15.07.2015   EuroSun2008-5

Efficiency test results

The collector was tested according to both steady state test (EN 12975-2;section 6.1) and dynamic test (EN 12975-2; section 6.3) methods. The corresponding characteristic parameters are presented in Table 1.

Table 1. Efficiency curve parameters after steady-state test results

Steady-state test parameters

Dynamic test parameters

По

ai

[W/°C. m2]

a2

[W/°C2.m2]

П)ь

Ci

[W/°C. m2]

C2

[W/°C2.m2]

C5

[J/kg°C]

Kd(0)

0.725

3.599

0.007

0.794

3.483

0.010

13647

0.725

Incidence angle modifier (IAM) values obtained, after both test methodologies, for longitudinal and transversal incidences are presented in Table 2.

Table 2. Steady-state and dynamic test results for transversal and longitudinal incidence angle modifier values

Test

0

10

15

20

25

30

35

40

50

60

Steady

Kt(0)

0.990

0.999

0.949

0.887

0.632

0.494

0.481

0.482

—

Ki(0)

—

—

—

—

—

—

0.957

—

0.853

Dynamic

Kt(0)

0.966

0.992

0.931

0.840

0.529

0.362

0.328

0.057

—

Ki(0)

—

—

—

—

—

—

0.991

—

0.781

Longitudinal and transversal IAM functions were constructed after 2-points based and linear approximations, respectively (Carvalho et al, 2007). The composed IAM, illustrated in figure 2, follows the McIntire (1983) approximation:

K(9) = K(9l,9t )* K(9l,0)K(0,9t) (8)

The weighted average hemispherical IAM, calculated according to Eq.(7), yields Kdfh =0.529.