Solar air heating devices have been employed in a wide range of industrial and home applications for solar energy conversion and recovery. It is a useful technique for increasing the rate of heat transfer by artificially creating repetitive roughness on the absorbing surface in the form of semicircular ribs. A thermo-hydraulic performance analysis for a fully developed turbulent flow through rib-roughened solar air heater (SAH) is presented in this article by employing computational fluid dynamics. Both 2-dimensional geometrical modeling and numerical solutions were performed in the finite volume package ANSYS FLUENT. The renormalization-group (RNG) k-ε turbulence model was used, as it is suitable for low Reynolds number (Re) turbulent flows. A thermo-hydraulic performance analysis of an SAH was carried out for a ranging Re, 3800–18,000 (6 sets); relative roughness pitch (RRP), 5–25 (12 sets); relative roughness height (RRH), 0.03–0.06 (3 sets); and heat flux, 1000 W/m². The numerical analysis revealed that with an RRP of 5 and an RRH of 0.06, the roughened duct produces the highest augmentation in average Nu_r in the order of 2.76 times that of a plain duct at an Re of 18,000. With an RRP = 10 and RRH = 0.06, the roughened duct was found to provide the most optimum thermo-hydraulic performance parameter (THPP). The THPP was determined to have a maximum value of 1.98 when the Re is equal to 15,000. It was found that semi-circular ribs which have a rib pitch = 20 mm and a rib height = 2 mm can be applied in an SAH to enhance heat transfer.

In this research work, environmental monitoring processes and assessments are carried out by the modeling and analysis of the water quality of the Chambal River in the state of Rajasthan. Various samples were collected from different locations along the course of the river flow. This water is used for different kinds of human, animal, and agriculture corp. activities. Comparative analyses were conducted on the water parameters, viz. biochemical oxygen demand, chemical oxygen demand, dissolved oxygen, total coliform, and conductivity, for the of consecutive years 2020 and 2021. A model was developed with the help of MATLAB Simulink software (Version R2019a) to find the causes of oxygen deficiency and reoxygenation in water with time and distance. The results of two consecutive years help to predict the responsible factors for the degradation of the river’s water quality. The water quality modeling and simulation results conclude that the water quality of the Chambal River flowing through Rajasthan can rejuvenate itself during an alarming oxygen deficit within a short period. According to the results of this study, the concentration of dissolved oxygen in the water of the Chambal River is high enough to support the survival of the endangered species that inhabit the area.