Resumen
Artificial roughness applied to a Solar Air Heater (SAH) absorber plate is a popular technique for increasing its total thermal efficiency (????-??h
?
t
-
t
h
). In this paper, the influence of geometrical parameters of V-down ribs attached below the corrugated absorbing plate of a SAH on the ????-??h
?
t
-
t
h
was examined. The impacts of key roughness parameters, including relative pitch ??/??
p
/
e
(6?12), relative height ??/??
e
/
D
(0.019?0.043), angles of attack ??
a
(30?75°), and Re (1000?20,000), were examined under real weather conditions. The SAH ????-??h
?
t
-
t
h
roughened by V-down ribs was predicted using an in-house developed conjugate heat-transfer numerical model. The maximum SAH ????-??h
?
t
-
t
h
was shown to be 78.8% as predicted under the steady-state conditions of Re = 20,000, solar irradiance G = 1000 W/m2, p/e = 8, e/D = 0.043, and a = 60. The result was 15.7% greater efficiency compared to the default smooth surface. Under real weather conditions, the ????-??h
?
t
-
t
h
of the roughened SAH with single- and double-glass covers were 17.7 and 20.1%, respectively, which were higher than those of the smooth SAH.