A closet dehumidifier is designed to absorb moisture from enclosed spaces, which in turn protects clothing and other valuables from the effects of mold and mildew. Closets being what they are rarely have any form of ventilation or airflow through them. Even though you may think you there is no damp problem, it only takes a bed sheet or garments that are not quite dry to cause problems with mustiness from the stagnant air.
airflow
Room air conditioners are small-sized units that are completely self-contained and are intended for use in just a single room. Most frequently, you will see these small air conditioners mounted in window openings and occasionally they are seen installed through an opening in an exterior wall. They must have the back portion of the unit installed so that it has clear access to the out-of-doors for airflow, in order to work correctly.