[1] Sun Jian, Shi Mingheng,. Numerical study on dehumidifying processin falling film dehumidifier [J]. Journal of Southeast University (English Edition), 2007, 23 (2): 272-277. [doi:10.3969/j.issn.1003-7985.2007.02.024]

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Numerical study on dehumidifying processin falling film dehumidifier()

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Journal of Southeast University (English Edition)[ISSN:1003-7985/CN:32-1325/N]

Volumn:

23

Issue:

2007 2

Page:

272-277

Research Field:

Chemistry and Chemical Engineering

Publishing date:

2007-06-30

Info

Title:

Numerical study on dehumidifying processin falling film dehumidifier

Author(s):

Sun Jian¹;  2;  Shi Mingheng¹

¹School of Energy and Environment, Southeast University, Nanjing 210096, China
²Department of Thermal Energy and Power Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001, China

Keywords:

dehumidifier;  liquid desiccant;  falling film;  numerical simulation

PACS:

TQ021

DOI:

10.3969/j.issn.1003-7985.2007.02.024

Abstract:

A counter flow model of simultaneous heat and mass transfer of a vapor absorption process in a falling film dehumidifier is developed.The governing equations with appropriate boundaries and interfacial conditions describing the dehumidifying process are set up. Calcium chloride is applied as the desiccant.The dehumidifying process between falling liquid desiccant film and process air is analyzed and calculated by the control volume approach.Velocity field, temperature distribution and outlet parameters for both the process air and desiccant solution are obtained.The effects of inlet conditions and vertical wall height on the dehumidification process are also predicted.The results show that the humidity ratio, temperature and mass fraction of salt decrease rapidly at the inlet region but slowly at the outlet region along the vertical wall height.The dehumidification processes can be enhanced by increasing the vertical wall height, desiccant solution flow rates or inlet salt concentration in the desiccant solution, respectively.Similarly, the dehumidification process can be improved by decreasing the inlet humidity ratio or flow rates of the process air.The obtained results can improve the performance of the dehumidifier and provide the theoretical basis for the optimization design, and the operation and modulation of the solar liquid desiccant air-conditioning systems.

References:

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[2] Pietruschka D, Eicker U, Huber M, et al.Experimental performance analysis and modelling of liquid desiccant cooling systems for air conditioning in residential buildings [J].International Journal of Refrigeration, 2006, 29(1):110-124.
[3] Gandhidasan P, Kettleborough C F, Ullah M R.Calculation of heat and mass transfer coefficients in a packed tower operation with a desiccant-air contact system [J].Journal of Solar Energy Engineering, 1986, 108(2):123-128.
[4] Gandhidasan P, Ullah M R, Kettleborough C F.Analysis of heat and mass transfer between a desiccant-air system in a packet tower [J].Journal of Solar Energy Engineering, 1987, 109(2):89-93.
[5] Radhwan A M, Gari H N, Elsayed M M.Parametric study of a packed bed dehumidifier/regenerator using CaCl₂ liquid desiccant [J]. Renewable Energy, 1993, 3(1):49-60.
[6] Ren Chengqin, Jiang Yi, Zhang Yianpin.Simplified analysis of coupled heat and mass transfer processes in packed bed liquid desiccant-air contact system [J].Solar Energy, 2006, 80(1):121-131.
[7] Stevens D I, Braun J E, Klein S A.An effectiveness model of liquid-desiccant system heat/mass exchanges [J].Solar Energy, 1989, 42(6):449-455.
[8] Rahamah A, Elsayed M M, Al-Najem N M.A numerical solution for cooling and dehumidification of air by a falling desiccant film in parallel flow [J].Renewable Energy, 1998, 13(3):305-322.
[9] Saman W Y, Alizadeh S.Modelling and performance analysis of a cross-flow type plate heat exchanger for dehumidification/cooling [J].Solar Energy, 2001, 70(4):361-372.
[10] ASHRAE Handbook.Fundamentals [M].Society of Heating, Refrigeration and Air-Conditioning Engineers, Inc., 1993.
[11] Tao Wenquan.Numerical heat transfer [M].2nd ed.Xi’an:Xi’an Jiaotong University Press, 2004.(in Chinese)

Memo

Memo:

Biographies: Sun Jian(1973—), male, graduate;Shi Mingheng(corresponding author), male, professor, mhshi@seu.edu.cn.

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