本文選題：油菜籽 + 太陽能　； 參考：《華中農(nóng)業(yè)大學(xué)》2017年碩士論文

【摘要】：油菜廣泛種植于我國長江流域,為植物油及飼用蛋白質(zhì)等的生產(chǎn)提供主要原料,是具有較高經(jīng)濟價值及發(fā)展?jié)摿Φ挠土献魑�。新收油菜籽具有含水率�?吸濕性強且不易散熱等特點,收獲時節(jié)潮濕的環(huán)境氣候極易導(dǎo)致油菜籽霉變、酸敗等現(xiàn)象,造成了嚴重損失。目前我國油菜籽干燥作業(yè)機械化水平較低,大部分農(nóng)戶仍采用傳統(tǒng)攤曬方式,不僅費時費工,而且干燥時雜質(zhì)(灰塵、土壤、沙石、昆蟲等)的混入,直接影響油菜籽的品質(zhì)。針對以上問題,應(yīng)選擇更加合理的機械干燥方式。機械干燥具有處理能力強,空間利用率高,干燥效率及品質(zhì)高等優(yōu)點,并可有效降低落地損失。根據(jù)我國農(nóng)村生產(chǎn)實際需要,結(jié)合目前全球化石能源匱乏現(xiàn)狀,使用太陽能作為干燥過程中的熱源,是一種比較好的干燥方式。設(shè)備所供給的太陽能熱風具有清潔衛(wèi)生,節(jié)能環(huán)保,成本低廉等優(yōu)勢。為進一步滿足油菜籽干燥過程中低能耗高效率的要求,設(shè)計研制了一種小型太陽能熱風油菜籽循環(huán)干燥設(shè)備。以此設(shè)備作為研究對象進行油菜籽干燥試驗,結(jié)合試驗結(jié)果對干燥設(shè)備關(guān)鍵部件太陽能集熱器內(nèi)部流場分布進行數(shù)值模擬,主要研究內(nèi)容和結(jié)論如下:以油菜籽為干燥對象進行試驗,研究干燥室進口熱風風速(2m/s-5m/s)、篩網(wǎng)葉輪轉(zhuǎn)速(30r/min-60r/min)、物料循環(huán)速率(500kg/h-800kg/h)等因素對含水率變化的影響,分析得出干燥室進口風速及物料循環(huán)速率對結(jié)果均存在一定影響,而不同篩網(wǎng)葉輪轉(zhuǎn)速下干燥曲線無明顯變化。當風速達到4-5m/s,物料循環(huán)速率為700-800kg/h,篩網(wǎng)葉輪葉片轉(zhuǎn)速保持在50r/min左右時,油菜籽含水率下降速度較快,可獲得較為理想的結(jié)果。根據(jù)單因素試驗結(jié)果,為探究設(shè)備最優(yōu)工藝參數(shù)組合,選取進口風速、物料循環(huán)速率、集熱方式三個試驗因素進行正交試驗研究,以干燥速率作為評價指標,可得對該指標影響的主次順序依次為:集熱方式、進口風速、物料循環(huán)速率。設(shè)備運行最優(yōu)參數(shù)組合為:選取波紋型太陽能集熱器,干燥室進口風速為5m/s,篩網(wǎng)葉輪轉(zhuǎn)速為50r/min,物料循環(huán)速率為800kg/h,對此條件下干燥曲線進行擬合獲得干燥特性方程數(shù)學(xué)模型。。運用CFD技術(shù)對干燥設(shè)備關(guān)鍵部件V型肋片集熱器及波紋板太陽能集熱器內(nèi)部溫度分布及流線分布進行數(shù)值模擬分析,結(jié)果顯示兩種集熱器內(nèi)部均存在空氣溫度分布不均勻的現(xiàn)象。其中V型肋片集熱器左半部分區(qū)域以及肋片周圍溫度較高,出現(xiàn)通風死區(qū)。波紋型集熱器左上角出現(xiàn)紅色高溫區(qū)域,該處空氣流速較低,產(chǎn)生的熱損失較大。當外界空氣自進風口進入集熱器內(nèi)部時,瞬間流速產(chǎn)生了大幅降低,這對對流換熱過程產(chǎn)生了較大影響,為解決以上問題對太陽能空氣集熱器進行相關(guān)結(jié)構(gòu)改進。為盡快達到干燥所需熱風溫度,改善太陽能集熱器內(nèi)部空氣流場均勻性,增強對流換熱,從通風口徑尺寸參數(shù)及吸熱板肋片結(jié)構(gòu)兩個角度出發(fā)對集熱器進行優(yōu)化,通過對比得出將通風口徑增至原有的1.5倍后,空氣流量有所增加,流過吸熱板時發(fā)生的對流換熱更充分。但在肋片作用下空氣流動方向受到一定制約,低速區(qū)域仍存在部分漩渦流動。為進一步解決太陽能集熱器內(nèi)部換熱不均的問題,對吸熱板表面肋片形狀及排布方式進行優(yōu)化,設(shè)計了一種I型肋片集熱器,將集熱器內(nèi)部氣體流域分割成5條蛇形迂回流道,進而增加換熱面積及路徑長度。數(shù)值模擬分析結(jié)果顯示,其溫度分布沿氣體流動方向遞增,呈現(xiàn)正向溫度梯度,出口空氣溫度相比改進前明顯升高。且內(nèi)部空氣流速明顯高于其他兩種類型集熱器,平均流速超過2.5m/s。該結(jié)構(gòu)優(yōu)化對改善集熱效率,提高熱風溫度,進而加快油菜籽干燥進程具有十分重要的意義。
[Abstract]:Rapeseed is widely cultivated in the Yangtze River Basin in China. It provides the main raw materials for the production of vegetable oil and feed protein. It is an oil crop with high economic value and development potential. The new rapeseed has the characteristics of high moisture content, strong hygroscopicity and not easy to heat dissipation. At present, the mechanization level of rapeseed drying in China is low, and most of the farmers still use the traditional way of spreading, not only time-consuming and working, but also the mixing of the impurities (dust, soil, sand, insects and so on) in the drying process, which directly affects the quality of rapeseed. In view of the above problems, more reasonable mechanical drying should be chosen. Mechanical drying has the advantages of strong handling capacity, high space utilization, high drying efficiency and high quality, and can effectively reduce the loss of landing. According to the actual needs of rural production in China, combined with the current global shortage of fossil energy, the use of solar energy as a heat source in the drying process is a better drying method. In order to meet the requirements of low energy efficiency and low energy efficiency in the process of rapeseed drying, a small solar hot air rapeseed drying equipment was designed to meet the requirements of low energy efficiency and high efficiency. The main research contents and conclusions are as follows: the main research contents and conclusions are as follows: with rapeseed as the drying object, the influence of the inlet hot wind speed (2m/s-5m/s), the speed of the sieve impeller (30r/min-60r/min), the material circulation rate (500kg/h-800kg/h) and other factors on the water content change It is concluded that the inlet wind speed and the material