THERMAL SCIENCE
International Scientific Journal
Thermal Science - Online First
online first only
Numerical study of flow boiling in inclined large length-diameter microchannels
ABSTRACT
The present study aims to numerically investigate the impact of inclination angle on the boiling heat transfer and pressure drop in rectangular microchannel tubes with a large length-diameter ratio. The volume of fluid approach was utilized to model the two-phase flow in microchannels using the computational fluid dynamics method. The effects of different inclination angles, aspect ratio and Reynolds number on heat transfer and pressure drop characteristics are analyzed by simulation. According to the latent heat percentage and saturation temperature differential, the mass transfer factor was calculated using the Lee model, which describes the mass and energy transfer throughout the boiling process. The convective heat transfer coefficients of the walls of structures at angles ranging from 0° to 90° (aspect ratios of 1.271, 1.017 and 0.763, respectively) were analyzed. It was found that with the decrease of aspect ratios, the convective heat transfer coefficients decreased by 16.64% and 11.56%, respectively. In order to keep the evaporator outlet superheat within 5 °C, the inlet Reynolds number should not be lower than 3000. The study offers insightful information for designing and refining microchannel evaporators in refrigeration systems, particularly for horizontal freezers with specific inclination angle arrangements.
KEYWORDS
PAPER SUBMITTED: 2025-04-06
PAPER REVISED: 2025-06-24
PAPER ACCEPTED: 2025-07-09
PUBLISHED ONLINE: 2025-08-02
- Jiang, X., et al., Design of micro-nano structures for counter flow diverging microchannel heat sink with extraordinarily high energy efficiency, Appl. Therm. Eng. 209 (2022) 118229
- Ates, A., et al., Flow boiling of dielectric fluid HFE-7000 in a minichannel with pin fin structured surfaces, Appl. Therm. Eng. 223 (2023) 120045
- Van Erp, R., et al., Co-designing electronics with microfluidics for more sustainable cooling, Nature. 585 (2020) 211-216
- Priy, A., et al., Bubble interaction and heat transfer characteristics of microchannel flow boiling with single and multiple cavities. J. Therm. Sci. Eng. Appl. 16 (2024) 061010
- Li, Y., et al., Experimental investigation of flow boiling performance in microchannels with and without triangular cavities-A comparative study, Int. J. Heat Mass Transf. 108 (2017) 1511-1526
- Kakati, A., et al., Influence of the presence of different signatures on the heat transfer profile of laminar flow inside a microchannel. J. Therm. Sci. Eng. Appl. 16 (2024) 101002
- Liang, X., et al., Manipulation of droplets and bubbles for thermal applications, Droplet. 1 (2022) 80-91
- Ma, X., et al., Flow boiling heat transfer characteristics on micro-pin-finned surfaces in a horizontal narrow microchannel. Int. J. Heat Mass Transf. 194 (2022) 123071
- Ma, X., et al., Flow boiling instability and pressure drop characteristics based on micro-pin-finned surfaces in a microchannel heat sink. Int. J. Heat Mass Transf. 195 (2022) 123168
- Yang, F., et al., Single-and two-phase thermal transport in microchannels with embedded staggered herringbone mixers, J. Microelectromech. Syst. 23 (2014) 1346-1358
- Datta, A., et al., The role of flow structures on the thermal performance of microchannels with wall features. J. Therm. Sci. Eng. Appl. 13 (2021) 021019
- Li, Y., Wu, H., Experiment investigation on flow boiling heat transfer in a bidirectional counter-flow microchannel heat sink, Int. J. Heat Mass Transf. 187 (2022) 122500
- Hung, T.C., et al., Analysis of heat transfer characteristics of double-layered microchannel heat sink, Int. J. Heat Mass Transfer. 55 (2012) 3090-3099
- Hung, T.C., Yan, W.M., Enhancement of thermal performance in double-layered microchannel heat sink with nanofluids, Int. J. Heat Mass Transfer. 55 (2012) 3225-3238
- Soleimani, A., et al., Thermal analysis of a microchannel heat sink cooled by two-phase flow boiling of al2o3 hfe-7100 nanofluid, Therm. Sci. Eng. Prog. 20 (2020) 100693
- Dai, X., et al., Enhanced single-and two-phase transport phenomena using flow separation in a microgap with copper woven mesh coatings, Appl. Therm. Eng. 54 (2013) 281-288
- Han, Q., et al., Enhanced thermal performance by spatial chaotic mixing in a saw-like microchannel, Int. J. Therm. Sci. 186 (2023) 108148
- Li, W., et al., Experimental and theoretical studies of critical heat flux of flow boiling in microchannels with microbubble-excited high-frequency two-phase oscillations, Int. J. Heat Mass Transf. 88 (2015) 368-378
- Morshed, A., et al., Enhanced flow boiling in a microchannel with integration of nanowires, Appl. Therm. Eng. 32 (2012) 68-75
- Tan, K., et al., Enhancement of flow boiling in the microchannel with a bionic gradient wetting surface, Appl. Therm. Eng. 230 (2023) 120784
- Eltaweel, A., Hassan, I., A multivariable numerical investigation of wavy-based microchannel heat sink geometry toward optimal thermal performance. J. Therm. Sci. Eng. Appl. 16 (2024) 111008
- Prajapati, Y.K., et al., Numerical investigation of subcooled flow boiling in segmented finned microchannels, Int. Commun. Heat Mass Transf. 86 (2017) 215-221
- Zu, Y.Q., et al., Confined bubble growth during flow boiling in a mini−/micro-channel of rectangular cross-section part II: approximate 3-D numerical simulation, Int. J. Therm. Sci. 50 (3) (2011) 267-273
