A SENSIBILITY STUDY OF PIPE DESIGN PARAMETERS FOR A FORCED CONVECTIVE BOILING TWO-PHASE FLOW

Open Access
Author:
Larimer, Nicholas
Area of Honors:
Mechanical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Matthew J Rau, Thesis Supervisor
  • Hosam Kadry Fathy, Honors Advisor
Keywords:
  • fluids
  • heat transfer
  • two-phase flow
  • convective boiling
  • pipe flow
  • homogeneous equilibrium model
  • variable area pipe
Abstract:
Understanding the fluid dynamics of a two-phase pipe flow is critical to piping system designers in a variety of industries. Specifically, with the drastic increase in computer chip technology over the past few decades, more efficient chip cooling systems are in high demand. An efficient cooling mechanism for a computer chip will remove as much heat from the chip as possible without drastically increasing the required pumping power. In an attempt to find a solution to this problem, a study of the effect of varying the cross-sectional area of a pipe was conducted and was compared to a pipe of constant diameter. The pipe was divided into small segments so that vapor quality could be calculated as a function of axial distance. Homogeneous equilibrium model equations and two-phase heat transfer equations were then used to calculate the total pressure drop and average heat transfer coefficient for an assortment of input pipe parameters. A parametric design study was performed to find the best pipe design using input parameter ranges representative of an electronics cooling application. The parametric design study found that for reasonable input pipe parameters, a straight pipe with no expansion angle was the best design. However, when the heat input was increased, the study found that a pipe with a small nonzero expansion angle resulted in a lower pressure drop and an overall more efficient design. Furthermore, when the heat input was increased more, the expansion angle for the best pipe design continued to increase. This study illustrates that as vapor generation rates within piping systems become large, pipes with variable cross-sectional areas can yield increases in cooling efficiency.