Abstract
The demand for energy due to the population boom, together with the harmful consequences of fossil fuels, makes it essential to explore renewable thermal energy. Solar Thermal Systems (STS’s) are important alternatives to conventional fossil fuels, owing to their ability to convert solar thermal energy into heat and electricity. However, improving the efficiency of solar thermal systems is the biggest challenge for researchers. Nanomaterial is an effective technique for improving the efficiency of STS’s by using nanomaterials as working fluids. Therefore, the present theoretical study aims to explore the thermal energy characteristics of the flow of nanomaterials generated by the surface gradient (Marangoni convection) on a disk surface subjected to two different thermal energy modulations. Instead of the conventional Fourier heat flux law to examine heat transfer characteristics, the Cattaneo–Christov heat flux (Fourier’s heat flux model) law is accounted for. The inhomogeneous nanomaterial model is used in mathematical modeling. The exponential form of thermal energy modulations is incorporated. The finite-difference technique along with Richardson extrapolation is used to treat the governing problem. The effects of the key parameters on flow distributions were analyzed in detail. Numerical calculations were performed to obtain correlations giving the reduced Nusselt number and the reduced Sherwood number in terms of relevant key parameters. The heat transfer rate of solar collectors increases due to the Marangoni convection. The thermophoresis phenomenon and chaotic movement of nanoparticles in a working fluid of solar collectors enhance the temperature distribution of the system. Furthermore, the thermal field is enhanced due to the thermal energy modulations. The results find applications in solar thermal exchanger manufacturing processes.
Highlights
Solar thermal energy plays a significant role in meeting the growing energy demand and in overcoming the consequences caused by the use of fossil fuels
The thermal surface layer thickness shrinks as Marangoni number (Ma) upsurges, this is due to the reduction in thermal diffusion that occurs as Ma escalates
Similar to the thermal layer, the solute layer falls as Ma increase
Summary
Solar thermal energy plays a significant role in meeting the growing energy demand and in overcoming the consequences caused by the use of fossil fuels. Improving the thermal energy (performance) of solar heat exchangers is one of the key challenges in energy saving, energy use, and design. Researchers have established a new technique (using nanomaterials as functional fluids) to improve the efficiency of solar thermal systems. Choi [1] conducted a comprehensive study on nanomaterials and concluded that nanomaterials possess superior thermal characteristics. Khanafer et al [2] proposed a homogeneous single-phase model to explore the phenomenon of heat transport by convection. Nield and Kuznetsov [4] studied the flow of nanomaterials on a plate using the Buongiorno model. The thermodynamic characteristics of nanomaterials on the surfaces of rotating discs have acquired great attention due to their extensive use in heat exchangers and solar thermal systems. Further work on nanomaterials can be seen in [5,6,7,8,9,10]
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