摘要
为确定自然环境下日光温室前屋面的采光效率,通过实测数据获得杨凌地区冬季长时间无雨状态下棚膜表面的灰尘积累分布情况以及不同太阳入射角及积灰程度下的棚膜透光率,构建了积灰分布模型及棚膜透光率衰减模型,在此基础上结合太阳入射角计算模型,采用MATLAB作为开发工具编写日光温室前屋面透光率的计算程序。通过输入温室地理坐标、日期时间、采光面曲线形状、朝向、棚膜材料种类,模拟出采光面上的透光率,并在杨凌地区对模型进行验证与应用。结果表明:同时考虑灰尘和太阳入射角的影响,建立的透光率模型与实测值的模拟精度较高,3个测点的模型计算值与实测值平均绝对误差分别为0.90%、2.13%和2.02%;以杨凌冬至日高采光效率为设计目标,将距温室前屋面底端0.8 m处的点作为控制点,确定2种曲线形状的温室,其前屋面控制点高度分别为0.6和0.8 m;朝向为南偏西5°时,在冬至日正午前后2h内,采光面的太阳入射角处于合理采光角范围内,采光效率较高;在弱光低温的冬季,为保障温室内较高的光照强度,建议选用的前屋面覆盖材料为白色PO膜。该研究可为日光温室棚膜表面采光效率的计算及采光面结构的设计优化提供依据。
Highly efficient use of solar energy depends mainly on the reasonable daylighting design of the front roof in a solar greenhouse.This study aims to establish a daylighting efficiency model for the front roof of a solar greenhouse in a natural environment.Taking Yangling district,Shanxi Province of China,as the study area,the dust accumulation and distribution were also acquired on the surface of greenhouse film under the conditions of no rain for a long time in winter.The light transmittance of greenhouse film was evaluated under different solar incidence angles and ash accumulation.An ash accumulation distribution model and a light transmittance attenuation model were constructed for the greenhouse film,further combining with the calculation model of solar incidence angles.Matlab platform was selected to develop the script for the calculation program of light transmittance for the front roof in a solar greenhouse.The transmittance of the daylighting surface was first simulated using the geographic coordinates of a greenhouse,date and time,the curve shape of the daylighting surface,orientation,and the type of film materials.A field test was also carried out to verify the model in the study area.The results showed that:1)There was a similar simulation accuracy of the transmittance model and the measured value when considering both the influence of dust accumulation and solar incidence angles.The average absolute error of calculated and measured values at three measuring points were 0.90%,2.13%,and 2.02%,respectively.The transmittance efficiency of greenhouse plastic film decreased by about 16.2%in the case of ash accumulation,compared with that without ash accumulation.This indicated that there was great significance of ash accumulation to precisely predict the light transmittance.2)The high transmittance of the winter solstice was taken as the design goal in the study area,while the point of 0.8 m away from the bottom of the front roof in the greenhouse was determined as the control point.The optimal heights of c
作者
张锐
刘一川
朱德兰
葛茂生
Zhang Rui;Liu Yichuan;Zhu Delan;Ge Maosheng(College of Water Resources and Architectural Engineering,Northwest A&F University,Yangling 712100,China;Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas,Ministry of Education,Northwest A&F University,Yangling 712100,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2021年第13期190-199,共10页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家重点研发计划(2021YFE0103000)
陕西省重点研发计划(2020ZDLNY01-01)
国家自然科学基金项目(52009111)。
关键词
温室
薄膜
积灰
曲线形状
朝向
透光率
greenhouse
film
ash accumulation
curve shape
orientation
light transmittance
