Abstract
An advanced mathematical model of flow and heat transfer in an oscillating heat pipe (OHP) is proposed. The capillary and gravitational forces are included in the momentum equation of the liquid slug. Detailed numerical simulation is carried out to investigate the surface tension and gravity effects on the oscillatory flow and heat transfer in an OHP with different inner diameters and orientations. The results show that gravity effect hinders the performance of top heat mode OHP while aids the operation of bottom heat mode OHP. Comparisons between the cases with surface tension and without surface tension indicate that the effects of surface tension on the performance of OHP are negligible even for small inner diameter. The effect of inclination angle on the performance of OHP is investigated.
Highlights
The increased demanding on high performance required by the IT industry has raised thermal design challenges due to both increased heat dissipation from the CPU and higher heat density
While conventional heat sinks or spreaders become severely inadequate at these high levels of heat fluxes, Oscillating Heat Pipe (OHP or PHP) shows promise to meet the generation CPU thermal requirements with a low profile heat sink
The results showed that the heat transfer in an oscillating heat pipe (OHP) is mainly due to the exchange of sensible heat and phasechange heat transfer is the driving force of the oscillation
Summary
The increased demanding on high performance required by the IT industry has raised thermal design challenges due to both increased heat dissipation from the CPU and higher heat density. Dobson and Harms (1999) developed a simple mathematical model to study the behavior of an OHP with an open-end. They assumed the heat transfer coefficients between heated pipe wall and the vapor and neglected the effect of surface tension and heat transfer between the liquid and its surroundings. Hosoda et al (1999) investigated the formation of vapor plugs in a meandering closed loop heat transport device (MCL-HTD) with a simplified numerical model neglecting liquid film between the tube wall and the vapor plug and the effect of surface tension. It was demonstrated that the initial temperature has a very profound effect in oscillating motion and heat transfer performance
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