基于LBM的泡沫金屬內(nèi)納米流體氣液兩相傳熱機(jī)理研究
發(fā)布時(shí)間：2018-10-25 07:21
【摘要】：目前,科技發(fā)展日新月異,工業(yè)產(chǎn)品設(shè)備對(duì)換熱特性的要求越來(lái)越高。熱管作為具有優(yōu)異的換熱性能的元件,在換熱領(lǐng)域具有很廣的應(yīng)用范圍。它通過(guò)內(nèi)部工質(zhì)相變帶走熱量,換熱工質(zhì)對(duì)于熱管的換熱性能起到主導(dǎo)作用。對(duì)熱管的研究又主要集中在兩個(gè)方面:一個(gè)是針對(duì)管內(nèi)換熱工質(zhì)納米流體的研究;另一方面是對(duì)多孔介質(zhì)的研究。本文基于格子Boltzmann方法(LBM)研究了多孔介質(zhì)內(nèi)納米流體沸騰換熱相變過(guò)程氣液兩相換熱機(jī)理;并基于離散元素法對(duì)三維多孔介質(zhì)進(jìn)行了重構(gòu)。具體的研究工作如下:(1)根據(jù)Shan-Chen提出的偽勢(shì)格子Boltzmann模型,考察納米顆粒直徑變化引起的納米流體的布朗力變化對(duì)沸騰換熱過(guò)程的影響,建立能夠描述納米流體相變分離的格子Boltzmann模型。通過(guò)比對(duì)純液體、納米顆粒直徑為5nm、10nm和20nm的納米流體沸騰過(guò)程的氣液兩相流型圖,考察氣液兩相質(zhì)量隨納米顆粒直徑的變化曲線,分析得出納米顆粒直徑越小,納米流體氣液兩相分離越快,沸騰換熱能力越強(qiáng)。另外,本文還發(fā)現(xiàn)過(guò)熱度對(duì)氣液兩相相變速度的影響變化,研究表明過(guò)熱度越大,納米流體氣泡生成加快,同一時(shí)間步長(zhǎng)氣相質(zhì)量越大,說(shuō)明可以通過(guò)控制熱負(fù)荷的大小來(lái)控制沸騰過(guò)程的相變快慢。(2)通過(guò)隨機(jī)配置的方法構(gòu)造了部分填充二維多孔介質(zhì)結(jié)構(gòu)模型,結(jié)合Zhao的相變模型。將納米流體相變格子Boltzmann模型與二維多孔介質(zhì)模型相結(jié)合,考慮固體的浸潤(rùn)和非浸潤(rùn)性質(zhì),得到部分填充多孔介質(zhì)內(nèi)的氣泡生成、長(zhǎng)大、相互融合以及與固體壁面的碰撞,反彈等現(xiàn)象。說(shuō)明相變格子Boltzmann模型與隨機(jī)多孔介質(zhì)相結(jié)合的可行性。考察了多孔介質(zhì)的孔隙率對(duì)多孔介質(zhì)的相變過(guò)程的影響,得出在一定范圍內(nèi),孔隙率越大,多孔介質(zhì)內(nèi)的相變速度加快,多孔介質(zhì)模型的換熱能力越強(qiáng)。(3)基于離散元素法堆積構(gòu)造了三維多孔介質(zhì)模型,探究了球形顆粒在不同相對(duì)邊界尺度下的孔隙率和孔密度的影響變化。研究發(fā)現(xiàn)多孔介質(zhì)模型的孔隙率隨著相對(duì)邊界尺度的增大而增大,孔密度則是隨著相對(duì)邊界尺度的增大而減小。考察了球形顆粒和不同長(zhǎng)細(xì)比的針狀顆粒因形狀變化對(duì)多孔介質(zhì)模型孔隙率的變化影響,結(jié)果表明在直徑相同的情況下,針狀顆粒堆積模型的孔隙率要大于球形顆粒堆積模型的孔隙率,并且針狀顆粒隨著長(zhǎng)細(xì)比的增大,模型的孔隙率也相應(yīng)增大。
[Abstract]:At present, with the rapid development of science and technology, industrial products and equipment require higher and higher heat transfer characteristics. Heat pipe, as a component with excellent heat transfer performance, has a wide range of applications in the field of heat transfer. It takes away the heat through the internal phase transformation of the working fluid, which plays a leading role in the heat transfer performance of the heat pipe. The research on heat pipe is mainly focused on two aspects: one is the study of the heat transfer fluid nanoscale fluid in the tube, the other is the study of porous media. In this paper, the gas-liquid two-phase heat transfer mechanism during boiling phase transition of nano-fluid in porous media is studied based on lattice Boltzmann method (LBM), and the three-dimensional porous medium is reconstructed based on discrete element method. The specific research works are as follows: (1) according to the pseudo-potential lattice Boltzmann model proposed by Shan-Chen, the effect of Brownian force change on the boiling heat transfer process caused by the change of nanoparticles diameter is investigated. A lattice Boltzmann model was established to describe the phase change separation of nanoscale fluids. By comparing the gas-liquid two-phase flow pattern of the boiling process of pure liquid, 5 nm or 10 nm nanocrystalline particles with 20nm, the variation curve of gas-liquid two-phase mass with the diameter of nano-particles was investigated. The smaller the particle diameter was, the smaller the particle diameter was. The faster the gas-liquid separation, the stronger the boiling heat transfer ability. In addition, the influence of superheat on the gas-liquid phase transition velocity is also found. It is shown that the higher the superheat degree, the faster the bubble formation and the larger the gas phase mass at the same time step. It is shown that the boiling process can be controlled by controlling the heat load. (2) the two-dimension porous media structure model with partial filling is constructed by random collocation, and the phase transition model of Zhao is combined. By combining the Boltzmann model of nano-fluid phase transition lattice with the two-dimensional porous media model and considering the wetting and non-wetting properties of solids, the formation, growth, fusion and collision with solid wall of partially filled porous media are obtained. Rebound, etc The feasibility of combining phase change lattice Boltzmann model with random porous media is demonstrated. The effect of porosity on the phase change process of porous media is investigated. It is concluded that the larger the porosity is, the faster the phase transition rate in porous media is. The heat transfer ability of porous media model is