General correlations for the heat and mass transfer coefficients in an air-solution contactor of a liquid desiccant system and an experimental case application

• Published in: International journal of heat and mass transfer 2018-05, Vol.120, p.851-860
• Main Authors: Varela, Richard Jayson, Yamaguchi, Seiichi, Giannetti, Niccolo, Saito, Kiyoshi, Harada, Masatoshi, Miyauchi, Hikoo
• Format: Article
• Language: English
• Subjects: Adiabatic flow; Air-solution contactor; Coefficients; Contactors; Correlation; Correlation analysis; Dehumidification; Desiccants; Experiments; Fluids; Heat transfer; Heat transfer coefficient; Humidity; Liquid desiccant system; Lithium chloride; Mass transfer; Mass transfer coefficient; Mathematical analysis; Nusselt number; Regeneration; Reynolds number; Sherwood number; Systems design; Thermophysical properties
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2017.12.089

•The heat and mass transfer coefficients were expressed into two general correlations.•The correlations summarize the properties of the air, solution, and contactor.•Experiments were conducted at typical applications of air and solution flow rates.•Particular equations for the heat and mass transfer coefficients were derived. This paper presents general types of correlation for the heat and mass transfer coefficients inside an air-solution contactor as expressions of Reynolds-Prandtl numbers and Reynolds-Schmidt numbers, respectively. These general equations summarize the physical and thermophysical properties of the air, the solution, and the contactor, which make them capable to be used for parametric studies provided they are fitted in a wide range of experimental data that include all the properties involved. In this work, a liquid desiccant system with an adiabatic structured packed bed as contactor and an aqueous lithium chloride as solution was constructed. The experimental data taken at various air superficial velocities and solution flow rates were fitted to the general correlations, and comparisons between the predicted and experimental results for both coefficients are within ±10%, for both dehumidification and regeneration processes. In addition, the calculated values of the outlet air humidity ratio and temperature agree well with the experimental data for both processes. The particular equations for the heat and mass transfer coefficients can be used to perform parametric studies at different air superficial velocities and solution flow rates with very good accuracy. Results from this study can help improve the system design and operation methods of air-solution contactors.