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Numerical simulation of a buried hot crude oil pipeline during shutdown 被引量:7
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作者 Xu Cheng Yu Bo +3 位作者 Zhang Zhengwei Zhang Jinjun Wei Jinjia Sun Shuyu 《Petroleum Science》 SCIE CAS CSCD 2010年第1期73-82,共10页
In this paper a mathematical model is built for a buried hot crude oil pipeline during shutdown, and an unstructured grid and polar coordinate grid are respectively applied to generating grids for the soil region and ... In this paper a mathematical model is built for a buried hot crude oil pipeline during shutdown, and an unstructured grid and polar coordinate grid are respectively applied to generating grids for the soil region and the three layers in the pipe (wax layer, pipe wall, and corrosion-inhibiting coating). The governing equations are discretized using the finite volume method. The variations in temperatures of static oil and soil were investigated during pipeline shutdown in both summer and winter, in which some important parameters of the soil and crude oils of a Northeast pipeline are employed. 展开更多
关键词 Moving boundary stagnation point equivalent thermal conductivity thermal influence region unstructured grid
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Ammonia volatilization losses and ^(15)N balance from urea applied to rice on a paddy soil 被引量:10
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作者 FAN Xiao-hui SONG Yong-sheng +2 位作者 LIN De-xi YANG Lin-zhang LUO Jia-fa 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2006年第2期299-303,共5页
Ammonia volatilization loss and ^15N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH4^... Ammonia volatilization loss and ^15N balance were studied in a rice field at three different stages after urea application in Taihu Lake area with a micrometeorological technique. Factors such as climate and the NH4^+-N concentration in the field floodwater affecting ammonia loss were also investigated. Results show that the ammonia loss by volatilization accounted for 18.6%-38.7% of urea applied at different stages, the greatest loss took place when urea was applied at the tillering stage, the smallest at the ear bearing stage, and the intermediate loss at the basal stage. The greatest loss took place within 7 d following the fertilizer application. Ammonia volatilization losses at three fertilization stages were significantly correlated with the ammonium concentration in the field floodwater after the fertilizer was applied. ^15N balance experiment indicated that the use efficiency of urea by rice plants ranged between 24.4% and 28.1%. At the early stage of rice growth, the fertilizer nitrogen use efficiency was rather low, only about 12%. The total amount of nitrogen lost from different fertilization stages in the rice field was 44.1%-54.4%, and the ammonia volatilization loss was 25.4%-33.3%. Reducing ammonia loss is an important treatment for improving N use efficiency. 展开更多
关键词 ammonia volatilization UREA ^15N balance RICE influence factors Taihu region
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