Investigating effects of heating orientations on nucleate boiling heat transfer, bubble dynamics, and wall heat flux partition boiling model for pool boiling

2019 ◽  
Vol 163 ◽  
pp. 114358 ◽  
Author(s):  
T.J. Chuang ◽  
Y.H. Chang ◽  
Y.M. Ferng
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Wall Heat Flux ◽  
Nucleate Boiling Heat Transfer

Boiling Heat Transfer and Critical Heat Flux Enhancement of Upward- and Downward-Facing Heater in Nanofluids

2013 ◽  
Vol 135 (7) ◽  
Author(s):  
Muhamad Zuhairi Sulaiman ◽  
Masahiro Takamura ◽  
Kazuki Nakahashi ◽  
Tomio Okawa
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Flux Enhancement ◽  
Optimum Configuration ◽  
Wall Superheat ◽  
Nucleate Boiling Heat Transfer

Boiling heat transfer (BHT) and critical heat flux (CHF) performance were experimentally studied for saturated pool boiling of water-based nanofluids. In present experimental works, copper heaters of 20 mm diameter with titanium-oxide (TiO2) nanocoated surface were produced in pool boiling of nanofluid. Experiments were performed in both upward and downward facing nanofluid coated heater surface. TiO2 nanoparticle was used with concentration ranging from 0.004 until 0.4 kg/m3 and boiling time of tb = 1, 3, 10, 20, 40, and 60 mins. Distilled water was used to observed BHT and CHF performance of different nanofluids boiling time and concentration configurations. Nucleate boiling heat transfer observed to deteriorate in upward facing heater, however; in contrast effect of enhancement for downward. Maximum enhancements of CHF for upward- and downward-facing heater are 2.1 and 1.9 times, respectively. Reduction of mean contact angle demonstrate enhancement on the critical heat flux for both upward-facing and downward-facing heater configuration. However, nucleate boiling heat transfer shows inconsistency in similar concentration with sequence of boiling time. For both downward- and upward-facing nanocoated heater's BHT and CHF, the optimum configuration denotes by C = 400 kg/m3 with tb = 1 min which shows the best increment of boiling curve trend with lowest wall superheat ΔT = 25 K and critical heat flux enhancement of 2.02 times.

scholarly journals Discussion of the Heat Flux Calculation Method During Pool Boiling on Meshed Heaters

2020 ◽  
Vol 2 (1) ◽  
pp. 247-252
Author(s):  
Łukasz J. Orman ◽  
Norbert Radek ◽  
Jacek Pietraszek ◽  
Dariusz Gontarski
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Distilled Water ◽  
Determination Method ◽  
Nucleate Boiling Heat Transfer ◽  
Calculation Results ◽  
Very High

AbstractThe paper discusses nucleate boiling heat transfer on meshed surfaces during pool boiling of distilled water and ethyl alcohol of very high purity. It presents a correlation for heat flux developed for heaters covered with microstructural coatings made of meshes. The experimental results have been compared with the calculation results performed using the correlation and have been followed by discussion. Conclusions regarding the heat flux determination method have been drawn with the particular focus on the usefulness of the considered model for heat flux calculations on samples with sintered mesh layers.

Experimental Study of Heat Transfer Enhancement in Pool Boiling by Using 2-Ethyl 1-Hexanol an Additive

2014 ◽  
Vol 592-594 ◽  
pp. 1601-1606 ◽  
Author(s):  
Sameer Sheshrao Gajghate ◽  
Anil R. Aacharya ◽  
Anil T. Pise ◽  
Ganesh S. Jadhav
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Optimum Level ◽  
Transfer Coefficients ◽  
Nichrome Wire

The addition of additives to the water is known to enhance boiling heat transfer. In the present investigation, boiling heat transfer coefficients are measured for Nichrome wire, immersed in saturated water with & without additive. An additive used is 2-Ethyl 1-Hexanol with varying concentrations in the range of 10-10000 ppm. Extensive experimentation of pool boiling is carried out above the critical heat flux. Boiling behavior i.e. bubble dynamics are observed at higher heat flux for nucleate boiling of water over wide ranges of concentration of additive in water. Results are encouraging and show that a small amount of surface active additive makes the nucleate boiling heat transfer coefficient considerably higher, and that there is an optimum additive (500-1000ppm) concentration for higher heat fluxes. An optimum level of enhancement is observed up to a certain amount of additive 500-1000ppm in the tested range. Thereafter significant enhancement is not observed. This enhancement may be due to change in thermo-physical properties i.e. mainly due to a reduction in surface tension of water in the presence of additive.

