研究了微肋管内R407C和R22的流动沸腾换热特性,采用威尔逊图解法对实验数据进行处理,主要分析实验工况、制冷剂物性、微肋管结构等变量的影响。结果表明:制冷剂R407C与R22与换热壁面之间的换热热阻均随热流密度、质流密度、干度、肋片...研究了微肋管内R407C和R22的流动沸腾换热特性,采用威尔逊图解法对实验数据进行处理,主要分析实验工况、制冷剂物性、微肋管结构等变量的影响。结果表明:制冷剂R407C与R22与换热壁面之间的换热热阻均随热流密度、质流密度、干度、肋片螺旋角等的增加而减小;由于制冷剂气液相密度比的差异性,R22传热系数比与R407C的高约18.5%—21.4%。选用关联式对微肋管内R407C流动沸腾换热特性进行预测评估,并对关联式预测精度随干度、质流密度等的变化趋势进行分析。在所选关联式内,Yu and Koyama关联式表现出最佳预测效果,其平均预测误差在±6.5%以内,且干度、质流密度对其预测精度的影响相近;而对于其它关联式,干度对关联式预测精度的影响比重普遍高于质流密度。展开更多
In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the prop...In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.展开更多
The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1?9 detail signals and th...The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1?9 detail signals and the 9th scale approximation signals. The pressure signals were studied by multi-scale and R/S analysis method. Hurst analysis method was applied to analyze multi-fractal characteristics of different scale signals. The results show that the characteristics of mono-fractal under scale 1 and scale 2, and bi-fractal under scale 3?9 are effective in deducing the hydrodynamics in slurry bubbling flow system. The measured pressure signals are decomposed to micro-scale signals, meso-scale signals and macro-scale signals. Micro-scale and macro-scale signals are of mono-fractal characteristics, and meso-scale signals are of bi-fractal characteristics. By analyzing energy distribution of different scale signals,it is shown that pressure fluctuations mainly reflects meso-scale interaction between the particles and the bubble.展开更多
文摘研究了微肋管内R407C和R22的流动沸腾换热特性,采用威尔逊图解法对实验数据进行处理,主要分析实验工况、制冷剂物性、微肋管结构等变量的影响。结果表明:制冷剂R407C与R22与换热壁面之间的换热热阻均随热流密度、质流密度、干度、肋片螺旋角等的增加而减小;由于制冷剂气液相密度比的差异性,R22传热系数比与R407C的高约18.5%—21.4%。选用关联式对微肋管内R407C流动沸腾换热特性进行预测评估,并对关联式预测精度随干度、质流密度等的变化趋势进行分析。在所选关联式内,Yu and Koyama关联式表现出最佳预测效果,其平均预测误差在±6.5%以内,且干度、质流密度对其预测精度的影响相近;而对于其它关联式,干度对关联式预测精度的影响比重普遍高于质流密度。
基金Supported by the National Basic Research Program of China(2012CB720500)the National Supporting Research Program of China(2013BAA03B01)+1 种基金the National Natural Science Foundation of China(21176178)China Scholarship Council(CSC[2015]3022)
文摘In our previous work, the reactive dividing wall column(RDWC) was proposed and proved to be effective for selective hydrogenation and separation of C3 stream. In the present paper, the dynamics and control of the proposed RDWC are investigated. Four control structures including composition and temperature controls are proposed. The feed forward controllers are employed in the four control strategies to shorten the dynamic response time, reduce the maximum deviations and offer an immediate adjustment. The control structures are compared by applying them into the RDWC system with 20% disturbances in both the feed flow rate and the feed compositions, and the results are discussed.
基金Project(NCET-05-0413)support by the Program for New Century Excellent Talents in UniversityProject(YB0142112) support by Priming Foundation of East China University of Science and Technology
文摘The Daubechies second order wavelet was applied to decompose pressure fluctuation signals with the gas flux varying from 0.18 to 0.90 m3/h and the solid mass fraction from 0 to 20% and scales 1?9 detail signals and the 9th scale approximation signals. The pressure signals were studied by multi-scale and R/S analysis method. Hurst analysis method was applied to analyze multi-fractal characteristics of different scale signals. The results show that the characteristics of mono-fractal under scale 1 and scale 2, and bi-fractal under scale 3?9 are effective in deducing the hydrodynamics in slurry bubbling flow system. The measured pressure signals are decomposed to micro-scale signals, meso-scale signals and macro-scale signals. Micro-scale and macro-scale signals are of mono-fractal characteristics, and meso-scale signals are of bi-fractal characteristics. By analyzing energy distribution of different scale signals,it is shown that pressure fluctuations mainly reflects meso-scale interaction between the particles and the bubble.
