Desiccant Dehumidifier Reactivation Stream : Unlocking Waste Heat Recovery Potential

Abstract: Northvolt is committed to developing the world’s greenest battery. To achieve this,energy-efficient production processes are essential and dehumidification is a crucial, yet energy-intensive, process for battery production. Waste heat recovery potential in the reactivation stream of a desiccant rotor dehumidification unit has been investigated as a means to improve energy efficiency. In this study, we model the load of two types of dehumidification units currently in use and expand the model to include an air-to-air cross-flow plate heat exchanger. By comparing the load on the electrical reactivation heater, the waste heat recovery potential is assessed. Models incorporating weather data and unit properties are developed for analysis. The results reveal that the inclusion of a heat exchanger in the reactivation process reduces the load on the reactivation heater respectively by 45% and 40% for the two different systems. Furthermore, a third option is explored, where two dehumidifier units of the first type share one heat exchanger, resulting in a 33% reduction in energy consumption per dehumidifier unit. This approach allows for a more energy efficient dehumidificationunit and by reducing the load on the electrical reactivation reactivation heater, energy costs are lowered. Additionally, this approach has a smaller impact on the local environment, as the exhaust air is released at a lower temperature.