scholarly journals Effect of internal surface structure of the north wall on Chinese solar greenhouse thermal microclimate based on computational fluid dynamics

PLoS ONE ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. e0231316
Author(s):  
Xingan Liu ◽  
He Li ◽  
Yiming Li ◽  
Xiang Yue ◽  
Subo Tian ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Surface Structure ◽  
Internal Surface ◽  
The North ◽  
Solar Greenhouse ◽  
North Wall

Effect of north wall internal surface structure on heat storage-release performance and thermal environment of Chinese solar greenhouse

2021 ◽  
pp. 174425912110134
Author(s):  
Yiming Li ◽  
Xiang Yue ◽  
Lei Zhao ◽  
Hui Xu ◽  
Xingan Liu ◽  
...  
Keyword(s):  
Heat Storage ◽  
Thermal Environment ◽  
Internal Surface ◽  
Surface Structures ◽  
Indoor Thermal Environment ◽  
The North ◽  
Yield And Quality ◽  
Solar Greenhouse ◽  
North Wall ◽  
Striped Wall

Chinese solar greenhouse (CSG) is an energy-saving agricultural building which is used to grow vegetables in winter. The north wall of CSG plays an crucial role in concerning the production yield and quality during the winter months. To improve the thermal performance of north wall, different internal surface structures (ISS) with same materials were compared. Based on the field experiment and the proposed valuation, the dynamic heat storage-release characteristics of the north walls have been analyzed and discussed. The results showed that compared with the flat wall and the striped wall, the alveolate wall has better properties of heat storage and thermal insulation. Moreover, relative humidity in this type of greenhouse is more suitable for growing crops. The alveolate wall can improve indoor thermal environment and reduce the sensitivity to external environment. The obtained results can provide a basis for the scientific construction of the CSG north wall. It has significant potential for the area in high latitude, high altitude and long winter.

scholarly journals Effect of the ridge position ratio on the thermal environment of the Chinese solar greenhouse

2021 ◽  
Vol 8 (5) ◽  
Author(s):  
Xiaoyang Wu ◽  
Xingan Liu ◽  
Xiang Yue ◽  
Hui Xu ◽  
Tianlai Li ◽  
...  
Keyword(s):  
Structural Design ◽  
Cfd Simulation ◽  
Thermal Environment ◽  
The South ◽  
The North ◽  
Dependency Relationship ◽  
Solar Greenhouse ◽  
Computational Fluid Dynamics Cfd ◽  
North Wall ◽  
Maximum Air Temperature

This paper clarified the mechanism of the south and north roofs' effect on the thermal environment of the Chinese solar greenhouse (CSG), using a new parameter: ridge position ratio (RPR), which can describe the dynamic dependency relationship between the south and north roofs. A mathematical model was established using a method of combining computational fluid dynamics (CFD) simulation with experiments, then the model was used to further analyse the effect of RPR on the thermal environment of the CSG. The experimental greenhouse was simulated as an empty building to obtain results independently from these factors including crop and ventilation conditions. The results showed that the occurrence time of the maximum air temperature will be delayed when RPR increases to 0.3 during the daytime. As RPR increases, the heat storage layer of the soil gradually becomes thinner, but the north wall remains unchanged. RPR has a relatively small effect on the minimum temperature of each greenhouse part during the night. Mathematical models of the relationships between RPR, the solar energy that entered the greenhouse and the released heat energy of the enclosure structures were established, respectively. This paper can provide theoretical guidance for the structural design of the CSG.

scholarly journals Solar Radiation Allocation and Spatial Distribution in Chinese Solar Greenhouses: Model Development and Application

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1108 ◽  
Author(s):  
Xiaodan Zhang ◽  
Jian Lv ◽  
Jianming Xie ◽  
Jihua Yu ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Solar Radiation ◽  
Heat Storage ◽  
Light Environment ◽  
Beam Radiation ◽  
Growth Environment ◽  
The North ◽  
Cloudy Weather ◽  
Solar Greenhouse ◽  
North Wall

