scholarly journals Improving boiling heat transfer with hydrophilic/hydrophobic patterned flat surface: A molecular dynamics study

2022 ◽  
Vol 182 ◽  
pp. 121974
Author(s):  
Wei Deng ◽  
Shakeel Ahmad ◽  
Huaqiang Liu ◽  
Jingtan Chen ◽  
Jiyun Zhao
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Boiling Heat Transfer ◽  
Flat Surface

Effect of CuO Nanoparticle Concentration on R134a/Lubricant Pool-Boiling Heat Transfer

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
M. A. Kedzierski
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Mass Fraction ◽  
Flat Surface ◽  
Volume Fraction ◽  
Nanoparticle Concentration ◽  
Transfer Enhancement ◽  
Fundamental Understanding ◽  
Determining Factor ◽  
Cuo Nanoparticle

This paper quantifies the influence of copper (II) oxide (CuO) nanoparticle concentration on the boiling performance of R134a/polyolester mixtures on a roughened horizontal flat surface. Nanofluids are liquids that contain dispersed nanosize particles. Two lubricant-based nanofluids (nanolubricants) were made with a synthetic polyolester and 30 nm diameter CuO particles to 1% and 0.5% volume fractions, respectively. As reported in a previous study for the 1% volume fraction nanolubricant, a 0.5% nanolubricant mass fraction with R134a resulted in a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) between 50% and 275%. The same study had shown that increasing the mass fraction of the 1% volume fraction nanolubricant resulted in smaller, but significant, boiling heat transfer enhancements. The present study shows that the use of a nanolubricant with half the concentration of CuO nanoparticles (0.5% by volume) resulted in either no improvement or boiling heat transfer degradations with respect to the R134a/polyolester mixtures without nanoparticles. Consequently, significant refrigerant/lubricant boiling heat transfer enhancements are possible with nanoparticles; however, the nanoparticle concentration is an important determining factor. Further research with nanolubricants and refrigerants is required to establish a fundamental understanding of the mechanisms that control nanofluid heat transfer.

Convective Boiling Heat Transfer Enhancement by Microgrooves in Plate Evaporator

2011 ◽  
Author(s):  
Hirofumi Arima ◽  
Nobuhiko Matsuo ◽  
Keita Shigyou ◽  
Akio Okamoto ◽  
Yasuyuki Ikegami
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Boiling Heat Transfer ◽  
Flat Surface ◽  
Saturation Pressure ◽  
Transfer Coefficients ◽  
Convective Boiling ◽  
Heat Transfer Coefficients ◽  
Boiling Heat Transfer Coefficient

In this experimental study, we investigate the enhancement of heat transfer in ammonia on a new plate evaporator whose surface is configured with microgrooves. The microgrooves have a depth of 30 μm and a width of 200 μm. The local boiling heat transfer coefficients were measured on the evaporator. To compare the heat transfer characteristics of the evaporator, the local boiling heat transfer coefficient on a flat surface and on two microgrooved surfaces—one vertical and one horizontal to the direction of the ammonia flow—were measured at different ranges of mass flux (2–7.5 kg/m2s), heat flux (10–20 kW/m2), and saturation pressure (0.7–0.9 MPa). The results show that the local boiling heat transfer coefficient of the horizontal and vertical microgrooved surfaces was larger than that of a flat surface. In particular, the horizontal microgrooved surface had the best heat transfer coefficient.

Molecular Dynamics Simulation of Pool Boiling Heat Transfer of Nanofluids on Rough Walls

2017 ◽  
Author(s):  
Xunyan Yin ◽  
Minli Bai ◽  
Chengzhi Hu ◽  
Jizu Lv
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Boiling Heat Transfer ◽  
Heating Temperature ◽  
Pool Boiling ◽  
Liquid Argon ◽  
Dynamics Simulation ◽  
Pool Boiling Heat Transfer ◽  
Rough Walls

Molecular dynamics simulation was performed to investigate pool boiling heat transfer of nanofluids on rough walls. Nanoparticle movement was calculated to investigate the physical mechanisms of boiling heat transfer. The simulated system consisted of four regions: vapor argon, liquid argon, solid copper, and copper nanoparticles, and three cases were considered: base fluids (case A), nanoparticles far from the wall (case B), and nanoparticles near the wall (case C). Boiling heat transfer was enhanced by the addition of nanoparticles, and the enhancement increased with increasing heating temperature. Case C showed that nanoparticles were adsorbed on the nonevaporated film and did not move with the fluids. Thus, nanoparticles enhanced heat and energy transfer between the wall and fluids. Case B showed that nanoparticles moved randomly in the fluid area, which enhanced heat transfer within the fluid.

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