Loading...

Numerical Modeling of Film Condensation in the Plate-Fin Heat Exchanger Used in the CO2 Capturing and Storage Process

Khorampoor, Nima | 2021

506 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53691 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Saeedi, Mohammad Hassan
  7. Abstract:
  8. Due to the wide application of plate-fin heat exchangers in various industries such as the petrochemical industry, aerospace industry, air conditioning systems, separation and liquefaction of gases, especially natural gas, boiling, condensation, and transportation industries, proper design of these heat exchangers is necessary. Most of the previous researches in the field of heat exchanger modeling has been done in single-phase mode. The two-phase modeling has been performed, often thermodynamically, and the effects of turbulence and surface tension have been ignored. Thus, in the present study, numerical modeling of the two-phase plate-fin heat exchanger is presented. In this project, modeling of film condensation in the annular flow pattern in a plate-fin heat exchanger will be presented. In this study, the effects of mass flux, gravity acceleration have been considered. This heat exchanger is used in the process of separation and storage of carbon dioxide, and its optimal design can have a significant impact on making this process more economical, and it further reduces power plant pollution. CFD modeling was performed using ANSYS Fluent simulation software in the presence of non-condensing gases. The working fluid consists of carbon dioxide, oxygen, nitrogen, and argon gases, which convert the carbon dioxide gas into the liquid. The mixture method is used to model two-phase flow and that the slip velocity between the phases will be considered. To model phase change, a model based on two-phase flow physics is used. The calculation of the diffusion coefficient of the species in the mixture is also done using a calculation code, based on the kinetic theory and Fick's law. In this study, the effect of mass flux, the mass percentage of non-condensable gases, and the angle of flow to the horizon have been evaluated. The results show that the performed CFD modeling will be able to be used with appropriate accuracy to simulate the film condensation process in the presence of non-condensable gases in the plate-fin heat exchanger. According to the results, by increasing the mass flux, the two-phase flow will be more inclined to the annular flow pattern. As the mass flux decreases from 80 kg/m2 s to 30 kg/m2 s, the flow pattern passes from the annular pattern to the wavy pattern. In cases where the mass flux of the stream is high and the flow is turbulent, the flow direction does not affect the rate of heat transfer. When the flow changes from horizontal to 45 ° and upward vertical, the pressure drop will be increased to 41.1% and 61%, respectively. Also, the results showed that by adding 10% to the mass fraction of carbon dioxide, the pressure drop was reduced to 39.4%, and the heat transfer coefficient was improved to 6.67%. In this case, the condensation rate of carbon dioxide is increased from 17.82% for the initial state to 22.46%
  9. Keywords:
  10. Carbon Dioxide Separation ; Computational Fluid Dynamics (CFD) ; Plate-Fine Heat Exchange ; Two-Phase Flow Modeling ; Gasphase Condensation ; Film Condensation

 Digital Object List

 Bookmark

No TOC