Combined heat-pump and hot-air drying of dehydrated vegetables

In order to improve the drying efficiency of heat pump for dehydrated vegetables during the falling drying period, the combined experiment of heat-pump and hot-air drying was carried out. The experimental results showed that the energy consumption of combined drying, was 74.1%, 84.7% and 9.4% of that of tunnel drying, band drying and vacuum freeze drying, respectively. After the carrot products were rehydrated for 24 hours, the rehydration of combined drying was 16.6% and 24.5% higher than that of heat-pump drying and hot-air convective drying, respectively. Therefore, compared with the conventional heat-pump drying, the energy consumption of the combined drying is reduced and the product quality is also improved.