circulation rate of the drying chamber have a certain effect on the results, but there is no obvious change in the drying curve at different impeller speeds. When the wind speed reaches 4-5m/s and the material circulation rate is 700-800kg/h, the speed of the rapeseed water cut is faster when the speed of the screen impeller blade is kept at the left and right of 50r/min. More ideal results. According to the results of the single factor test, in order to explore the optimal combination of the equipment, three experimental factors are selected, which are the inlet wind speed, the material circulation rate and the heat collection mode, and the drying rate is used as the evaluation index. The order of the main and secondary effects on the index is as follows: the heat collection method, the import wind speed, the material. The optimal operation parameters of the equipment are as follows: selecting the corrugated solar collector, the inlet wind speed of the drying chamber is 5m/s, the speed of the screen impeller is 50r/min, the material circulation rate is 800kg/h. The drying curve is fitted to the mathematical model of the drying characteristic equation under the condition of the drying curve. The V fin of the key parts of the drying equipment is used by CFD technology. The internal temperature distribution and flow line distribution of the collector and corrugated plate solar collector are numerically simulated. The results show that there is an uneven air temperature distribution inside the two heat exchangers. The left half of the V fin heat collector and the high temperature around the ribs are in the dead zone. The upper left corner of the corrugated collector is out of the upper corner. In the present red high temperature region, the air flow velocity is low and the heat loss is larger. When the air inlet is entered into the collector, the instantaneous flow velocity is greatly reduced, which has a great influence on the convection heat transfer process. In order to solve the above problems, the relative structure of the solar air collector is improved. It is dry as soon as possible. The heat air temperature is needed to improve the uniformity of the air flow field inside the solar collector and to enhance the convection heat transfer. From the two angles of the size parameters of the ventilation diameter and the structure of the fin plate of the heat absorbing plate, the air flow rate is increased and the air flow through the heat absorbing plate has been increased by comparing the ventilation diameter to the original 1.5 times. The flow direction of the flow is more sufficient, but the direction of the air flow is restricted under the action of the ribs, and there is still some vortex flow in the low speed region. In order to further solve the problem of the uneven heat transfer inside the solar collector, the shape of the fin surface and the arrangement of the surface of the heat absorbing plate are optimized. A type of I fin heat collector is designed, and the internal gas of the collector is designed. The drainage area is divided into 5 serpentine circuitous channels, and then the heat transfer area and the path length are increased. The numerical simulation results show that the temperature distribution increases along the gas flow direction, presents a positive temperature gradient, and the outlet air temperature is obviously higher than that before the improvement. The internal air velocity is obviously higher than the other two types of heat collector, and the average flow velocity is over. The optimization of the structure after 2.5m/s. is of great significance for improving the collector efficiency, raising the hot air temperature and accelerating the drying process of rapeseed.

【學(xué)位授予單位】：華中農(nóng)業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S226.6

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