Study on the optimal solution recirculation ratio of liquid desiccant dehumidification system based on matching rate evaluation

Abstract

The recirculation of dehumidification and regeneration solutions has shown promising moisture removal rates and energy-saving effects in liquid desiccant dehumidification systems. The different combinations of dehumidification solution recirculation ratio and regeneration solution recirculation ratio under varying operating conditions can have different impacts on the system. Nevertheless, the system performance under full operating conditions has not been comprehensively studied. To address this research gap, this study proposes a liquid desiccant dehumidification system with a solution recirculation structure, defines a new evaluation index — matching rate, and conducts a parameterized study and optimization of the steady-state performance of the liquid desiccant dehumidification system with a solution recirculation structure within the range of solution recirculation ratios under all operating conditions, by integrating the system cooling capacity and energy effectiveness ratio. The performance of the system is studied by varying seven key parameters: dehumidification solution recirculation ratio, regeneration solution recirculation ratio, total solution mass flow rate, dehumidification solution inlet temperature, regeneration solution inlet temperature, and ambient air temperature-humidity ratio. The results show that under design conditions, the solution recirculation ratio within the full operating range can process air to a range of 17.8℃～18.5℃ and 12.5 g/kg～17.4 g/kg. The maximum system cooling capacity, energy effectiveness ratio and matching rate values are 21.5 kW, 0.21 and 0.42 respectively. The recommended (dehumidification solution recirculation ratio, regeneration solution recirculation ratio) schemes for high, medium and low demand of system cooling capacity are (0.7～0.9, 0～0.5), (0.4～0.6, 0～0.7) and (0～0.3, 0.4～0.7) respectively, based on the requirements of system cooling capacity.