Heat transfer study of a double-pass counterflow solar air heater with porous media and multiple C-shaped roughness absorber

ABSTRACT

Heat transfer augmentation of counterflow double-pass (DP) solar air heater (SAH) was investigated experimentally. Best artificial roughness was selected from previous work and it experimented with porous screen matrix of different porosity range from 0.74 to 0.9. Counterflow DP arrangement gives the best results with the combination of porous screen matrix. Correlations for Colburn factor, Nusselt number, friction factor, and thermal efficiency were developed over a wide range of geometrical configurations of porous media, i.e. wire diameters ranging from 1.06 to 1.4 mm, pitch ranging from 2.54 to 3.01 mm, and layer count ranging from 2 to 9. Correlations have been discovered to predict experimental values accurately.

KEYWORDS:

• Artificial roughness
• correlations
• counter-flow DP SAH
• porous screen matrix
• regression analysis

Highlights

• Performance of the counterflow double pass solar air heater has been performed experimentally.

• Effects of operating range on performance were analyzed.

• Comparisons between absorber duct with and without artificial roughness were done and optimum results were obtained.

• Correlations were developed for Colburn factor, Nusselt number, friction factor, and thermohydraulic efficiency.

• All correlations show good agreement with experimental results.

Acknowledgments

The authors would like to express their gratitude to BCUD, SPPU, Pune, India for the research funding (Grant No. 15SCI001003).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Board of College and University Development, Savitribai Phule Pune University [15SCI001003].