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A thermal design method for the performance optimization of multi-stream plate-fin heat exchangers
Zhe Wang,Fenghui Han,Bengt Sundén,Yanzhong Li 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6
An optimization design method based on field synergy principle is developed for Multi-stream plate-fin heat exchangers (MPHEs)with a segmented differential model. The heat exchanger is divided into a number of sub-exchangers along the main stream, and eachsub-exchanger consists of N passages along the height of the exchanger. Compared with the traditional heat exchanger design, this methodallows temperature and pressure fields to be obtained via coupling calculation with consideration of variable physical properties andthe axial heat loss of the heat exchanger. Finally, the heat exchanger is optimally designed using a temperature-difference uniformityoptimization factor based on field synergy principle. This design model can provide an accurate temperature field and pressure field,because the stream properties are determined by the mean temperature and pressure of each local sub-exchanger. Optimum results indicatethat the temperature distribution on the cross section of the heat exchanger is relatively uniform and that the temperature differenceof heat transfer for each stream is always a small value. These characteristics prove the feasibility and effectiveness of this design model. In this paper, a case of five stream plate-fin heat exchangers for an ethylene plant is designed under a practical cold box operating conditionwith the proposed model, the structure and heat transfer of which are optimally determined. The design model and optimizationmethod proposed in this work can provide theoretical and technical support to the optimization design of MPHEs.
Effect of External Heat Input on Fluid Sloshing Dynamic Performance in a Liquid Oxygen Tank
Liu Zhan,Feng Yuyang,Liu Yuanliang,Yan Jia,Li Yanzhong 한국항공우주학회 2020 International Journal of Aeronautical and Space Sc Vol.21 No.4
In the present study, a numerical model is developed to research the effect of the heat input on fluid sloshing. The volume of fluid method is used to simulate fluid reciprocating motion during sloshing with the mesh motion treatment being coupled. The external sloshing excitation is realized by user-defined functions and the convection thermal boundary condition is adopted to consider the heat exchange between the tank and the external environment. The model validation is made with the relative error being less than five percent. Based on the developed numerical model, the variation of fluid pressure, interface fluctuation, fluid sloshing hydrodynamics and fluid temperature distribution are, respectively, analyzed. Some conclusions are obtained finally. The present study is significant to the fluid sloshing suppression in cryogenic fuel storage tanks.