# Fewer Dimensions for Higher Thermal Performance: A Review on 2D Nanofluids
## 3 Application of 2D Nanofluids
### Concentrated Solar Power  
Two-dimensional nanofluids containing Gr, CNTs, and metal chalcogenides possess thermophysical properties of great interest in the CSP field of technology, such as improved long-term and thermal stabilities, enhanced heat transfer rates, and TC in reference to the traditional heat transfer synthetic oils currently employed in the CSP stations. The present subsection will briefly describe the potential applicability of two-dimensional nanofluids in the CSP area of actuation, its drawbacks, and the associated future challenges. In recent decades, CSP technology has become one of the most attractive options for energy harvesting and conversion. The increasing interest in this route has resulted in several studies on the more effective configuration of CSP systems. For instance, in systems with parabolic trough collectors, a heat transfer fluid flows through an absorber tube positioned along the central axis of the mounted mirrors in which the solar radiation is concentrated. The absorber tube is coated with a selective absorber, enabling the maximization the absorbed radiation amount by the collector in CSP plants. One of the most interesting solutions for improving the efficiency of CSP plants is to improve the thermophysical characteristics of the employed thermal fluid. Several works have stated that incorporating low concentrations of nanoparticles to a base liquid may enhance its thermophysical characteristics, including the TC and HTC. Moreover, nanoparticles usually minimize the thermal resistance between the existing sublayers of the heat transfer fluid, reducing the drop in temperature from the wall to the liquid bulk. The changing of the heat transfer properties contributes to the efficiency improvements in the base fluid and, consequently, in the overall efficiency of CSP plants. Metallic and metallic oxide nanoparticles are appealing to several researchers due to their superior TC. The transition metal dichalcogenides are also an important part of the recent advances in the sector because of their two-dimensional laminar nanostructure with promising characteristics, such as those in graphite. Two-dimensional nanomaterials present covalent intra-laminar distributions with interlaminar van der Waals forces interactions, resulting in enhanced high in-plane TC and much reduced out-of-plane losses. Due to these facts, the investigation of nanofluids incorporating transition metal dichalcogenide fillers is of great interest in the heat transfer field of research. Research has also been performed which considers how nanofluids improve the overall efficiency of solar thermal collectors, including the utilization of the two-dimensional nanofluids of interest in solar thermal energy applications. Furthermore, the use of 2D nanomaterials is expected to enhance the long-term stability of nanofluids due to their large surface area. In this direction, the liquid phase exfoliation technique is one of the easiest and most promising preparation methods for 2D nanomaterials [2]. The stability of nanofluids without the formation of aggregates can be enhanced by the inclusion of surfactants or dispersants in synthesis formulations and by adjusting their pH. Regarding CSP systems, the added nanoparticles have a remarkable impact on improving the heat transfer capability of the heat transfer base fluid and in increasing the absorption of incident solar radiation, resulting in noticeable improvements in the efficiency of solar plants. Additionally, due to the verified enhancement in the solar irradiation absorption induced by the nanoparticles, some authors have recommended the use of nanofluids in direct solar collectors. For instance, Kasaeian [142] investigated MWCNTs suspended in ethylene glycol nanofluids as working heat transfer fluids in a direct absorption parabolic trough collector. The best results were achieved using nanofluids at 0.3% wt. of MWCNTs, with an optical efficiency of approximately 71% and a thermal efficiency increase of 17%. In the study performed by Martinez-Merino et al.