Solar radiation is the sole energy source for Chinese solar greenhouse agriculture. A favorable light environment is the foundation of a desirable crop growth environment, and it is key in solar greenhouse design. In this study, a mathematical model is established to quantitatively evaluate the solar greenhouse light environment. The model was developed considering the greenhouse shape parameters, materials’ optical properties, and interior solar radiation evolution, including the beam radiation, diffuse radiation, and multi-reflection. The model was validated under different weather conditions, and the results reveal a mean percentage error of 1.67 and 10.30% for clear sunny weather and cloudy weather, respectively, and a determination coefficient of 0.9756. By using this model, the solar radiation allocation in a solar greenhouse was calculated to determine the solar radiation availability for the heat-storage north wall and the entire greenhouse, and the dynamical spatial distribution of the solar radiation was obtained to describe the light environment quality. These allow the optimization of the greenhouse lighting regulation and planting pattern. Moreover, several optimizing measures are derived according to the model for improving the low-light environment near the north wall and maximizing the north wall’s heat storage/release capacity in a solar greenhouse.

Investigation of Temperature and Air Flow inside Para Rubber Greenhouse Solar Dryer Incline Roof Type by Using CFD Technique

2014 ◽  
Vol 931-932 ◽  
pp. 1238-1242 ◽  
Author(s):  
Praphanpong Somsila ◽  
Umphisak Teeboonma
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Air Flow ◽  
Solar Dryer ◽  
Solar Greenhouse ◽  
Product Surface ◽  
Air Circulation ◽  
Dynamics Method

Para rubber solar greenhouse dryer is a one method of drying and it can be responded to requirement of agriculturist on amount of drying product. Present, the dryer was being built many type for made drying agriculture product. The air circulation and temperature scatter havent been used for the dryer built process, which are cause of fungus on product surface and product dehydrate not all over. Therefore, the objective of this research is to study temperature distributes and air circulations inside Para rubber solar greenhouse dryer of incline roof type using computational fluid dynamics method. The result showed that temperature and velocity of air were good distributing all area and havent air cluster under the roof.

scholarly journals Numerical investigation of the north wall passive thermal performance for Chinese solar greenhouse

2020 ◽  
Vol 24 (6 Part A) ◽  
pp. 3465-3476
Author(s):  
Yiming Li ◽  
Xingan Liu ◽  
Fengsheng Qi ◽  
Li Wang ◽  
Tianlai Li
Keyword(s):  
Solar Energy ◽  
Wall Thickness ◽  
Thermal Performance ◽  
Thermal Environment ◽  
Energy Utilization ◽  
Wall Material ◽  
The North ◽  
Solar Energy Utilization ◽  
Solar Greenhouse ◽  
North Wall

The fully passive solar energy utilization system of Chinese solar greenhouse is efficient for ensuring year-round cultivation of vegetables, owing to the high amount of heat charge and discharge characteristic of the north wall enclosure. In the present research, the thermal performance is investigated using CFD. A 3-D mathematical model has been established to evaluate the wall thickness, layered configuration and material property. The predicted thermal environments are in good agreement with the experimental measurements, indicating the reliability of the established numerical model. The results showed that the increase of north wall thickness could cause the waste of resources due to the thermal masses mainly concentrate in the superficial layer. Constructing layered configuration is rec-ommended for the north wall which uses Styrofoam in the outer layer to reduce heat loss. Nevertheless, the property of north wall material has little effect on the thermal environment. The research results, thus obtained, will give good guidance for completing the Chinese solar greenhouse engineering database and optimizing the solar energy utilization.

scholarly journals Design and Optimization of a Diffuser for a Horizontal Axis Hydrokinetic Turbine using Computational Fluid Dynamics based Surrogate Modelling

Mechanika ◽  
2020 ◽  
Vol 26 (2) ◽  
pp. 161-170
Author(s):  
Salma Sherbaz
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flat Plate ◽  
Fossil Fuels ◽  
Global Climate ◽  
Maximum Velocity ◽  
Internal Surface ◽  
Horizontal Axis ◽  
Design And Optimization ◽  
Hydrokinetic Turbine