Boiling Heat Transfer and Critical Heat Flux Enhancement of Upward- and Downward-Facing Heater in Nanofluids

2012 ◽  
Author(s):  
Muhamad Zuhairi Sulaiman ◽  
Masahiro Takamura ◽  
Kazuki Nakahashi ◽  
Tomio Okawa
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Flux Enhancement ◽  
Optimum Configuration ◽  
Wall Superheat ◽  
Nucleate Boiling Heat Transfer

Boiling heat transfer (BHT) and critical heat flux (CHF) performance were experimentally studied for saturated pool boiling of water-based nanofluids. In present experimental works, copper heaters of 20 mm diameter with titanium-oxide (TiO2) nanocoated surface were produced in pool boiling of nanofluid. Experiments were performed in both upward and downward facing nanofluid coated heater surface. TiO2 nanoparticle was used with concentration ranging from 0.004 until 0.4 kg/m3 and boiling time of tb = 1, 3, 10, 20, 40 and 60 minutes. Distilled water was used to observed BHT and CHF performance of different nanofluids boiling time and concentration configurations. Nucleate boiling heat transfer observed to deteriorate in upward facing heater, however, in contrast effect of enhancement for downward. Maximum CHF for upward- and downward-facing heater are 2.1 and 1.9, respectively. Reduction of mean contact angle demonstrate enhancement on the critical heat flux for both upward-facing and downward-facing heater configuration. However, nucleate boiling heat transfer shows inconsistency in similar concentration with sequence of boiling time. For both downward- and upward-facing nanocoated heater’s BHT and CHF, the optimum configuration denotes by C = 400 kg/m3 with tb = 1 minute which shows the best increment of boiling curve trend with lowest wall superheat ΔT = 25 K and critical heat flux enhancement of 2.02 times.

Optimization of Microporous Structures in Enhancing Pool Boiling Heat Transfer of Saturated R-123, FC-72 and Water

2007 ◽  
Author(s):  
Joo H. Kim ◽  
Madhav R. Kashinath ◽  
Sang M. Kwark ◽  
Seung M. You
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Particle Sizes ◽  
Microporous Coating ◽  
Nucleate Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient ◽  
Enhanced Surface

The present research is an experimental study for the enhancement of boiling heat transfer using microporous coating techniques. The effects of different metal particle sizes in the coating compound for microporous coatings on pool boiling performance of refrigerants and water are investigated. All boiling tests were performed with 1×1cm2 test heaters in the horizontal, upward-facing orientation under increasing heat flux conditions at atmospheric pressure in saturated R-123, FC-72, and water. Results showed that the enhanced surface by microporous coating technique significantly augmented both nucleate boiling heat transfer coefficient and critical heat flux of FC-72 and R-123 over a plain surface. However, the enhancement of boiling performance for water was comparatively insignificant compared to the other liquids.

Lattice Boltzmann Simulations of Macro/Microscale Effects on Saturated Pool Boiling Curves for Heated Horizontal Surfaces

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Ping Cheng ◽  
Chaoyang Zhang ◽  
Shuai Gong
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Lattice Boltzmann ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Saturation Temperature ◽  
Correlation Equation ◽  
Nucleate Boiling ◽  
Nucleate Boiling Heat Transfer

Results of lattice Boltzmann (LB) simulations of macroscale effects (heating modes, heater size, and saturation temperature) as well as microscale effects (wettability and roughness) on saturated pool boiling from superheated horizontal surfaces are summarized in this paper. These effects on pool boiling curves from natural convection through nucleate boiling to critical heat flux (CHF) and from transition boiling to film boiling are illustrated. It is found that macroscale effects have negligible influence on nucleate boiling heat transfer, and Rohsenow's correlation equation fits well with the simulated nucleate boiling heat transfer on smooth hydrophilic and hydrophobic horizontal surfaces. Both macroscale and microscale effects have important influence on critical heat flux and transition boiling heat transfer.

Pool Boiling Heat Transfer Characteristics of Inclined pHEMA-Coated Surfaces

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Abdolali Khalili Sadaghiani ◽  
Ahmad Reza Motezakker ◽  
Alsan Volkan Özpınar ◽  
Gözde Özaydın İnce ◽  
Ali Koşar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Surface Orientation ◽  
Maximum Enhancement ◽  
Pool Boiling Heat Transfer ◽  
Coated Surfaces

