Thermal-hydraulic performance evaluation of solar air heaters containing longitudinal vortex generators: review and meta-analysis

Author(s)

Pinto, Rodrigo Vidonscky ; Duarte, Rafael Modolo Dias ; Ferreira, Wallace Gusmao ; Dezan, Daniel Jonas

• Document type: Journal article
• Source: Journal of the Brazilian Society of Mechanical Sciences and Engineering; v. 47, n. 4, p. 20-pg., 2025-04-01.

Abstract

This comprehensive review explores the thermal-hydraulic performance enhancement obtained using various types of longitudinal vortex generators mounted on single-pass solar air heater channels. These generators include baffles, grooves/corrugations, protrusions/intrusions, ribs, tapes, winglets, wings, and combinations of these configurations. From the detailed literature review, there is a growing research interest in solar air heaters with longitudinal vortex generators, particularly in developing countries such as India and Thailand. The key characteristics of different types of solar air heaters with longitudinal vortex generators are systematically evaluated, including their modifications that result in high thermal-hydraulic performance. Overall, it is found that the highest heat transfer enhancements range from 1.83 to 8.00 for Reynolds numbers ranging from 12,000 to 30,000, with baffles reaching the highest enhancement values. From the meta-analysis, notable performances were obtained using delta-shaped wings and introducing geometry modifications, such as holes. Statistical analysis indicates an overall mean range of the thermal enhancement factor between 1.18 and 2.05, with baffles presenting the highest expected performance among all evaluated roughness geometries. Also, no clear trend of Reynolds number at which the maximum thermal-hydraulic performance is commonly achieved for every roughness geometry could be observed. For example, baffles show distant maximum values at Reynolds numbers between 2000-2500 and 30,000-35000. However, for winglets and combined types, the best performances are mostly observed at Reynolds numbers between 3500 and 5500. (AU)

• FAPESP's process: 22/12073-1 - Thermo-hydraulic and exergoeconomic optimization of solar air heaters mounted with louvered fins with potential application on Brazilian agrobusiness
• Grantee: Daniel Jonas Dezan
• Support Opportunities: Regular Research Grants