Abstract:
With the increasing demand of high performance electronic devices, computer systems,
integrated circuits (Ie) and microchips, the power densities in the electronic systems
are increasing rapidly. Packaging and thermal management of electric equipments have
become an important problem because of the increased power level and simultaneous
miniaturization of the devices. It is very important to facilitate optimum cooling of
electronic components in an electronic device because integrated circuit lifetime
depends on it. An increasing market demand on powerful gadgets in smaller and
smaller cabinets creates a trade off situation: either to enlarge the package to accept
additional cooling or to sacrifice Ie lifetime. This is a great challenge in thermal design
management. Among other cooling techniques heat pipe emerges a very effective and
appropriate technology, also cost effective thermal design solution because of its
excellent heat transfer capability, high efficiency and its structural simplicity. Thus
application of heat pipe has expended gradually. Due to the space constraint in most of
the personal computers and telecommunication devices, the size of heat pipes has to be
carefully decided. So investigations on heat pipes are indispensable for further
development and improvement of its performance.
This experimental study has been performed to investigate the heat transfer
. characteristics of looped parallel micro heat pipe (LPMHP). LPMHP consists of two
single tube micro heat pipes of circular geometry having inner diameter of 1.8 mm and
length of 150 mm placed parallel, connected by two U tubes of same diameter at the
top and bottom ends. The experimental parameters are condenser inclination angle, heat
input and properties of the working fluid. Taking acetone and ethanol as working
fluids, heat transfer characteristics are determined experimentally for different
condenser inclination angles at different heat inputs.
An analysis of the experimental data gives the following results: Condenser
inclination angle has a very little effect on the performance of LPMHP. Better
performance is found for the vertical position of condenser. Heat input has significant
effect on the performance of LPMHP. It is found that overall heat transfer coefficient is
higher for higher heat input. Finally, it is observed that for the same heat input and
condenser inclination angle LPMHP with acetone as working fluid performs better.
An empirical correlation has also been developed which correlates all the
experimental data within approximately "= 15% error.
