1. Schmidt E L, Klocker K, Flacke N, et al. Applying the transcritical CO2 process to a drying heat pump. Int J Refrig, 1998, 21: 202–211
2. Strommen I, Eikevik T M, Alves-Filho O, et al. Low temperature drying with heat pumps new generations of high quality dried products. In: Proceedings of the 13th International Drying Symposium, 2002
3. Claussen I C, Ustad T S, Strommen I, et al. Atmospheric freeze drying — a review. Dry Technol, 2007, 25: 957–967
4. Prasertsan S, Saen-saby P. Heat pump drying of agricultural materials. Dry Technol, 1998, 16: 235–250
5. Soponronnarit S, Nathakaranakule A, Wetchacama S, et al. Fruit drying using heat pump. RERIC Int Energy J, 1998, 20: 39–53