<p>A dryer for particulate material combines the drying effect of a stream of heated gas circulated by a blower in a closed duct system with that of a radiator structure which is in the drying chamber and is an a heat pump circuit. The condenser of the heat pump circuit is in the duct system where it condenses moisture from the gas which has passed through the particulate material. The heat pump compressor is driven by an internal combustion engine which is in a compartment in heat exchange relationship with the duct system. The engine cooling system radiator is immediately downstream from the condensor and the engine exhaust system includes a heat exchanger which is in the duct downstream from the engine cooling radiator.</p>
