The design process of shell and tube heat exchanger is difficult due to the complex geometric parameters with thermodynamic and fluid dynamic factors, which consume more time and minimum possibility for an optimum result in the case of conventional design. The optimum design of shell and tube heat exchanger was determined to predict optimum heat transfer coefficient with the effect of geometrical parameters such as number of baffles (NB), Shell diameter (Ds), Tube pitch (Pt) and Baffle spacing (LB). The analytical calculations were done using Response Surface Methodology on four factors, three level, central composite face centered design matrix with full replications technique by 95% confidence level. The results indicate that the geometrical parameters with optimum design.

The emission of greenhouse gases is widely acknowledged as the primary driver of global warming. The adoption of renewable energy sources is paramount to address the dependence on fossil fuels, which contribute significantly to this issue and account for 84.3% of current energy production. Solar thermal energy stands out as a prominent option, representing 54.1% of the world's solar energy derived from solar collectors. However, solar thermal energy encounters challenge due to the suboptimal thermal properties of the liquids used in these collectors. Incorporating particles into the liquids offers a potential solution to enhance absorption and thermal properties. Nanofluids, formed by reducing solid particles to nanoscale dimensions, provide an avenue for improvement. This study aimed to produce an Ag nanofluid through mechanical exfoliation and assess its impact on radiation absorption compared to a GO nanofluid. Under a simulated power of 1 unit, the Ag nanofluid demonstrated temperature differences of 4 to 7°C, while pure water showed no significant deviation. Moreover, the evaporation efficiency of the Ag nanofluid reached up to 40.8% for concentrations of 200 and 500 ppm, compared to 28.6% for pure water. These findings highlight the potential of Ag nanofluid as a promising option for direct absorption solar collectors, owing to its cost-effectiveness, low toxicity, and similar benefits to graphene. Incorporating nanofluids, particularly the Ag nanofluid produced through mechanical exfoliation, can significantly enhance the efficiency of direct absorption solar collectors.

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