Enhancement of Absorption Performance Due to the Wavy Film of the Vertical Absorber Tube

  • Kim Jung-Kuk (Graduate School of Mechanical Engineering, Sungkyunkwan University) ;
  • Cho Keum-Nam (School of Mechanical Engineering, Sungkyunkwan University)
  • Published : 2006.06.01


Absorption performance at the vertical interface between refrigerant vapor and liquid solution of $LiBr-H_{2}O$ solution was enhanced by the waves formed due to the interfacial shear stress. The present study investigated experimentally and analytically the improvements of absorption performance in a falling film by wavy film flow. The dynamic parameter was the film Reynolds numbers ranged from 50 to 150. The energy and diffusion equations were solved simultaneously to find the temperature and concentration profiles at the interface of liquid solution and refrigerant vapor. Absorption characteristics due to heat and mass transfer were analyzed for the falling film of the LiBr aqueous solution contacted by refrigerant vapor in the absorber. Absorption performance showed a peak value at the solution flow rate of $Re_{f}>100$. Absorption performance for the wavy film flow was found to be greater by approximately 10% than that for uniform film flow. Based on numerical and experimental results, the maximum absorption rate was obtained for the wavy flow caused by spring insert. The difference between the measured and the predicted results were ranged from 5.8 to 12%.



  1. Grossman, G., 1983, Simultaneous heat and mass transfer in film absorption under laminar flow, Int. J. Heat and Mass Transfer, Vol. 26, No.3, pp. 357 - 371 https://doi.org/10.1016/0017-9310(83)90040-6
  2. Andberg, J. W. and Vliet, G. C., 1983, Design guidelines for water-lithium bromide absorbers, ASHRAE Transactions, Vol. 89, No. 1B, pp.220-232
  3. Yueksel, I. and Schluender, W., 1988, A model of an ammonia-water falling film absorber, ASHRAE Transactions, Vol. 94, No. 1, pp.467-483
  4. Patnaik, V., Perez-Blanco, H. and Miller, W. A., 1992, Experimental validation of a simple analytical model for the design of vertical tube absorbers, In progress
  5. Conlisk, A. T., 1995, Analytical solution for the heat and mass transfer in a falling film absorber, Chemical Engineering Science, V ol, 50, No.4, pp. 651-660 https://doi.org/10.1016/0009-2509(94)00261-O
  6. Yoon, J. I., Oh, H. K. and Takao, K., 1995, Characteristics of heat and mass transfer for a falling film type absorber with insert spring tubes, Transaction of KSME, Vol. 19, No.6, pp. 1501-1509
  7. Morioka, I. and Kiyota, M., 1987, Absorption of water vapor into a lithium-bromide water solution film falling along a vertical plate, Transactions of the JSME (Part B), Vol. 53, No. 485, pp. 236-240 https://doi.org/10.1299/kikaib.53.236
  8. Ohm, K. C., Kashiwagi, T. and Sea, J. Y, 1993, Characteristics of absorption and heat transfer for film falling along a vertical inner tube (Characteristics of absorption), Korean Journal of Air-Conditioning and Refrigeration Engineering, Vol. 5, No.1, pp.I-9
  9. Kim, K.J., Berman, N. S. and Wood, B. D., 1995, Absorption of water vapor into falling films of aqueous lithium bromide, Int. J. Refrigeration, Vol. 18, No.7, pp. 486-494 https://doi.org/10.1016/0140-7007(95)93787-K
  10. Moffat, R.J., 1985, Using uncertainty analysis in the planning of an experiment, Trans. of the ASME: J. Of Fluid Engineering, Vol. 107, pp. 173-182 https://doi.org/10.1115/1.3242452
  11. Kim, J. K. and Cho, K. N., 2002. Influence of spring on the absorption performance of a vertical absorber tube, Transaction of SAREK (in Korean), Vol. 14, No. 10, pp.825-832