An Experimental investigation of Thermal Performance of Inner-Grooved Closed Loop Pulsating Heat Pipes with water-MWCNT nanofluid

Due to the importance of using nanofluids in heat pipes and not providing a report on the use of nanofluids in inner groove pulsating heat pipe (IGPHP), In this research, the thermal performance of IGPHP investigated using water- MWCNT (Multi-walled carbon nanotube) nanofluid as a working fluid. Experiments were performed on the optimal filling ratio (60%) and the input heat range of 50-300W in the vertical position in four volume fractions of 0.05, 0.1, 0.2, 0.4% with MWCNT nanofluid. The results showed that the lowest thermal resistance was obtained in the volume fraction of 0.1% and then increasing the concentration of nanofluid increases the thermal resistance of IGOHP, which seems to be the main reason for increasing the viscosity of nanofluid. The results showed that the use of MWCNT 0.1% nanofluid reduced the thermal resistance about 11% and increased the effective thermal conductivity about 12%.The results showed that the fluctuations in nanofluids started earlier than distilled water and the best performance occurred at higher input heat, which can be attributed to the large number of continuous fluctuations.