CFD Analysis of the Impact of Temperature Variation on Condensation and Phase Transition Performance in Heat Exchangers

Year 2025, Volume: 10 Issue: 2, 80 - 93, 30.06.2025

Fuat Tan , Hamid Orhun Tur

https://doi.org/10.46578/humder.1646589

Abstract

This study investigates condensation in a rectangular copper heat exchanger with six circular tubes exposed to temperature variations. Three different temperature levels (380 K, 420 K and 460 K) were compared by examining heat transfer and phase change over a 5-second period with 1.25 s increments. A transient two-dimensional analysis model was developed. Physical modeling was performed using the Volume of Fluid (VOF) phase model and the Standard k-ε turbulence model. The analysis results were monitored along two horizontal lines at different heights on the plate. The simulation results show that rapid condensation occurs at low and medium temperature levels due to high heat transfer. At the high temperature level, a delayed phase change leads to a longer condensation duration. The study serves as a guide for thermal device design by emphasizing the need to select appropriate temperature ranges while considering both the amount and duration of condensation.

Keywords

CFD , Phase Transition , Heat Exchanger , Temperature , Condensation

Isı Eşanjörlerinde Sıcaklık Değişiminin Yoğuşma ve Faz Geçiş Performansı Üzerindeki Etkisinin CFD Analizi

Abstract

Yürütülen bu çalışma, sıcaklık değişimine maruz 6 adet dairesel boru içeren dikdörtgen bir bakır ısı eşanjöründeki yoğuşma konusunu incelemektedir. Üç farklı sıcaklık seviyesi (380 K, 420 K ve 460 K) ve 1,25 s artımlarla 5 saniye boyunca gerçekleşen ısı transferi ve faz geçişi ortaya konularak karşılaştırılmıştır. Geçici rejimde 2 boyutlu bir analiz modeli oluşturularak VOF(Volume of Fluid) faz modeli ve Standart k-ε türbülans modeli ile fiziksel modelleme yapılmıştır. Analiz sonuçları plaka üzerinde oluşturulan farklı yüksekliklerdeki yatay iki çizgi boyunca grafikle izlenmiştir. Simülasyon sonuçlarına göre, düşük ve orta sıcaklık seviyesinde yüksek bir ısı transferi neticesinde yoğuşma işleminin hızlıca gerçekleştiği gözlemlenirken, yüksek sıcaklık seviyesinde faz değişiminin gecikerek yoğuşma süresinin diğer sıcaklık seviyelerine göre arttığı gözlenmiştir. Çalışma, ısıl cihaz tasarımı yapılırken uygun sıcaklık aralıkları seçilerek yoğuşma miktarı ve süresinin de gözönünde bulundurulmasını ortaya koyan rehber niteliğinde bir çalışmadır.

