Low-temperature drying allows foods such as fruit and vegetables to be dried without losing the original color and texture. The system of dehydrating consists of desiccant dehumidifier which removes the moisture from the air and increases its adsorption capacity. Airflow rate and regeneration temperature of the dehumidifier will be controlled to ensure minimal damage to the food during the drying process in comparison with tray drying. The fruit and vegetable dried with rotary desiccant bed dehumidifier has superior color, flavor and maximum retention of various nutrients.
The schematic of the desiccant dehumidifier is a device that removes moisture from air but do so without cooling the air below its dew point. In case of a desiccant dehumidifier, water vapor from a process stream of moist air adsorbs onto the surface of a desiccant material. Eventually, the desiccant material becomes saturated with water and must be regenerated through a drying process. In desiccant dehumidifier, the process and regeneration air streams operate at the same time and a wheel of desiccant material rotates between the streams. At any given time, a portion of the desiccant is being regenerated while the remainder is adsorbing water from the process stream. The regeneration air comes from the same source as the process air and is heated to lower its relative humidity. The process air enters the dehumidifier at a certain state (usually relatively cool and moist). As water adsorbs onto the desiccant, it gives up its heat of sorption, warming the surrounding air.
The process air leaves the dehumidifier drier and warmer than it entered. Desiccant dehumidifiers are quite different from cooling-based dehumidifiers. Instead of cooling the air to condense its moisture, desiccants attract moisture from the air by creating an area of low vapor pressure at the surface of the desiccant. The pressure exerted by the water in the air is higher, so the water molecules move from the air to the desiccant and the air is dehumidified. Dehumidifier consists of silica desiccant bed, fans and reactivation heater. Desiccant dehumidifier dry and increase the temperature of the process air which is further introduced in the dying chamber. The fans at both side (process and reactivation side), used to suck and blow the air. The reactivation takes place at reactivation side of the dehumidifier and the reactivation heater is used to heat the reactivation inlet air and then the hot air is used to regenerate the desiccant bed.
Rotary bed desiccant…