Public Abstract
First Name:Shimin
Middle Name:
Last Name:Wang
Adviser's First Name:James
Adviser's Last Name:Bryan
Co-Adviser's First Name:
Co-Adviser's Last Name:
Graduation Term:SP 2009
Department:Mechanical & Aerospace Engineering
Degree:PhD
Title:MODELING TOOLS AND PROTOTYPE DESIGN OF LOOP HEAT PIPE FOR ELECTRONICS
COOLING
In this dissertation, a set of modeling tools for loop heat pipe (LHP) design is developed, and original
analytical models for annular two-phase flow are proposed.
LHPs are promising two-phase thermal transport devices for electronics cooling. The developed modeling
tools include a system level model, criteria of selecting working fluids, and individual component models for
modularized design of LHP condenser and evaporator. Based on these tools, new figures of merit for
measuring capillary limit and heat leak effects are defined, the condensation pressure drop is shown to be
always dominating the loop pressure drop in air-cooled LHPs, and a published LHP prototype for laptop
computer cooling is simulated. The modeling results agree well with the available experimental data and
reveal that the air flow is the bottleneck of this prototype.
The analytical models for annular two-phase flow presented in this work is fundamentally different from the
previous two-phase flow models in that both the velocity and temperature distributions for the liquid and
gas/vapor phases are represented based on the governing equations for laminar flows and based on the
universal profiles for turbulent flows. As a result, analytical relations of void fraction, frictional pressure
gradient, acceleration pressure gradient, and heat transfer coefficient for all possible flow regimes are
derived on a self-contained and self-consistent basis, with the classical single-phase relations as their
extreme limits. Detailed comparison with the modeling results shows that the prevailing empirical
correlations in engineering practice generally fail to provide reliable and accurate predictions for annular
two-phase flows.