This study aims to mitigate crosswind-induced performance degradation in Natural Draft Dry Cooling Towers used in power plants by developing and assessing windbreak configurations that enhance ventilation while minimi...This study aims to mitigate crosswind-induced performance degradation in Natural Draft Dry Cooling Towers used in power plants by developing and assessing windbreak configurations that enhance ventilation while minimizing additional airflow resistance.Three novel windbreak designs,namely single-windbreak configuration with curved profile,double-windbreak configuration with curved profile,and double-windbreak configuration with inverted curved profile,are proposed accordingly and evaluated against conventional solutions.Three-dimensional numerical models of a 120 m high NDDCT equipped with these windbreaks,together with a conventional Y-shaped windbreak,are developed for systematic comparison.The results demonstrate that windbreak effectiveness strongly depends on crosswind intensity.At low crosswind speeds of 0-6 m/s,the Y-shaped windbreak provides the greatest enhancement,increasing the ventilation rate by 25.45%and the heat rejection rate by 21.37%at 6 m/s compared with the no-windbreak configuration.In contrast,under moderate to strong crosswinds of 6-18 m/s,the single-windbreak configuration with curved profile exhibits superior performance.At 18 m/s,it increases the ventilation rate by 148.88%and the heat rejection rate by 79.74%relative to the baseline case,outperforming the Y-shaped windbreak by 26.59%in ventilation rate and 17.01%in heat rejection capacity.Analysis of airflow structure,temperature fields,and velocity distributions confirms that the single-windbreak configuration with curved profile more effectively suppresses crosswind penetration and promotes stable upward airflow at higher wind speeds.Based on a comprehensive assessment of aerodynamic and thermal performance,the Y-shaped windbreak is recommended for regions where crosswind speeds remain below 6 m/s,whereas the single-windbreak configuration with curved profile is preferable for sites exposed to stronger crosswinds exceeding this threshold.展开更多
Objective To explore the diagnositc role of heat shock protein ( HSP) 70 in acute rejection after pancreatioduodenal transplantation in rats. Methods Groups of Wistar rats underwent total pancreatioduodenal transplant...Objective To explore the diagnositc role of heat shock protein ( HSP) 70 in acute rejection after pancreatioduodenal transplantation in rats. Methods Groups of Wistar rats underwent total pancreatioduodenal transplantation from allogeneic SD or syngeneic Wistar rats. The grafts were harvested on the posttransplantation day 3,5 and 7 and were used to detect the expression of HSP70 by immunohistochemistry and Western Blotting quantitative methods. The correlation between HSP70 expression and pathological findings was observed. Results The level of HSP70 in the isografts did not change greatly( P 】 0.05); the level of HSP70 in the allografts was increased progressively on the posttransplantation day3, 5 and 7 ( P 【 0.01). There was a significant correlation between HSP70 and pathological score in the allograft group (P 【 0.01, r = 0.934). Conclusion HSP70 involved in pancreas allograft rejection and could be useful for early diagnosis of acute rejection following pancreas transplantation. 8 refs,2 tabs.展开更多
Efforts to limit CO2 emissions from buildings in the tropics either focus on reducing energy demand, i.e., air-conditioning, or on replacing fossil with renewable sources. The link between energy demand and supply is ...Efforts to limit CO2 emissions from buildings in the tropics either focus on reducing energy demand, i.e., air-conditioning, or on replacing fossil with renewable sources. The link between energy demand and supply is often overlooked, especially the effect of the temperature lift of air-conditioning systems on energy consumption. But while heat and humidity gains define energy demand, operating temperatures of the system define the necessary energy input. We aim to transfer our experience of usin~ the LowEx paradigm for heat pump systems in moderate climates to the tropical climate of Sinsapore. In this paper, we took a systematic overview of a range of heat sinks, to which we refer to as anergy sinks. We analysed their thermal properties and their effect on the performance of air-conditioning systems, expressed as COP. The predominantly used dry air-cooled condenser units performed worst, especially when subject to a stack effect in （semi-）confined spaces. The performance is highest for cooling towers using the wet bulb temperature followed by water body based anergy sinks and the soil. The wide spread of results confirms that the heat rejection temperature is a decisive factor for the performance of the overall cooting system and the input of primary energy.展开更多
Air-conditioners used in high-rise residential or office buildings often have outdoor units installed on the side-walls or roofs in the confined space of the buildings.The heat released from the outdoor units causes t...Air-conditioners used in high-rise residential or office buildings often have outdoor units installed on the side-walls or roofs in the confined space of the buildings.The heat released from the outdoor units causes the tem-perature rise in the confined installation space and leads to uncomfortable thermal environment and deteriorative performance of air-conditioners.The factors affecting the performance of air-conditioners are the heat released from the outdoor units,the solar radiation and the ventilation of the confined installation space,which are inves-tigated in this study and simulated by FLUENT using the porous model and discrete ordinates (DO) radiation model.It is proved that the porous model is more reliable than the solid model.The optimal installation distance from the supporting wall is obtained.The average temperature of the exit without wind is 1.18% higher than that with wind.The results show that the heat released from the outdoor units and the ventilation of the confined in-stallation space are the main factors affecting the thermal environment in the confined installation space.The in-fluence of the solar radiation is negligible.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52476206)the Key R&D Program of Shandong Province,China(Grant No.2025CXGC010203)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2025A1515012123)the Shandong Natural Science Foundation(Grant No.ZR2022ME008).
