Hao Tang^1,2,3, Jianchang Yang^1,2,3, Yunxin Zhou^1,2,3, Jianxin Xu^1,2,3,*, Hua Wang^1,2,3

FDMP-Fluid Dynamics & Materials Processing, Vol.21, No.7, pp. 1571-1600, 2025, DOI:10.32604/fdmp.2025.063741 - 31 July 2025

Abstract This research explores the characteristics of boiling in inclined pipes, a domain of great importance in engineering. Employing an experimental visualization technique, the boiling dynamics of deionized water are examined at varying inclination angles, paying special attention to the emerging flow patterns. The findings demonstrate that the inclination angle significantly impacts flow pattern transitions within the 0° to 90° range. As the heat flux rises, bubbles form in the liquid. The liquid’s inertia extends the bubble-wall contact time, thereby delaying the onset of bulk bubble flow. Beyond a 90° inclination, however, the patterning behavior is… More > Graphic Abstract

Wei Zhang^*, Haojie Chen, Kunyu Cheng, Yulong Zhang

Frontiers in Heat and Mass Transfer, Vol.23, No.1, pp. 361-381, 2025, DOI:10.32604/fhmt.2025.059837 - 26 February 2025

Abstract The present work deals with the numerical study of the two-phase flow pattern and heat transfer characteristics of single-loop pulsating heat pipes (PHPs) under three modified surfaces (superhydrophilic evaporation section paired with superhydrophilic, superhydrophobic, and hybrid condensation section). The Volume of Fluid (VOF) model was utilized to capture the phase-change process within the PHPs. The study also evaluated the influence of surface wettability on fluid patterns and thermo-dynamic heat transfer performance under various heat fluxes. The results indicated that the effective nucleation and detachment of droplets are critical factors influencing the thermal performance of the… More > Graphic Abstract

Victor Kozlov^1,2,*, Yuriy Litvinenko¹, Andrey Shmakov^1,2, Alexander Pavlenko¹

Frontiers in Heat and Mass Transfer, Vol.22, No.6, pp. 1695-1717, 2024, DOI:10.32604/fhmt.2024.056866 - 19 December 2024

Abstract The objective of the present study is an experimental investigation of diffusion combustion of round microjets, i.e., mixtures of hydrogen with methane, helium, and nitrogen. It is found that the evolution of burning microjets is associated with generation of a “bottleneck flame region” close to the nozzle exit, as it was observed earlier during hydrogen combustion. Combustion of a mixture of hydrogen and methane with increasing flow velocity occurs with the transformation of the torch. At first, a torch stabilized on the nozzle is observed, then it is divided into a stabilized part in contact… More >

Zhengyuan Pei¹, Yasushi Koito^2,*

Frontiers in Heat and Mass Transfer, Vol.22, No.5, pp. 1381-1397, 2024, DOI:10.32604/fhmt.2024.056624 - 30 October 2024

Abstract Extended experiments were conducted on the oscillation characteristics of merged liquid slugs in a horizontally oriented polymer pulsating heat pipe (PHP). The PHP’s serpentine channel comprised 14 parallel channels with a width of 1.3 and a height of 1.1 . The evaporator and condenser sections were 25 and 50 long, respectively, and the adiabatic section in between was 75 mm long. Using a plastic 3D printer and semi-transparent filament made from acrylonitrile butadiene styrene, the serpentine channel was printed directly onto a thin polycarbonate sheet to form the PHP. The PHP was charged with hydrofluoroether-7100.… More >

Nobuhito Nagasato¹, Zhengyuan Pei¹, Yasushi Koito^2,*

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 49-63, 2024, DOI:10.32604/fhmt.2024.047502 - 21 March 2024

Abstract Visualization experiments were conducted to clarify the operational characteristics of a polymer pulsating heat pipe (PHP). Hydrofluoroether (HFE)-7100 was used as a working fluid, and its filling ratio was 50% of the entire PHP channel. A semi-transparent PHP was fabricated using a transparent polycarbonate sheet and a plastic 3D printer, and the movements of liquid slugs and vapor plugs of the working fluid were captured with a high-speed camera. The video images were then analyzed to obtain the flow patterns in the PHP. The heat transfer characteristics of the PHP were discussed based on the… More >

