Experimental investigation of thermal efficiency, heat losses, and economic feasibility of glazed and unglazed solar air heaters
This study presents an experimental evaluation of the thermal performance of glazed and unglazed solar air heaters with dimensions of 114 cm × 109 cm × 8 cm, mounted at a 39° tilt to optimize solar gain during winter. Both collectors were equipped with seven transverse perforated absorber plates to...
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| Main Author: | |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-09-01
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| Series: | Results in Engineering |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2590123025020766 |
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| Summary: | This study presents an experimental evaluation of the thermal performance of glazed and unglazed solar air heaters with dimensions of 114 cm × 109 cm × 8 cm, mounted at a 39° tilt to optimize solar gain during winter. Both collectors were equipped with seven transverse perforated absorber plates to enhance thermal exchange. Experiments were conducted under clear-sky conditions from March 14 to 18, 2024, across five airflow rates ranging from 0.017 to 0.035 kg/s. The peak solar irradiance recorded was 988 W/m², and the highest inlet temperature reached 21 °C at an airflow rate of 0.022 kg/s. At the lowest flow rate (0.017 kg/s), the glazed unit achieved a maximum outlet temperature of 50.4 °C and a temperature rise (ΔT) of 28.5 °C, while the unglazed unit recorded 45 °C and 23 °C, respectively. The ΔT closely followed the solar intensity profile, peaking at midday and declining thereafter. Thermal efficiency increased with airflow rate, ranging from 41 % to 60 % for the glazed collector and 33 % to 44 % for the unglazed. The maximum useful heat gains were 476 W/m² and 354 W/m², respectively. The total useful energy collected was 4.46 MJ, decreasing to 3.16 MJ after accounting for cover losses. Pressure drop analysis indicated minimal resistance at lower flow rates. The system met the estimated 2.79 MJ heat load needed to raise a 210 m³ room by 10 °C. These findings confirm the superior performance of the glazed collector and support the application of solar air heaters as efficient winter heating solutions. |
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| ISSN: | 2590-1230 |