Contrary to conventional design methods that assume uniform and slow temperature changes tied to atmospheric conditions,single-layer spherical reticulated shells undergo significant non-uniform and time-variant temper...Contrary to conventional design methods that assume uniform and slow temperature changes tied to atmospheric conditions,single-layer spherical reticulated shells undergo significant non-uniform and time-variant temperature variations due to dynamic environmental coupling.These differences can affect structural performance and pose safety risks.Here,a systematic numerical method was developed and applied to simulate long-term temperature variations in such a structure under real environmental conditions,revealing its non-uniform distribution characteristics and time-variant regularity.A simplified design method for non-uniform thermal loads,accounting for time-variant environmental factors,was theoretically derived and validated through experiments and simulations.The maximum deviation and mean error rate between calculated and tested results were 6.1℃ and 3.7%,respectively.Calculated temperature fields aligned with simulated ones,with deviations under 6.0℃.Using the design method,non-uniform thermal effects of the structure are analyzed.Maximum member stress and nodal displacement under non-uniform thermal loads reached 119.3 MPa and 19.7 mm,representing increases of 167.5%and 169.9%,respectively,compared to uniform thermal loads.The impacts of healing construction time on non-uniform thermal effects were evaluated,resulting in construction recommendations.The methodologies and conclusions presented here can serve as valuable references for the thermal design,construction,and control of single-layer spherical reticulated shells or similar structures.展开更多
Solar greenhouse is extensively used in horticultural production in China.Natural ventilation is one of the key technological means to adjust the inside environment of greenhouse,while the effects of window opening st...Solar greenhouse is extensively used in horticultural production in China.Natural ventilation is one of the key technological means to adjust the inside environment of greenhouse,while the effects of window opening styles on the inside environment are still not well understood.In the present study,the temperature and air flow field of five operation styles,namely back roof central opening style(G1),back roof evenly spaced opening style(G2),top roof full opening style(G3),style of G1+G3,and style of G2+G3 were simulated using the CFD method.The results indicated that:(1)the simulated and measured results exhibited favorable agreement,with relative errors within 5%;(2)In the case of the windows opening area was the same and only single ventilation style was applied,back roof full opening style exhibited the best cooling effect.The inside average temperature of the greenhouse with G1 style decreased by 0.5°C and 1.6°C respectively compared with those of greenhouses with G2 and G3.(3)The cooling effect of the style of G2+G3 was more favorable than that of the style of G1+G3.The style of G2+G3 exhibited better cooling effect than the single ventilation styles,with the lowest temperature(27.5°C)and temperature uniformity coefficient(0.36).展开更多
In order to investigate the application performances of the solar greenhouses with new types of backwall(greenhouse W_(2),and greenhouse W_(3))and the ordinary clay brick backwall greenhouse(greenhouse W_(1)),and prov...In order to investigate the application performances of the solar greenhouses with new types of backwall(greenhouse W_(2),and greenhouse W_(3))and the ordinary clay brick backwall greenhouse(greenhouse W_(1)),and provide a theoretical basis for the construction of solar greenhouse in Yangling Demonstration Zone,Shaanxi,China,two greenhouses with different new types of backwall were designed.The backwall of one of them was built with lightweight aggregate concrete block(greenhouse W_(2))and that of the other one was assembled with a row of sand-filled cement pipes(greenhouse W_(3)).The tested greenhouses were constructed in Yangling Demonstration Zone.Based on the data collected on typical sunny and cloudy days,the indoor temperature,inside wall temperature,and the heat flow of the greenhouses with new types of backwall were compared with those detected in the ordinary clay brick backwall solar greenhouse,and the tested results were numerically simulated.According to the comparison of the physiological indicators of tomatoes planted in the greenhouses and the construction costs,the greenhouse type with the best practicability was found.The results indicated that:The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside was 15.1℃,15.9℃,17.3℃,and−0.4℃ on the night of a sunny day,and the air temperature in W_(3)was the highest.The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside were 9.5℃,13.3℃,11.0℃,and−5.5℃ on the night of a cloudy day,the air temperature in W_(2)was the highest.In the depth of 0-330 mm from the interface of the backwalls,the walls were obviously affected by the solar radiation,and the temperature changed greatly.The wall temperature on the sunny days exhibited an ascending order of W_(1),W_(2),W_(3),while on the cloudy days was in the ascending order of W_(1),W_(3),W_(2).The wall of W_(3)absorbed the most heat during the daytime and released the most heat at night on the sunny day,while W_(2)exhibited the second most heat absorption during the daytime,however,it exhibited the highest heat release at night on the cloudy day,which were almost equaled to its heat absorption.Tomatoes in W_(3)grew well and exhibited the highest yield,and this greenhouse had the lowest construction costs.Comprehensively considering the physiological indicators of tomatoes and the corresponding construction costs of greenhouses,W_(3)has the best application performance in Yangling Demonstration Zone.展开更多
基金This work is supported by the National Natural Science Foundation of China(Nos.51578491 and 52238001).
