Reference crop evapotranspiration (ETo) is essential for irrigation, water resources management and environmental assessment. The indirect estimation of ETo is based a) on energy budget approach using meteorological d...Reference crop evapotranspiration (ETo) is essential for irrigation, water resources management and environmental assessment. The indirect estimation of ETo is based a) on energy budget approach using meteorological data and b) pan evaporation measurements (Epan) multiplied by pan coefficients (kp) adapted to the surrounding environmental conditions. Significant interest is shown for the kp equations, which have to be tested before their use. The purpose of this study is to evaluate six different kp equations, such as those of Cuenca, Allen and Puitt, Snyder, Pereira et al., Orang, Raghuwanshi and Wallender for the summer growing season (April to October) of Thessaloniki plain in Greece, which is characterized by a semi-arid Mediterranean environment. The evaluation of the kp equations is performed by two years Epan measurements, using as reference the daily ETo values estimated by the ASCE-standardized Penman-Monteith equation (ASCE-PM) in hourly time step. The results of this study showed that Cuenca’s equation provided more accurate daily estimations. Additional analysis is performed in other methods such as those of FAO-56 and Hargreaves based on the calculation time step (hourly or daily) and their correspondence to the ASCE-PM.展开更多
The particle collision behavior and heat transfer performance are investigated to reveal the heat transfer enhancement and fouling prevention mechanism in a Na_(2)SO_(4) circulating fluidized bed evaporator.The partic...The particle collision behavior and heat transfer performance are investigated to reveal the heat transfer enhancement and fouling prevention mechanism in a Na_(2)SO_(4) circulating fluidized bed evaporator.The particle collision signals are analyzed with standard deviation by varying the amount of added particles ε(1%–3%),circulation flow velocity u(0.37–1.78 m·s^(-1)),and heat flux q(7.29–12.14 kW·m^(-2)).The results show that the enhancement factor reach up to 14.6%by adding polytetrafluoroethylene particles at ε=3%,u=1.78 m·s^(-1),and q=7.29 kW·m^(-2).Both the standard deviation of the particle collision signal and enhancement factor increase with the increase in the amount of added particles.The standard deviation increases with the increase in circulation flow velocity;however,the enhancement factor initially decreases and then increases.The standard deviation slightly decreases with the increase in heat flux at low circulation flow velocity,but initially increases and then decreases at high circulation flow velocity.The enhancement factor decreases with the increase in heat flux.The enhancement factor in Na_(2)SO_(4) solution is superior to that in water at high amount of added particles.The empirical correlation for heat transfer is established,and the model results agree well with the experimental data.展开更多
A high-performance liquid chromatographic method was applied to the determination of stachydrine hydrochloride concentration in TJF granule (Chinese name: Tiao-Jing-Fang), using a mobile phase of methanol-acetonitrile...A high-performance liquid chromatographic method was applied to the determination of stachydrine hydrochloride concentration in TJF granule (Chinese name: Tiao-Jing-Fang), using a mobile phase of methanol-acetonitrile (50:50, v/v) by the Agilent Kromasi NH2 column (250 mm × 4.6 mm, 5 μm, S/N: 22N25110). Detection wavelength was 201 nm. The result revealed good linearity of stachydrine hydrochloride and was obtained within the range of 0.20 - 1.98 μg/mL (R = 0.9995). The average recovery was 97.01%;the relative standard deviation (RSD) was 0.19%. To the best of our knowledge, this is the first report dedicated to the determination of stachydrine hydrochloride by the evaporative light scattering detector-high-performance liquid chromatographic (ELSD-HPLC) method.展开更多
文摘Reference crop evapotranspiration (ETo) is essential for irrigation, water resources management and environmental assessment. The indirect estimation of ETo is based a) on energy budget approach using meteorological data and b) pan evaporation measurements (Epan) multiplied by pan coefficients (kp) adapted to the surrounding environmental conditions. Significant interest is shown for the kp equations, which have to be tested before their use. The purpose of this study is to evaluate six different kp equations, such as those of Cuenca, Allen and Puitt, Snyder, Pereira et al., Orang, Raghuwanshi and Wallender for the summer growing season (April to October) of Thessaloniki plain in Greece, which is characterized by a semi-arid Mediterranean environment. The evaluation of the kp equations is performed by two years Epan measurements, using as reference the daily ETo values estimated by the ASCE-standardized Penman-Monteith equation (ASCE-PM) in hourly time step. The results of this study showed that Cuenca’s equation provided more accurate daily estimations. Additional analysis is performed in other methods such as those of FAO-56 and Hargreaves based on the calculation time step (hourly or daily) and their correspondence to the ASCE-PM.
基金This work is supported by the open foundation of State Key Laboratory of Chemical Engineering(SKL-ChE-18B03)the Municipal Science and Technology Commission of Tianjin,China under Contract No.2009ZCKFGX01900.
文摘The particle collision behavior and heat transfer performance are investigated to reveal the heat transfer enhancement and fouling prevention mechanism in a Na_(2)SO_(4) circulating fluidized bed evaporator.The particle collision signals are analyzed with standard deviation by varying the amount of added particles ε(1%–3%),circulation flow velocity u(0.37–1.78 m·s^(-1)),and heat flux q(7.29–12.14 kW·m^(-2)).The results show that the enhancement factor reach up to 14.6%by adding polytetrafluoroethylene particles at ε=3%,u=1.78 m·s^(-1),and q=7.29 kW·m^(-2).Both the standard deviation of the particle collision signal and enhancement factor increase with the increase in the amount of added particles.The standard deviation increases with the increase in circulation flow velocity;however,the enhancement factor initially decreases and then increases.The standard deviation slightly decreases with the increase in heat flux at low circulation flow velocity,but initially increases and then decreases at high circulation flow velocity.The enhancement factor decreases with the increase in heat flux.The enhancement factor in Na_(2)SO_(4) solution is superior to that in water at high amount of added particles.The empirical correlation for heat transfer is established,and the model results agree well with the experimental data.
文摘A high-performance liquid chromatographic method was applied to the determination of stachydrine hydrochloride concentration in TJF granule (Chinese name: Tiao-Jing-Fang), using a mobile phase of methanol-acetonitrile (50:50, v/v) by the Agilent Kromasi NH2 column (250 mm × 4.6 mm, 5 μm, S/N: 22N25110). Detection wavelength was 201 nm. The result revealed good linearity of stachydrine hydrochloride and was obtained within the range of 0.20 - 1.98 μg/mL (R = 0.9995). The average recovery was 97.01%;the relative standard deviation (RSD) was 0.19%. To the best of our knowledge, this is the first report dedicated to the determination of stachydrine hydrochloride by the evaporative light scattering detector-high-performance liquid chromatographic (ELSD-HPLC) method.
