1st Nordic Drying Conference - NDC'01, Trondheim, Norway, June 27-29, 2001

POTENTIAL APPLICATIONS FOR A NEW CO2 HEAT PUMP DRYER Trygve M. Eikevik1, Odilio Alves-Filho1, Ingvald Strømmen2 1 SINTEF Energiforskning AS, Refrigeration and Air Conditioning, Norway 2 Norwegian University of Science and Technology (NTNU), Department of Refrigeration and Air Conditioning, Norway Telephone: +47 73593750; Fax: +47 73593950 E-mails: Trygve.M.Eikevik@energy.sintef.no, Odilio.Alves@energy.sintef.no, Ingvald.Strommen@kkt.ntnu.no ABSTRACT A new prototype fluidised bed heat pump dryer with CO2 as working medium is constructed and build in the Centre of Dewatering R&D at NTNU and SINTEF. The dryer is designed to operate with inert gas in the drying chamber. This will give new possibilities to dry products with under and over atmospheric pressure and to investigate how this influence on the heat and mass transfer under the drying process and the quality of the product. The drying chamber can operate as a fluidised and static bed in both continuous and batch operation. The drying chamber can handle ingoing materials as granulates, foamed products and liquids. It is also possible to perform the multiple tasks of coating, granulation, agglomeration and drying. To meet the hygienic standards the dryer is designed with CIP and the drying circuit can be sterilized using 2.2 bar pressurised steam. The heat pump circuit is constructed to use CO2 as the refrigerant and the maximum design pressure is 130 bar. The heat pump process can run as a sub-, trans- and supercritical process. This gives the dryer possibilities to operate with air temperature from ­30°C to +110°C at the drying chamber air inlet, depending of the products thermal sensitivity. This paper describes this new heat pump and the possibilities using CO2 with respect to construction, COP and SMER.

NDC'2001 - List of Contents       << Previous paper       Next paper >>