Heat-pump assisted dryer using refrigerant mixtures -- Batch mode drying

Abstract

The transient simulation of a closed-loop heat pump assisted dryer (HPAD) using a binary zeotropic refrigerant mixture of R-134a and R-32 is performed. The application chosen is clothes drying. The performance is compared with that of an HPAD using pure R-134a. The simulation is carried out assuming the same volumetric flow rates of air, refrigerant, and cooling water and also the same values for the total surface areas and overall heat transfer coefficient for all the heat exchangers in both cases. Results indicate that the HPAD using mixtures results in an energy savings of about 69% over open-loop systems and about 8% over an HPAD using pure refrigerant. Also, the drying time for the HPAD using the refrigerant mixture is about 13% less than that of open-loop systems and about 33% less than that of an HPAD using pure R-134a. The installed power of the compressor in the case of the mixture is about 104% more than that using pure R-134a. The transient variation of different parameters of interest is also discussed.