Knowledge Management System Of Institute of Oceanology, Chinese Academy of Sciences
|Place of Conferral||中国科学院海洋研究所|
|Keyword||水产温室 计算流体力学 小气候 中空膜保温 太阳能蓄能|
采用计算流体力学（CFD）方法模拟中空膜无小梁太阳能水产温室误差率≤8.9 %。其他地区水产温室亦可参考本研究所用CFD方法，用太阳射线跟踪算法通过经纬度加载太阳辐射模型，选用离散坐标DO辐射模型模拟温室各结构表面的辐射强度，湍流模式采用标准 k-ε 方程模型，根据温室结构参数与环境参数建立模型，模拟温室内部环境因子的变化，本研究所建CFD模型对其他地区水产温室的建模具有参考意义。
双层中空膜的透光率低于单层塑料膜，双层中空膜透过光的光照强度为单层膜透过光的光照强度的75-95 %。中空膜无小梁太阳能水产温室上午形成自南部向北部呈放射性运动的气流场，之后因太阳辐射能的积累，形成自南向北，自东向西的顺时针的环流。夜晚气流在北部自下向上流动，北部顶部气压高，之后再向南部流动，形成与之前相反的环流。温室四周的气流流速高于中部气流流速，顶部的流速高于底部的流速。水产温室温度场在不同高度水平面，东西向、南北向垂直面分布不均。水平方向上：南北向温度场呈波纹状，北高南低；东西向温度场日出后东部升温快、温度高，之后西部热量输入增多，温度下降较东部慢。夜晚各点温差减小到1 ℃以内。垂直方向上：白天顶部升温最快、温度最高，夜晚底部温度最高，温度场趋向均匀。
水产温室的保温性能优劣顺序为，中空膜无小梁太阳能水产温室>光明型水产温室>半黑暗型温室>日光温室。为更好的提高中空膜无小梁太阳能水产温室的保温性能，对其墙体结构展开研究发现：北部墙体热量流失量远大于入射量，需进行改良优化。墙体膜间热量留存大、难以输出可采用气/水换热的方法蓄能。在气/水换热试验中发现：无气/水换热部分室温先上升后下降呈单峰型，有气/水换热部分室温呈先上升后下降再上升趋势，气/水换热器对室温具有削峰作用，其整体温度低于无气/水换热部分温室。二者温差也呈单峰型，温差先增大，在11:30左右温差最大为24.7 ℃，之后减小至2.3 ℃。对有气/水换热部分温室进行进一步研究发现：进行气/水换热后水温上升，室温呈先上升后下降再上升趋势。室温和水温之差以及出水口和进水口温差都呈现扩大减小交替出现的关系，气/水换热效率受室温和水温温差影响，室温和水温温差大，气/水换热效率高，温差少，则效率低。
At present, aquaculture greenhouses in China mostly draw on planting greenhouses. Planting greenhouses are used for providing plants with suitable light and temperature conditions for their growth. Without professional design, there are many problems in aquaculture greenhouses, such as significant difference in diurnal temperature range, difference between air and water temperature, poor labor production environment, low solar energy utilization and high energy consumption. However, in the northern part of China, both of the temperature and sunlight coverage is low in winter, and aquaculture depends on external heating equipment to increase the water temperature in order to maintain the growth and development of aquatic products, which is costly and not environmentally friendly. Drawing on the cultivation of greenhouses for aquaculture workshops can only play a limited role in early spring and late autumn. Therefore, designing and optimizing aquaculture greenhouses and improving their solar energy utilization and production efficiency have become an urgent demand for the development of aquaculture in northern China. In this research, the self-developed trabeculeless solar aquaculture greenhouse with hollow membrane was taken as the research object, and its design and construction, CAD modeling, simulation and verification of microclimate changes, also winter insulation performance and insulation strategy were studied. The results were as follows:
The error rate of using CFD method to simulating trabeculeless solar aquaculture greenhouse with hollow membrane was ≤8.9%. The solar radiation model can be loaded by latitude and longitude using the solar ray tracking algorithm. And the discrete coordinate DO radiation model was used to simulate the radiation intensity on the surface of the greenhouse. The turbulence model adopt the standard k-ε equation model. The model was established according to the greenhouse structural parameters and environmental parameters. It can simulate the changes of the environmental factors inside the greenhouse, which has a reference significance for the modeling of aquatic greenhouses in other regions.
The light transmittance of the double-layer hollow film was lower than that of the single-layer plastic film. The light intensity of the light transmitted through the double-layer hollow membrane was 75-95% of the single-layer membrane. The aquatic greenhouse formed an airflow field that moved radioactively from the south to the north in the morning. Afterwards, due to the accumulation of solar radiation energy, a clockwise circulation was formed from the top to the south, the north to the low, the bottom to the south, and the south to the high. At night, the airflow flowed from the bottom to the top in the north, the air pressure in the top of the north was high, and then it flowed to the south, forming an opposite circulation to the previous one. The airflow velocity around was higher than the internal, and the top was higher than the bottom. The thermal fields of aquatic greenhouse in the horizontal planes at different heights, in the east-west, north-south vertical planes were unevenly distributed. In the horizontal direction, temperature in the north was higher than in the south. In the east-west thermal field, the temperature in the east rose more rapidly than in the west, but the heat input in the west increased in the afternoon, and the temperature in the west decreased more slowly than in the east. At night, the temperature variation between different locations was within 1 ℃. Vertically, the top heated up fastest and the temperature was highest during the day and the temperature at the bottom was highest at night and the temperature field tended to be even.
The envelope structure affected the light intensity. The solar radiation affected the distribution of the temperature field. Accordingly this temperature field affected the distribution of the airflow, and the airflow had a further influence on the temperature field too. Various environmental factors affected each other and restricted each other, which together constituted the microclimate inside the aquatic greenhouse.
The thermal insulation performance of the aquatic greenhouse was as follows: the trabeculeless solar aquaculture greenhouse with hollow membrane> bright aquatic greenhouse> semi-dark greenhouse> sunlight greenhouse. However, in the trabeculeless solar aquaculture greenhouse with hollow membrane, the amount of heat lost from the northern wall was much larger than the amount of incident, which needed to be improved and optimized. The heat retention between the membranes of the wall was large and it was difficult to output. The energy can be stored by the method of air-water heat exchange.
It was found in the air-water heat exchange test that the control greenhouse temperature showed a unimodal rise and then decreased. While the air-water heat exchange greenhouse temperature showed a trend of increasing, then decreasing and then increasing again. Its overall temperature was lower than the control greenhouse. The temperature difference between the two greenhouses also showed in a unimodal trend. The temperature difference first increased to its maximum at 24.7 ℃ around 11:30, and then decreased to 2.3 ℃. Carrying out the study of greenhouses with air-water heat exchange found that after air-water heat exchanged, the water temperature increased. The room temperature increased first, then decreased, and then increased. The difference between room and water temperature, as well as the difference between the water outlet and the inlet temperature, appear to increased and decreased alternately. The air-water heat transfer efficiency was affected by the difference between room and water temperature. When the difference between room and water temperature was less, the efficiency was getting low.
|MOST Discipline Catalogue||理学 ; 理学::海洋科学|
|Table of Contents|
|尉莹. 中空膜无小梁太阳能水产温室的构建及其小气候研究[D]. 中国科学院海洋研究所. 中国科学院大学,2020.|
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