Chenlin Zhu¹, Yan Zhao¹, Zhitao Jiang¹, Jiafeng Xie³, Lifang Zeng^2,*, Lijuan Qian^1,*

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 107-127, 2024, DOI:10.32604/fhmt.2023.044433 - 21 March 2024

Abstract Efficient and secure refueling within the vehicle refueling systems exhibits a close correlation with the issues concerning fuel backflow and gasoline evaporation. This paper investigates the transient flow behavior in fuel hose refilling and simplified tank fuel replenishment using the volume of fluid method. The numerical simulation is validated with the simplified hose refilling experiment and the evaporation simulation of Stefan tube. The effects of injection flow rate and injection directions have been discussed in the fuel hose refilling part. For both the experiment and simulation, the pressure at the end of the refueling pipe… More >

Zongjun Yin^*, Rong Su, Hui Xu

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.3, pp. 487-504, 2024, DOI:10.32604/fdmp.2023.042631 - 12 January 2024

Abstract In this study, numerical simulations of the pinching-off phenomena displayed by the dispersed phase in a continuous phase have been conducted using COMSOL Multiphysics (level-set method). Four flow patterns, namely “drop flow”, “jet flow”, “squeeze flow”, and “co-flow”, have been obtained for different flow velocity ratios, channel diameter ratios, density ratios, viscosity ratios, and surface tension. The flow pattern map of two-phase flow in coaxial microchannels has been obtained accordingly, and the associated droplet generation process has been critically discussed considering the related frequency, diameter, and pinch-off length. In particular, it is shown that the More > Graphic Abstract

Shaopeng Liu¹, Guowei Wang^2,3,*, Pengfei Liu¹, Dong Ye¹, Jian Song¹, Xing Liu¹, Yang Cheng^2,3

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.12, pp. 3045-3058, 2023, DOI:10.32604/fdmp.2023.029810 - 27 October 2023

Abstract Foam drainage is the flow of liquid through the interstitial spaces between bubbles driven by capillarity and gravity and resisted by viscous damping. The so-called foam drainage gas recovery technology is a technique traditionally used to mitigate the serious bottom-hole liquid loading in the middle and late stages of gas well production. In this context, determining the optimal concentration of the bubble drainage agent is generally crucial for the proper application of this method. In this study, a combination of indoor experiments and theoretical analysis have been used to determine the pressure drop related to… More >

Namphon Pipatpaiboon^a , Teerapat Chompookham^b, Sampan Rittidech^b, Yulong Ding^c, Thanya Parametthanuwat^d, Surachet Sichamnan^a,*

Frontiers in Heat and Mass Transfer, Vol.19, pp. 1-9, 2022, DOI:10.5098/hmt.19.24

Abstract When nanofluid (NF) is used as the working fluid in a rectangular two-phase closed thermosyphon (RTPCT), the formations and heat performance of two-phase flow patterns are explored qualitatively. Silver nanoparticles were mixed with deionized water at a concentration of 0.5 wt% in the NF. Nanoparticles improved the thermal contact surface area within the base flow, allowing the base fluid to boil quickly and easily. When the working fluid was boiled, NF also demonstrated high thermal conductivity capabilities, which diffused and moved along with the dual flow patterns. As a result, these qualities improved the RTPCT's More >

M. Gh. Mohammed Kamil^1,*, M. S. Kassim¹, R. A. Mahmood^2,3, L. AZ Mahdi⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.4, pp. 985-998, 2022, DOI:10.32604/fdmp.2022.018938 - 06 April 2022

Abstract This work investigates the steam condensation phenomena in an air-cooled condenser. The considered horizontal flattened tube has a 30 mm hydraulic diameter, and its length is a function of the steam quality with a limit value between 0.95 and 0.05. The mass flow rate ranges from 4 to 40 kg/m².s with a saturated temperature spanning an interval from 40°C to 80°C. A special approach has been implemented using the Engineering Equation Solver (EES) to solve a series of equations for the two-phase flow pattern and the related heat transfer coefficients. A wavy-stratified structure of the two-phase flow More >