文摘This study aims to mitigate crosswind-induced performance degradation in Natural Draft Dry Cooling Towers used in power plants by developing and assessing windbreak configurations that enhance ventilation while minimizing additional airflow resistance.Three novel windbreak designs,namely single-windbreak configuration with curved profile,double-windbreak configuration with curved profile,and double-windbreak configuration with inverted curved profile,are proposed accordingly and evaluated against conventional solutions.Three-dimensional numerical models of a 120 m high NDDCT equipped with these windbreaks,together with a conventional Y-shaped windbreak,are developed for systematic comparison.The results demonstrate that windbreak effectiveness strongly depends on crosswind intensity.At low crosswind speeds of 0-6 m/s,the Y-shaped windbreak provides the greatest enhancement,increasing the ventilation rate by 25.45%and the heat rejection rate by 21.37%at 6 m/s compared with the no-windbreak configuration.In contrast,under moderate to strong crosswinds of 6-18 m/s,the single-windbreak configuration with curved profile exhibits superior performance.At 18 m/s,it increases the ventilation rate by 148.88%and the heat rejection rate by 79.74%relative to the baseline case,outperforming the Y-shaped windbreak by 26.59%in ventilation rate and 17.01%in heat rejection capacity.Analysis of airflow structure,temperature fields,and velocity distributions confirms that the single-windbreak configuration with curved profile more effectively suppresses crosswind penetration and promotes stable upward airflow at higher wind speeds.Based on a comprehensive assessment of aerodynamic and thermal performance,the Y-shaped windbreak is recommended for regions where crosswind speeds remain below 6 m/s,whereas the single-windbreak configuration with curved profile is preferable for sites exposed to stronger crosswinds exceeding this threshold.
文摘Objective To explore the diagnositc role of heat shock protein ( HSP) 70 in acute rejection after pancreatioduodenal transplantation in rats. Methods Groups of Wistar rats underwent total pancreatioduodenal transplantation from allogeneic SD or syngeneic Wistar rats. The grafts were harvested on the posttransplantation day 3,5 and 7 and were used to detect the expression of HSP70 by immunohistochemistry and Western Blotting quantitative methods. The correlation between HSP70 expression and pathological findings was observed. Results The level of HSP70 in the isografts did not change greatly( P 】 0.05); the level of HSP70 in the allografts was increased progressively on the posttransplantation day3, 5 and 7 ( P 【 0.01). There was a significant correlation between HSP70 and pathological score in the allograft group (P 【 0.01, r = 0.934). Conclusion HSP70 involved in pancreas allograft rejection and could be useful for early diagnosis of acute rejection following pancreas transplantation. 8 refs,2 tabs.
文摘Efforts to limit CO2 emissions from buildings in the tropics either focus on reducing energy demand, i.e., air-conditioning, or on replacing fossil with renewable sources. The link between energy demand and supply is often overlooked, especially the effect of the temperature lift of air-conditioning systems on energy consumption. But while heat and humidity gains define energy demand, operating temperatures of the system define the necessary energy input. We aim to transfer our experience of usin~ the LowEx paradigm for heat pump systems in moderate climates to the tropical climate of Sinsapore. In this paper, we took a systematic overview of a range of heat sinks, to which we refer to as anergy sinks. We analysed their thermal properties and their effect on the performance of air-conditioning systems, expressed as COP. The predominantly used dry air-cooled condenser units performed worst, especially when subject to a stack effect in （semi-）confined spaces. The performance is highest for cooling towers using the wet bulb temperature followed by water body based anergy sinks and the soil. The wide spread of results confirms that the heat rejection temperature is a decisive factor for the performance of the overall cooting system and the input of primary energy.
基金supported by National Basic Research Program of China (973 Program)(No.2012CB720406)the Fundamental Research Funds for the Central Universities (No.FRF-AS-10-005B)
文摘Air-conditioners used in high-rise residential or office buildings often have outdoor units installed on the side-walls or roofs in the confined space of the buildings.The heat released from the outdoor units causes the tem-perature rise in the confined installation space and leads to uncomfortable thermal environment and deteriorative performance of air-conditioners.The factors affecting the performance of air-conditioners are the heat released from the outdoor units,the solar radiation and the ventilation of the confined installation space,which are inves-tigated in this study and simulated by FLUENT using the porous model and discrete ordinates (DO) radiation model.It is proved that the porous model is more reliable than the solid model.The optimal installation distance from the supporting wall is obtained.The average temperature of the exit without wind is 1.18% higher than that with wind.The results show that the heat released from the outdoor units and the ventilation of the confined in-stallation space are the main factors affecting the thermal environment in the confined installation space.The in-fluence of the solar radiation is negligible.
