Heat-pump-assisted dryer part 2: experimental study

The performance of an experimental heat-pump-assisted dryer under operating conditions of some practical interest was studied. The system was operated using R11 and R12. The approach velocity of air to the evaporator and the superheat of the working fluid at the exit of the evaporator were identified as the critical parameters for optimization. The system was evaluated with respect to coefficient of performance (COP) and specific energy consumption (SEC). The (COP)A, and (SEC) values obtained using R11 were 3.5 and 3500 kJ/kg, respectively, and the corresponding values for R12 were 2.5 and 1800 kJ/kg. In spite of the lower (COP)A, for R12, the corresponding (SEC) values were better because the system could be operated without any additional electrical heating with R12