Dehumidification Application
The choice for desiccant dehumidification ® ® Reg. TM Bry-Air (Asia) Pvt. Ltd.
D
ESICCANT
D
EHUMIDIFICATION IN
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NION
D
RYING
Bry-Air environmental control systems allow for consistent and quality products to be produced efficiently with dry air. Photo Courtesy of MCT Direct Photos
Dessicant Dehumidification - 59139 I
n the process of drying onions, a drying oven (such as a Proctor Schwartz) is commonly used in conjunction with a desiccant dehumidifying system. The
dehumidifier is usually applied in the final stage in which very dry air is required. If this drying were attempted only with heat, the onions would be damaged and unfit for consumption. The
dehumidifier supplies cooler, drier air which ensures that the onions will be dried without the damage associated with high temperatures. In most cases, 100% outside air is pre-cooled, dehumidified and delivered to the final stage (commonly known as the D-stage) at a condition of less than 100°F at 15 gr/lb or lower (approximately 4-7% RH). Storage Conditions In order to store onions for any length of time, it is necessary to keep them in a cool, dry environment. When humidity levels and temperatures are too high the onions may decay or begin to sprout. The ideal storage condition for onions is 32°F at a relative humidity of 65 - 70%. In order to maintain this temperature, the coil temperature will be well below freezing. A
desiccant dehumidifier can control the humidity and eliminate the need for defrost cycles, allowing the cooling system to maintain a steady temperature. These conditions will ensure that the onions remain dormant. Refrigerated storage is often used to hold onions for approximately six months. Onions to be kept in cold storage should be placed there immediately following the curing process. The temperature of 32° F will keep the onions dormant and free from decay, provided the onions are sound and properly cured prior to storage. Sprout growth can indicate that the’ storage temperature is too high, the bulbs are poorly cured or that they are immature bulbs. Root growth can indicate that the relative humidity is too high. Photo Courtesy of MCT Direct Photos
