors like evacuated tube and flat-plate solar collectors are the most commonly used solar collectors for their simplicity of installation and maintenance. They are mostly used for domestic applications such as solar water heaters. Nanofluids can improve the thermal properties of the working fluid which can improve the performance of a collector. This review paper discussed the effect of different parameters on the stationary solar collector's performance, such as nanoparticle use, nanoparticle size, concentration, and the base fluid of the nanofluid. This review paper also aims to summarize previous studies performed on the use of different nanofluids on the two types of circulation that can be either thermosiphon or forced circulation for both collectors to investigate the energetic and exergetic efficiencies. The theoretical performance analysis equations of stationary solar collectors are provided too. From the reviewed results, it was concluded that a substantial improvement in both the energetic and exergetic efficiencies of both collectors had been obtained from the use of carbon-based nanofluids compared to a significant number of different nanofluids. The paper also discusses the significant challenges of nanofluid use and how to overcome them in stationary solar collectors.
- energy efficiency
- evacuated tube solar collector
- exergy efficiency
- flat-plate solar collector
- forced circulation