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The time constant for drying a 1-inch-thick (25 mm) red oak board at 150 °F is then = days, which is the time required to reduce the moisture content to 1/e = 37% of its initial deviation from equilibrium.
In some products having a relatively high initial moisture content, an initial linear reduction of the average product moisture content as a function of time may be observed for a limited time, often known as a "constant drying rate period". Usually, in this period, it is surface moisture outside individual particles that is being removed.
The final moisture content for drying must be adequate for storage. The more oil the grain has, the lower its storage moisture content will be (though its initial moisture for drying will also be lower). Cereals are often dried to 14% w/w, while oilseeds, to 12.5% (soybeans), 8% (sunflower) and 9% (peanuts).
The oven-dry method requires drying a sample (of soil, wood, etc.) in a special oven or kiln and checking the sample weight at regular time intervals. When the drying process is complete, the sample's weight is compared to its weight before drying, and the difference is used to calculate the sample's original moisture content.
The moisture content of grains is an essential property in food storage. The moisture content that is safe for long-term storage is 12% for corn, sorghum, rice and wheat and 11% for soybean [1] At a constant relative humidity of air, the EMC will drop by about 0.5% for every increase of 10 °C air temperature. [2]
Moisture dew point is the temperature at which moisture condenses out of a gas. This parameter is inherently related to the moisture content, which defines the amount of water molecules as a fraction of the total. Both can be used as a measure of the amount of moisture in a gas and one can be calculated from the other fairly accurately.
Freeze-drying causes less damage to the substance than other dehydration methods using higher temperatures. Nutrient factors that are sensitive to heat are lost less in the process as compared to the processes incorporating heat treatment for drying purposes. [2] Freeze-drying does not usually cause shrinkage or toughening of the material being ...
Benzophenone is often used to generate such a soluble drying agent. An advantage to this application is the intense blue color of the ketyl radical anion. Thus, sodium/benzophenone can be used as an indicator of air-free and moisture-free conditions in the purification of solvents by distillation. [6] [7]