Investigation on surface drying and energy savings of the hybrid dryer

The feasibility study of a novel heat pump integrated with rotary dehumidifier (desiccant wheel) system for drying process is conducted to obtain the design parameters of the hybrid dryer. The system employed a refrigerant circuit in conjunction with a heat reactivated desiccant wheel to provide efficient drying capability and supply low dew point temperature (DPT) conditions. To increase the economic practicality of such a hybrid system, the combined system utilises the heat dissipated by the condenser heat energy in regenerating the desiccant wheel. The study shows that the proposed hybrid system can deliver supply air at much lower DPT compared to the single refrigerant circuit and a desiccant wheel. By operating the combined system in tandem, greater amount of dehumidification could be realised when the ratio of latent to total load at the hybrid system was improved. Up to 60% heat energy can be saved in rapid surface drying applications by using the proposed hybrid system.