Closed-loop, low-temperature drying

Heat-pump drying uses a refrigerant cycle to heat and dehumidify air in a closed loop, which is far more efficient than venting hot air to atmosphere. Air-to-air exchangers inside the loop recover heat between the dehumidified supply and the humid return, raising the effective COP of the dryer.

Suitable exchanger types and how they work

A sensible plate exchanger between the dry supply and wet return air recovers the condenser’s heat before the air passes the evaporator again. Where two airstreams are separated by the cabinet, a heat pipe core moves energy with no moving parts. Counterflow plates give the highest recovery.

Design considerations for heat-pump loops

The airstream is humid and often slightly corrosive from process off-gassing, so specify corrosion-resistant, washable plates and condensate management. Keep pressure drop low to protect the refrigerant fans, and ensure the recovered heat is actually reused in the loop rather than dumped. Match the exchanger to the dryer’s operating temperature band.