**4.3 Photos and drawings of the opaque houses in detail**

In order to compare two opaque houses being tested, the details of the relevant parameters, in depth in drawings are presented with Photo1 and Photo 2, and in Figs.9 and 10. The actual scheme on the "South-North model" of the opaque house and its outside view when loading the stacked lumber on a trolley in Fig.9, and Photo 1, and that of the "East-West model" with its front view of the opaque house in Fig. 10 and Photo 2 respectively. Fig.9 and Fig.10 are the complete formation, dimensions and arrangements of the parts and so on, as shown by the drawings of the front picture and the plan picture in detail of the actual opaque houses, "South-North model" and "East-West model" respectively. In Fig.9, the "South-North model" has one set of two fan-convectors involving a fin-tube heater and a small fan (50 W×2)on the east floor of the house, and one set of four small fans (25 W×4) on the ceiling on the west side, and the same sort of parts and the same numbers as those are on the opposite floor and ceiling. Those two groups of each set are intermittently operated in the opposite direction in half a day in order to circulate uniformly the inside air as a breeze. In Fig.10, the "East-West model" has only one set of two fan-convectors (50 W×2 each) on the south floor of the house, and only one set of four small fans (25 W×4) on the ceiling part on the north side. Moreover, a floor heater (feed pump; 25 W×2) is molded in the black concrete floor, and we can see the stacked lumber (net volume 10 m3 in max.) in the central part of both houses. The small fan circulates slowly the inside air of the opaque house to increase the drying speed and to dry lumber uniformly. Hence, air speed of 0.2m/sec between the lumbers is sufficient due to the inside of the opaque house is filled with infrared radiation beam. While, the fan-cons and the floor heater contribute to heat supply for drying auxiliary, however, in summer season or in good weather conditions both auxiliary heats are not necessary.

Photo 1. A Fully Passive Solar Lumber Drying House Loading Larch Lumber (2x4 material); (South-North model)

Fig. 9. A Fully Passive Solar Lumber Drying House (South-North model)

Photo 2. Front View of A Fully Passive-type Soalr Lumber Drying House; (East-West model)

Fig. 9. A Fully Passive Solar Lumber Drying House (South-North model)

Photo 2. Front View of A Fully Passive-type Soalr Lumber Drying House; (East-West model)

Fig. 10. A Fully Passive Solar Lumber Drying House (East-West model)

#### **4.4 Hourly variation of S. R. incidence and solar heat collected, and the others**

Fig. 11 shows hourly variations of volumetric S. R. incidence and volumetric solar heat collected over all the opaque house of "South-North model", after obtaining the hourly S. R. incidence on the tilt surface, such as a roof surface and every vertical wall surfaces, applying the normal calculation method to the actual S. R. measurements at the proving test site. In Fig.11, lumber drying test period of fourteen days, between Feb. 19th~Mar. 4th,'/07, in early spring, is a representative graph of several data; two day's graphs on Feb.23rd (cloudy day) and 24th (fine day) are shown. From this Figure, we can see hourly variation of S. R. incidence on each surface, volumetric S. R. incidence I(H)VI kJ/h , volumetric solar heat collected qVC kJ/h and air velocity in insulated cylinder Ve×0.1m/s.

Fig. 11. Hourly variation of the measurement of volumetric S. R. incidence upon each surface and volumetric solar heat collected on cloudy day (23rd) and fine day (24th)

Fig.12 shows hourly variation of all the measured quantities inside and outside the "South-North model" on every day, during the fourteen days of the proving test. Where, To is outside temperature ºC, Ti is inside temperature ºC, Ho is outside humidity %, Hi is inside humidity %, I(H)HT is horizontal total S.R. incidence kJ/m2h, Ve is air velocity ×0.1m/s in an insulated cylinder. Outside temperature changes between -20~0 ºC every day, while the outside humidity changes inversely between 40~90 % every day. Inside temperature changes between 35~40 ºC, with average value going slightly up near the end of drying period. Inside humidity is 40~45 % initially, however, with progress of lumber drying it gradually goes down to about 10 % near the end with varying wavy. Fig.13 shows the estimated efficiency of volumetric solar heat collected ηVC of "South-North model" and "East-West model" transferred from Fig.6 and Fig.8. The ηVC obtained by the normal calculation method, substituting the measured results of five proving tests during one year, from the first test in Oct. 31st~Nov. 15th/'06 to the fifth test in Aug. 16th~30th/'07 were plotted on the same figure for easy comparison of the quantities. The ηVC of "East-West model" is a little greater than that of "South-North model". Moreover, on the former a coincidence between the estimated value and the measured one can be seen. The yearly average estimated value of 140 % for "South-North model" is nearly equal to 141 % of "East-West model", but on the measured value of 157 % for the former, is always greater than 125 % of the latter. However, if several simplifications on the calculation process, and characteristics of the field test were considered, these numerical differences could be negligible.

