| Title |
Heat transfer enhancement in flue-gas systems with radiation-intensifying inserts: an analytical approach |
| Authors |
Menkeliūnienė, Justina ; Jonynas, Rolandas ; Paukštaitis, Linas ; Balčius, Algimantas ; Buinevičius, Kęstutis |
| DOI |
10.3390/en18133383 |
| Full Text |
|
| Is Part of |
Energies.. Basel : MDPI. 2025, vol. 18, iss. 13, art. no. 3383, p. 1-23.. ISSN 1996-1073 |
| Keywords [eng] |
convection ; energy efficiency ; flue-gas flow ; insert ; passive heat transfer enhancement ; radiative heat transfer ; turbulator |
| Abstract [eng] |
A significant portion of energy losses in industrial systems arises from the inefficient use of high-temperature exhaust gases, emphasizing the need for enhanced heat recovery strategies. This study aims to improve energy efficiency by examining the effects of radiation-intensifying inserts on combined radiative and convective heat transfer in flue-gas heated channels. A systematic literature review revealed a research gap in understanding the interaction between these mechanisms in flue-gas heat exchangers. To address this, analytical calculations were conducted for two geometries: a radiation-intensifying plate between parallel plates and the same insert in a circular pipe. The analysis covered a range of gas-flue and wall temperatures (560–1460 K and 303–393 K, respectively), flow velocities, and spectral emissivity values. Key performance metrics included Reynolds and Nusselt numbers to assess flow resistance and heat transfer. Results indicated that flue-gas temperature has the most significant effect on total rate of heat transfer, and the insert significantly enhanced radiative heat transfer by over 60%, increasing flow resistance. A local Nusselt number minimum at a length-to-diameter ratio of approximately 26 suggested transitional flow behavior. These results provide valuable insights for the design of high-temperature heat exchangers, with future work planned to validate the findings experimentally. |
| Published |
Basel : MDPI |
| Type |
Journal article |
| Language |
English |
| Publication date |
2025 |
| CC license |
|
