傾斜式太陽能蒸餾器實驗及CFD模擬研究
發(fā)布時間：2018-10-21 17:51
【摘要】：淡水資源短缺是人類一直面臨的難題,尤其是在電力匱乏的偏遠山區(qū)以及海島。太陽能海水淡化技術(shù)對于解決海島淡水資源短缺、偏遠且電力資源不可到達的缺水地區(qū)的苦咸水淡化具有重要的意義。太陽能蒸餾器以其結(jié)構(gòu)簡單、取材方便、不需要常規(guī)能源等優(yōu)點適合于海島海水淡化以及偏遠地區(qū)的苦咸水淡化,但是目前研制的太陽能蒸餾器普遍存在運行溫度低、產(chǎn)水量不高、太陽能利用效率較低及設(shè)備投資較高等弊端,其在工程實際中的推廣應用受到一定的限制。因此在現(xiàn)有的太陽能蒸餾技術(shù)研究基礎(chǔ)上,通過改變實驗條件來提高太陽能蒸餾器的熱效率和產(chǎn)水量具有重要的現(xiàn)實意義。本文主要對蓄熱式傾斜芯型太陽能蒸餾裝置進行設(shè)計,采用實驗測試和數(shù)值模擬方法,重點研究和分析了傾斜角度、給水流速和相變蓄熱材料等因素對蒸餾器產(chǎn)水量的影響規(guī)律。在不同實驗條件下對蓄熱式傾斜芯型太陽能蒸餾器產(chǎn)水量的影響因素進行了實驗研究。給水流量的范圍為10至40L/h,傾斜角度分別為30°和45°,在相近的天氣條件下進行實驗研究,結(jié)果表明:給水流速的大小和蒸餾器傾斜角度是影響產(chǎn)水量的主要因素,產(chǎn)水量隨著海水給水流量的增大而降低,在允許范圍內(nèi),應盡量降低給水流速,但要保證腔體內(nèi)有足夠的水量蒸發(fā);傾斜角度越接近當?shù)鼐暥?吸收的太陽能輻射越大,有利于提高蒸發(fā)效率;根據(jù)季節(jié)的氣候特點,可選用不同熔點的相變蓄熱材料,加入相變蓄熱材料后,白天產(chǎn)水量會略微降低,而在夜晚通過相變釋放大量熱能,在低溫條件下加熱海水,為海水蒸發(fā)提供驅(qū)動力,在夜間可提高近一倍的產(chǎn)水量,從而使總產(chǎn)水量增大。加入蓄熱材料后,夜間產(chǎn)水量可提高88%至104%,總產(chǎn)水量最高可達到5.16L/m2。建立了傾斜式太陽能蒸餾器三維兩相模型,在理想條件下對傾斜式太陽能蒸餾器進行CFD仿真模擬,并與實驗數(shù)據(jù)進行了對比分析。在不同底板加熱溫度、流速、傾斜角度條件下對蒸餾器內(nèi)的蒸發(fā)冷凝過程進行數(shù)值模擬,模擬結(jié)果表明,隨著底板加熱溫度的增大,蒸餾器腔體內(nèi)水膜和蓋板之間的溫差增大,從而增大了冷凝速率;產(chǎn)水量隨著流速的增大以遞減的趨勢降低,即流速越大,熱損失越大,產(chǎn)水量越低;傾角為45°時的產(chǎn)水量要高于30°時的產(chǎn)水量。根據(jù)實際測得的溫度數(shù)據(jù),對蒸餾器一天的產(chǎn)水量進行仿真計算,模擬數(shù)據(jù)與實驗數(shù)據(jù)大體上保持一致,偏差在15%以內(nèi),驗證了模擬的可靠性和有效性。
[Abstract]:The shortage of fresh water is a difficult problem for human beings, especially in remote mountain areas and islands. The solar desalination technology is of great significance to solve the desalination of brackish water in the water shortage, remote and inaccessible areas of the island. Solar distiller is suitable for desalination of sea water and desalination of brackish water in remote areas because of its simple structure, convenient selection of materials and no need of conventional energy. However, the operating temperature of solar distillation is generally low. Water production is not high, solar energy utilization efficiency is low and equipment investment is high, so its popularization and application in engineering practice is limited to a certain extent. Therefore, it is of great practical significance to improve the thermal efficiency and water production of solar distillation by changing the experimental conditions on the basis of the existing research on solar distillation technology. In this paper, the regenerative tilting core solar distillation unit is designed, and the inclination angle is studied and analyzed by means of experimental test and numerical simulation. The effect of feed water flow rate and phase change heat storage material on the water yield of distiller. The factors affecting water production of regenerative inclined core solar distillation were studied under different experimental conditions. The range of feed water flow is 10 to 40 L / h, and the inclination angle is 30 擄and 45 擄respectively. The experimental results show that the magnitude of feed water velocity and the tilting angle of distiller are the main factors affecting water yield. The water production decreases with the increase of seawater water supply flow. Within the allowable range, the flow velocity should be reduced as far as possible, but enough water should be evaporated in the cavity. The closer the tilt angle is to the local latitude, the more solar radiation is absorbed. According to the climate characteristics of the season, the phase change heat storage materials with different melting points can be selected. After adding the phase change storage materials, the water production will be slightly reduced during the day, and a large amount of heat energy can be released through the phase change at night. Heating seawater at low temperature provides a driving force for seawater evaporation, which can increase the water yield by nearly twice at night, thus increasing the total water production. After adding heat storage materials, the night water production can be increased by 88% to 104%, and the total water yield can reach 5.16 L / m ~ (2). Three-dimensional two-phase model of tilted solar distillation was established. The CFD simulation of tilted solar distillation was carried out under ideal conditions, and the results were compared with experimental data. The evaporative condensation process in the distiller is simulated at different bottom heating temperature, flow rate and inclined angle. The simulation results show that the temperature difference between the water film and the cover plate increases with the increase of the bottom heating temperature. As a result, the condensation rate is increased, and the water production decreases with the increase of flow velocity, that is, the larger the velocity, the greater the heat loss and the lower the water yield, and the higher the water yield is when the inclination angle is 45 擄, which is higher than that at 30 擄. According to the measured temperature data, the water production of the distiller is calculated by simulation. The simulation data are consistent with the experimental data, and the deviation is less than 15%, which verifies the reliability and validity of the simulation.
