Chinese yam drying can be divided into three stages: warming stage, constant speed drying and moisture removal stage, speed reducing and shaping stage.
1.Warming stage: Put those sliced Chinese yam on the drying shelf horizontally and send them to the drying room. Start up the heat pump dryer in order to deliver hotair into cabinet gradually. When the cabinet temperature reaches 50℃, Keep heating for 30 minutes to 1.5 hours. Afterwards, start to dehumidify when the humidity increases. When dehumidifying, it can keep constant temperature state if the LanGuan brand heat pump integrated drying and dehumidifying machine is applied.
2.Constant speed drying and moisture removal stage: It should be divided into two phases, namely high humidity, low temperature phase and medium humidity, medium temperature phase. For the high humidity, low temperature phase, the exact temperature range should be 40℃ to 50℃ and time should be 3 to 3.5 hours. In this way, the yam color will not be influenced by high temperature and high humidity.Besides, in this phase, the yam should be dehumidified by observing the surface water vapor change. As for medium humidity, medium temperature phase, the exact temperature range should 50℃ to 60℃. The fresh air should be sent for dehumidifying and be adjusted according to humidity.
3.Speed reducing and shaping stage: This stage can be also named as low humidity, high temperature phase whose temperature should be 60℃ to 70℃ and the time should be 5- 7 hours. It must not pass 70℃ for the early stage and also it should not pass 75℃ for the later stage.