Fig. 11. Hourly variation of the measurement of volumetric S. R. incidence upon each surface and volumetric solar heat collected on cloudy day (23rd) and fine day (24th)

negligible.

Fig.12 shows hourly variation of all the measured quantities inside and outside the "South-North model" on every day, during the fourteen days of the proving test. Where, To is outside temperature ºC, Ti is inside temperature ºC, Ho is outside humidity %, Hi is inside humidity %, I(H)HT is horizontal total S.R. incidence kJ/m2h, Ve is air velocity ×0.1m/s in an insulated cylinder. Outside temperature changes between -20~0 ºC every day, while the outside humidity changes inversely between 40~90 % every day. Inside temperature changes between 35~40 ºC, with average value going slightly up near the end of drying period. Inside humidity is 40~45 % initially, however, with progress of lumber drying it gradually goes down to about 10 % near the end with varying wavy. Fig.13 shows the estimated efficiency of volumetric solar heat collected ηVC of "South-North model" and "East-West model" transferred from Fig.6 and Fig.8. The ηVC obtained by the normal calculation method, substituting the measured results of five proving tests during one year, from the first test in Oct. 31st~Nov. 15th/'06 to the fifth test in Aug. 16th~30th/'07 were plotted on the same figure for easy comparison of the quantities. The ηVC of "East-West model" is a little greater than that of "South-North model". Moreover, on the former a coincidence between the estimated value and the measured one can be seen. The yearly average estimated value of 140 % for "South-North model" is nearly equal to 141 % of "East-West model", but on the measured value of 157 % for the former, is always greater than 125 % of the latter. However, if several simplifications on the calculation process, and characteristics of the field test were considered, these numerical differences could be

Fig. 12. Daily Variation on Main Data Inside and Outside the Solar Lumber Drying

Fig. 13. Comparison betweeen the Estimation and the Measurements of Efficiency of Volumetric Solar Heat Collection ηvc

Where, ηVC of the "East-West model" appears always to be greater than that of "South-North model", the reason is due to the fact that calculation assumed for the former that the roof surface is 10° tilted toward south as shown in Fig.7, while for the latter, that the surface is horizontal. Table 3 shows the averages of the measurements picked from Fig.10, and the other, from the initial two days and final two days. The difference of air density between the inside and outside of the opaque house, results in the difference of pressure between the inside and outside of the house. As a result, the negative pressure Fd in the insulated cylinder induced by Eq.(7) is a function of the difference of air density γ and the height of insulated cylinder h. The height of the insulated cylinder is 5.0 m and diameter is 300 mm.

$$F\_d = h(\chi\_o - \chi\_i) \times 9.8 \text{ P}\_a \tag{7}$$

where, (γo-γi) is the density difference between inside and outside of the house in kg/m3.


Table 3. Experimental Results on the 2nd Drying Test around a Winter Solstice (Dec. 13th~28th/'06)

The draft force is induced in the insulated cylinder as shown in Fig.12, air velocity in the insulated cylinder goes up over 1m/s when the inside temperature goes up in daytime, and goes down less than 1m/s when the inside temperature goes down at night. Table 3 also specially shows the important results in comparing the opaque houses with each other with their data measured around the winter solstice. The results of the fourth drying test (Feb. 19th~Mar. 4th/'07), in Fig.14, shows the performance factors of both "South-North" and "East-west" by a bar chart graph. S. R. incidence on a floor area of the opaque house, measured at the proving test site, the efficiency of volumetric solar heat collected ηVC estimated from the database in March was 140 % for "South-North model"; it was nearly equal to ηVC=148%. Thus, the differences in performance factors between "South-North model" and "East-West model" are caused by the fact that the former is a prediction estimated from the past statistics weather data and the latter is that given from a normal calculations using S. R. measured.

