Subcooled Pool Film Boiling Heat Transfer From Spheres With Superhydrophobic Surfaces: An Experimental Study

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Li-Wu Fan ◽  
Jia-Qi Li ◽  
You-You Su ◽  
Huan-Li Wang ◽  
Ting Ji ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Superhydrophobic Surfaces ◽  
Film Boiling ◽  
Vapor Film ◽  
Wall Superheat ◽  
Static Contact

Pool film boiling was studied by visualized quenching experiments on stainless steel spheres in water at the atmospheric pressure. The surfaces of the spheres were coated to be superhydrophobic (SHB), having a static contact angle greater than 160 deg. Subcooled conditions were concerned parametrically with the subcooling degree being varied from 0 °C (saturated) to 70 °C. It was shown that film boiling is the overwhelming mode of heat transfer during the entire course of quenching as a result of the retention of stable vapor film surrounding the SHB spheres, even at very low wall superheat that normally corresponds to nucleate boiling. Pool boiling heat transfer is enhanced with increasing the subcooling degree, in agreement with the thinning trend of the vapor film thickness. The heat flux enhancement was found to be up to fivefold for the subcooling degree of 70 °C in comparison to the saturated case, at the wall superheat of 200 °C. A modified correlation in the ratio form was proposed to predict pool film boiling heat transfer from spheres as a function of the subcooling degree.

An Experimental Study of Transition and Film Boiling Heat Transfer in Liquid-Saturated Porous Bed

1986 ◽  
Vol 108 (1) ◽  
pp. 117-124 ◽  
Author(s):  
S. Fukusako ◽  
T. Komoriya ◽  
N. Seki
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Circular Cylinder ◽  
Boiling Heat Transfer ◽  
Heating Surface ◽  
Local Maximum ◽  
Nucleate Boiling ◽  
Film Boiling ◽  
Experimental Investigations ◽  
Porous Bed

Experimental investigations of transition and film boiling in a liquid-saturated porous bed are reported. The porous bed contained in a vertical circular cylinder is made up of packed spherical beads whose diameters range from 1.0 to 16.5 mm, while the depth of the bed overlying the heating surface varies from 10 to 300 mm. Water and fluorocarbon refrigerants R-11 and R-113 are adopted as testing liquids. Special attention is focused on the effect of the diameter of spherical beads on boiling heat transfer in the transition boiling region. It is found that for the small bead diameters the steady boiling heat transfer rises monotonically with temperature from nucleate boiling through the film boiling region, without going through a local maximum.

Experimental Study on Structured Surfaces for Nucleate Pool Boiling Enhancement

2017 ◽  
Author(s):  
Vishal V. Nirgude ◽  
Mayank Modak ◽  
Avadhesh K. Sharma ◽  
Santosh K. Sahu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Atmospheric Pressure ◽  
Boiling Heat Transfer ◽  
Heat Transfer Performance ◽  
Pool Boiling ◽  
Transfer Performance ◽  
Structured Surfaces ◽  
Wall Superheat ◽  
Boiling Enhancement

In the present experimental study an attempt has been made to study the boiling heat transfer characteristics of variety of enhanced surfaces. Three different copper test surfaces: polished copper and two structured surfaces were used in the present investigation. The heat transfer performance of each surface is studied under saturated pool boiling conditions at atmospheric pressure by using water and isopropyl as pool liquid. The effect of intersecting tunnel geometry with 0.5 mm and 1 mm depth on heat transfer performance has been studied. The comparison of heat transfer coefficient indicates that the intersecting tunnel structure enhanced the boiling heat transfer performance and reduced the wall superheat at given heat flux inputs.

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.

Experimental Study on the Effect of Orientation of Heating Circular Plate on Film Boiling Heat Transfer for Fluorocarbon Refrigerant R-11

1978 ◽  
Vol 100 (4) ◽  
pp. 624-628 ◽  
Author(s):  
N. Seki ◽  
S. Fukusako ◽  
K. Torikoshi
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Circular Plate ◽  
Boiling Heat Transfer ◽  
Film Boiling ◽  
Brass Plate ◽  
Bottom Side ◽  
Film Coefficient

The characteristics of film boiling heat transfer from a heated horizontal circular brass plate to a pool of fluorocarbon R-11 are examined for the case in which only the top side of the plate is in contact with the liquid (facing upward) and for the case in which the bottom side of the plate is in contact with the liquid (facing downward). It is found that the film coefficient for the facing downwards orientation of the plate was found to be closely correlated by the following: Nu=0.35(L/CpΔT)Gr0.25·Pr0.25

Effect of Nanofluid on the Film Boiling Behavior at Vapor Film Collapse

2009 ◽  
Author(s):  
Takahiro Arai ◽  
Masahiro Furuya
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Direct Contact ◽  
Film Surface ◽  
Film Boiling ◽  
Vapor Film ◽  
Quenching Temperature ◽  
Steel Sphere ◽  
Film Collapse ◽  
Al2o3 Nanofluid

A high-temperature stainless-steel sphere was immersed into Al2O3 nanofluid to investigate film boiling heat transfer and collapse of vapor film. Surface temperature is referred to the measured value of thermocouples embedded into and welded onto a surface of the sphere. A direct contact between the immersed sphere and Al2O3 nanofluids is quantified by the acquired electric conductivity. The Al2O3 nanofluid concentration is varied from 0.024 to 1.3 vol%. A film boiling heat transfer rate of Al2O3 nanofluid is almost the same or slightly lower than that of water. A quenching temperature rises slightly with increased the Al2O3 nanofluid concentrations. In both water and Al2O3 nanofluid, the direct contact signals between the sphere and coolant were not detected before vapor film collapse.

Sign in / Sign up

Export Citation Format

Share Document