Numerical Study of Pool Boiling Heat Transfer From Surface With Protrusions Using Lattice Boltzmann Method

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Kaushik Mondal ◽  
Anandaroop Bhattacharya
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Boiling Heat Transfer ◽  
Plane Surface ◽  
Pool Boiling ◽  
Geometrical Parameters ◽  
Maximum Heat ◽  
Pool Boiling Heat Transfer ◽  
Boltzmann Method

Abstract This paper reports our numerical studies on pool boiling heat transfer from a plane and with protruding surface using single component pseudo-potential phase change model of lattice Boltzmann method. The surface protrusions are assumed to be rectangular in shape with a given height and width. The surface protrusions are seen to promote nucleation of bubbles from the heated surface resulting in significantly higher heat transfer rates compared to the plane surface. Spatial and temporal averaged heat fluxes from all these protruding surfaces are found to be 3–4 times higher than that of a plane surface. The effects of the protrusion height, width, spacing, and associated geometrical parameters on surface heat flux have been investigated in order to arrive at an optimal design for maximum heat transfer.

Pore-Scale Simulation on Pool Boiling Heat Transfer and Bubble Dynamics in Open-Cell Metal Foam by Lattice Boltzmann Method

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jie Qin ◽  
Zhiguo Xu ◽  
Xiaofei Ma
Keyword(s):  
Heat Transfer ◽  
Lattice Boltzmann ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Metal Foam ◽  
Pool Boiling ◽  
Open Cell ◽  
Pool Boiling Heat Transfer ◽  
Boltzmann Method ◽  
Foam Thickness

Abstract Based on the newly developed geometrical model of open-cell metal foam, pool boiling heat transfer in open-cell metal foam, considering thermal responses of foam skeletons, is investigated by the phase-change lattice Boltzmann method (LBM). Pool boiling patterns are obtained at different heat fluxes. The effects of pore density and foam thickness on bubble dynamics and pool boiling heat transfer are revealed. The results show that “bubble entrainment” promotes fluid mixing and bubble sliding inside metal foam. Based on force analysis, the sliding bubble is pinned on the heating surface and cannot lift off completely at high heat flux due to the increasing surface tension force. Pool boiling heat transfer coefficient decreases with increasing pore density and foam thickness due to high bubble escaping resistance.

scholarly journals Simulation of Boiling Heat Transfer at Different Reduced Temperatures with an Improved Pseudopotential Lattice Boltzmann Method

Symmetry ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1358
Author(s):  
Matheus dos Santos Guzella ◽  
Luiz Eduardo Czelusniak ◽  
Vinícius Pessoa Mapelli ◽  
Pablo Fariñas Alvariño ◽  
Gherhardt Ribatski ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Pool Boiling ◽  
Numerical Results ◽  
Boltzmann Method ◽  
Nucleation Growth

The pseudopotential Lattice Boltzmann Method has attracted much attention in the recent years for the simulation of boiling heat transfer. Many studies have been published recently for the simulation of the bubble cycle (nucleation, growth and departure from a heated surface). This paper puts forward two-dimensional simulations of bubble nucleation, growth and departure using an improved pseudopotential Lattice Boltzmann Model from the literature at different reduced temperatures, Tr=0.76 and Tr=0.86. Two different models using the Bhatnagar–Gross–Krook (BGK) and the Multiple-Relaxation-Time (MRT) collision operators with appropriate forcing schemes are used. The results for pool boiling show that the bubbles exhibit axial symmetry during growth and departure. Numerical results of departure diameter and release period for pool boiling are compared against empirical correlations from the literature by varying the gravitational acceleration. Reasonable agreement is observed. Nucleate boiling trends with heat flux are also captured by the simulations. Numerical results of flow boiling simulations are compared by varying the Reynolds number for both reduced temperatures with the MRT model. It was found that the departure diamenter and release period decreases with the increase of the Reynolds number. These results are a direct effect of the drag force. Proper conclusions are commented at the end of the paper.

A New Perspective on Heat Transfer Mechanisms and Sonic Limit in Pool Boiling

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Superheated Liquid ◽  
Heater Surface ◽  
Liquid Stream ◽  
Maximum Heat ◽  
Pool Boiling Heat Transfer ◽  
Maximum Heat Transfer ◽  
Secondary Evaporation

Pool boiling is postulated as a single-phase heat transfer process with nucleating bubbles providing a liquid pumping mechanism over the heater surface. This results in three fluid streams at the heater surface—outgoing vapor and liquid streams, and an incoming liquid stream. Heat transfer during periodic replacement of the liquid in the influence region around a nucleating bubble is well described by transient conduction (TC) and microconvection (MiC) mechanisms. Beyond this region, free convection (FC) or macroconvection (MaC) contributes to heating of the liquid. A bubble growing on the heater surface derives its latent heat from the surrounding superheated liquid and from the microlayer providing a direct heat conduction path. Secondary evaporation occurs in the bubbles rising in the bulk after departure, and at the free surface. This secondary evaporation does not directly contribute to the heat transfer at the heater surface but provides a means of dissipating liquid superheat. A sonic limit-based model is then presented for estimating the theoretical upper limit for pool boiling heat transfer by considering the three fluid streams to approach their respective sonic velocities. Maximum heat transfer rates are also estimated using this model with two realistic velocities of 1 and 5 m/s for the individual streams and are found to be in general agreement with available experimental results. It is postulated that small bubbles departing at high velocity along with high liquid stream velocities are beneficial for heat transfer. Based on these concepts, future research directions for enhancing pool boiling heat transfer are presented.

scholarly journals Numerical Investigation of Pool Boiling Under Ocean Conditions with Lattice Boltzmann Simulation. Part Ⅰ: Heaving Condition

2021 ◽  
Vol 9 ◽  
Author(s):  
Qifan Zou ◽  
Xiuliang Liu ◽  
Yongyan Hu ◽  
Yuxuan Chang ◽  
Pengkun Li
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Lattice Boltzmann ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Pool Boiling Heat Transfer ◽  
Ocean Conditions ◽  
Static Conditions ◽  
Transient Heat Flux

Pool boiling is the heat-transfer mechanism of many heat exchangers inside ocean nuclear power plants working under the complex marine circumstances. Also, ocean conditions will create a new acceleration field other than gravity for the fluid, which induces some unique thermal–hydraulic characteristics. In this study, pool boiling under heaving conditions is numerically simulated using multiple relaxation time phase change lattice Boltzmann method. Firstly, the simulated results under static condition have been validated with recognized empirical equations, such as Rohsenow’s correlation at nucleate boiling, Zuber’s model, and Kandlikar’s model about critical heat flux (CHF). Then, pool boiling patterns, the boiling curve of time-averaged heat flux, transient heat flux, and heaving effects on different pool boiling regions are investigated. The results show that pool boiling curves of time-averaged heat flux between heaving conditions and static conditions with middle superheat degrees are similar. Heat transfer under heaving conditions at low superheat is somewhat enhanced, and it is weakened at high superheat, which leads to a slightly smaller critical heat flux with larger superheat compared with that under static conditions. Moreover, distinct fluctuation of the transient heat flux of pool boiling under heaving conditions is found for all boiling regimes. Furthermore, the heaving condition shows both positive and negative effects on pool boiling heat transfer at high-gravity and low-gravity regions, respectively. Besides, both the larger heaving height and shorter period time bring out more violent heaving motion and make a greater impact on pool boiling heat transfer.

Sign in / Sign up

Export Citation Format

Share Document