發(fā)布時(shí)間：2018-08-04 18:08

【摘要】：脈沖氣流干燥機(jī)內(nèi)空氣的流動(dòng)狀態(tài)對(duì)其內(nèi)部物料干燥有重大影響。本研究運(yùn)用商用軟件Fluent模擬脈沖氣流干燥機(jī)內(nèi)的流場(chǎng)和溫度場(chǎng)并進(jìn)行分析,為深入理解脈沖氣流干燥機(jī)理和干燥機(jī)改進(jìn)設(shè)計(jì)提供理論指導(dǎo)。本研究以脈沖氣流干燥機(jī)為對(duì)象,以計(jì)算流體力學(xué)(CFD)為理論基礎(chǔ),以Navier-Stokes方程作為控制方程組,采用標(biāo)準(zhǔn)k-ε湍流模型,運(yùn)用Fluent軟件對(duì)脈沖氣流干燥機(jī)內(nèi)的流場(chǎng)和溫度場(chǎng)進(jìn)行三維穩(wěn)態(tài)模擬,研究結(jié)果如下：在直管情況下對(duì)氣流干燥進(jìn)行模擬時(shí),入口速度越大干燥的效果越不好,這是因?yàn)樵谥惫芮闆r下物料達(dá)到溫度平衡基本都處于管路的后半段,而入口速度的增大會(huì)使物料在干燥段內(nèi)的時(shí)間減少,導(dǎo)致能量損失的同時(shí)不能保證物料干燥達(dá)到合格。對(duì)脈沖氣流干燥機(jī)的干燥段流場(chǎng)進(jìn)行數(shù)值模擬。在考慮重力的情況下,得到干燥段內(nèi)部流場(chǎng)的速度、壓力、顆粒運(yùn)動(dòng)軌跡等,并對(duì)這些數(shù)據(jù)進(jìn)行了分析與比較。通過(guò)數(shù)值模擬得出：脈沖管路的主要作用是提高物料和空氣的相對(duì)速度,相對(duì)速度差異越大,物料彌散在熱介質(zhì)中的表面積越大,使表面水分迅速蒸發(fā)。各個(gè)參數(shù)的的劇烈變化階段大部分集中在管路的入口處到和上升段彎管連接的脈沖管路之間,即粒子在經(jīng)過(guò)轉(zhuǎn)彎段的上半段的時(shí)候,干燥就已經(jīng)基本完成,這說(shuō)明脈沖管路對(duì)物料的干燥具有良好的促進(jìn)作用,但增加脈沖管路必然會(huì)加大能量的損耗,所以在考慮到干燥效率的同時(shí)必須考慮能量損耗。
[Abstract]:The flow state of the air in the pulse air dryer has a great influence on the material drying. In this study, the flow field and temperature field in the pulse airflow dryer were simulated and analyzed by using commercial software Fluent, which provided theoretical guidance for further understanding the mechanism of pulse airflow drying and improving the design of the dryer. In this study, the pulse airflow dryer was used as the object, the computational fluid dynamics (CFD) was taken as the theoretical basis, the Navier-Stokes equation was taken as the governing equations, and the standard k- 蔚 turbulence model was adopted. Three-dimensional steady state simulation of the flow field and temperature field in the pulse airflow dryer is carried out by using Fluent software. The results are as follows: when the airflow drying is simulated under the condition of straight pipe, the larger the inlet velocity is, the worse the drying effect is. This is because in the case of straight tube, the material temperature balance is basically in the second half of the pipeline, and the increase of inlet speed will reduce the time of material in the drying section, which leads to energy loss and can not guarantee the material drying to be up to standard. The numerical simulation of the flow field in the drying section of the pulse airflow dryer is carried out. Considering gravity, the velocity, pressure and particle trajectory of the flow field in the dry section are obtained, and these data are analyzed and compared. The numerical simulation shows that the main function of pulse pipeline is to increase the relative velocity of material and air. The greater the difference of relative velocity, the larger the surface area of material dispersion in hot medium, which makes the surface moisture evaporate rapidly. Most of the dramatic changes in the parameters are between the entrance of the pipe and the pulse pipe connected by the bend in the rising section, that is, by the time the particle passes through the upper half of the turning section, the drying is basically complete. This shows that the pulse pipeline has a good effect on the drying of materials, but increasing the pulse pipeline will inevitably increase the energy loss, so we must consider the energy loss while considering the drying efficiency.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TB4

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