Study of the parameters and characteristics of flat heat pipe with nanofluids subjected to periodic heat load on its performance

A study is presented on the transient cooling of an electronic component by flat heat pipe (FHP) with nanofluid. The electronic component has periodic power output of maximum value 400 W and works for 12.8 s. The effects of Cu, CuO and Al2O3 nanoparticles on the heat pipe performance are investigated for different wick porosities and wick thicknesses. The effects of diameter and volume fraction of the solid nanoparticles added to the working fluid on the performance of the heat pipe are considered. Also, the effect of using nanofluid on the fluid flow is studied. A comparison of the temperature of the electronic component cooled by the heat pipe and copper block is presented for the periodic heat load. The results show good agreement between the experimental and the numerical results. They show that the maximum temperature of the heat pipe decreases by using nanofluids at different wick porosities and thicknesses. The temperature of the heat pipe decreases with decreasing the diameter and with increasing the volume fraction of the solid nanoparticles. Cu, CuO and Al2O3 nanoparticles added to the working fluid increases mass evaporated, mass condensed, liquid velocity and liquid pressure. The amplitude of the heat pipe temperature, mass condensed, mass evaporated, liquid velocity and liquid pressure decreases with time. Also, this amplitude decreases with increasing wick thickness and wick porosity. At wick thickness 1.4 mm, volume fraction 0.06 and wick porosity 0.4, a decrease of electronic component temperature by about 10 K is obtained by using Cu-water nanofluid compared with heat pipe using only water and 25 K compared to the equivalent copper block.