This dehumidifier from Hydrosorbent includes an inbuilt recharge indicator. The indicator is originally orange in color, but it turns itself apparent when it needs a reactivation. This humidity is drained out or collected in an inner tank though the dryer air is launched in the room. This process will work https://dstdehumidifiers.co.uk/case-studies/desiccant-dehumidifiers-in-cold-stores/