stronger. (3) the three-dimensional porous media model is constructed based on the discrete element method, and the effect of spherical particles on porosity and pore density at different boundary scales is investigated. It is found that the porosity of the porous media model increases with the increase of the relative boundary scale, while the pore density decreases with the increase of the relative boundary scale. The effects of spherical particles and needle-shaped particles with different aspect ratios on the porosity of porous media model were investigated. The porosity of the model is larger than that of the spherical model, and the porosity of the model increases with the increase of the slenderness ratio.
【學(xué)位授予單位】：江蘇科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG139.8
本文編號(hào)：2293021
[Abstract]:At present, with the rapid development of science and technology, industrial products and equipment require higher and higher heat transfer characteristics. Heat pipe, as a component with excellent heat transfer performance, has a wide range of applications in the field of heat transfer. It takes away the heat through the internal phase transformation of the working fluid, which plays a leading role in the heat transfer performance of the heat pipe. The research on heat pipe is mainly focused on two aspects: one is the study of the heat transfer fluid nanoscale fluid in the tube, the other is the study of porous media. In this paper, the gas-liquid two-phase heat transfer mechanism during boiling phase transition of nano-fluid in porous media is studied based on lattice Boltzmann method (LBM), and the three-dimensional porous medium is reconstructed based on discrete element method. The specific research works are as follows: (1) according to the pseudo-potential lattice Boltzmann model proposed by Shan-Chen, the effect of Brownian force change on the boiling heat transfer process caused by the change of nanoparticles diameter is investigated. A lattice Boltzmann model was established to describe the phase change separation of nanoscale fluids. By comparing the gas-liquid two-phase flow pattern of the boiling process of pure liquid, 5 nm or 10 nm nanocrystalline particles with 20nm, the variation curve of gas-liquid two-phase mass with the diameter of nano-particles was investigated. The smaller the particle diameter was, the smaller the particle diameter was. The faster the gas-liquid separation, the stronger the boiling heat transfer ability. In addition, the influence of superheat on the gas-liquid phase transition velocity is also found. It is shown that the higher the superheat degree, the faster the bubble formation and the larger the gas phase mass at the same time step. It is shown that the boiling process can be controlled by controlling the heat load. (2) the two-dimension porous media structure model with partial filling is constructed by random collocation, and the phase transition model of Zhao is combined. By combining the Boltzmann model of nano-fluid phase transition lattice with the two-dimensional porous media model and considering the wetting and non-wetting properties of solids, the formation, growth, fusion and collision with solid wall of partially filled porous media are obtained. Rebound, etc The feasibility of combining phase change lattice Boltzmann model with random porous media is demonstrated. The effect of porosity on the phase change process of porous media is investigated. It is concluded that the larger the porosity is, the faster the phase transition rate in porous media is. The heat transfer ability of porous media model is stronger. (3) the three-dimensional porous media model is constructed based on the discrete element method, and the effect of spherical particles on porosity and pore density at different boundary scales is investigated. It is found that the porosity of the porous media model increases with the increase of the relative boundary scale, while the pore density decreases with the increase of the relative boundary scale. The effects of spherical particles and needle-shaped particles with different aspect ratios on the porosity of porous media model were investigated. The porosity of the model is larger than that of the spherical model, and the porosity of the model increases with the increase of the slenderness ratio.
