Introduction to Advanced Drying Equipment and Methods

Desiccant dehumidifiers remove moisture from air through adsorption — the chemical attraction of moisture to the desiccant material in the rotating drum — rather than the condensation process used by refrigerant systems. This difference makes desiccants effective across a far wider temperature and humidity range.

How desiccant systems work: air from the drying environment passes through the desiccant rotor, which contains a hygroscopic material (typically silica gel or lithium chloride impregnated into a cellular matrix). The desiccant material adsorbs moisture from the process air stream. The rotor then moves into the regeneration zone where a separate heated air stream drives the adsorbed moisture off the desiccant and exhausts it outside the building. The regenerated desiccant rotates back into the process air stream, ready to adsorb more moisture.

Performance advantages: desiccant systems maintain effective moisture removal at temperatures down to minus 20 degrees Celsius and can achieve interior RH levels below 10 per cent — performance levels that are not achievable with refrigerant systems. On Australian restoration jobs, desiccant systems are most commonly deployed in cold-climate winter losses, in large commercial losses requiring very rapid moisture removal, and in situations requiring very low RH for specialty drying applications such as heritage timber or industrial equipment.

Sizing desiccant systems: desiccant capacity is measured in kilograms of moisture removed per hour at standard conditions. For large commercial losses, trailer-mounted desiccant systems with very high capacity are available from specialty equipment suppliers. Coordinate delivery, placement, and setup of large desiccant systems before other equipment deployment, as they determine the air management strategy for the entire project.

Setup considerations: desiccant systems require a exhaust duct to remove the regeneration air stream outside the building. The exhaust air is hot and humid — it must be directed well clear of building openings to prevent re-entry. The process air inlet must draw from the highest-humidity zone in the drying environment to maximise removal efficiency.