【學位授予單位】：河北工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P747.14
本文編號：2285889
[Abstract]:The shortage of fresh water is a difficult problem for human beings, especially in remote mountain areas and islands. The solar desalination technology is of great significance to solve the desalination of brackish water in the water shortage, remote and inaccessible areas of the island. Solar distiller is suitable for desalination of sea water and desalination of brackish water in remote areas because of its simple structure, convenient selection of materials and no need of conventional energy. However, the operating temperature of solar distillation is generally low. Water production is not high, solar energy utilization efficiency is low and equipment investment is high, so its popularization and application in engineering practice is limited to a certain extent. Therefore, it is of great practical significance to improve the thermal efficiency and water production of solar distillation by changing the experimental conditions on the basis of the existing research on solar distillation technology. In this paper, the regenerative tilting core solar distillation unit is designed, and the inclination angle is studied and analyzed by means of experimental test and numerical simulation. The effect of feed water flow rate and phase change heat storage material on the water yield of distiller. The factors affecting water production of regenerative inclined core solar distillation were studied under different experimental conditions. The range of feed water flow is 10 to 40 L / h, and the inclination angle is 30 擄and 45 擄respectively. The experimental results show that the magnitude of feed water velocity and the tilting angle of distiller are the main factors affecting water yield. The water production decreases with the increase of seawater water supply flow. Within the allowable range, the flow velocity should be reduced as far as possible, but enough water should be evaporated in the cavity. The closer the tilt angle is to the local latitude, the more solar radiation is absorbed. According to the climate characteristics of the season, the phase change heat storage materials with different melting points can be selected. After adding the phase change storage materials, the water production will be slightly reduced during the day, and a large amount of heat energy can be released through the phase change at night. Heating seawater at low temperature provides a driving force for seawater evaporation, which can increase the water yield by nearly twice at night, thus increasing the total water production. After adding heat storage materials, the night water production can be increased by 88% to 104%, and the total water yield can reach 5.16 L / m ~ (2). Three-dimensional two-phase model of tilted solar distillation was established. The CFD simulation of tilted solar distillation was carried out under ideal conditions, and the results were compared with experimental data. The evaporative condensation process in the distiller is simulated at different bottom heating temperature, flow rate and inclined angle. The simulation results show that the temperature difference between the water film and the cover plate increases with the increase of the bottom heating temperature. As a result, the condensation rate is increased, and the water production decreases with the increase of flow velocity, that is, the larger the velocity, the greater the heat loss and the lower the water yield, and the higher the water yield is when the inclination angle is 45 擄, which is higher than that at 30 擄. According to the measured temperature data, the water production of the distiller is calculated by simulation. The simulation data are consistent with the experimental data, and the deviation is less than 15%, which verifies the reliability and validity of the simulation.
【學位授予單位】：河北工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P747.14
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1 李強;傾斜式太陽能蒸餾器實驗及CFD模擬研究[D];河北工業(yè)大學;2015年
，本文編號：2285889
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