Numerical Simulation of Pool Boiling: A Review

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Vijay K. Dhir ◽  
Gopinath R. Warrier ◽  
Eduardo Aktinol
Keyword(s):  
Numerical Simulation ◽  
Conjugate Heat Transfer ◽  
Numerical Models ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Film Boiling ◽  
Gravity Level ◽  
Designed Experiments ◽  
Wall Superheat ◽  
Multiple Bubbles

A review of numerical simulation of pool boiling is presented. Details of the numerical models and results obtained for single bubble, multiple bubbles, nucleate boiling, and film boiling are provided. The effect of such parameters such as wall superheat, liquid subcooling, contact angle, gravity level, noncondensables, and conjugate heat transfer are also included. The numerical simulation results have been validated with data from well designed experiments.

Transition Boiling Curves in Saturated Pool Boiling From Horizontal Cylinders

1996 ◽  
Vol 118 (3) ◽  
pp. 654-661 ◽  
Author(s):  
E. K. Ungar ◽  
R. Eichhorn
Keyword(s):  
High Speed ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Heat Fluxes ◽  
Film Boiling ◽  
High Speed Flow ◽  
Wall Superheat ◽  
Speed Flow ◽  
Single Transition ◽  
Horizontal Cylinders

Pool boiling heat flux versus wall superheat boiling curves were obtained for horizontal 3.18-mm-dia thin-walled brass tubes heated by an internal high-speed flow of ethylene glycol. The boiling liquids were saturated n-pentane, R-113, acetone, methanol ethanol, benzene, and isopropanol. Boiling results include nucleate and transition boiling in all the test liquids, but film boiling was achieved only with methanol. The measured peak heat fluxes are well correlated by available predictions. The methanol experiments clearly display two transition boiling curves, one obtained on increasing the cylinder temperature from nucleate boiling, the other on decreasing the cylinder temperature from film boiling. For the cases in which the highest cylinder temperature reached only into the transition regime, a single transition boiling curve resulted.

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.

Subcooled Pool Boiling Experiments on Horizontal Heaters Coated With Carbon Nanotubes

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
V. Sathyamurthi ◽  
H-S. Ahn ◽  
D. Banerjee ◽  
S. C. Lau
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Heat Flux ◽  
Pool Boiling ◽  
Type A ◽  
Nucleate Boiling ◽  
Film Boiling ◽  
Test Fluid ◽  
Type B ◽  
Coated Surfaces

Pool boiling experiments were conducted with three horizontal, flat, silicon surfaces, two of which were coated with vertically aligned multiwalled carbon nanotubes (MWCNTs). The two wafers were coated with MWCNT of two different thicknesses: 9 μm (Type-A) and 25 μm (Type-B). Experiments were conducted for the nucleate boiling and film boiling regimes for saturated and subcooled conditions with liquid subcooling of 0–30°C using a dielectric fluorocarbon liquid (PF-5060) as test fluid. The pool boiling heat flux data obtained from the bare silicon test surface were used as a base line for all heat transfer comparisons. Type-B MWCNT coatings enhanced the critical heat flux (CHF) in saturated nucleate boiling by 58%. The heat flux at the Leidenfrost point was enhanced by a maximum of ∼150% (i.e., 2.5 times) at 10°C subcooling. Type-A MWCNT enhanced the CHF in nucleate boiling by as much as 62%. Both Type-A MWCNT and bare silicon test surfaces showed similar heat transfer rates (within the bounds of experimental uncertainty) in film boiling. The Leidenfrost points on the boiling curve for Type-A MWCNT occurred at higher wall superheats. The percentage enhancements in the value of heat flux at the CHF condition decreased with an increase in liquid subcooling. However the enhancement in heat flux at the Leidenfrost points for the nanotube coated surfaces increased with liquid subcooling. Significantly higher bubble nucleation rates were observed for both nanotube coated surfaces.

