Push-pull ventilation systems provide excellent control of contaminants and harmful gases.However,since both a push inlet and a pull outlet are used in the push-pull ventilation system,the flow rate required by the sy...Push-pull ventilation systems provide excellent control of contaminants and harmful gases.However,since both a push inlet and a pull outlet are used in the push-pull ventilation system,the flow rate required by the system is large.In that case,the energy consumption of the system is large.The purpose of this paper is to study the flow field and economic characteristics of a parallel push-pull ventilation system by reducing the flow rate of the exhaust outlet,which will be achieved by reducing the size of the exhaust hood.The three commonly used push-pull ventilation systems were analyzed:a high velocity push-pull system with high air supply velocity,a low velocity push-pull system with wide airflow and small velocity,and a parallel push-pull system with wide airflow and uniform air supply velocity.Results showed that the parallel push-pull ventilation system was the only one in which the flow rate of the exhaust outlet could be reduced,reducing the overall energy consumption.Under conditions of the parallel air supply jet,the diffusion range of contaminants in the push-pull flow field was the smallest and reducing the exhaust air flow rate did not affect the capture efficiency of pollutants.These results may be useful in guiding the design of push-pull ventilation system and optimize economic constraints.展开更多
The seeds of wheat and the young roots of rice were treated with SU15-C-5 and B15-C-5.The effects of crown ether on economic characters of the spike and some physiological properties in both crops were studied.The res...The seeds of wheat and the young roots of rice were treated with SU15-C-5 and B15-C-5.The effects of crown ether on economic characters of the spike and some physiological properties in both crops were studied.The results showed that crown ethers could promote the growth of wheat seedling, improve the contents of chlorophyll (a+b), reduce the ratio of chlorophyll a to b in the leaves of rice,thus bring about good effects of economic characters of the spike. Especially, it suggests that SU15-C-5 showed better physiological effects than B15-C-5.展开更多
文摘Push-pull ventilation systems provide excellent control of contaminants and harmful gases.However,since both a push inlet and a pull outlet are used in the push-pull ventilation system,the flow rate required by the system is large.In that case,the energy consumption of the system is large.The purpose of this paper is to study the flow field and economic characteristics of a parallel push-pull ventilation system by reducing the flow rate of the exhaust outlet,which will be achieved by reducing the size of the exhaust hood.The three commonly used push-pull ventilation systems were analyzed:a high velocity push-pull system with high air supply velocity,a low velocity push-pull system with wide airflow and small velocity,and a parallel push-pull system with wide airflow and uniform air supply velocity.Results showed that the parallel push-pull ventilation system was the only one in which the flow rate of the exhaust outlet could be reduced,reducing the overall energy consumption.Under conditions of the parallel air supply jet,the diffusion range of contaminants in the push-pull flow field was the smallest and reducing the exhaust air flow rate did not affect the capture efficiency of pollutants.These results may be useful in guiding the design of push-pull ventilation system and optimize economic constraints.
文摘The seeds of wheat and the young roots of rice were treated with SU15-C-5 and B15-C-5.The effects of crown ether on economic characters of the spike and some physiological properties in both crops were studied.The results showed that crown ethers could promote the growth of wheat seedling, improve the contents of chlorophyll (a+b), reduce the ratio of chlorophyll a to b in the leaves of rice,thus bring about good effects of economic characters of the spike. Especially, it suggests that SU15-C-5 showed better physiological effects than B15-C-5.
