本文選題：圓錐扭帶 + 數(shù)值模擬��； 參考：《昆明理工大學(xué)》2015年碩士論文

【摘要】：隨著工業(yè)的發(fā)展,換熱器強(qiáng)化傳熱技術(shù)不斷取得了顯著的改進(jìn)和發(fā)展。近幾年在國家節(jié)能減排的背景下,以能源消耗強(qiáng)度低、有效利用率高為特點(diǎn)的新型節(jié)能換熱器,成為未來換熱器強(qiáng)化傳熱技術(shù)研究的新方向。從強(qiáng)化傳熱機(jī)理的角度而言,目前國內(nèi)外所開發(fā)出的各種異型扭帶均是以壁面強(qiáng)化擾流為特點(diǎn),以增加流體的湍流度達(dá)到強(qiáng)化換熱的目的,縱然這些異型扭帶在一定程度上提高了換熱管的熱交換率,卻也因此使得流體的壓降過高,導(dǎo)致流體輸送功耗成倍增加,有時(shí)甚至超過強(qiáng)化傳熱所帶來的效益。本文從另一角度出發(fā),基于全新的核心流強(qiáng)化傳熱原理提出了新型低阻力扭帶——圓錐扭帶,采用數(shù)值模擬的方法分析了圓錐扭帶在湍流狀況下插入光管及波紋管內(nèi)的流動(dòng)與換熱特性。首先,分析了光管內(nèi)插入扭曲比δ=3.0,錐角θ分別為θ=1：3.6、8=1：5、8=1：7、8=1：9的圓錐扭帶在Re=4000～14000范圍內(nèi)的傳熱和阻力特性,并與傳統(tǒng)光滑直扭帶進(jìn)行了比較。通過對管內(nèi)的溫度場、壓力場進(jìn)行分析,并運(yùn)用綜合強(qiáng)化傳熱性能評價(jià)指標(biāo)(PEC)指標(biāo)對其進(jìn)行分析,得出了在模擬的范圍內(nèi),圓錐扭帶在保持一定的擾流強(qiáng)化傳熱性能的前提下,能夠有效減小流體的流動(dòng)阻力,具有更佳的綜合換熱性能。其次,針對圓錐扭帶幾何參數(shù)(錐角θ)對傳熱和阻力特性影響進(jìn)行了分析,得出了錐角0=1：5的圓錐扭帶PEC值達(dá)到峰值,具有最佳的綜合強(qiáng)化傳熱性能,使得換熱和阻力達(dá)到最佳匹配。該結(jié)果從另一方面反映出：持續(xù)增加湍流流體的擾流,將使得扭帶對換熱和阻力的貢獻(xiàn)值發(fā)生逆轉(zhuǎn),造成換熱管的換熱性能在無明顯改善的情況下所耗費(fèi)的流體輸送能量急劇上升。因此針對湍流區(qū)內(nèi)的流體,單純地依靠增加流體擾動(dòng)強(qiáng)度的傳統(tǒng)強(qiáng)化傳熱措施存在一定的局限性,內(nèi)插件的擾流性能的強(qiáng)弱與換熱管的綜合換熱性能并無直接聯(lián)系,而具有核心擾流特性的圓錐扭帶則具有更加優(yōu)異的綜合強(qiáng)化傳熱性能。最后,本文結(jié)合第三代復(fù)合強(qiáng)化傳熱理論,研究了錐角8=1：5,扭曲比δ分別為δ=2.0、δ=4.4、δ=6.0的3種不同扭曲比的圓錐扭帶在波紋管和光管內(nèi)的傳熱和流阻特性,并探究了扭曲比δ對其換熱和阻力特性的影響。得出扭曲比6越小的圓錐扭帶,其綜合換熱性能越高。并且將同一扭帶在光管與波紋管內(nèi)進(jìn)行比較,發(fā)現(xiàn)圓錐扭帶在波紋管內(nèi)的綜合換熱性能更高,并對其中的原因進(jìn)行了解釋。最終證明圓錐扭帶在復(fù)合強(qiáng)化傳熱中仍具有相當(dāng)廣泛的運(yùn)用價(jià)值,為新型高效節(jié)能換熱器的設(shè)計(jì)及傳統(tǒng)換熱器的升級改造提供了一定參考。
[Abstract]:With the development of industry, the heat transfer technology of heat exchanger has been greatly improved and developed. In the background of national energy saving and emission reduction in recent years, a new type of energy saving heat exchanger with low energy consumption intensity and high effective utilization rate has become a new direction for the research of heat transfer enhancement technology in the future. At present, all kinds of special-shaped torsional bands developed at home and abroad are characterized by wall intensification turbulence, which can increase the turbulent degree of fluid to achieve the purpose of strengthening heat exchange. Even though these twisted tapes increase the heat exchange rate of the heat transfer tubes to a certain extent, the pressure drop of the fluid is too high and the power dissipation of the fluid is multiplied. In this paper, based on the new core flow strengthening heat transfer principle, a new low resistance torsional band, conical torsional belt, is proposed from another point of view. The flow and heat transfer characteristics of the tapered torsional band in the turbulent flow and the bellows are analyzed by numerical simulation. The characteristics of heat transfer and resistance in a conical torsional band with a twist ratio of [delta] =3.0 and a cone angle theta (theta) of theta =1:3.6,8=1:5,8=1:7,8=1:9 respectively in the range of Re=4000 to 14000 are analyzed. The comparison is made with the traditional smooth straight torsional band. By analyzing the temperature field and pressure field in the tube, the comprehensive heat transfer performance evaluation index (PEC) is used. According to the analysis of the index, it is concluded that in the range of simulation, the conical torsional band can effectively reduce the flow resistance of the fluid and have better comprehensive heat transfer performance on the premise of maintaining a certain heat transfer performance. Secondly, the influence of the geometric parameters of the tapered torsional band (cone angle theta) on the heat transfer and resistance characteristics is analyzed. The PEC value of conical torsional band of cone 0=1:5 reaches its peak value, and it has the best comprehensive heat transfer performance, which makes the heat transfer and resistance reach the best match. In the case of improvement, the energy of fluid transport is rising rapidly. Therefore, there are some limitations on the traditional heat transfer measures for the fluid in the turbulent zone, which simply relies on the increase of the intensity of the fluid disturbance. The strength of the disturbing flow performance of the internal plug-in is not directly related to the heat transfer of the heat transfer tube, but has the core disturbing characteristics. The tapered torsional band has a more excellent comprehensive heat transfer performance. Finally, this paper studies the heat transfer and flow resistance characteristics of the cone angle 8=1:5, the twist ratio Delta =2.0, Delta =4.4 and delta =6.0 in the bellows and light tubes, and explores the distortion ratio Delta for the change of the twisted ratio Delta. The influence of heat and resistance characteristics is obtained. It is found that the taper twisted belt with smaller twist ratio 6 has higher comprehensive heat transfer performance. And the same twisted belt is compared with the bellows in the light tube. It is found that the comprehensive heat transfer performance of the tapered torsional band is higher in the bellows, and the reasons are explained. Finally, it is proved that the tapered torsional belt is in the compound strengthening heat transfer. It still has a very wide range of application value, and provides a reference for the design of new energy-efficient heat exchanger and upgrading and upgrading of traditional heat exchanger.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TK172.4

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本文編號：1985584