First and Second Laws Analysis and Optimization of a Solar Absorber; Using Insulator Mixers and MWCNTs Nanoparticles
In this paper, forced convection flow and heat transfer of MWCNTs-water nanofluid in heat sink collector equipped with mixers are studied. The three-dimensional governing equations are numerically solved in the domain by the control volume approach based on the SIMPLE algorithm. Reynolds numbers are considered in laminar-turbulent range of 50<Re<12,000. The optimization was carried out by comparison of different parameters to reach the optimal case with the maximum exergy efficiency. From this study, it is concluded that in the case of using heat sink, instead of shell and tubes, the time that the fluid is inside the collector increases and leads to outlet temperature increase from the collector the exergy efficiency increases. Also, it is realized that using mixers enhance the outlet fluid temperature, energy efficiency and exergy efficiency. Generally, while the trend of exergy efficiency variation with effective parameters is increasing, applying the mixers precipitate the efficiency increment. In addition, for the case that the trend of exergy efficiency variation with changing these parameters is decreasing, the decreasing trend gets slow. Finally, the highest exergy efficiency was obtained for the nanoparticle volume fraction of ?=0.10%.
