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Solidification of Fluid Inside the Pipeline to Fix or Replace the Defective Component

Taheri, Mohammad Ali | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 47667 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Saeedi, Mohammad Hassan
  7. Abstract:
  8. Pipe freezing has become well established in industry as a method of short-termisolation in order to carry out maintenance or repairs. It is often necessary to repair system components without plant shutdown or drainage of system having many piping structures which may have hazardous or expensive fluid. Therefore, a series of tests has been arranged to investigate the ice plug formation in two standard pipes with different diameter size. The freeze zone on the pipe has been created by means of an aluminum jacket which liquid nitrogen flows in it. In the tests the freezing time, amount of liquid nitrogen usage andthe pressure tolerance of ice plug have been determined. Moreover, the numerical simulation of freezing process in two and three dimension has been carried out to establish a solution method to determine the freezing time in other cases. To verify the numerical solution a comparison has been conducted between simulation and experimental results. The maximum differences between 2D and 3D result of freezing time with experiment are 11.8% and 2.9% respectively. Consequently, the effect of pipe diameter and liquid material on freezing time has been accomplished through two dimensional modeling due to the well prediction of 2D solution and its high convergence rate. The results show the freezing time grows exponentially with increase of pipe diameter
  9. Keywords:
  10. Solidification Time ; Two Dimentional Modeling ; Three Dimensional Modeling ; Ice Formation ; Numerical Modeling

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  • 1 Chapter One: Introduction
    • 1.1 Literature review
    • 1.2 Ice Adhesion to Material surface
    • 1.3 Industrial applications
  • 2 Chapter Two: Theory
    • 2.1 Heat transfer during pipe freezing
    • 2.2 Phase-Change Problems
      • 2.2.1 Mathematical formulation of phase-change problems [17]
        • 2.2.1.1 Effects of Density Change
      • 2.2.2 Generalization to Multidimension
      • 2.2.3 Dimensionless Variables of Phase-Change Problem
      • 2.2.4 Variable time step method for solving phase change problems: A numerical solution
      • 2.2.5 Enthalpy method for solution of phase-change problems
    • 2.3 The Properties of Nitrogen
    • 2.4 The Structure of Ice
    • 2.5 Regelation
    • 2.6 The Production of Clear Ice
    • 2.7 The effect of relative expansion between the ice and the pipe
  • 3 Chapter Three: Numerical Modeling
    • 3.1 Problem Definition
    • 3.2 Geometry
    • 3.3 Problem setup
    • 3.4 Governing Equations
      • 3.4.1 One Dimensional Equation
    • 3.5 Solution Method
      • 3.5.1 Fixed-Grid Methods
        • 3.5.1.1 Interface Conditions
        • 3.5.1.2 Determination of Time Steps
        • 3.5.1.3 Implicit enthalpy method for solidification at a single phase-change temperature
    • 3.6 Three Dimensional Modeling
      • 3.6.1 Energy Equation
  • 4 Chapter Four: Experimental Investigation
    • 4.1 Experimental Setup
      • 4.1.1 Test apparatus
    • 4.2 Experimentation 1: Freezing of Water in 2 inch Pipe
      • 4.2.1 Results and Discussion
    • 4.3 Experiments 2: Freezing of Water in 4 inch Pipe
    • 4.4 Experiments 3: Freezing of Diesel Fuel
  • 5 Chapter Five: Results and Discussion
    • 5.1 Numerical Results Validation
    • 5.2 Two Dimensional Modeling
    • 5.3 Three Dimensional Modeling
  • 6 Chapter Six: Conclusion and Proposal for Future Works
    • 6.1 Proposals for Future Work
  • 7 References
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