Journal of Selected Topics in Energy

Copper oxide nanofluid that is obtained by dispersion of copper oxide nanoparticles in water base fluid is used as heat pipe working fluid. Nanofluids because of having better thermophysical properties in comparison with conventional heat transfer fluids, cause heat pipe performance improvement as an effective heat transfer equipment. In this work, a computational fluid dynamic method (CFD) is used to study the effect of using nanofluid and varying volume fraction, size and shape of suspended nanoparticles in nanofluid on heat pipe thermal performance. The results show thermal resistance reduction and heat pipe performance improvement by using nanofluid in comparison with pure water. Also volume fraction enhancement, nanoparticle’s diameter reduction and using cylindrical nanoparticles cause the evaporator and condenser temperature gradient reduction that in low volume fractions the effect of using nanoparticles with small diameter on heat transfer is more than using non spherical nanoparticles

In this work thermal performance of a cylindrical heat pipe at steady state has been investigated empirically. The used heat pipe, made of copper, has been designed and manufactured by considering effective parameters on heat pipe thermal performance. Then heat pipe has been charged by water as the working fluid. By installing sensors and the other equipment, the test set up has been prepared. After preparing the test set up by changing voltage, various input powers have been inserted into evaporator and the heat pipe surface temperature distribution has been obtained for each case. Then by using the obtained temperature distributions, thermal resistance variations and equivalent thermal conductivity coefficient have been computed. and variation of them versus input power have been plotted. The results show that the thermal resistance has its minimum value at maximum operating limit (maximum passing power) and equivalent thermal conductivity has its maximum value at this point.