3D transient model of vapour chamber: Effect of nanofluids on its performance

This paper presents three-dimensional transient model for vapour chamber (flat heat pipe) and the effect of nanofluids on its performance. The vapour chamber consists of two copper plates, two copper/water wick regions and a vapour region sandwiched between the two wick regions. The numerical model consists of 3D transient thermal model coupled with a 3D transient hydrodynamic model. The 3D transient model takes into consideration the return liquid between the two wick regions. An implicit finite difference method is used to solve the numerical model and the numerical model is validated by an experimental work. The effect of Cu, CuO and Al2O3 nanofluids on the vapour chamber performance is investigated for different wick porosities. Three volume fractions of nanoparticles added to the working fluid of the vapour chamber 0.03%, 0.06% and 0.09% are used in the study. A good agreement is found between the results of the numerical and experimental work and the numerical results illustrate well the heat transfer and the fluid flow for the vapour chamber. The results show that the nanoparticles added to the working fluid decrease vapour chamber temperature, liquid velocity and liquid pressure and increase mass evaporated. They also show that Cu nanofluid has the greatest effect on the vapour chamber temperature compared with CuO and Al2O3 nanofluids. The increase of volume fraction of nanoparticles decreases vapour chamber temperature and liquid velocity and increases mass evaporated. At volume fraction 9% of Cu nanoparticles, the maximum temperature gradient of vapour chamber decreases by about 19.5% for wick porosity 0.75 and 15.7% for wick porosity 0.35. (C) 2012 Elsevier Ltd. All rights reserved.