多股流板翅式换热器的传热温差场优化研究

发布时间：2018-12-26 07:54

【摘要】：板翅式换热器是一种高效紧凑型换热器,被广泛应用于石油化工、气体分离和天然气液化等工业中。与两股流换热器相比,多股流板翅式换热器内流体介质多,结构和换热过程更为复杂,各通道内不同流体的速度场以及温差场相互影响、相互协同,众多因素使多股流板翅式换热器的性能研究与优化变得十分困难。本文以混合工质天然气液化流程中的板翅式换热器内多股流换热过程作为研究对象,通过Aspen plus模拟对比完全协同换热和独立换热两种换热模式的换热集成曲线,结果表明独立换热无法满足换热工艺要求。对完全协同换热和独立换热过程进行?分析,结果表明独立换热?损是协同换热?损的十倍以上,协同换热的?效率达到92.82%,但是几种不同流量比例下的独立换热的?效率在45%左右,说明完全协同换热可以减小?损以及增强多股流换热过程的?效率。为了研究通道排列对板翅式换热器换热性能的影响,使用板翅式换热器设计软件Aspen Muse模拟比较几种不同的通道排列对应的多股流换热过程的zigzag图,根据此图评估各通道排列的优劣。模拟过程中发现Aspen Muse软件存在一定局限性,因此本文对多股流板翅式换热器建立模型,调用Aspen Plus的混合工质物性数据库,使用VBA编制程序。选择Chen公式计算沸腾换热系数,Shah公式计算冷凝换热系数。利用模拟软件对天然气液化过程中的多股流换热过程进行计算,对比分析复叠布置的相邻冷流的协同性对整个换热过程的影响。改变相邻冷流之间的换热热阻,对换热温差场进行分析,结果表明若计算过程不考虑相邻冷流之间的协同作用,换热过程将无法进行,相邻冷流间协同性越好,多股流换热的换热量越大,换热效果越好。说明相邻冷流之间的协同作用对整个多股流换热过程十分重要。因此在多股流板翅式换热器的设计中,相邻冷流之间协同换热的影响应计入其中。
[Abstract]:Plate-fin heat exchanger is an efficient compact heat exchanger, which is widely used in petrochemical, gas separation and natural gas liquefaction industries. Compared with the two flow heat exchangers, the multi-flow plate-fin heat exchanger has more fluid media, more complicated structure and heat transfer process, and the velocity field and temperature difference field of different fluid in each channel interact with each other and cooperate with each other. Many factors make it difficult to study and optimize the performance of multi-flow plate-fin heat exchanger. In this paper, the heat transfer process of plate-fin heat exchanger in plate-fin heat exchanger with mixed working fluid is taken as the research object, and the heat transfer integration curves of two kinds of heat transfer modes are compared by Aspen plus simulation. The results show that independent heat transfer can not meet the requirements of heat transfer process. For fully coordinated heat transfer and independent heat transfer processes? The results show that the heat transfer is independent. Damage is coordinated heat transfer? More than ten times the damage, synergistic heat transfer? The efficiency reaches 92.82%, but how many different flow ratios are independent heat transfer? The efficiency is about 45%, which indicates that the total synergistic heat transfer can be reduced. Loss and enhancement of multistream heat transfer processes? Efficiency. In order to study the influence of channel alignment on the heat transfer performance of plate-fin heat exchanger, the zigzag diagrams of several different channel arrangement corresponding to the heat transfer process of multi-strand flow were simulated and compared by using the plate-fin heat exchanger design software Aspen Muse. According to this figure, the channel arrangement is evaluated. In the process of simulation, it is found that the Aspen Muse software has some limitations, so this paper establishes a model for the multi-strand flow plate-fin heat exchanger, calls the mixed working fluid physical property database of Aspen Plus, and uses VBA to compile the program. Chen formula is used to calculate boiling heat transfer coefficient and Shah formula to calculate condensation heat transfer coefficient. The simulation software was used to calculate the heat transfer process of multi-stream flow in the process of natural gas liquefaction, and the effect of the superimposed adjacent cold flow on the whole heat transfer process was compared and analyzed. By changing the heat transfer resistance between adjacent cold flows and analyzing the heat transfer temperature difference field, the results show that if the synergy between adjacent cold flows is not taken into account in the calculation process, the heat transfer process will not be carried out, and the better the synergy between adjacent cold flows is, The larger the heat transfer of multi-strand flow, the better the heat transfer effect. It shows that the synergy between adjacent cold flows is very important for the whole heat transfer process of multi-stream flow. Therefore, in the design of multi-stream plate-fin heat exchangers, the effect of coordinated heat transfer between adjacent cold flows should be included.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK172

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