Abstract:
Thermoloop, a kind of pulsated two-phase thermosyphon (PTPT), is a device with a
promise of dealing with very high heat flux requirements for electronics cooling. It
comprises of three main components: evaporator, condenser and a liquid reservoir. In
the present study, the thermal performance of the thermo loop has been studied to
address some issues on design and heat transfer performance both experimentally and
analytically. These issues include variations in thermal load, evaporator fill ratio and
condenser convection condition of thermo Ioop.
Outside dimension of the two evaporators employed in the test were 72.5 mm x 60
mm x 20 mm for Prototype-I and 77 mm x 65 mm x 8 mm for Prototype-2 with
inside volumes of 75 cm3 and 30 cm3
, respectively. Same reservoir was used for the
two prototypes with a liquid storage capacity of 80 cm3• Most of the studies were
conducted with prototype- I using water as the working fluid.
For thermal load variation from 100 W to 250 W, the maximum temperature of the
evaporator wall increased from 106°C to 1120C and minimum temperature of
evaporator wall increased from 730C to 950C at an evaporator fill ratio of 30%. The
values of other functional parameter such as cycle time, height of liquid column in the
reservoir and condenser temperature also increased with an increase in thermal load.
At a constant heat load and for the same working fluid, the effect of liquid fill ratio on
the maximum temperature of the evaporator wall and on cycle time appeared to be
insignificant. The addition offan to cool the condenser increased the operational limit
of the device from 125 W to 275 W. Further, the various functional parameters of the
thermoloop attained a steady value after 5 to 6 heat transport cycles.
In the analytical part, a simple mathematical model on the thermo loop heat transfer
concept is developed based on the hydrodynamics and heat transfer to have a better
understanding of the physics involved, which needs to be tested or verified by the
experimental data.
