Do Dryers Use Forced Convection?

Food Dryers

• Food dryers dehydrate food to reduce its weight and increase its shelf life. Non-electric solar dryers and conventional ovens use a passive drying method that takes anywhere from several hours to several days. Electric countertop dryers or convection ovens speed the process by using forced air to hasten the drying.

Forced Convection

• Forced convection drying uses a fan to push air over the food. This ensures that the food is dried evenly and more quickly than it would be using a passive drying technique without a fan. This type of drying is needed if you live in a humid area, because the level of moisture in the air may prevent food from drying quickly enough to inhibit mold formation. If you live in a hot, arid region, you likely will not need a forced convection dryer. Forced convection is used to dry foods indirectly and directly.

Direct Drying

• The most basic solar dryers use a direct method for removing moisture from the food. These basic dryers might be no more than a mesh screen placed out in the sun. Direct exposure to the sun will slowly dry the food, but add a fan and you have a faster, forced convection dryer. If using direct drying for your garden harvest, secure the food in place between a pair of mesh screens before directing the air flow from a fan. This will keep the food from being blown away.

Indirect Drying

• Indirect drying takes place away from direct sunlight, instead using the sun to warm the inside of a solar oven. Fans moving air around the inside of the oven help dry the food. Without heating the air or using a fan, drying the food will take longer. At home, you can place a fan inside a solar oven along with the food you are drying as an energy-free alternative to the convection oven in your kitchen.