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.
Typical Application Environments
Heat recovery is valuable wherever a building or process expels warm, stale air while drawing in cold or hot fresh air. Common sites include factory make-up air systems, commercial kitchens, paint booths, drying rooms, laboratories, and cleanrooms. In each case the exhausted air still holds usable thermal energy, and capturing it reduces the heating or cooling demand placed on the primary plant.
Matching the Unit to the Duty
The right selection starts with the air volume, the temperature difference between streams, and the cleanliness of the exhaust. Clean, steady flows suit plate exchangers; humid or dusty exhaust may need a rotary wheel with purge or a unit arranged for easy wash-down. Pressure drop must stay within the fan curve, and the core material must resist any contaminants present in the airstream.
Integration Tips
For the Heat Exchanger for Heat Pump Drying duty, position the exchanger so the exhaust is filtered before it reaches the core, and provide condensate drainage where the supply side may drop below the dew point. Balanced supply and exhaust fans keep the building neutral in pressure, which protects indoor air quality and process control. A bypass damper lets the system free-cool in mild weather.
Frequently Asked Questions
Can it handle greasy kitchen air? Yes, with a rotary wheel and a wash cycle, though the exhaust should first pass a grease filter. Will it cause condensation? Some condensate is normal in winter; provide a drain or a defrost strategy on the supply side.
