Performance-oriented evaluation of regeneration strategies from industrial waste heat to chemical energy with preheating and internal heating

Industrial waste heat represents a promising energy source for liquid desiccant systems, yet its effective utilization depends on how efficiently regeneration energy is converted into useable latent load handling capacity at the system level. This study proposes a performance-oriented evaluation framework to assess regeneration strategies driven by industrial waste heat in liquid desiccant systems. Baseline regeneration, solution preheating, air preheating, internal heating, and their combination are experimentally compared under identical operating conditions. Results show that increasing regeneration temperature or energy input enhances chemical energy storage, but with pronounced diminishing returns. For solution preheating, increasing regeneration temperature from 60 °C to 80 °C raises the regeneration rate by approximately 30–35%, while further increases yield less than 10% additional gain per 5 °C increment. Useable latent load handling capacity does not scale proportionally with regeneration energy input: a 30–40% increase in regeneration energy results in only a 10–15% improvement in useable latent capacity, revealing a clear decoupling between chemical energy storage and effective dehumidification performance. Internal heating markedly improves spatial and temporal stability, reducing axial temperature drop by 15–25%, suppressing regeneration-rate fluctuation by nearly 20%, and achieving a latent load retention ratio of 0.96 after 4 h of continuous operation, compared with approximately 0.82 for preheating-dominated regeneration. The proposed framework and operation map provide quantitative guidance for selecting regeneration strategies under different waste heat availability and stability requirements.