Читать книгу Osmosis: The Molecular Theory - Larry Howlett - Страница 12

We next examine storage in hermetic container using the seed vapor pressure model. This model is shown in figure 4. The properties of seed and atmosphere using the vapor pressure model are shown in table 2.

The initial seed properties from figure 4 and atmosphere properties are: (S1 – S4 & A1 – A5) Note that we used the seed vapor pressure to determine the atmosphere relative humidity from psychrometric data

Next we define a one cubic foot volume of seed and one cubic foot volume of atmosphere within the within the hermetic container. As in our macro model for hermetic containers, the mass of seed and seed moisture content is much greater that the mass of dry air and moisture in the air. Data is shown as (S5 – S7 & A6 – A9)

We now raise the storage temperature to 90°F. From figure 4, we find that the seed vapor pressure rises to 0.47 psia from psychrometric data, the atmosphere with in the hermetic container must be at 67% relative humidity to for equilibrium between the seed and its local atmosphere. At 90ºF and 0.47 psia vapor pressure, the final data is (S8 – S10 & A10 – A14).

Again, we find that the total moisture in the local atmosphere is very small compared to the total moisture in the seed. Note that the total mass of dry air does not change within the hermetic container. The total moisture content of the air at 90 F is very small. Therefore, the seed moisture content must remain practically constant. We reach the same conclusion. Changing storage temperature and the resulting changed moisture content of the air has a very small effect on the moisture content of the seed. Thus, the change in equilibrium conditions from 50°F to 90°F storing temperature creates a negligible change in moisture content of the air and moisture content in the seed.