A novel method for measuring and improving the dehumidification process inside a direct contact condensation unit

Abstract

This paper reveals some of the experimental results retained during the comprehensive experimental research on the direct contact dehumidification process in a washer dryer machine. Pressurized spray water is injected into the moist air subject to dehumidification; the interplay between the saturated water droplet and process air leads to direct contact condensation occurring on the droplet surface. As a result, latent heat of condensation is released, and saturated water temperature increases. This study investigates the detailed interaction between these two streams and evaluates the effects of temperature distribution with the elapsed time over the moisture removal rates. Results show that numerical results are generally in line with the experimental work, which proves the applicability of the Computational Fluid Dynamic (CFD) solutions to this tedious system modelling process.

Keywords

• Drying technologies
• dehumidification
• direct contact condensation
• CFD

References

1. [1] Gumruk, S., Aktas, M.K. (2015). Experimental study of direct contact condensation of steam on water droplets. In: Proceedings of the World Congress on Engineering 2015 Vol II, WCE 2015, July 1-3, 2015, London, UK , 1071-1075
2. [2] Gulawani, S.S., Joshi, J.B., Shah, M.S., RamaPrasad, C.S., Shukla, D.S. (2006). CFD analysis of flow pattern and heat transfer in direct contact steam condensation. Chemical Engineering Science, 61(16):5204-5230. doi:10.1016/j.ces.2006.03.032
3. [3] Montazeri, H., Blocken, B., Hensen, J.L.M. (2015). Evaporative cooling by water spray systems: CFD simulation, experimental validation and sensitivity analysis. Building and Environment, 83:129-141. doi: 10.1016 /j.buildenv. 2014.03.022.
4. [4] Fletcher, D.F., Guo, B., Harvie, D.J.E., Langrish, T.A.G., Nijdam, J.J., Williams, J. (2006). What is important in the simulation of spray dryer performance and how do current CFD models perform. Applied Mathematical Modeling, 30(11):1281-1292. doi:10.1016/j.apm.2006.03.006
5. [5] Li, Q.S., Wang, P., Lu, T. (2015). Numerical simulation of direct contact condensation of subsonic steam injected in a water pool using VOF method and LES turbulence model. Progress in Nuclear Energy, 78: 201 – 215. doi:10.1016/j.pnucene.2014.10.002
6. [6] Apanasevich, P., Lucas, D., Beyer, M., Szalinksi, L. (2014). CFD based approach for modelling direct contact condensation heat transfer in two phase turbulent stratified flows. International Journal of Thermal Sciences, 95:123-135. doi:10.1016/j.ijthermalsci.2014.11.015
7. [7] Lekic, A., Fordi J.D. (1980). Direct contact condensation of vapor on a spray of subcooled liquid droplets. International Journal of Heat and Mass Transfer, 23(11):1531 – 1537. doi:10.1016/0017-9310(80)90156-8
8. [8] Lee, S.Y., Tankin, R.S. (1984). Study of liquid spray (water) in a condensable environment (steam). International Journal of Heat and Mass Transfer, 27(3):363-374. doi:10.1016/0017-9310(84)90283-7

9. [9] Celata, G.P., Cumo, M., Farello, G.E., Focardi, G. (1989). A comprehensive analysis of direct contact condensation of saturated steam on subcooled liquid jets. International Journal of Heat and Mass Transfer, 32(4):639 – 654. doi:10.1016/0017-9310(89)90212-3
10. [10] Mayinger, F., Chavez, A. (1992). Measurement of direct contract condensation of pure saturated vapour on an injection spray by applying pulsed laser holography. International Journal of Heat and Mass Transfer, 35(3):691-702. doi:10.1016/0017-9310(92)90128-F
11. [11] Li, S. Q., Wang, P., & Lu, T. (2015). Numerical simulation of direct contact condensation of subsonic steam injected in a water pool using VOF method and LES turbulence model. Progress in Nuclear Energy, 78: 201–215. doi:10.1016/j.pnucene.2014.10.002
12. [12] Zbiciński, I. (1995). Development and experimental verification of momentum, heat and mass transfer model in spray drying. The Chemical Engineering Journal and The Biochemical Engineering Journal, 58(2):123–133. doi:10.1016/0923-0467(94)02943-1
13. [13] Madejski, P., Kuś, T., Michalak, P., Karch, M., Subramanian, N. (2022). Direct Contact Condensers: A Comprehensive Review of Experimental and Numerical Investigations on Direct-Contact Condensation. Energies, 15(24):9312. doi:10.3390/en15249312
14. [14] Takahashi, M., Nayak, A. K., Kitagawa, S. I., Murakoso, H. (2001). Heat transfer in direct contact condensation of steam to subcooled water spray. Journal of Heat Transfer, 123(4): 703–710. doi:10.1115/1.1370510
15. [15] AHLBORN Thermo -Anemometer probe, FVAD 35- TH5 type https://www.ahlborn.com/download/pdfs/kap09/eng/dthermoane.pdf
16. [16] ASHRAE Fundamentals Handbook Section 14, ASHRAE Standard 111, 2008