CFD-Based Calibration of Representative Elementary Units for Dry Pressure Drop in Structured Packings

Abstract

Representative Elementary Unit (REU) simplification has become a standard approach for CFD modeling of structured packings; however, its reliability in predicting dry pressure drop remains a critical yet underexplored issue. In particular, the sensitivity of hydraulic performance to internal geometric parameters is often overlooked in the current literature. This study addresses this gap by calibrating an REU model for Mellapak 500.Y against the semi-empirical correlation of Stichlmair et al. (1989) and experimental data from Tsai (2010). Single-phase simulations were conducted using the SST 𝑘−𝜔 turbulence model over a gas-load range of 0.72–4.32 Pa0.5. Grid independence was established at 0.53 million cells per REU. A domain-sensitivity analysis using one, four, and six REUs yielded deviations below 10%, confirming that a single-unit domain provides sufficient accuracy for dry-flow calibration. The results show that the nominal 2.00 mm sheet spacing leads to substantial underprediction of pressure drop, whereas an effective spacing of 0.24 mm brings the CFD predictions into agreement with Tsai’s measurements within a ±20% error band and consistent with the Stichlmair correlation across the operating window. These findings identify the effective sheet spacing as the dominant geometric calibration parameter and provide a reproducible, computationally efficient baseline REU for subsequent hydrodynamics simulations in Mellapak 500.Y.

Keywords

• dry pressure drop
• representative elementary unit
• computational fluid dynamics
• separation process
• structured packing

Supporting Institution

No external funding was received for this study.

Ethical Statement

This study does not require ethics committee approval since it does not involve human participants, animals, or any data obtained from such groups. The authors declare that the study complies with research and publication ethics.

Thanks

The numerical calculations reported in this paper were partially performed at TUBITAK ULAKBIM, High Performance and Grid Computing Center (TRUBA resources).

Yapılandırılmış Dolgularda Kuru Basınç Düşümü için Temsili Eleman Birimlerinin CFD Tabanlı Kalibrasyonu

Abstract

Temsili Eleman Birimi (TEB, Representative Elementary Unit - REU) sadeleştirmesi, yapılandırılmış dolguların CFD ile modellenmesinde standart bir yaklaşım hâline gelmiştir; ancak kuru basınç düşüşünü öngörmedeki güvenilirliği hâlen kritik ve yeterince incelenmemiş bir konu olarak kalmaktadır. Özellikle, hidrolik performansın iç geometrik parametrelere olan duyarlılığı mevcut literatürde sıklıkla göz ardı edilmektedir. Bu çalışma, Mellapak 500.Y için geliştirilen bir REU modelinin, Stichlmair ve arkadaşlarının (1989) yarı-ampirik korelasyonu ve Tsai’nin (2010) deneysel verileri ile kalibre edilmesi yoluyla bu boşluğu doldurmayı amaçlamaktadır. Tek fazlı akış simülasyonları, 0.72–4.32 Pa0.5 gaz yükü aralığında SST 𝑘–𝜔 türbülans modeli kullanılarak gerçekleştirilmiştir. Ağ bağımsızlığı, REU başına 0.53 milyon hücrede sağlanmıştır. Bir, dört ve altı REU kullanılarak yapılan alan-duyarlılık analizi, %10’un altında sapmalar vermiş ve tek birimlik bir hesaplama alanının kuru akış kalibrasyonu için yeterli doğruluk sağladığını doğrulamıştır. Elde edilen sonuçlar, nominal 2.00 mm sac aralığının basınç düşüşünün önemli ölçüde düşük tahmin edilmesine yol açtığını; buna karşılık 0.24 mm’lik etkin aralığın, CFD tahminlerini Tsai’nin ölçümleriyle ±%20 hata bandı içinde uyumlu hâle getirdiğini ve tüm işletme aralığında Stichlmair korelasyonu ile tutarlılık sağladığını göstermektedir. Bu bulgular, etkin sac aralığının baskın geometrik kalibrasyon parametresi olduğunu ortaya koymakta ve Mellapak 500.Y için sonraki hidrodinamik simülasyonlarda kullanılabilecek, tekrarlanabilir ve hesaplama açısından verimli bir temel REU modeli sunmaktadır.

