Lowering the regeneration temperature of a rotary wheel dehumidification system using exergy analysis

Rotary wheel dehumidification is an effective air drying method. This paper analyzes the factors influencing the regeneration temperature from the perspective of exergy. When the dehumidification capacity is fixed, there are two main ways to reduce the regeneration temperature. One is to decrease the exergy destruction during heat and mass transfer in the desiccant wheel, and the other is to decrease the thermal exergy obtained by the processed air after dehumidification. For the first way, the exergy destruction is influenced by the uniformity of the heat and mass transfer driving forces in the desiccant wheel, which can be described by the unmatched coefficient ς. The wheel should be evenly divided, and the two streams of air should have the same flow rate to reduce the exergy destruction. The regeneration temperature can be reduced from above 130 °C to below 70 °C when the air is dehumidified from 20 g/kg to 11 g/kg. For the second way, the thermal exergy obtained by the processed air is influenced by the temperature variation range during dehumidification. Multi-stage dehumidification and pre-cooling are effective mode, with required regeneration temperature lower than 40 °C.