There are two main types of commercial dehumidifiers, refrigerant (also known as mechanical) dehumidifiers and desiccant dehumidifiers. Both remove moisture from the air and lower humidity but do so in quite different ways, which frequently determines when you should use one instead of the other.
Commercial desiccant dehumidifiers performs exceptionally well when used in cooler temperatures, or when a low dew point is required. As there is no actual water produced during the process, these units can work effectively at sub-zero temperatures. In comparison commercial refrigerant dehumidifiers are more economical at higher temperatures i.e. 20°C.