Nucleate pool boiling heat transfer: Review of models and bubble dynamics parameters

Understanding nucleate pool boiling heat transfer and, in particular the accurate prediction of conditions that can lead to critical heat flux, is of the utmost importance in many industries. Due to the safety issues related to the nuclear power plants, and for the efficient operation of many heat transfer units including fossil fuel boilers, fusion reactors, electronic chips, etc., it is important to understand this kind of heat transfer. In this paper, a comprehensive review of analytical and numerical work on nucleate pool boiling heat transfer is presented. In order to understand this phenomenon, existing studies on boiling heat transfer coefficient and boiling heat flux are also discussed, as well as characteristics of boiling phenomena such as bubble departure diameter, bubble departure frequency, active nucleation site density, bubble waiting and growth period and their impact on pool boiling heat transfer.

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Effects of Heat Exchanger Tube Parameters on Nucleate Pool Boiling Heat Transfer

Journal of Heat Transfer ◽

10.1115/1.2824272 ◽

1998 ◽

Vol 120 (2) ◽

pp. 468-476 ◽

Cited By ~ 50

Author(s):

Moon-Hyun Chun ◽

Myeong-Gie Kang

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Surface Roughness ◽

Boiling Heat Transfer ◽

Pool Boiling ◽

Tube Diameter ◽

Nucleate Pool Boiling ◽

Pool Boiling Heat Transfer ◽

Horizontal Tubes ◽

Vertical Tubes

In an effort to determine the combined effects of major parameters of heat exchanger tubes on the nucleate pool boiling heat transfer in the scaled in-containment refueling water storage tank (IRWST) of advanced light water reactors (ALWRs), a total of 1966 data points for q″ versus ΔT have been obtained using various combinations of tube diameters, surface roughness, and tube orientations. The experimental results show that: (1) increased surface roughness increases the heat transfer coefficient for both horizontal and vertical tubes, and the effect of surface roughness is more pronounced for the vertical tubes compared to the horizontal tubes, (2) the two heat transfer mechanisms, i.e., increased heat transfer due to liquid agitation by bubbles generated and reduced heat transfer by the formation of large vapor slugs and bubble coalescence, are different in two regions of low heat flux (q″ ≤ 50 kW/m2) and high heat flux (q″ > 50 kW/m2) depending on the orientation of tubes and the degree of surface roughness, and (3) the heat transfer rate decreases as the tube diameter is increased for both horizontal and vertical tubes, but the effect of tube diameter on the nucleate pool boiling heat transfer for vertical tubes is greater than that for horizontal tubes. Two empirical heat transfer correlations for q″, one for horizontal tubes and the other for vertical tubes, are obtained in terms of surface roughness (ε) and tube diameter (D). In addition, a simple empirical correlation for nucleate pool boiling heat transfer coefficient (hb) is obtained as a function of heat flux (q″) only.

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Experimental Study of Effect of Nucleation Site Size on Bubble Dynamics during Nucleate Pool Boiling Heat Transfer

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.592-594.1596 ◽

2014 ◽

Vol 592-594 ◽

pp. 1596-1600 ◽

Cited By ~ 3

Author(s):

Abdul Najim ◽

Anil R. Aacharya

Keyword(s):

Heat Transfer ◽

Boiling Heat Transfer ◽

Bubble Dynamics ◽

Bubble Diameter ◽

Pool Boiling ◽

Growth Period ◽

Nucleation Site ◽

Hypodermic Needle ◽

Nucleate Pool Boiling ◽

Pool Boiling Heat Transfer

In this paper, effect of nucleation site size on bubble dynamics during nucleate pool boiling heat transfer in saturated water is studied experimentally. Single bubble was generated using right angle tip of a hypodermic needle as a nucleation site. The hypodermic needles were used of inner diameters 0.413mm, 0.514mm, and 0.603 mm with a constant depth of 25mm. The bubble dynamics was studied using SONY Cyber-shot DSC-H100 camera operating at 30 frames per second at atmospheric pressure and at a wall superheat of 5K. The results show that, bubble diameter, bubble height and bubble volume increases with increase in diameter of nucleation site. The bubble growth period is found to be dependent on nucleation site size, and it decreases with increase in diameter of nucleation site. This happens because as volume of vapor bubble increases, buoyancy force starts dominates the capillary force and bubble detaches earlier. Effect of nucleation site size on bubble departure diameter and bubble release frequency is also discussed.

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