2003
GSTC
Graduate Student Thesis Abstracts
University
of Alaska Fairbanks - Department
of Mechanical Engineering
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| LINK | TITLE | STUDENT | EMAIL | ADVISOR |
| Abstract | Heat
Transfer Models for Designing Cooling Systems for Electronic Chips | Devdatta
Kulkarni | ftdpk@uaf.edu | Debendra
K. Das | | Abstract | Simulations
of Vehicle/Tire Ground Interface using Simulink | Prasanna
Saitana | ftdps@uaf.edu | C.S.Lin |
| Heat
Transfer Models for Designing Cooling Systems for Electronic Chips | Devdatta
Kulkarni | ftdpk@uaf.edu | Debendra
K. Das | | ABSTRACT |
| Now
a days a great deal of research is being undertaken for proper cooling of micro
electronic components for efficient operation. The new generation high performance
microprocessors will generate large amount of heat and will require proper heat
sink design to cool them. As a preliminary model, we have adopted as a design
case, an Intel Pentium III chip to develop necessary equations. For this unit,
we have developed, conduction, convection and radiation equations for heat transfer
from the chip to the heat sink and eventually to the surrounding air and we found
that heat dissipated from the aluminum heat sink varied from 14 W to 43 W, based
upon different modes of airflow over the fins. The manufacturer reports that this
chip generates 23 W of heat. Considering different emissivities of heat sink surfaces,
we calculated the radiative heat transfer to vary from 0.5 W to 8 W. The radiative
heat loss was found to be 2% of total heat dissipation from the present aluminum
heat sink, but could be increased to nearly 34% of total heat dissipation with
a paint of high emissivity of the order of 0.98. We also performed transient heat
transfer analysis to determine how long does it take to attain the steady state
temperature for the processor and the heat sink from the time the unit is switched
on. Our calculations showed that 4 seconds were required for microprocessor chip
and 48 minutes were required for the heat sink to attain the steady state temperature
of 620C. Next, we refined our analytical convection analysis using the computational
fluid dynamics code FLUENT to obtain accurate velocity fields over the fins. Using
these improved velocities, convective heat transfer coefficients were computed
and convection results showed 16 W to 47 W of heat dissipation. |
| Simulations
of Vehicle/Tire Ground Interface using Simulink | Prasanna
Saitana | ftdps@uaf.edu | C.S.Lin |
| ABSTRACT |
| This
research involves the study of the interfaces between tire and ground, and also
between tires and a vehicle body. The tire (unsprung mass) is considered as an
elastic body, attached to a rigid body (sprung mass) equipped with independent
passive linear suspension systems. This vehicle body has seven degrees of freedom,
and this vehicle is studied on grounds, which include hardened snow, and regular
paved road surfaces. The tire ground interface study includes the effects of tire
slip and cornering on all the interface forces and moments, which consist of friction/traction
force, lateral force and aligning moment. The tire parameters are refined from
the finite element analysis data using curve fitting methods. The necessary empirical
equations are derived and studied. This vehicle is modeled in Simulink, a dynamic
system simulation software. The results of this vehicle behavior will be presented. |
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