Effects of carbon nanodots coating and airflow rate on the thermal efficiency of flat plate collector

ABSTRACT

The application of nanoparticle coating in a collector could resolve the issues of lesser heat transfer rate and lower thermal efficiency associated with the flat plate collector (FPC). In this study, carbon nanodots (CNDs) synthesized from fish scales wwere coated over the black paint coating to enhance the thermal efficiency of FPC. The effect of various concentrations (0, 0.1, 0.2, and 0.5%w/v) of CND coatings and mass flow rates of air (0.011 kg/s (natural convection) and 0.015, 0.029, and 0.044 kg/s (forced convection)) on the collector outlet air temperature and efficiency of the FPC were evaluated with a control (black paint). Solar radiation ranged from 382 to 913 W/m² on the experimental days, and the atmospheric temperature and relative humidity values varied from 26.2 to 34.8°C and 50–72%, respectively. Fourier transform infrared spectroscopic studies of absorber plate coating revealed that the CNDs interacted with the black paint surface through phenolic OH, C=O, and NH mainly by hydrogen bonding. It was observed that the exit air temperature of the collector varied from 55 to 65°C. The thermal efficiency of 59.97%, 62.72%, 71.87%, and 67.75% was obtained for control (black-paint), 0.1%, 0.2%, and 0.5% CNDs coating, respectively, at the airflow rate of 0.044 kg/s. The coating of 0.2% CNDs recorded a maximum thermal efficiency of 71.87% at 0.044 kg/s. Overall, the CNDs coating on the absorber surface enhanced the thermal efficiency of the collector by 19.84% over the black paint-coated surface (control). It can be concluded from the study that CNDs coating resulted in enhanced outlet air temperature and improved thermal efficiency, which can be utilized for low-temperature applications like the drying of food materials.

KEYWORDS:

• Carbon nanodots
• concentration
• airflow rate
• flat plate collector
• thermal efficiency

Acknowledgements

The authors sincerely thank the Director, ICAR - Central Institute of Fisheries Technology and the staff of the Engineering section for offering their support to conduct this study.

Disclosure statement

No declarations of interest was reported by authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [Aniesrani Delfiya D S], upon reasonable request.

Authors Contributions

DSADelfiya, Conceptualisation and Planning, data analysis and writing of the manuscript

SMurali, Fabrication of flat plate thermal collector, sensor operation, review and editing

VSAnju, Application of CNDs, Laboratory experiments and data collection

PMAshraf, Conceptualisation, CNDs preparation, Review

George Ninan, Resource allocation, review

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567036.2023.2213175.

Additional information

Notes on contributors

Aniesrani Delfiya D.S

Dr Aniesrani Delfiya D.S., is a Scientist in the Engineering Division, ICAR-Central Institute of Fisheries Technology, Cochin, India. She obtained her Ph.D. from Tamil Nadu Agricultural University, Coimbatore. Her research areas are post-harvest equipment design in fisheries sector, and renewable energy based equipment.

Murali S

Dr. Murali S., is a Scientist in the Engineering Division, ICAR-Central Institute of Fisheries Technology, Cochin, India. He obtained his Ph.D. from Indian Agricultural Research Institute (IARI), New Delhi. His research interest includes solar thermal energy conversion systems, the design and development of fish processing equipment and machinery.

Anju V.S

Anju V S., is a Research Scholar at School of Materials Science and Engineering, NIT, Calicut, India. She completed her under graduation and post-graduation in Chemistry from Sacred Heart College, Thevara, Cochin. Her research area involves Energy conversion and storage systems.

Muhamed Ashraf P

Dr Muhamed Ashraf P., is a Principal Scientist in the Fishing Technology Division, ICAR-Central Institute of Fisheries Technology, Cochin, India. He obtained his Ph.D. from University of Kerala, India. His area of research is nanomaterials, biofouling, corrosion, sensors, and bio optics.

George Ninan

Dr. George Ninan., is presently the Director, ICAR-Central Institute of Fisheries Technology, Cochin, India. He obtained his Ph.D. from Cochin University of Science and Technology, Cochin. His research interest includes fish processing technology, value addition, fishery by-products and waste utilization.