Similarly, based on S. R. incidence on the floor area of the opaque house, efficiency of volumetric solar heat collection ηVI is 232.4 % for "South-North model" and 294.8 % for "East-West model". The fact that "East-West model" 's efficiency is always larger than that of "South-North model" is caused by assuming that the roof surface of "East-West model" is tilted 10° toward south as described above. Fig.15 (Koga, S., et al. Oct., 2007) shows the result of drying test of larch lumber (2×4 material). Size of the specimen of lumber is 50 mm D×100 mm W×3,650 mm L and number of the specimen is 441 pieces, so that net volume of the stacked lumber is 8 m3. In general, net volume 10m3 of the lumber can be loaded in the opaque house. Larch lumber with initial moisture content 40 % (D.B.) was dried out less than 10% in two weeks, however, the other results of "South-North mode" and "East-West model" are about same with each other. In the case an auxiliary heat was supplied, the solar heat fractions were about same, 30 % in both cases. In summer, lumber drying by only solar heat is capable of drying out less than 20 % within two weeks, during which the solar heat fraction is 100 %. (Koga, S., et al., Oct., 2008)

South-North model

36.7℃/13.0 %

21.8 GJ

3.6 GJ

11.2 %

1010 kg

37%→9 % (D.B.)


166 % 208 %

16.4 % 18.3 %

37.0℃ /14.0 %

East-West model

4.3 GJ

23.6 GJ

980 kg

38%→10 % (D.B.)

10.1 %

Table 3. Experimental Results on the 2nd Drying Test around a Winter Solstice

The draft force is induced in the insulated cylinder as shown in Fig.12, air velocity in the insulated cylinder goes up over 1m/s when the inside temperature goes up in daytime, and goes down less than 1m/s when the inside temperature goes down at night. Table 3 also specially shows the important results in comparing the opaque houses with each other with their data measured around the winter solstice. The results of the fourth drying test (Feb. 19th~Mar. 4th/'07), in Fig.14, shows the performance factors of both "South-North" and "East-west" by a bar chart graph. S. R. incidence on a floor area of the opaque house, measured at the proving test site, the efficiency of volumetric solar heat collected ηVC estimated from the database in March was 140 % for "South-North model"; it was nearly equal to ηVC=148%. Thus, the differences in performance factors between "South-North model" and "East-West model" are caused by the fact that the former is a prediction estimated from the past statistics weather data and the latter is that given from a normal

Similarly, based on S. R. incidence on the floor area of the opaque house, efficiency of volumetric solar heat collection ηVI is 232.4 % for "South-North model" and 294.8 % for "East-West model". The fact that "East-West model" 's efficiency is always larger than that of "South-North model" is caused by assuming that the roof surface of "East-West model" is tilted 10° toward south as described above. Fig.15 (Koga, S., et al. Oct., 2007) shows the result of drying test of larch lumber (2×4 material). Size of the specimen of lumber is 50 mm D×100 mm W×3,650 mm L and number of the specimen is 441 pieces, so that net volume of the stacked lumber is 8 m3. In general, net volume 10m3 of the lumber can be loaded in the opaque house. Larch lumber with initial moisture content 40 % (D.B.) was dried out less than 10% in two weeks, however, the other results of "South-North mode" and "East-West model" are about same with each other. In the case an auxiliary heat was supplied, the solar heat fractions were about same, 30 % in both cases. In summer, lumber drying by only solar heat is capable of drying out less than 20 % within two weeks, during which the solar heat

(Dec. 13th~28th/'06)

Outside Temp. To / Outside Humid. Ho Inside Temp. Ti / Inside Humid. Hi

Items

Efficiency of Volumetric Solar Heat

Volumetric Solar Heat Collected Qvc

Total Heat Input Qin

Solar Heat Fraction Fs

Water Evaporated We v

Rate of Evaporation Heat Rev

Decreas of Moisture Contents ΔMc

Collection ηvc

calculations using S. R. measured.

fraction is 100 %. (Koga, S., et al., Oct., 2008)

Fig. 14. Performance factor on Solar Lumber Drying Test; Feb. 19th~Mar. 4th (2007)

Fig. 15. Comparison of Drying Speed between South-North model & East-West model
