Experimental verification of a heat pump assisted continuous dryer simulation model

The experimental and predicted performance of a prototype heat pump assisted continuous dryer is reported. The dryer was shown to be capable of specific moisture extraction rates (SMERs) of between 1.5 and 2.5 kg/kWh using wetted foam rubber as the test material being dried. The results highlight the importance of maintaining conditions of high relative humidity within the air stream entering the evaporator; an increase in the relative humidity from 30 to 80% was shown to give a two‐fold increase in the SMER. An optimum evaporator bypass air ratio of between 60 and 70% was observed for this dryer. The effects on performance of deviations from this optimum condition were found to be less significant than had been indicated by earlier models. The predicted performance of the dryer using a simulation model developed previously by the authors was in good agreement with the corresponding measured values.