Keywords

CFD , Faz Değişimi , Isı Eşanjörü , Sıcaklık , Yoğuşma

References

• W. Srimuang, W., Amatachaya, P. (2012). A review of the applications of heat pipe heat exchangers for heat recovery. Renewable and Sustainable Energy Reviews, 16(6), 4303-4315.
• Schneider, D., Lauer, M., Voigt, I., & Drossel, W. G. (2016). Development and examination of switchable heat pipes. Applied thermal engineering, 99, 857-865.
• Faghri, A. (2018). Heat pipes and thermosyphons. Handbook of thermal science and engineering, 2163-2211.
• Chen, X., Gao, P., Tan, S., Yu, Z., & Chen, C. (2018). An experimental investigation of flow boiling instability in a natural circulation loop. International Journal of Heat and Mass Transfer, 117, 1125-1134.
• Yankov, G. G., Milman, O. O., Minko, K. B., & Artemov, V. I. (2023). Simulation of the condensation processes of R113 in a horizontal pipe by the VOF method. Thermal Engineering, 70(11), 860-874.
• Su, Z., Li, Z., Wang, K., Kuang, Y., Wang, H., & Yang, J. (2024). Investigation of improved VOF method in CFD simulation of sodium heat pipes using a multi-zone modeling method. International Communications in Heat and Mass Transfer, 157, 107669.
• M Najafian, M., & Mortazavi, S. (2023). A numerical study of drop evaporation at high density ratios using Front-Tracking method. Computers & Mathematics with Applications, 134, 1-15.
• Tang, M., Xin, Z., & Wang, L. (2024). Physics-Informed neural network for level set method in vapor condensation. International Journal of Heat and Fluid Flow, 110, 109651.
• Lyras, P., Hubert, A., & Lyras, K. G. (2023). A conservative level set method for liquid-gas flows with application in liquid jet atomisation. Experimental and Computational Multiphase Flow, 5(1), 67-83.
• Fadhl, B., Wrobel, L. C., & Jouhara, H. (2015). CFD modelling of a two-phase closed thermosyphon charged with R134a and R404a. Applied Thermal Engineering, 78, 482-490.
• Yang, Z., Peng, X. F., & Ye, P. (2008). Numerical and experimental investigation of two-phase flow during boiling in a coiled tube. International Journal of Heat and Mass Transfer, 51(5-6), 1003-1016.
• Fadhl, B., Wrobel, L. C., & Jouhara, H. (2013). Numerical modelling of the temperature distribution in a two-phase closed thermosyphon. Applied Thermal Engineering, 60(1-2), 122-131.
• Mroue, H., Ramos, J. B., Wrobel, L. C., & Jouhara, H. (2015). Experimental and numerical investigation of an air-to-water heat pipe-based heat exchanger. Applied Thermal Engineering, 78, 339-350.
• Temimy, A. A., & Abdulrasool, A. A. (2019, May). CFD Modelling for flow and heat transfer in a closed Thermosyphon charged with water–A new observation for the two phase interaction. In IOP Conference Series: Materials Science and Engineering (Vol. 518, No. 3, p. 032053). IOP Publishing.
• Lin, Z., Wang, S., Shirakashi, R., & Zhang, L. W. (2013). Simulation of a miniature oscillating heat pipe in bottom heating mode using CFD with unsteady modeling. International Journal of Heat and Mass Transfer, 57(2), 642-656.
• Song, E. H., Lee, K. B., Rhi, S. H., & Kim, K. (2020). Thermal and flow characteristics in a concentric annular heat pipe heat sink. Energies, 13(20), 5282.
• Yuan, Y., Cao, J., Zhang, Z., Xiao, Z., & Wang, X. (2024). Experimental and numerical simulation study of a novel double shell-passes multi-layer helically coiled tubes heat exchanger. International Journal of Heat and Mass Transfer, 227, 125497.
• Z. Li, Z. Z., Ding, Y. D., Liao, Q., Cheng, M., & Zhu, X. (2021). An approach based on the porous media model for numerical simulation of 3D finned-tubes heat exchanger. International Journal of Heat and Mass Transfer, 173, 121226.
• Ebrahimnia-Bajestan, E., Gharibnavaz, M., Jin, M., Li, R., Brinkerhoff, J., & Milani, A. (2022). CFD Simulation of Condensation Heat Transfer In Mini/Micro-Channels—Application In Waste Heat Recovery.
• Lee, W. H. (1980). A pressure iteration scheme for two-phase flow modeling. Multiphase transport fundamentals, reactor safety, applications, 1, 407-431.
• Wang, X., Wang, Y., Chen, H., & Zhu, Y. (2018). A combined CFD/visualization investigation of heat transfer behaviors during geyser boiling in two-phase closed thermosyphon. International Journal of Heat and Mass Transfer, 121, 703-714.
• Zhang, Y., Li, G., Zhang, G., & Ding, S. (2023). Development and modified implementation of Lee model for condensation simulation. Applied Thermal Engineering, 231, 120872.
• Knudsen, M., (1934). The kinetic theory of gases, methuen & co. London Ltd, 1.
• De Schepper, S. C., Heynderickx, G. J., & Marin, G. B. (2009). Modeling the evaporation of a hydrocarbon feedstock in the convection section of a steam cracker. Computers & Chemical Engineering, 33(1), 122-132.
• Jouhara, H., Fadhl, B., & Wrobel, L. C. (2016). Three-dimensional CFD simulation of geyser boiling in a two-phase closed thermosyphon. International Journal of Hydrogen Energy, 41(37), 16463-16476.
• Prandtl, L. (1942). Bemerkungen zur Theorie der freien Turbulenz. ZAMM‐Journal of Applied Mathematics and Mechanics/Zeitschrift für Angewandte Mathematik und Mechanik, 22(5), 241-243.