Thermal Performance of Solar Air Heater Having Absorber Plate with V-Down Discrete Rib Roughness for Space-Heating Applications

Figure 6

Thermal efficiency of roughened solar air heater as function of temperature parameter (𝑇_𝑖−𝑇_𝑎)/𝐼 at 𝑇_𝑎=278 K (𝐿=2 m, 𝐻=10 mm, 𝑒/𝐷_ℎ=0.07, 𝜀_𝑝=0.95, 𝛽=45^∘, 𝑇_𝑖=295 K, ℎ_𝑤=5 W/m² K).