Optimizing Device Performance of Multi-Pass Flat-Plate Solar Air Heaters on Various Recycling Configurations

Chii-Dong Ho (), Hsuan Chang (), Chih-Wei Yeh, Choon-Aun Ng and Ping-Cheng Hsieh
Additional contact information
Chii-Dong Ho: Department of Chemical and Materials Engineering, Tamkang University, New Taipei 251301, Taiwan
Hsuan Chang: Department of Chemical and Materials Engineering, Tamkang University, New Taipei 251301, Taiwan
Chih-Wei Yeh: Department of Chemical and Materials Engineering, Tamkang University, New Taipei 251301, Taiwan
Choon-Aun Ng: Faculty of Engineering and Green Technology, Universiti of Tunku Abdul Rahman, Kampar 31900, Perak, Malaysia
Ping-Cheng Hsieh: Department of Chemical and Materials Engineering, Tamkang University, New Taipei 251301, Taiwan

Energies, 2023, vol. 16, issue 6, 1-22

Abstract: Various external-recycle configurations of multi-pass flat-plate solar air collectors were studied theoretically to examine the optimal thermal performance under the same working dimension and operation conditions. An absorber plate and insulation sheet were implemented horizontally and vertically, respectively, into an open rectangular conduit to conduct a recycling four-pass operation, which the device lengthens the air flow channel and increases the air mass flow rate within the collector, and thus, a more heat transfer efficiency is obtained. Four recycling types with different external-recycle patterns were introduced and expected to augment the heat transfer rate due to the turbulent convective intensity through four subchannels in the present study. Coupling energy balances into one-dimensional modeling equations were derived by making the energy-flow diagram within a finite element, which the longitudinal temperature distributions for each subchannel were obtained. The theoretical predictions show that the improved four-pass device is accomplished due to the multiple heating pathways over and under the absorber plate, from which the turbulence intensity augmentation results in the heat transfer rate as compared to that in the device without inserting the absorber plate and insulation sheet (say a downward-type single-pass solar air collector). The theoretical results also show that the external-recycle configuration (say Type C in the present study) acts as an optimal collector thermal efficiency and leading to a beneficial design in multi-pass solar air collectors for improving heat-transfer rate and increasing resident time under the same operation conditions. Theoretical predictions show a higher heat-transfer efficiency for the present recycling configurations up to a maximum 115% device enhancement in comparison to that of a single-pass device. Examination of implementing the absorber plate and insulation sheet on the heat-transfer efficiency enhancement as well as the hydraulic dissipated power increment were also delineated, and deliberated the suitable external-recycle configuration with respect to an economic consideration.

Keywords: thermal efficiency; four-pass operation; solar air collector; recycling operation; hydraulic dissipated power (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/1996-1073/16/6/2568/pdf (application/pdf)
https://www.mdpi.com/1996-1073/16/6/2568/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:16:y:2023:i:6:p:2568-:d:1091753

Access Statistics for this article

Energies is currently edited by Ms. Agatha Cao

More articles in Energies from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().