Investigation on the regeneration performance of liquid desiccant by adding surfactant PVP-K30

Abstract

The liquid desiccant cooling system (LDCS) is a promising alternative for the conventional vapor compression system due to its high energy efficiency. To enhance the mass transfer between the regeneration air and liquid desiccant in the regenerator, the paper firstly introduced a kind of surfactant called polyvinyl pyrrolidone (PVP-K30) which was added into the LiCl solution for better desiccant regeneration performance. The falling film characteristics and regeneration performance were investigated and compared with and without surfactant. The results indicated that the contact angle of desiccant solution on plate decreased from 58.5° to 28.0° by adding surfactant with 0.4% of concentration. The average wetting area increased from 0.174 m2 to 0.209 m2 with a relative increment of 20.1% with the addition of surfactant. Correspondingly, the film thickness had a reduction of 0.103 mm from 0.696 mm to 0.593 mm averagely. The regeneration rate had an average enhancement of 26.3% under the same working conditions, resulting from the decrement of solution contact angle with the addition of the surfactant. Finally, correlations to predict the mass transfer coefficient were proposed with and without surfactant and the mean absolute relative deviation between the results of correlations and the experiments were kept within 8%. The results and findings of present paper could be applied to guide the design of compact regenerator for higher regeneration performance.