The 787 has this "zonal drying" system, made by CTT Systems AB of Sweden:
The system effectively removes moisture using established industrial technology. The system takes air from the crown area or cargo area and feeds it though zonal dryer units between the cabin and the outer skin of the aircraft using a specially designed piccolo duct. This lowers the dew point in the crown area preventing the condensation process from occurring, thus keeping the insulation blankets dry.
Depending on aircraft type, the Zonal Drying™ System consists of one or more zonal dryer units installed at strategic points in the aircraft. Each unit features a slow-moving rotor impregnated with silica gel.
The Zonal Drying™ System is standard equipment on Boeing 787 "Dreamliner" and furthermore available as BFE option on Boeing 737NG.
CTT Systems