Numerical simulation study on heat performance and pressure loss of solar air heater with sinusoidal baffles

Heat performance and internal pressure loss are important reference standards in solar air heaters (SAH). In order to solve the problem of too large a pressure loss in SAH, an innovative SAH with sinusoidal baffles was proposed on the basis of folded baffle and semi-circular baffle air heaters. A computational fluid dynamics (CFD) simulation calculation was performed for the SAH with sinusoidal baffles, and the relevant parameters, such as the heat collection efficiency and the pressure loss, were analyzed. The results showed that the sinusoidal baffle had a better heat collection performance and a smaller pressure loss compared to the folded baffle and the semi-circular baffle. A sinusoidal baffle can further improve the thermal performance of SAH. The simulation calculation of wave lengths for sinusoidal baffles revealed that when the wavelength value was 200 mm, the SAH had the best heat collection effect, and the heat collection efficiency was 64.49%. On the basis of determining the wavelength, the wave height of the sinusoidal baffle was studied. When the wave height was 30 mm, the minimum pressure loss of the SAH was 17.51 Pa, and the maximum heat collection efficiency was 64.91%. Analyses and research on the Reynolds number of the air inlet showed that as the Reynolds number increased, the collection efficiency and internal pressure loss gradually increased, while the outlet temperature decreased. The curve fitting of the imported Reynolds number and the pressure loss showed that the accuracy of pressure loss fitting curve is 0.997. Research on a double-layer SAH showed that the cross different inlet (CDI) had the best collector performance. This research has a high practicality and can provide a theoretical basis for winter air heating.