Alexander A. Fedorets¹, Eduard E. Kolmakov¹, Leonid A. Dombrovsky^1,2,3,*

Frontiers in Heat and Mass Transfer, Vol.22, No.1, pp. 1-14, 2024, DOI:10.32604/fhmt.2024.049335

Abstract New experimental results, which are important for the potential use of small levitating droplets as biochemical microreactors, are reported. It is shown that the combination of infrared heating and reduced evaporation of saline water under the droplet cluster is sufficient to produce equilibrium saltwater droplets over a wide temperature range. The resulting universal dependence of droplet size on temperature simplifies the choice of optimal conditions for generating stable droplet clusters with droplets of the desired size. A physical analysis of the experimental results on the equilibrium size of saltwater droplets makes it possible to separate the effects related to the… More > Graphic Abstract

Fengchao Wang^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.27, No.2, pp. 1-1, 2023, DOI:10.32604/icces.2023.09711

Abstract Wetting and capillary phenomena on the macroscale are ubiquitous and have been well understood. However, the relevant physics and mechanics on the nano-scale still remain mysterious. In this talk, I would like to discuss the exploration of capillarity from a nanoscopic perspective, including wetting, evaporation and condensation. At the solid/liquid interface, the liquid exhibits a pronounced layered structure that extends over several intermolecular distances from the solid surface. Our recent studies have shown that such molecular detail could provide some new understanding on century-old classical theory in this field, such as Young’s equation [1] and Kelvin equation [2]. More >

Yue Hu¹, Lu-Wen Zhang^1,*

The International Conference on Computational & Experimental Engineering and Sciences, Vol.26, No.1, pp. 1-1, 2023, DOI:10.32604/icces.2023.010595

Abstract Liquid accretion control plays a key role across a wide range of industrial applications, such as anti-icing, power generation, sewage treatment, water desalination, and energy harvesting. In condensation system, durable dropwise condensation of saturated vapor for heat transfer and energy saving in extensive industrial applications. While numerous superhydrophobic surfaces can promote steam condensation, maintaining discrete microdroplets on surfaces without the formation of a flooded filmwise condensation at high subcooling remains challenging. Here, we report the development of carbon nanotube arrayembedded hierarchical composite surfaces that enable ultra-durable dropwise condensation under a wide range of subcooling temperatures (∆T_sub = 8 K–38 K),… More >

Huan Zheng^a,*, Yuliang Ma^b , Huaping Mei^c , Xiaohong Xu^a , Xiguang Chen^d , Xunchen Cao^e

Frontiers in Heat and Mass Transfer, Vol.11, pp. 1-6, 2018, DOI:10.5098/hmt.11.34

Abstract The supersonic separator has proved to be an effective method to condense and separate CO₂ from natural gas, and the inlet temperature plays a vital role on condensation characteristics of CO₂ in the supersonic separator due to the instability temperature of wellhead natural gas. In this paper, the physical and mathematical models for the supersonic condensation process of CO₂ in the natural gas were established on the basis of CO₂ droplet surface tension, nucleation and growth model. The flow and condensation parameters were investigated under different temperature conditions. The results show that when the inlet gas pressure is 8.0 MPa,… More >

Zijie Chen^a , Sanat Modak^a, Massoud Kaviany^a,* , Richard Bonner^b

Frontiers in Heat and Mass Transfer, Vol.14, pp. 1-11, 2020, DOI:10.5098/hmt.14.1

Abstract In dropwise condensation on vertical surface, droplets grow at nucleation sites, coalesce and reach the departing diameter. In biphilic surfaces, when the hydrophobic domain is small, the maximum droplet diameter is controlled by the shortest dimension where the droplets merge at the boundary. Through direct numerical simulations this size-effect heat transfer coefficient enhancement is calculated. Then the 1-D biphilic surface is optimized considering the size-dependent hydrophilic domain partial flooding (directly simulated as a liquid rivulet and using the capillary limit), the subcooling (heat flux) and condenser length effects. The predicted performance is in good agreement with the available experiments. More >

