A linear equation (Eq. 3) that has a second order dependency on the suction velocity and the wind speed was used for modeling the efficiency of the experiment.

П = A(U) + B(U )VS + C(U )V2 (A = J a,, B = І b, and C = £ c,) (3)

i=0 i=0 /=0

where in Eq.3 q is the efficiency of perforated solar collector, Vs is the suction velocity and U is the wind speed. The parameters a; , b and c were determined by a least square method to minimize deviation of calculated efficiencies from experimental ones. The obtained parameters are listed in Table.4. These parameters are only valid within the experimental region of suction velocity and wind speed. The maximum and average absolute deviation of calculated efficiency was obtained by using the parameters a;, b and c and Eq.3.