Keywords

• Ayırma prosesi
• yapılsal dolgu
• kuru basınç kaybı
• temsili eleman hücresi
• hesaplamalı akışkanlar dinamiği

Supporting Institution

Bu çalışma herhangi bir dış fon tarafından desteklenmemiştir.

Ethical Statement

Bu çalışma insan veya hayvan denek içermediği için etik kurul iznine tabi değildir. Çalışma araştırma ve yayın etiğine uygundur.

Thanks

Bu araştırmada yer alan kısmi nümerik hesaplamalar TÜBİTAK ULAKBİM, Yüksek Başarım ve Grid Hesaplama Merkezi’nde (TRUBA kaynaklarında) gerçekleştirilmiştir.

References

1. Ambekar, A. S., Peters, E., Hinrichsen, O., Buwa, V. V., & Kuipers, J. (2024). Understanding the role of perforations on the local hydrodynamics of gas–liquid flows through structured packings. Chemical Engineering Journal, 486, 150084. https://doi.org/10.1016/j.cej.2024.150084
2. ANSYS, Inc. (2024). ANSYS Fluent theory guide: Release 2024 R2. ANSYS, Inc.
3. Aroonwilas, A., Tontiwachwuthikul, P., & Chakma, A. (2001). Effects of operating and design parameters on CO2 absorption in columns with structured packings. Separation and Purification Technology, 24(3), 403–411. https://doi.org/10.1016/S1383-5866(01)00140-X
4. Ataki, A., & Bart, H.-J. (2006). Experimental and CFD simulation study for the wetting of a structured packing element with liquids. Chemical Engineering & Technology, 29(3), 336–347. https://doi.org/10.1002/ceat.200500302
5. Bertling, J. (2023). Simulation of liquid flow in structured packings using CFD methods. Chemical Engineering Science, 269, 118405. https://doi.org/10.1016/j.ces.2022.118405
6. Billet, R., & Schultes, M. (1993). Predicting mass transfer in packed columns. Chemical Engineering & Technology, 16(1), 1–9. https://doi.org/10.1002/ceat.270160102
7. Brunazzi, E., Nardini, G., Paglianti, A., & Petarca, L. (1995). Interfacial area of Mellapak packing: Absorption of 1,1,1- trichloroethane by Genosorb 300. Chemical Engineering & Technology, 18(4), 248–255. https://doi.org/10.1002/ceat.270180405
8. Czarnecki, N. J., Giannetti, L., Owens, S. A., Barnicki, S., & Eldridge, R. B. (2024). Energy and economic evaluation of wall placement for divided wall distillation columns. Industrial & Engineering Chemistry Research, 63(43), 18513–18524. https://doi.org/10.1021/acs.iecr.4c01691