New requirements for heat exchangers offered pool boiling heat transfer on structured and coated surfaces as one of the promising methods for effective heat removal. In this study, pool boiling experiments were conducted on polyhydroxyethylmethacrylate (pHEMA)-coated surfaces to investigate the effect of surface orientation on bubble dynamics and nucleate boiling heat transfer. pHEMA coatings with thicknesses of 50, 100, and 200 nm were deposited using the initiated chemical deposition (iCVD) method. De-ionized water was used as the working fluid. Experiments were performed on horizontal and inclined surfaces (inclination angles of 10 deg, 30 deg, 50 deg, and 70 deg) under the constant heat flux (ranging from 10 to 80 kW/m2) boundary condition. Obtained results were compared to their plain surface counterparts, and heat transfer enhancements were observed. Accordingly, it was observed that the bubble departure phenomenon was affected by heat flux and wall superheat on bare silicon surfaces, while the supply path of vapor altered the bubble departure process on pHEMA-coated surfaces. Furthermore, the surface orientation played a major role on bubble dynamics and could be considered as a mechanism for fast vapor removal from surfaces. Bubble coalescence and liquid replenishment on coated surfaces had a promising effect on heat transfer coefficient enhancement on coated surfaces. For horizontal surfaces, a maximum enhancement of 25% relative to the bare surface was achieved, while the maximum enhancement was 105% for the inclined coated surface under the optimum condition. iCVD was proven to be a practical method for coating surfaces for boiling heat transfer applications due to the obtained promising results.

Pool Boiling Heat Transfer with Nanotube Arrays Surface on Titanium

2012 ◽  
Vol 550-553 ◽  
pp. 2913-2916 ◽  
Author(s):  
Jin Liang Tao ◽  
Xin Liang Wang ◽  
Pei Hua Shi ◽  
Xiao Ping Shi
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Test Fluid ◽  
Porous Coating ◽  
Pool Boiling Heat Transfer ◽  
Nucleate Boiling Heat Transfer ◽  
Boiling Heat Transfer Coefficient

In this paper, a new porous coating was formed directly on the surface of titanium metal via anodic oxidation. And by the SEM, the morphology of the coating, which is composed of well-ordered perpendicular nanotubes, was characterized. Moreover, taking deionized water as the test fluid, a visualization study of the coating on its pool boiling heat transfer performance was made. The results demonstrated that compared with the smooth surface, the nucleate boiling heat transfer coefficient can increase 3 times while the nucleate boiling super heat was reduced 30%.

Pool Boiling Heat Transfer From Plain and Microporous, Square Pin Finned Surfaces in Saturated FC-72

1999 ◽  
Author(s):  
K. N. Rainey ◽  
S. M. You
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Large Scale ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Small Scale ◽  
Surface Microstructure ◽  
Transfer Coefficients ◽  
Microporous Coating ◽  
Nucleate Boiling Heat Transfer

Abstract The present research is an experimental study of “double enhancement” behavior in pool boiling from heater surfaces simulating microelectronic devices immersed in saturated FC-72 at atmospheric pressure. The term “double enhancement” refers to the combination of two different enhancement techniques: a large-scale area enhancement (square pin fin array) and a small-scale surface enhancement (microporous coating). Fin lengths were varied from 0 (flat surface) to 8 mm. Effects of this double enhancement technique on critical heat flux (CHF) and nucleate boiling heat transfer in the horizontal orientation (fins are vertical) are investigated. Results showed significant increases in nucleate boiling heat transfer coefficients with the application of the microporous coating to the heater surfaces. CHF was found to be relatively insensitive to surface microstructure for the finned surfaces except in the case of the surface with 8 mm long fins. The nucleate boiling and CHF behavior has been found to be the result of multiple, counteracting mechanisms: surface area enhancement, fin efficiency, surface microstructure (active nucleation site density), vapor bubble departure resistance, and re-wetting liquid flow resistance.

Experimental Study of Surfactant Effects on Pool Boiling Heat Transfer

1990 ◽  
Vol 112 (1) ◽  
pp. 207-212 ◽  
Author(s):  
Ying Liang Tzan ◽  
Yu Min Yang
Keyword(s):  
Heat Transfer ◽  
Binary Mixtures ◽  
Boiling Heat Transfer ◽  
Sodium Lauryl Sulfate ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Additive Concentration ◽  
Lauryl Sulfate ◽  
Diffusion Effect ◽  
Nucleate Boiling Heat Transfer

In the first part of this work, nucleate boiling of aqueous solutions of sodium lauryl sulfate (SLS) over relatively wide ranges of concentration and heat flux was carried out in a pool boiling apparatus. The experimental results show that a small amount of surface active additive makes the nucleate boiling heat transfer coefficient h considerably higher, and that there is an optimum additive concentration for higher heat fluxes. Beyond this optimum point, further increase in additive concentration makes h lower. In the second part of this work, nucleate boiling heat transfer rate for n-propanol-water binary mixtures with various amounts of sodium lauryl sulfate were measured in the same pool boiling apparatus. The importance of the mass diffusion effect, which is caused by preferential evaporation of the more volatile component at the vapor-liquid interface on the boiling of the binary mixture, has been confirmed. However, it is shown that the effect exerted by the addition of a surfactant dominates over the mass diffusion effect in dilute binary mixtures.

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