**4. Conclusions**

To confirm the impact of the arrangemen<sup>t</sup> of triangular shaped baffles fitted in an air-type PVT collector, the airflow characteristics in the collector was analyzed through a validated CFD model in this study. The heat transfer characteristics, pressure drop, and thermal efficiency of the collector were examined, and the results can be summarized as follows.


Based on the results of this study, it can be deduced that the thermal performance improvement according to the staggered arrangemen<sup>t</sup> spacing of triangular baffles in the air-type PVT collector was not significant, but it was advantageous in terms of heat transfer in the collector when the baffle spacing was even.

**Author Contributions:** Conceptualization, J.-S.Y., J.-T.K., and J.-H.K.; methodology, J.-H.K., and J.-S.Y.; software, J.-S.Y.; validation, J.-T.K., J.-H.K. and J.-S.Y.; formal analysis, J.-S.Y.; investigation, J.-H.K. and J.-S.Y.; resources, J.-T.K.; data curation, J.-H.K. and J.-S.Y.; writing—original draft preparation, J.-S.Y.; writing—review and editing, J.-T.K., J.-H.K. and J.-S.Y.; visualization, J.-T.K., J.-S.Y.; supervision, J.-T.K.; project administration, J.-S.Y.; funding acquisition, J.-T.K. and J.-H.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry and Energy (MOTIE) of the Republic of Korea, gran<sup>t</sup> number 20188550000480 and 20173010013420.

**Conflicts of Interest:** The authors declare no conflict of interest.