9. Flagiello, D., Parisi, A., Lancia, A., & Di Natale, F. (2021). A review on gas–liquid mass transfer coefficients in packed-bed columns. ChemEngineering, 5(3), 43. https://doi.org/10.3390/chemengineering5030043
10. Henriques de Brito, M., von Stockar, U., Menendez Bangerter, A., Bomio, P., & Laso, M. (1994). Effective mass-transfer area in a pilot plant column equipped with structured packings and with ceramic rings. Industrial & Engineering Chemistry Research, 33(3), 647–656. https://doi.org/10.1021/ie00027a023
11. Isoz, M., & Haidl, J. (2018). Computational-fluid-dynamics analysis of gas flow through corrugated-sheet-structured packing: Effects of packing geometry. Industrial & Engineering Chemistry Research, 57(34), 11785–11796. https://doi.org/10.1021/acs.iecr.8b00676
12. Khosravi Nikou, M. R., & Ehsani, M. R. (2008). Turbulence models application on CFD simulation of hydrodynamics, heat and mass transfer in a structured packing. International Communications in Heat and Mass Transfer, 35(9), 1211–1219. https://doi.org/10.1016/j.icheatmasstransfer.2008.05.017
13. Kiss, A. A., & Smith, R. (2020). Rethinking energy use in distillation processes for a more sustainable chemical industry. Energy, 203, 117788. https://doi.org/10.1016/j.energy.2020.117788
14. Li, Q., Wang, T., Dai, C., & Lei, Z. (2016). Hydrodynamics of novel structured packings: An experimental and multi-scale CFD study. Chemical Engineering Science, 143, 23–35. https://doi.org/10.1016/j.ces.2015.12.014
15. Macfarlan, L. H. (2021). A computational fluid dynamics (CFD)- based investigation of structured packing geometry for gas-phase hydrodynamic and mass transfer performance. Chemical Engineering Science, [article in press]. https://doi.org/10.1016/j.ces.2021.110844
16. Olenberg, A., & Kenig, E. Y. (2017). Numerical simulation of two- phase flow in representative elements of structured packings. Computer Aided Chemical Engineering, 40, 2089–2094. https://doi.org/10.1016/B978-0-444-63965-3.50350-0
17. Olujić, Ž. (1999). Effect of column diameter on pressure drop of a corrugated sheet structured packing. Chemical Engineering Research and Design, 77(6), 505–510. https://doi.org/10.1205/026387699526539
18. Rocha, J. A., Bravo, J. L., & Fair, J. R. (1993). Distillation columns containing structured packings: A comprehensive model for their performance. 1. Hydraulic models. Industrial & Engineering Chemistry Research, 32(4), 641–651. https://doi.org/10.1021/ie00016a010
19. Schug, S. (2018). Untersuchung der fluiddynamik in packungskolonnen mittels computertomographie (Doctoral dissertation). Friedrich-Alexander-Universität Erlangen-Nürnberg.
20. Shojaee, S., Hosseini, S. H., & Razavi, B. S. (2012). Computational fluid dynamics simulation of multiphase flow in structured packings. Journal of Applied Mathematics, 2012(1), 917650. https://doi.org/10.1155/2012/917650
21. Singh, R. K., Galvin, J. E., & Sun, X. (2018). Multiphase flow studies for microscale hydrodynamics in the structured packed column. Chemical Engineering Journal, 353, 949–963. https://doi.org/10.1016/j.cej.2018.07.067
22. Singh, R. K., Bao, J., Wang, C., Fu, Y., & Xu, Z. (2020). Hydrodynamics of countercurrent flows in a structured packed column: Effects of initial wetting and dynamic contact angle. Chemical Engineering Journal, 398, 125548. https://doi.org/10.1016/j.cej.2020.125548
23. Suess, P., & Spiegel, L. (1992). Hold-up of Mellapak structured packings. Chemical Engineering and Processing: Process Intensification, 31(2), 119–124. https://doi.org/10.1016/0255-2701(92)85005-M
24. Sulzer Chemtech Ltd. (2003). Structured packings for distillation, absorption and reactive distillation (Brochure reviewed and supplemented in 2002/2003). Sulzer Chemtech Ltd.
25. Sun, B., Zhang, J., Xie, H., & Zhu, L. (2021). Study on hydrodynamic performance of structured packings for gas–liquid flow: Effects of geometry parameters. Chemical Engineering Research and Design, 168, 318-330. https://doi.org/10.1016/S0263-8762(21)00003-4
26. Tsai, R. E. (2010). Mass transfer area of structured packing (Doctoral dissertation). The University of Texas at Austin.
27. Wang, Q., Liu, X., Wu, X., Yang, C., & Qiu, T. (2020). A multi-scale approach to optimize vapor–liquid mass transfer layer in structured catalytic packing. Chemical Engineering Science, 214, 115434. https://doi.org/10.1016/j.ces.2019.115434
28. Wehrli, M., Kogl, T., Linder, T., & Arlt, W. (2018). An unobstructed view of liquid flow in structured packing. Chemical Engineering Transactions, 69, 775–780. https://doi.org/10.3303/CET1869130