文摘Contrary to conventional design methods that assume uniform and slow temperature changes tied to atmospheric conditions,single-layer spherical reticulated shells undergo significant non-uniform and time-variant temperature variations due to dynamic environmental coupling.These differences can affect structural performance and pose safety risks.Here,a systematic numerical method was developed and applied to simulate long-term temperature variations in such a structure under real environmental conditions,revealing its non-uniform distribution characteristics and time-variant regularity.A simplified design method for non-uniform thermal loads,accounting for time-variant environmental factors,was theoretically derived and validated through experiments and simulations.The maximum deviation and mean error rate between calculated and tested results were 6.1℃ and 3.7%,respectively.Calculated temperature fields aligned with simulated ones,with deviations under 6.0℃.Using the design method,non-uniform thermal effects of the structure are analyzed.Maximum member stress and nodal displacement under non-uniform thermal loads reached 119.3 MPa and 19.7 mm,representing increases of 167.5%and 169.9%,respectively,compared to uniform thermal loads.The impacts of healing construction time on non-uniform thermal effects were evaluated,resulting in construction recommendations.The methodologies and conclusions presented here can serve as valuable references for the thermal design,construction,and control of single-layer spherical reticulated shells or similar structures.
基金This research was financially supported by National Natural Science Foundation of China(31901420)and Shaanxi Provincial Key Research and Development Program(2019TSLNY01-03).
文摘Solar greenhouse is extensively used in horticultural production in China.Natural ventilation is one of the key technological means to adjust the inside environment of greenhouse,while the effects of window opening styles on the inside environment are still not well understood.In the present study,the temperature and air flow field of five operation styles,namely back roof central opening style(G1),back roof evenly spaced opening style(G2),top roof full opening style(G3),style of G1+G3,and style of G2+G3 were simulated using the CFD method.The results indicated that:(1)the simulated and measured results exhibited favorable agreement,with relative errors within 5%;(2)In the case of the windows opening area was the same and only single ventilation style was applied,back roof full opening style exhibited the best cooling effect.The inside average temperature of the greenhouse with G1 style decreased by 0.5°C and 1.6°C respectively compared with those of greenhouses with G2 and G3.(3)The cooling effect of the style of G2+G3 was more favorable than that of the style of G1+G3.The style of G2+G3 exhibited better cooling effect than the single ventilation styles,with the lowest temperature(27.5°C)and temperature uniformity coefficient(0.36).
基金This research was financially supported by the Shaanxi Provincial Key Research and Development Program(Grant No.2019TSLNY01-03)the National Natural Science Foundation of China(Grant No.31901420)the Young Scientist Promotion Project of Jiangsu Science and Technology Association(Grant No.2020-2-46).
文摘In order to investigate the application performances of the solar greenhouses with new types of backwall(greenhouse W_(2),and greenhouse W_(3))and the ordinary clay brick backwall greenhouse(greenhouse W_(1)),and provide a theoretical basis for the construction of solar greenhouse in Yangling Demonstration Zone,Shaanxi,China,two greenhouses with different new types of backwall were designed.The backwall of one of them was built with lightweight aggregate concrete block(greenhouse W_(2))and that of the other one was assembled with a row of sand-filled cement pipes(greenhouse W_(3)).The tested greenhouses were constructed in Yangling Demonstration Zone.Based on the data collected on typical sunny and cloudy days,the indoor temperature,inside wall temperature,and the heat flow of the greenhouses with new types of backwall were compared with those detected in the ordinary clay brick backwall solar greenhouse,and the tested results were numerically simulated.According to the comparison of the physiological indicators of tomatoes planted in the greenhouses and the construction costs,the greenhouse type with the best practicability was found.The results indicated that:The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside was 15.1℃,15.9℃,17.3℃,and−0.4℃ on the night of a sunny day,and the air temperature in W_(3)was the highest.The average air temperature in greenhouses W_(1),W_(2),and W_(3)and outside were 9.5℃,13.3℃,11.0℃,and−5.5℃ on the night of a cloudy day,the air temperature in W_(2)was the highest.In the depth of 0-330 mm from the interface of the backwalls,the walls were obviously affected by the solar radiation,and the temperature changed greatly.The wall temperature on the sunny days exhibited an ascending order of W_(1),W_(2),W_(3),while on the cloudy days was in the ascending order of W_(1),W_(3),W_(2).The wall of W_(3)absorbed the most heat during the daytime and released the most heat at night on the sunny day,while W_(2)exhibited the second most heat absorption during the daytime,however,it exhibited the highest heat release at night on the cloudy day,which were almost equaled to its heat absorption.Tomatoes in W_(3)grew well and exhibited the highest yield,and this greenhouse had the lowest construction costs.Comprehensively considering the physiological indicators of tomatoes and the corresponding construction costs of greenhouses,W_(3)has the best application performance in Yangling Demonstration Zone.