Experimental investigation of pool boiling heat transfer performance of refrigerant R-134a on differently roughened copper surfaces

2021 ◽  
Author(s):  
Anil S. Katarkar ◽  
Ajay D. Pingale ◽  
Sachin U. Belgamwar ◽  
Swapan Bhaumik
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
Transfer Performance ◽  
Copper Surfaces ◽  
Pool Boiling Heat Transfer ◽  
R 134A

Influence of Copper Oxide on Femtosecond Laser Surface Processed Copper Pool Boiling Heat Transfer Surfaces

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Corey Kruse ◽  
Alfred Tsubaki ◽  
Craig Zuhlke ◽  
Dennis Alexander ◽  
Mark Anderson ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Oxide Layer ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
Laser Surface ◽  
Transfer Performance ◽  
Reference Surface ◽  
Copper Surfaces ◽  
Pool Boiling Heat Transfer

Pool boiling heat transfer with the use of femtosecond laser surface processing (FLSP) on copper surfaces has been studied. FLSP creates a self-organized micro/nanostructured surface. In the previous pool boiling heat transfer studies with stainless steel FLSP surfaces, enhancements in critical heat flux (CHF) and heat transfer coefficients (HTCs) were observed compared to the polished reference surface. However, this study shows that copper FLSP surfaces exhibit reductions in both CHF and HTCs consistently. This reduction in heat transfer performance is a result of an oxide layer that covers the surface of the microstructures and acts as an insulator due to its low thermal conductivity. The oxide layer was observed and measured with the use of a focused ion beam milling process and found to have thickness of a few microns. The thickness of this oxide layer was found to be related to the laser fluence parameter. As the fluence increased, the oxide layer thickness increased and the heat transfer performance decreased. For a specific test surface, the oxide layer was selectively removed by a chemical etching process. The removal of the oxide layer resulted in an enhancement in the HTC compared to the polished reference surface. Although the original FLSP copper surfaces were unable to outperform the polished reference curve, this experiment illustrates how an oxide layer can significantly affect heat transfer results and dominate other surface characteristics (such as increased surface area and wicking) that typically lead to heat transfer enhancement.

Experimental and Mechanism Investigation on Boiling Heat Transfer Characteristics of Alumina/Water Nanofluid on a Cylindrical Tube

NANO ◽  
2019 ◽  
Vol 14 (10) ◽  
pp. 1950124
Author(s):  
Hao Zhang ◽  
Zeng-en Li ◽  
Shan Qing ◽  
Zhuangzhuang Jia ◽  
Jiarui Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Particle Deposition ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
Heating Surface ◽  
Cylindrical Tube ◽  
Influential Factors ◽  
Transfer Performance ◽  
Pool Boiling Heat Transfer

Nucleate pool boiling heat transfer experiments have been conducted to nanofluids on a horizontal cylinder tube under atmospheric pressure. The nanofluids are prepared by dispersing Al2O3 nanoparticles into distilled water at concentrations of 0.001, 0.01, 0.1, 1 and 2[Formula: see text]wt.% with or without sodium, 4-dodecylbenzenesulfonate (SDBS). The experimental results showed that: nanofluids at lower concentrations (0.001[Formula: see text]wt.% to 1[Formula: see text]wt.%) can obviously enhance the pool boiling heat transfer performance, but signs of deterioration can be observed at higher concentration (2[Formula: see text]wt.%). The presence of SDBS can obviously enhance the pool boiling heat transfer performance, and with the presence of SDBS, a maximum enhancement ratio of BHTC of 69.88%, and a maximum decrease ratio of super heat of 41.12% can be found in Group NS5 and NS4, respectively. The tube diameter and wall thickness of heating surface are the influential factors for boiling heat transfer coefficient. Besides, we find that Rohsenow formula failed to predict the characteristics of nanofluids. The mechanism study shows that: the decrease of surface tension, which leads to the decrease of bubble departure diameter, and the presence of agglomerates in nanofluids are the reasons for the enhanced pool boiling heat transfer performance. At higher concentration, particle deposition will lead to the decrease of distribution density of the vaporization core, and as a result of that, the boiling heat transfer performance will deteriorate.

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