HEAT PUMP DRYERS: RESEARCH AND DEVELOPMENT NEEDS AND OPPORTUNITIES

ABSTRACT

As some previous research works on heat pump dryers (HPD) gave contradictory results, there is a need to review and identify R&D needs and opportunities in HPD. It was found that mathematical modeling cannot ignore the interdependence of the heat pump working fluid and the process air of the dryer. The performances of various HPD configurations with respect to all operating varibles need further investigation. A well defined mathematical model of combined dryer-drying material characteristic is required for the system modeling. The relative specific drying cost and relative useful energy were introduced as the dryer selection criteria. The role of the heat pump in the HPD system, CFC alternatives and non-conventional heat pump cycles using air or steam as working fluids deserve further investigation.

Key words and phases:

• Heat pump dryer
• Research needs
• Dryer performance
• CFC alternatives
• COP