基于系统行为过程的效能概念框架及度量方法,建立了系统目标树的层级模型以及反映系统内、外因素行为关联关系的系统贡献度模型,根据该模型推导出了一组系统效能指数和效能因子的计算公式,通过对系统内外因素状态变化对系统效能贡献度...基于系统行为过程的效能概念框架及度量方法,建立了系统目标树的层级模型以及反映系统内、外因素行为关联关系的系统贡献度模型,根据该模型推导出了一组系统效能指数和效能因子的计算公式,通过对系统内外因素状态变化对系统效能贡献度影响的过程分析计算,验证了所建立的模型和方法的合理性.所给出的通过系统行为贡献度模型求解系统效能指数和效能因子的方法.可以简称为贡献度模型法,或SEIF(System effectiveness index and factor)法,适用于对系统效能变化规律的分析和实际运行效能的量化评估.展开更多
The present work aims to investigate the influence of extended surfaces(fins)on the multi-objective optimization of a tubular heat exchanger network(THEN).An increase in the heat transfer area using various extended s...The present work aims to investigate the influence of extended surfaces(fins)on the multi-objective optimization of a tubular heat exchanger network(THEN).An increase in the heat transfer area using various extended surfaces(fins)to enhance the performance of the heat exchanger was used while considering the effectiveness and total heat transfer area as two objective functions.In addition to the simulation of simple fins,a new set of fins,called constructal fins,was designed based on the constructal theory.Tubular heat exchanger network design parameters were chosen as optimization variables,and optimization results were achieved in such a way as to enhance the effectiveness and decrease the total heat transfer area.The results show the importance of constructal fins in improving the objective functions of heat exchangers.For instance,the simple fins case enhances the effectiveness by up to 5.3%compared to that without fins(usual heat exchanger)while using constructal fins,in addition to the 7%increment of effectiveness,reduces the total heat transfer area by 9.47%.In order to optimize the heat exchanger,the heat transfer rate and cold fluid temperature must increase,and at the same time,the hot exiting fluid temperature should decrease at the same constant total heat transfer area,which is higher in the constructal fins case.Finally,optimized design variables were studied for different cases,and the effects of various fins were reported.展开更多
文摘基于系统行为过程的效能概念框架及度量方法,建立了系统目标树的层级模型以及反映系统内、外因素行为关联关系的系统贡献度模型,根据该模型推导出了一组系统效能指数和效能因子的计算公式,通过对系统内外因素状态变化对系统效能贡献度影响的过程分析计算,验证了所建立的模型和方法的合理性.所给出的通过系统行为贡献度模型求解系统效能指数和效能因子的方法.可以简称为贡献度模型法,或SEIF(System effectiveness index and factor)法,适用于对系统效能变化规律的分析和实际运行效能的量化评估.
文摘The present work aims to investigate the influence of extended surfaces(fins)on the multi-objective optimization of a tubular heat exchanger network(THEN).An increase in the heat transfer area using various extended surfaces(fins)to enhance the performance of the heat exchanger was used while considering the effectiveness and total heat transfer area as two objective functions.In addition to the simulation of simple fins,a new set of fins,called constructal fins,was designed based on the constructal theory.Tubular heat exchanger network design parameters were chosen as optimization variables,and optimization results were achieved in such a way as to enhance the effectiveness and decrease the total heat transfer area.The results show the importance of constructal fins in improving the objective functions of heat exchangers.For instance,the simple fins case enhances the effectiveness by up to 5.3%compared to that without fins(usual heat exchanger)while using constructal fins,in addition to the 7%increment of effectiveness,reduces the total heat transfer area by 9.47%.In order to optimize the heat exchanger,the heat transfer rate and cold fluid temperature must increase,and at the same time,the hot exiting fluid temperature should decrease at the same constant total heat transfer area,which is higher in the constructal fins case.Finally,optimized design variables were studied for different cases,and the effects of various fins were reported.
