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.

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 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 Effect of North Wall Materials on the Thermal Environment in Chinese Solar Greenhouse (Part A: Experimental Researches)

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 752-767 ◽  
Author(s):  
Xingan Liu ◽  
Yiming Li ◽  
Anhua Liu ◽  
Xiang Yue ◽  
Tianlai Li
Keyword(s):  
Heat Storage ◽  
Thermal Environment ◽  
Coal Ash ◽  
Northern China ◽  
Brick Wall ◽  
Clay Brick ◽  
Fine Coal ◽  
Solar Greenhouse ◽  
Wall Materials ◽  
North Wall

Abstract In order to clarify the dependence relationship between the heat storage & preservation wall and the thermal environment, and to provide data base and theory foundation for the north wall construction of the Chinese solar greenhouse (CSG), the experimental measures has been employed to investigate the distributions of temperature, humidity and heat transfer of three different wall materials (i.e. perforated brick, fine coal ash brick, common clay brick). The dynamic variations of the heat-storage and heat-release processes were identified, and the thermal response characteristics were discussed. The effect of north wall materials on the thermal environment of the solar greenhouse in northern China was revealed. The results indicated that the daily heat-storage and heat-release of fine coal ash brick wall can reach ϕimput = 34.5~130.6 W·m−2 and ϕoutput = −24.15~-45 W·m−2, respectively. The daily heat-storage time can reach t = 5~8 h, and the wall temperature at night can be 3~4∘C higher than the air temperature. Moreover, the maximum indoor temperature of the fine coal ash brick wall can be maintained at t ≤ 16.7 ≤ 31.1∘C, the minimum humidity can be maintained at 29.75~45%. Fortunately, the construction cost is moderate, while the physical properties are obviously better than those of perforated brick and common clay brick in the CSG. The overall thermal performance of fine coal ash brick is the best of the three north wall materials, and it can make the most advantage of the heat-storage and heat-preservation performances of the CSG. As a consequence, the fine coal ash brick wall of the solar greenhouse has good promotion value in northern China and other high latitude, high altitude and long winter regions.

Feasibility of Employing a Heat Insulation Wall as the North Wall of a Chinese Solar Greenhouse in a Severely Cold Area of China

2019 ◽  
Vol 35 (6) ◽  
pp. 903-910
Author(s):  
Ming Li ◽  
Pingzhi Wang ◽  
Weitang Song
Keyword(s):  
Heat Loss ◽  
Air Temperature ◽  
Heat Insulation ◽  
Environmental Damage ◽  
The North ◽  
Solar Greenhouse ◽  
Cold Area ◽  
North Wall ◽  
Insulation Wall ◽  
The Impact

Abstract. The conventional north wall of a Chinese solar greenhouse (hereafter referred to as a “solar greenhouse”) can release heat inside and help maintain a high indoor air temperature (T) during winter nights. However, the construction of conversational walls face problems of high cost, low construction quality, environmental damage, etc. Based on this, heat insulation walls have aroused much interest. However, this kind of wall can barely store and release heat, putting the solar greenhouse at risk of low T. The purpose of this study is to investigate whether the impact of the heat insulation wall could be weakened by decreasing the heat loss through the greenhouse envelope. The thermal environment of a solar greenhouse located in a severe cold area of China (Mohe County, Heilongjiang Province) was examined during sunny days, of which the north wall was constructed from polystyrene boards and plastered with 10 mm-thick mortar. During the experiment, the outdoor air temperature (T) was -22.8±5.6°C during the night, reaching a low of -34.7°C. The amount of heat released from the north wall can be neglected, as it was 5.4% of the total heat obtained by the test solar greenhouse. In comparison with conventional solar greenhouses, both heat loss through the building envelope and the heat obtained from the test solar greenhouse during the night decreased. As a result, T was maintained at 10.6±2.9°C, with a low of 6.8°C, during the night, which was within the normal range of a conventional solar house located in northern China. Thus, the impact of the heat insulation wall on T in the sunny days was weakened by decreasing the heat loss through the greenhouse envelope. Nevertheless, more work on the performance of test solar greenhouse on cloudy days and summer days should be conducted to fully validate the proposed hypothesis. Keywords: Chinese solar greenhouse, Heat insulation wall, Heat loss, Indoor temperature.

scholarly journals Spatial Distribution of Lichens in Metrosideros excelsa in Northern New Zealand Urban Forests

Diversity ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 170
Author(s):  
Gladys N. Benitez ◽  
Glenn D. Aguilar ◽  
Dan Blanchon
Keyword(s):  
Spatial Distribution ◽  
Species Richness ◽  
New Zealand ◽  
Lichen Species ◽  
Positive Correlation ◽  
Breast Height ◽  
Lichen Community ◽  
The North ◽  
The City ◽  
Lichen Flora

The spatial distribution of corticolous lichens on the iconic New Zealand pōhutukawa (Metrosideros excelsa) tree was investigated from a survey of urban parks and forests across the city of Auckland in the North Island of New Zealand. Lichens were identified from ten randomly selected trees at 20 sampling sites, with 10 sites classified as coastal and another 10 as inland sites. Lichen data were correlated with distance from sea, distance from major roads, distance from native forests, mean tree DBH (diameter at breast height) and the seven-year average of measured NO2 over the area. A total of 33 lichen species were found with coastal sites harboring significantly higher average lichen species per tree as well as higher site species richness. We found mild hotspots in two sites for average lichen species per tree and another two separate sites for species richness, with all hotspots at the coast. A positive correlation between lichen species richness and DBH was found. Sites in coastal locations were more similar to each other in terms of lichen community composition than they were to adjacent inland sites and some species were only found at coastal sites. The average number of lichen species per tree was negatively correlated with distance from the coast, suggesting that the characteristic lichen flora found on pōhutukawa may be reliant on coastal microclimates. There were no correlations with distance from major roads, and a slight positive correlation between NO2 levels and average lichen species per tree.

scholarly journals Spatial Distribution and Geographical Mechanism of Natural Resources in China under the Orientation of the New Economic Demands

2021 ◽  
Vol 13 (14) ◽  
pp. 7956
Author(s):  
Xiangmin Zhang ◽  
Bin Yu ◽  
Hailong Yu ◽  
Zhuofan Li ◽  
Shen Luo ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Natural Resources ◽  
New Economy ◽  
The South ◽  
The North ◽  
Ecological Resources ◽  
Demand Structure ◽  
Administrative Units ◽  
Location Map ◽  
Resource Elements

The demand structure of resources for new economy is different from the traditional one in that its development may significantly change China’s economic location map and spatial pattern. Based on 343 administrative units of prefecture-level cities in China, this research constructs the measurement index system of terrestrial surface natural resources under the orientation of the new economic demands; this research mainly analyses the spatial distribution characteristics and geographical mechanism of natural resources by means of the spatial autocorrelation and spatial similarity calculation methods. The results show that: (1) The structure and endowment of natural resources under the orientation of the new economic demands need to be reexamined. The significance of a good environment and ecological resources has been highlighted. The coupling of resource elements better reveals the availability of natural resources. (2) The natural resources decrease from southeast to northwest, showing a pattern of “abundant in the south and east and scarce in the north and west”. Natural resources have a significant positive correlation in spatial distribution with two types of agglomeration: high-high agglomeration and low-low agglomeration, showing the local agglomeration feature of “high in the south and low in the north”. (3) Natural factors such as temperature, precipitation and altitude affect the spatial distribution of natural resources, with the temperature being the most significant. This indicates that the original natural environment and its role are the geographical mechanism for the formation and distribution of natural resources. The results could provide a reference for the development and the optimization of China’s new economy.

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