**4.1 Volumetric solar heat collected by a normal calculation method**

Applying the authors' separation method (Baba, H., Kanayama, K., July, 1985) for directscattered components of S. R. incidence, volumetric S. R. incidence on the opaque house can be calculated, and then the volumetric solar heat collected QVC can be obtained. This calculation process is fairly complicated, therefore, only an outline of the method will be given as follows: As shown in the left part of Fig.3, assuming tilt angle θn° and azimuth angle an° on a tilt surface An respectively, the volumetric S. R. incidence I(H)VI upon an opaque house, can be calculated by multiplying S. R. incidence I(θn, an) by each tilt surface An of simplified model in the right part of Fig.3 and summing up all of each product An・I(θn, an), n=1,2 ・・・n. Therefore, using the same method , on the actual model of the opaque house, volumetric S. R. incidence upon the opaque house I(H)VI can be calculated by Eq.(2), and the volumetric S. R. incidence I(Q)VI, and volumetric solar heat collected QVC of the actual opaque houses in Fig.5 and Fig.7, can be obtained.

$$I(H)\_{VI} = A\_{\tau f} I(\theta\_{\tau f}, a\_{\tau f}) + A\_{w\epsilon} I(\90, -\theta0) + A\_{ws} I(\90, 0) + A\_{ww} I(\90, \theta0) + A\_{wn} I(\90, -180) \tag{2}$$

where, the first term, ‥‥, and the fifth term of the right hand of Eq. (2), indicate the S. R. incident on the roof surface, on the east wall surface, on the south wall surface, on the west wall surface and on the north wall surface respectively. Where, I(H)VI is volumetric S. R. incidence in kJ/h, I(θ, a) is S. R. incidence on the tilt surface with setting angles (θ, a) in kJ/m2h. Arf is roof area m2, Awe is east wall area m2, Aws is south wall area m2, Aww is west wall area m2, and Awn is north wall area m2. Now, the S. R. incidence I(θ, a) on a tilt surface Atilt with setting angle (θ, a) can be calculated from Eq.(3) by substituting Eqs. (4)~(6).

$$I(\theta, a) = I\_{\rm ND} \cos i + I\_{\rm SC} \frac{(1 + \cos \theta)}{2} + \rho\_g I\_{\rm HT} \frac{(1 - \cos \theta)}{2} \tag{3}$$

where, IND is the direct S. R. incidence kJ/m2h, ISC is the scattering S. R. incidence kJ/m2h, IHT is the horizontal total S. R. incidence kJ/m2h, *ρ*g is the reflectance of the earth, i is the incidence angle between incident ray and the normal to the tilt surface. By integrating Eq.(2) from sunrise time to sunset time, we obtained the volumetric S. R. incidence on a tilt surface par day.

$$\cos i = \sin h \cos \theta + \sin \theta \cosh \cos(A - a) \tag{4}$$

$$
\sin \delta t = \sin \phi \sin \delta + \cos \phi \cos \delta \cos t \tag{5}
$$

$$
\sin A = \cos \theta \sin t \,/\cos h \tag{6}
$$

where, h is the solar altitude angle °, A is the solar azimuth angle °, t is solar time in °, φ is the latitude of the site in °, δ is solar declination angle in°.

By the way, the normal calculation method was utilized to calculate the efficiency of volumetric solar heat collection ηVC using the real measurements of S. R. incidence at the proving test site; Ashoro, and the results obtained were plotted in Fig.13.

#### **4.2 Solar radiation (S. R.) incidence on each surface, volumetric S. R. incidence and volumetric solar heat collected**

A fully passive-type solar lumber drying house has the peculiar characteristics that not only S. R. incidence upon a roof surface, but also the S. R. incidence upon the wall surfaces around the opaque house can be utilized as solar heat collected. Fig.5 shows the calculation schemes of the "South-North model" of the opaque house. (floor area 25.0 m2 (=5.0 m×5.0 m), height 3.4 m).

