Thermal Performance Improvement of Solar Parabolic Dish System Using Modified Spiral Coil Tubular Receiver

The present research intends to design an efficient receiver for solar thermal applications with a solar dish concentrator system. Thermal and dynamic analysis is carried out for different convolutions of a spiral coil, and experiments are performed for testing the modified absorber. Experimental results are validated for the spiral absorber with numerical results. Three receivers of different numbers of convolutions are analyzed, and simulation steps are performed for these receivers to make improvements in the system efficiency. Finally, 5 convolutions of a spiral coil tubular absorber are taken for the modified design of the system. Absorber position for every spiral convolution is kept at the focus of the concentrated solar dish collector to achieve maximum efficiency. Material used for the reflective surface is anodized aluminum and copper for the absorber. The diameter of the aperture for the parabolic dish collector is 1.4 m. The maximum absorber temperature for May month comes out to be 296°C, and the maximum working fluid outlet temperature is found to be 294.2°C which is near to simulating temperature of 289.59°C and 288.15°C, respectively. This innovative design of the absorber consists of a feature of a 5 mm extension to the spiral tube at the exit and entry; hence, the turbulence effect could be overcome. Experimental thermal efficiency was found the highest (i.e., η th max = 75.98 % ) for May. This work emphasizes on improving thermal performance by obtaining optimum absorber size using convolution strategy. Investigation of 5 convolutions of spiral coil tubular absorber with extended ends for obtaining optimum performance than existing work is the superiority of this work.

A Significant Solar Energy Note on Powell-Eyring Nanofluid with Thermal Jump Conditions: Implementing Cattaneo-Christov Heat Flux Model

PTSCs (parabolic trough solar collectors) are widely employed in solar-thermal applications to attain high temperatures. The purpose of this study is to determine how much entropy is created when Powell-Eyring nanofluid (P-ENF) flows across porous media on a horizontal plane under thermal jump circumstances. The flow in PTSC was generated by nonlinear surface stretching, thermal radiation, and Cattaneo-Christov heat flux, which was utilized to compute heat flux in the thermal boundary layer. Using a similarity transformation approach, partial differential equations were converted into ordinary differential equations with boundary constraints. Then, the boundary restrictions and partial differential equations were merged to form a single set of nonlinear ordinary differential equations. To obtain approximate solutions to ordinary differential equations, the Keller-Box approach is utilized. Nanofluids derived from silver- and copper-based engine oil (EO) has been employed as working fluids. The researchers observed that changing the permeability parameter reduced the Nusselt number while increasing the skin frictional coefficient. Total entropy variation was also calculated using the Brinkman number for flow rates with Reynolds number and viscosity changes. The key result is that thermal efficiency is inversely proportional to particular entropy production. For example, using Cu-EO nanofluid instead of Ag-EO nanofluid increased the heat transport rate efficiency to 15–36%.