【學(xué)位授予單位】：江蘇科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG139.8
【參考文獻(xiàn)】
相關(guān)期刊論文 前10條
1 何延龍;蒲春生;景成;谷瀟雨;劉洪志;崔淑霞;李曉;宋俊強(qiáng);;基于Hoshen-Kopelman算法的三維多孔介質(zhì)模型中黏土礦物的構(gòu)建[J];石油學(xué)報(bào);2016年08期
2 施娟;陳振乾;馬強(qiáng);;多孔泡沫金屬內(nèi)氣泡動(dòng)力學(xué)行為的格子波爾茲曼方法模擬[J];東南大學(xué)學(xué)報(bào)(自然科學(xué)版);2015年04期
3 王記;陳威;毛玉博;葉飛虎;;多孔介質(zhì)強(qiáng)化池內(nèi)沸騰換熱特性[J];低溫與超導(dǎo);2015年03期
4 Ahmad Azari;Mansour Kalbasi;Masoud Derakhshandeh;Masoud Rahimi;;恒熱流直管中納米流體對(duì)流傳熱的實(shí)驗(yàn)研究(英文)[J];Chinese Journal of Chemical Engineering;2013年10期
5 郭亞麗;徐鶴函;沈勝?gòu)?qiáng);;納米流體液滴在水平加熱面上的變形行為特性[J];化工學(xué)報(bào);2012年10期
6 王波;寧正福;姬江;;多孔介質(zhì)模型的三維重構(gòu)方法[J];西安石油大學(xué)學(xué)報(bào)(自然科學(xué)版);2012年04期
7 唐瀟;刁彥華;趙耀華;張冀;;δ-Al_2O_3-R141b納米流體的池內(nèi)核態(tài)沸騰傳熱特性[J];化工學(xué)報(bào);2012年01期
8 劉振華;楊雪飛;;納米流體在回路型重力熱管中的沸騰傳熱特性[J];上海交通大學(xué)學(xué)報(bào);2011年06期
9 張凱;于明州;林建忠;;納米顆粒在人類支氣管中沉降率的研究[J];中國(guó)計(jì)量學(xué)院學(xué)報(bào);2010年02期
10 張邵波;駱仲泱;壽春暉;倪明江;岑可法;;層流區(qū)CuO-水納米流體流動(dòng)與對(duì)流換熱特性(英文)[J];中國(guó)電機(jī)工程學(xué)報(bào);2009年32期
相關(guān)博士學(xué)位論文 前2條
1 曾建邦;基于氣泡生長(zhǎng)及多相流動(dòng)的格子Boltzmann模型及應(yīng)用研究[D];重慶大學(xué);2011年
2 趙凱;基于孔隙尺度的多孔介質(zhì)流動(dòng)與傳熱機(jī)理研究[D];南京理工大學(xué);2010年
，本文編號(hào)：2293021
本文鏈接：http://sikaile.net/kejilunwen/jiagonggongyi/2293021.html
最近更新
教材專著