On the Mechanism of Pool Boiling Critical Heat Flux Enhancement in Nanofluids

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Hyungdae Kim ◽  
Ho Seon Ahn ◽  
Moo Hwan Kim
Keyword(s):  
Heat Flux ◽  
Critical Heat Flux ◽  
Heated Surface ◽  
Pure Water ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Titania Nanoparticles ◽  
Nanoparticle Layer ◽  
Wall Superheat ◽  
Dry Spot

The pool boiling characteristics of water-based nanofluids with alumina and titania nanoparticles of 0.01 vol % were investigated on a thermally heated disk heater at saturated temperature and atmospheric pressure. The results confirmed the findings of previous studies that nanofluids can significantly enhance the critical heat flux (CHF), resulting in a large increase in the wall superheat. It was found that some nanoparticles deposit on the heater surface during nucleate boiling, and the surface modification due to the deposition results in the same magnitude of CHF enhancement in pure water as for nanofluids. Subsequent to the boiling experiments, the interfacial properties of the heater surfaces were examined using dynamic wetting of an evaporating water droplet. As the surface temperature increased, the evaporating meniscus on the clean surface suddenly receded toward the liquid due to the evaporation recoil force on the liquid-vapor interface, but the nanoparticle-fouled surface exhibited stable wetting of the liquid meniscus even at a remarkably higher wall superheat. The heat flux gain attainable due to the improved wetting of the evaporating meniscus on the fouled surface showed good agreement with the CHF enhancement during nanofluid boiling. It is supposed that the nanoparticle layer increases the stability of the evaporating microlayer underneath a bubble growing on a heated surface and thus the irreversible growth of a hot/dry spot is inhibited even at a high wall superheat, resulting in the CHF enhancement observed when boiling nanofluids.

Determination of Dimensionality of Pool Boiling on a Thin Horizontal Disk Under Subcooled Conditions Using Thin-Film Thermocouples

2008 ◽  
Author(s):  
Vijaykumar Sathyamurthi ◽  
Debjyoti Banerjee
Keyword(s):  
Thin Film ◽  
Heat Flux ◽  
Correlation Dimension ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Constant Heat Flux ◽  
Film Boiling ◽  
Steady State Condition ◽  
Experimental Apparatus ◽  
Thin Film Thermocouples

Subcooled pool boiling experiments are conducted at subcooling levels of 10 °C on a thin silicon disk (∼ 400μm thickn, 3 – inch diameter) with in situ micro-machined K-type thin film thermocouples (TFT) using a perfluorocarbon liquid refrigerant (PF-5060) with a boiling point of 56 °C. The experimental apparatus is of constant heat flux type. Surface temperature (from TFT) and heat flux data is obtained at each steady state condition to generate the pool boiling curve. The time – delay embedding technique is used to re-construct higher dimensional vectors with the optimal delay being estimated from the first minimum of mutual information. The correlation dimension measure is then estimated from the delay re – constructed phase space vectors. In this preliminary study correlation dimension measures are seen to vary from ∼ 12 in nucleate boiling, to ∼ 7 – 9 near Critical Heat Flux (CHF) condition, and ∼ 7 – 8 in film boiling. The results suggest that the attractors underlying thermal transport mechanisms in nucleate boiling are affected by a greater number of parameters than that at CHF. The dimension of the attractor is reduced further in the film boiling regime.

Effect of Fouling on Nucleate Pool Boiling in Microgravity and Earth Gravity

1999 ◽  
Author(s):  
Daiju Motoya ◽  
Ikuya Haze ◽  
Masahiro Osakabe
Keyword(s):  
Heat Flux ◽  
High Speed ◽  
Pool Boiling ◽  
Film Boiling ◽  
Gravity Level ◽  
Nucleate Pool Boiling ◽  
Bubble Volume ◽  
High Speed Video ◽  
Earth Gravity ◽  
Bare Surface

