Upgrading Waste Heat from 90 to 110 °C: The Potential of Adsorption Heat Transformation

Abstract

Low‐grade heat is abundantly available below 100 °C, whereas industry mainly needs heat above 100 °C. Thus, the industry cannot directly utilize low‐grade heat to save primary energy and emissions. Low‐grade heat can be utilized by adsorption heat transformers (AdHTs); however, closed AdHTs to upgrade heat above 100 °C are only investigated by idealized steady‐state analyses, which indicate the maximal theoretical performance. For evaluating the performance achievable in practice, this work studies a closed AdHT in a one‐bed configuration using dynamic simulation. For the working pair AQSOA‐Z02/H 2 O, the performance is optimized via the design of the adsorber heat exchanger and the control of the AdHT cycle. When heat is upgraded from 90 to 110 °C, releasing waste heat at 35 °C, the maximum exergetic coefficient of performance (COP exergetic ) is 0.64, and the maximum specific heating power (SHP) is 590 W kg −1 . The maximum SHP can increase by 35% when releasing waste heat at 25 °C. Both performance indicators strongly depend on design, control, and the available temperature of the waste heat. Overall, AdHTs with optimized design and control are promising to utilize low‐grade waste heat.