倾斜式太阳能蒸馏器实验及CFD模拟研究
发布时间：2018-10-21 17:51
【摘要】：淡水资源短缺是人类一直面临的难题,尤其是在电力匮乏的偏远山区以及海岛。太阳能海水淡化技术对于解决海岛淡水资源短缺、偏远且电力资源不可到达的缺水地区的苦咸水淡化具有重要的意义。太阳能蒸馏器以其结构简单、取材方便、不需要常规能源等优点适合于海岛海水淡化以及偏远地区的苦咸水淡化,但是目前研制的太阳能蒸馏器普遍存在运行温度低、产水量不高、太阳能利用效率较低及设备投资较高等弊端,其在工程实际中的推广应用受到一定的限制。因此在现有的太阳能蒸馏技术研究基础上,通过改变实验条件来提高太阳能蒸馏器的热效率和产水量具有重要的现实意义。本文主要对蓄热式倾斜芯型太阳能蒸馏装置进行设计,采用实验测试和数值模拟方法,重点研究和分析了倾斜角度、给水流速和相变蓄热材料等因素对蒸馏器产水量的影响规律。在不同实验条件下对蓄热式倾斜芯型太阳能蒸馏器产水量的影响因素进行了实验研究。给水流量的范围为10至40L/h,倾斜角度分别为30°和45°,在相近的天气条件下进行实验研究,结果表明:给水流速的大小和蒸馏器倾斜角度是影响产水量的主要因素,产水量随着海水给水流量的增大而降低,在允许范围内,应尽量降低给水流速,但要保证腔体内有足够的水量蒸发;倾斜角度越接近当地纬度,吸收的太阳能辐射越大,有利于提高蒸发效率;根据季节的气候特点,可选用不同熔点的相变蓄热材料,加入相变蓄热材料后,白天产水量会略微降低,而在夜晚通过相变释放大量热能,在低温条件下加热海水,为海水蒸发提供驱动力,在夜间可提高近一倍的产水量,从而使总产水量增大。加入蓄热材料后,夜间产水量可提高88%至104%,总产水量最高可达到5.16L/m2。建立了倾斜式太阳能蒸馏器三维两相模型,在理想条件下对倾斜式太阳能蒸馏器进行CFD仿真模拟,并与实验数据进行了对比分析。在不同底板加热温度、流速、倾斜角度条件下对蒸馏器内的蒸发冷凝过程进行数值模拟,模拟结果表明,随着底板加热温度的增大,蒸馏器腔体内水膜和盖板之间的温差增大,从而增大了冷凝速率;产水量随着流速的增大以递减的趋势降低,即流速越大,热损失越大,产水量越低;倾角为45°时的产水量要高于30°时的产水量。根据实际测得的温度数据,对蒸馏器一天的产水量进行仿真计算,模拟数据与实验数据大体上保持一致,偏差在15%以内,验证了模拟的可靠性和有效性。
[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 掳and 45 掳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 掳, which is higher than that at 30 掳. 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.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P747.14
本文编号：2285890
[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 掳and 45 掳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 掳, which is higher than that at 30 掳. 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.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P747.14
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1 李强;倾斜式太阳能蒸馏器实验及CFD模拟研究[D];河北工业大学;2015年
，本文编号：2285890
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