Abstract Nucleate pool boiling of water on clean and fouling surfaces was conducted in microgravity and earth gravity. The microgravity experiments were conducted in 8 s JAMIC drop shaft in Hokkaido of Japan. Platinum wires of 0.2 mm in diameter with or without fouling scale were used to provide uniform heat flux and measurement of the mean temperature of wires. The generated bubble volume was measured with high-speed video or CCD images. The more vigorous bubbling was observed on the fouling wire compared to that on the clean wire at a same heat flux both in earth gravity and microgravity. The enhancement of the bubbling was associated with the fact that the hydrophilic porous structure in the fouling scale provided the sufficient number of active sites for bubbling nucleation. The wettability of the surface with the fouling scale was much higher than that of the clean bare surface. The bubble departure diameter on the fouling wire was smaller due to the high wettability than that on the clean wire. The latent heat transportation ratio to the total heat flux was calculated with the generated bubble volume measured with high-speed video or CCD images. The ratio was approximately the same at the clean and fouling wires in spite of the apparent difference in bubbling behavior, but it was significantly affected with the gravity level. The ratio increased with an increase of the heat flux in the earth gravity but it remained at the smaller value in the microgravity. The nucleate heat transfer coefficient on the bare surface did not depend on the gravity levels although the bubbling behavior strongly affected with the gravity level. As the wire radius is small compared to the capillary length scale in microgravity, a growing and coalescing bubble sometimes completely covered the clean wire, evaporating all liquid in contact with the surface and inducing a transition to film boiling. However, on the fouling wire, many small bubbles were generated and sprang from the surface in various directions in microgravity. The spring out action of bubbles suppressed the transition to the film boiling on the fouling wire in the present experimental range.

Numerical Simulation of Film Boiling Near Critical Pressures With a Level Set Method

1998 ◽  
Vol 120 (1) ◽  
pp. 183-192 ◽  
Author(s):  
G. Son ◽  
V. K. Dhir
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Level Set Method ◽  
Level Set ◽  
Vapor Phase ◽  
Film Boiling ◽  
Release Pattern ◽  
Wall Superheat ◽  
Change Effect ◽  
Good Agreement

Attempts have recently been made to numerically simulate film boiling on a horizontal surface. It has been observed from experiments and numerical simulations that during film boiling the bubbles are released alternatively at the nodes and antinodes of a Taylor wave. Near the critical state, however, hydrodynamic transition in bubble release pattern has been reported in the literature. The purpose of this work is to understand the mechanism of the transition in bubble release pattern through complete numerical simulation of the evolution of the vapor-liquid interface. The interface is captured by a level set method which is modified to include the liquid-vapor phase change effect. It is found from the numerical simulation that at low wall superheats the interface moves upwards, bubbles break off, and the interface drops down alternatively at the nodes and antinodes. However, with an increase in wall superheat, stable vapor jets are formed on both the nodes and antinodes and bubbles are released from the top of the vapor columns. The numerical results are compared with the experimental data, and visual observations reported in the literature are found to be in good agreement with the data.

Experimental Studies on Pool Boiling Characteristics of Titanium Dioxide-Water Nano-Fluids

2010 ◽  
Author(s):  
Tomio Okawa ◽  
Takahito Kamiya
Keyword(s):  
Heat Flux ◽  
Time Scale ◽  
Base Fluid ◽  
Heated Surface ◽  
Pool Boiling ◽  
Experimental Studies ◽  
Nucleate Boiling ◽  
High Heat Flux ◽  
Nanoparticle Concentration ◽  
Wall Superheat

It is known that dispersion of a small amount of nanometer-sized particles in liquid can cause substantial improvement of the critical heat flux in pool boiling. Nanofluids (colloidal suspensions of nanoparticles in a base fluid) may therefore be used as the coolant in industrial applications in which high-heat-flux removal is needed. If it is supposed that the deposition of nanoparticles onto the heated surface during nucleate boiling is the main cause of the CHF enhancement in nanofluids, a certain time period is considered to be necessary for the CHF to be improved. In view of this, preliminary experiments were performed in the present work to investigate the time scale of CHF improvement; here, distilled water was used as a base fluid, and TiO2 and copper were selected as the materials of nanoparticles and heated surface, respectively. Under a particular experimental conditions of nanoparticle concentration and nucleate boiling heat flux (40 mg/l and 500 kW/m2), an approximate time scale of CHF improvement was 10 min; this value might not be negligibly short in some nanofluid applications. The measured time-variations of the wall superheat during the nucleate boiling in nanofluid suggested that longer time periods are required for the CHF enhancement at lower heat fluxes and lower nanoparticle concentrations. In particular, 40 min was not sufficient for the wall superheat to reach a steady-state value at the lowest nanoparticle concentration of tested in this work (9 mg/l).

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