- Pi, S., et al., Numerical investigation of thermal performance of key components of electric vehicles using nucleate boiling, J. Therm. Sci. Eng. Appl. 13 (6) (2021) 061021-061027
- Y. C. Liu, et al., Study on pressure drop characteristics of multiangle gravity separated heat pipe evaporator. Scientific and Technological Innovation (12) (2020) 39-40
- Y. C., Liu, et al., Effect of inclination angle on performance of annular heat pipe evaporator. J. Therm. Sci. Technol. 20 (06) (2021) 537-546
- S. Saisorn, et al., The difference in flow pattern, heat transfer and pressure drop characteristics of mini-channel flow boiling in horizontal and vertical orientations. Int. J. Multiphase Flow. 101 (2018) 97-112
- Oliveira, et al., An experimental investigation on flow boiling heat transfer of R-600a in a horizontal small tube. Int J Refrig. 72 (2016) 97-110
- Ghajar, A.J., Tang, C.C., Heat transfer measurements, flow pattern maps, and flow visualization for non-boiling two-phase flow in horizontal and slightly inclined pipe. Heat Transf. Eng. 28(6) (2007) 525-540
- Li, W., et al., Experimental and theoretical studies of critical heat flux of flow boiling in microchannels with microbubble-excited high-frequency two-phase oscillations, Int. J. Heat Mass Transf. 88 (2015) 368-378
- Qu, W., Mudawar, I., Measurement and correlation of critical heat flux in two-phase micro-channel heat sinks, Int. J. Heat Mass Transf. 47 (2004) 2045-2059
- Cui, P., Liu, Z., Experimental study on flow boiling in ultrahigh-aspect-ratio copper microchannel heat sink, Appl. Therm. Eng. 223 (2023) 119975
- Wang, Y., et al., Flow boiling in high-aspect ratio mini-and micro-channels with FC-72 and ethanol: Experimental results and heat transfer correlation assessments, Exp. Therm Fluid Sci. 36 (2012) 93-106
- Lee, W.H., A Pressure Iteration Scheme for Two-Phase Flow Modeling. (2002)
- Kharangate, C.R., Mudawar, I., Review of computational studies on boiling and condensation. Int J Heat Mass Transf. 108 (2017) 1164-1196
- Yang, Z., et al., Numerical and experimental investigation of two-phase flow during boiling in a coiled tube. Int J Heat Mass Transf. 51(5) (2008) 1003-1016
- Bahreini, M., et al., Numerical simulation of bubble behavior in subcooled flow boiling under velocity and temperature gradient. Nucl. Eng. Des. 293 (2015) 238-248
- Lee, J., et al., 3-D computational investigation and experimental validation of effect of shear-lift on two-phase flow and heat transfer characteristics of highly subcooled flow boiling in vertical upflow. Int J Heat Mass Transf. 150 (2020) 119291.1-119291.19
- Devahdhanush, V.S., et al., Assessing advantages and disadvantages of macro- and micro-channel flow boiling for high-heat-flux thermal management using computational and theoretical/empirical methods. Int J Heat Mass Transf. 169 (2021) 120787.1-120787.25
- Hasanpour, B., et al., Numerical investigation of saturated upward flow boiling of water in a vertical tube using VOF model: effect of different boundary conditions. Heat and Mass Transfer. 54 (2018) 1925-1936
- Hedau, G., et al., Experimental and numerical investigation of the effect of number of parallel microchannels on flow boiling heat transfer. Int J Heat Mass Transf. 158 (2020) 119973.1-119973.18
- Huang, F., et al., Numerical analysis on flow pattern and heat transfer characteristics of flow boiling in the mini-channels. Numer. heat transf. 78(4) (2020) 221-247
- Bahreini, M., et al., Numerical simulation of subcooled flow boiling under conjugate heat transfer and microgravity condition in a vertical mini-channel. Appl. Therm. Eng. 113 (2017) 170-185
- Lorenzini, D., Joshi, Y.K., Computational fluid dynamics modeling of flow boiling in microchannels with nonuniform heat flux. J Heat Transfer. 140(1) (2018) 011501.1-011501.11
- Yeo, I., Lee, S., 2D computational investigation into transport phenomena of subcooled and saturated flow boiling in large length to diameter ratio micro-channel heat sinks. Int J Heat Mass Transf. 183 (2022) 122128.1-122128.23
- Dong, F., et al., A novel interphase mass transfer model toward the VOF simulation of sub-cooled flow boiling. NUMER HEAT TR A-APPL. 76(4) (2019) 1-12
- Qiu, G.D., et al, Analysis on the value of coefficient of mass transfer with phase change in Lee's equation. Journal of the Harbin Institute of Technology. (2014) n.pag
- Hirt, C.W., Nichols, B.D., Volume of fluid (VOF) method for the dynamics of free boundaries, J. Comput. Phys. 39 (1) (1981) 201-225
- Rajalingam, A., Shubhankar, C., Fluid flow and heat transfer characteristics of a microstructured microchannel heat sink under flow boiling condition, Appl. Therm. Eng. 248 (2024) 123265
- Pan, L., et al., Experimental study on the flow boiling pressure drop characteristics in parallel multiple microchannels, Int. J. Heat Mass Transf. 116 (2018) 642-654
- Lorenzini, D., Joshi, Y., Effect of surface wettability on flow boiling in a microchannel, in: Proceedings of CHT-15. 6th International Symposium on Advances In Computational Heat Transf Res, 2015
- Lee, W.H., Pressure iteration scheme for two-phase flow modeling, In" Multiphase transport: fundamentals, reactor safety, applications". (1980) 407-432
- Andredaki, M., et al., The effect of channel aspect ratio on flow boiling characteristics within rectangular micro-passages. Int. J. Heat Mass Transf. 183 (2022) 122201