Fossil fuels have remained at the backbone of the global energy portfolio. With the growth in the number of factories, population, and urbanization; the burden on fossil fuels has also been increasing. Most importantly, fossil fuels have been causing damage to the global climate since industrialization. The stated issues can only be resolved by shifting to environment friendly alternate energy options. The horizontal axis hydrokinetic turbine is considered as a viable option for renewable energy production. The aim of this project is the design and optimization of a diffuser for horizontal axis hydrokinetic turbine using computational fluid dynamics based surrogate modeling. The two-dimensional flat plate airfoil is used as a benchmark and flow around the airfoil is simulated using Ansys Fluent.  Later, computational fluid dynamics analyses are carried out for baseline diffuser generated from the flat plate airfoil. The performance of this diffuser was optimized by achieving an optimum curved profile at the internal surface of the diffuser. The response surface methodology is used as a tool for optimization. A maximum velocity augmentation of 31.70%  is achieved with the optimum diffuser.

scholarly journals Computational Fluid Dynamics-Based Simulation of Crop Canopy Temperature and Humidity in Double-Film Solar Greenhouse

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Wei Jiao ◽  
Qi Liu ◽  
Lijun Gao ◽  
Kunyu Liu ◽  
Rui Shi ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Porous Medium ◽  
Canopy Temperature ◽  
Simulation Method ◽  
Solar Greenhouse ◽  
Temperature And Humidity ◽  
Carbon Dioxide Detection ◽  
Dynamics Simulations ◽  
Mean Square Errors

The microenvironment of the crop area in a greenhouse is the main factor that affects its growth, quality, and pest control. In this study, we propose a double-layer film solar greenhouse microenvironment testing system based on computational fluid dynamics simulations of a celery canopy with a porous medium. A real greenhouse was examined with a sensor system for soil, air, radiation, and carbon dioxide detection to verify the simulation results. By monitoring the internal environment of celery canopies with heights of 0.8 and 1 m during a period of temperature fluctuations, we found the temperature and humidity of the canopy interior changed spatially and differed greatly from the those in the greenhouse under solar radiation conditions. The temperature and humidity of the celery canopy were 4–14°C lower and 10%–30% higher than those of the surroundings. As the canopy grew, the differences in temperature and humidity between the canopy and other parts of the greenhouse increased. The root mean square errors of the temperature and humidity with the 0.8 m high celery canopy were found to be 0.56 and 2.86 during the day and 0.24 and 0.81 at night, respectively; the corresponding values for the 1 m high celery canopy were found to be 0.51 and 2.26 during the day and 0.26 and 0.78 at night. The porous medium model expressed the temperature and humidity characteristics of the celery crop appropriately, and the simulation method was shown to be effective and feasible. With the simulation method proposed in this study, the production of crops in complex microenvironments in greenhouses can be modeled and digitized.

scholarly journals Improving natural ventilation in renovated free-stall barns for dairy cows: Optimized building solutions by using a validated computational fluid dynamics model

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Nicoletta Tomasello ◽  
Francesa Valenti ◽  
Giovanni Cascone ◽  
Simona M.C. Porto
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Dairy Cows ◽  
Natural Ventilation ◽  
Time Lapse ◽  
Cfd Model ◽  
North West ◽  
The North ◽  
Livestock Buildings ◽  
Wall Openings

Natural ventilation is the most used system to create suitable conditions, removing gases, introducing oxygen in livestock buildings. Its efficiency depends on several factors and above all on the number, the dimensions and the position of wall openings and internal layout of livestock buildings. The aim of this research was to develop optimized layout solutions for improving natural ventilation effectiveness in free-stall barns for dairy cows by using a CFD approach. A validated computational fluid dynamics (CFD) model was applied in a case study which is highly representative of building interventions for renovating the layout of free-stall barns for dairy cows located in an area of the Mediterranean basin. Firstly, dairy cow behaviour was analysed by visual examination of time-lapse video-recordings. Then, simulations were carried out by using the validated CFD model and changing the position of internal and external building elements (i.e., internal office and external buildings for milking) in order to find the best condition for the thermal comfort of the animals. The results showed that the best conditions were recorded for a new configuration of the building in terms of air velocity distribution within the resting area, the service alley and the feeding alley for dairy cows, and in the pens for calves. In this new layout, the office areas and the north-west wall openings were located by mirroring them along the transversal axis of the barn. Therefore, the CFD approach proposed in this study could be used during the design phase, as a decision support system aimed at improving the natural ventilation within the barn.

Sign in / Sign up

Export Citation Format

Share Document