First, using Eq.(3) the S. R. incidence on the roof surface, and on each vertical wall, with every azimuth angle is calculated , and thus the volumetric S. R. incidence I(H)VI is determined by summing up the S. R. incidence upon each surface, and after substituting into Eq.(2) and integrating with the sun shine hour, volumetric S. R. incidence I(Q)VI overall the opaque house can be determined. The volumetric solar heat collected QVC, can be determined as the product of I(Q)VI and (τ・α)CS[=0.6]. Where, the roof surface of the Quonset hut is assumed to be a horizontal flat surface for simplification. However, Fig.6 shows the performance factors on the "South-North model" with data table calculated by

( ) ( , ) (90, 90) (90,0) (90,90) (90, 180) *VI rf rf rf we ws ww wn IH A I a A I A I A I A I*

where, the first term, ‥‥, and the fifth term of the right hand of Eq. (2), indicate the S. R. incident on the roof surface, on the east wall surface, on the south wall surface, on the west wall surface and on the north wall surface respectively. Where, I(H)VI is volumetric S. R. incidence in kJ/h, I(θ, a) is S. R. incidence on the tilt surface with setting angles (θ, a) in kJ/m2h. Arf is roof area m2, Awe is east wall area m2, Aws is south wall area m2, Aww is west wall area m2, and Awn is north wall area m2. Now, the S. R. incidence I(θ, a) on a tilt surface Atilt

(1 cos ) (1 cos ) ( , ) cos 2 2 *ND SC g HT I a I iI <sup>I</sup>*

where, IND is the direct S. R. incidence kJ/m2h, ISC is the scattering S. R. incidence kJ/m2h, IHT is the horizontal total S. R. incidence kJ/m2h, *ρ*g is the reflectance of the earth, i is the incidence angle between incident ray and the normal to the tilt surface. By integrating Eq.(2) from sunrise time to sunset time, we obtained the volumetric S. R. incidence on a tilt surface

> cos sin cos sin cosh cos( ) *i h*

sin sin sin cos cos cos *h t* 

> sin cos sin / cos *A*

where, h is the solar altitude angle °, A is the solar azimuth angle °, t is solar time in °, φ is

By the way, the normal calculation method was utilized to calculate the efficiency of volumetric solar heat collection ηVC using the real measurements of S. R. incidence at the

**4.2 Solar radiation (S. R.) incidence on each surface, volumetric S. R. incidence and** 

A fully passive-type solar lumber drying house has the peculiar characteristics that not only S. R. incidence upon a roof surface, but also the S. R. incidence upon the wall surfaces around the opaque house can be utilized as solar heat collected. Fig.5 shows the calculation schemes of the "South-North model" of the opaque house. (floor area 25.0 m2 (=5.0 m×5.0 m), height 3.4 m). First, using Eq.(3) the S. R. incidence on the roof surface, and on each vertical wall, with every azimuth angle is calculated , and thus the volumetric S. R. incidence I(H)VI is determined by summing up the S. R. incidence upon each surface, and after substituting into Eq.(2) and integrating with the sun shine hour, volumetric S. R. incidence I(Q)VI overall the opaque house can be determined. The volumetric solar heat collected QVC, can be determined as the product of I(Q)VI and (τ・α)CS[=0.6]. Where, the roof surface of the Quonset hut is assumed to be a horizontal flat surface for simplification. However, Fig.6 shows the performance factors on the "South-North model" with data table calculated by

 

> 

 

(3)

*A a* (4)

*t h* (6)

(5)

with setting angle (θ, a) can be calculated from Eq.(3) by substituting Eqs. (4)~(6).

(2)

the latitude of the site in °, δ is solar declination angle in°.

**volumetric solar heat collected** 

proving test site; Ashoro, and the results obtained were plotted in Fig.13.

par day.

the conventional calculation method, using the database of S. R. incidence at the proving test. Also in the same way Fig.7 shows the calculation scheme for the "East-West model", and also Fig.8 is the results on the "East-West model" with data table of the performance factors calculated by the conventional calculation method, using the database as above.