Louay Abd Al-Azez Mahdi, Mohammed A. Fayad, Miqdam T. Chaichan^*

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.9, pp. 2201-2214, 2023, DOI:10.32604/fdmp.2023.027166

Abstract A theoretical study based on the Penalty factor (PF) method by Cavallini et al. is conducted to show that the pressure drop occurring in a wire-on-tube heat exchanger can be converted into a temperature difference for two types of refrigerants R-134a and R-600a typically used for charging refrigerators and freezers. The following conditions are considered: stratified or stratified-wavy flow condensation occurring inside the smooth tube of a wire-on-tube condenser with diameter 3.25, 4.83, and 6.299 mm, condensation temperatures 35°C, 45°C, and 54.4°C and cover refrigerant mass flow rate spanning the interval from 1 to 7 kg/hr. The results show that the… More > Graphic Abstract

Rongge Xiao^a,*, Shuaishuai Jin^a, Xin Feng^b, Peng Zhang^c, Zheng Dai^c

Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-7, 2021, DOI:10.5098/hmt.16.25

Abstract With the increasing production and use of natural gas, the supersonic nozzle has become focus of the impurity removal research. In this paper, the modified classical nucleation model is used as the condensation nucleation model, and the Gyarmathy growth model is selected as the droplet growth model. Based on the assumption of no phase slip and Eulerian two fluid model, the flow control equation of wet natural gas is established. By giving the selection criteria as a turbulence equation, the SRK real gas equation is used to carry out the corresponding numerical simulation. The required supersonic nozzle structure and grid… More >

Kapil Dev Choudhary, Shyam Sunder Yadav^† , Mani Sankar Dasgupta

Frontiers in Heat and Mass Transfer, Vol.16, pp. 1-10, 2021, DOI:10.5098/hmt.16.14

Abstract In the current work, we simulate the condensation of supercritical CO₂ during its high speed flow inside two different converging-diverging nozzles. We use the homogeneous equilibrium method and the classical nucleation theory based non-equilibrium phase change model for this purpose. The simulation results indicate significant influence of the nozzle inlet condition, nozzle shape and the fluid thermophysical behaviour on the nonequilibrium conditions prevailing inside the nozzles. We observe very low, ∼0.15 K, supercooling for the flow of CO₂ inside the Claudio Lettieri nozzle compared to the supercooling of ∼3 K observed for the Berana nozzle. Very high nucleation rate (∼… More >

Daoming Shen^1,*, Jinhong Xia¹, Chao Gui¹, Songtao Xue²

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.6, pp. 1411-1424, 2023, DOI:10.32604/fdmp.2023.024924

Abstract The thermal transmission coefficient for a micro-ribbed tube has been determined using theoretical relationships and the outcomes of such calculations have been compared with experiments conducted using a R1234yf refrigerant undergoing condensation. In particular four theoretical single-phase flow and three multi-phase flow models have been used in this regard. The experimental results show that: the Oliver et al. criterion equation overestimates the experimental results as its accuracy is significantly affected by the specific conditions realized inside micro-fin tubes; the Miyara et al. criterion equation prediction error is less than 15%; the Cavallini et al. approach gives the highest prediction accuracy;… More >

Yong Zheng¹, Lei Zhao¹, Yujiang Wang¹, Feng Chang¹, Weijia Dong^2,*, Xinying Liu², Yunfei Li², Xiaohan Zhang², Ziyuan Zhao³

Energy Engineering, Vol.120, No.2, pp. 529-540, 2023, DOI:10.32604/ee.2023.022765

Abstract Supersonic separation technology is a new natural gas sweetening method for the treatment of natural gas with high CO₂ (carbon dioxide) content. The structures of the Laval nozzle and the supersonic separator were designed, and the mathematical models of supersonic condensation and swirling separation for CO₂-CH₄ mixture gas were established. The supersonic condensation characteristics of CO₂ in natural gas and the separation characteristics of condensed droplets under different inlet pressures were studied. The results show that higher inlet pressure results in a larger droplet radius and higher liquid phase mass fraction; additionally, the influence of centrifugal force is more pronounced,… More >