The collector used inexpensive materials such as bamboo
slats and plastic cords, and was installed on open ground
instead on a rooftop. Thus, the investment cost was significantly
reduced compared to the steel‐frame collector used for
Vol. 52(4): 1255-1259 1257
Figure 4. SRA‐4B dryer with upward airflow.
Figure 5. SRA‐4B dryer with downward airflow, using solar heat.
Figure 6. At sunset, the coal furnace is fired.
the macaroni dryer. The solar collector and the coal furnace
can be used separately or in combination (fig. 6).
Tests were done at Long‐An Province in March 2007, the
driest month of the year. The MC was measured every hour
by a Korean‐made GMK‐303RS MC meter, which had been
calibrated against the drying oven. The airflow was obtained
by multiplying the drying bed area by the average superficial
velocity, measured by a rotameter at 30 points over the drying
bed. The rotameter had been calibrated by the orifice method
(Ower and Pankhurst, 1997).
The contribution of solar energy was examined by two calculations.
One calculation used the index product (Ip, °C・h),
which is the product of the temperature increase and the corresponding
heating time. The I p using solar energy was
compared to the total Ip using both coal and solar energy; the
ratio indicated the share of solar heat. The second calculation
considered the percentage saving of coal due to solar energy,
compared to the case in which only coal was used without solar
heat. Table 1 in the Results and Discussion section illustrates
these calculations.
The collector used inexpensive materials such as bamboo
slats and plastic cords, and was installed on open ground
instead on a rooftop. Thus, the investment cost was significantly
reduced compared to the steel‐frame collector used for
Vol. 52(4): 1255-1259 1257
Figure 4. SRA‐4B dryer with upward airflow.
Figure 5. SRA‐4B dryer with downward airflow, using solar heat.
Figure 6. At sunset, the coal furnace is fired.
the macaroni dryer. The solar collector and the coal furnace
can be used separately or in combination (fig. 6).
Tests were done at Long‐An Province in March 2007, the
driest month of the year. The MC was measured every hour
by a Korean‐made GMK‐303RS MC meter, which had been
calibrated against the drying oven. The airflow was obtained
by multiplying the drying bed area by the average superficial
velocity, measured by a rotameter at 30 points over the drying
bed. The rotameter had been calibrated by the orifice method
(Ower and Pankhurst, 1997).
The contribution of solar energy was examined by two calculations.
One calculation used the index product (Ip, °C・h),
which is the product of the temperature increase and the corresponding
heating time. The I p using solar energy was
compared to the total Ip using both coal and solar energy; the
ratio indicated the share of solar heat. The second calculation
considered the percentage saving of coal due to solar energy,
compared to the case in which only coal was used without solar
heat. Table 1 in the Results and Discussion section illustrates
these calculations.
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