An experimental study on pulsating heat pipe (PHP) is presented in this work. A closed loop PHP with a single U
turn is fabricated and tested. The transient and steady state experiments are conducted and operating temperatures are
measured. The experiments are carried out for different working fluids, heat input and for different evacuation levels.
The derived parameters include thermal resistance and heat transfer coefficient of PHP. The results of these
experiments show an intermittent motion of the working fluid at lower heat input. The temperature difference
between evaporator and condenser at steady state is found lower for acetone compared to water, ethanol and
methanol. Lower value of thermal resistance and higher value of heat transfer coefficient are observed in case of
acetone compared to water, ethanol and methanol. Lower values of temperature difference between evaporator and
condenser and thermal resistance and higher value of heat transfer coefficient are observed at atmospheric conditions
of operation of PHP compared to evacuation conditions. The Power Spectral Density Analysis is also carried out on
the results of these experiments using FFT technique to analyse the pulsating motion of the fluid in a PHP. In the
Power Spectral Density analysis, the frequency distribution of temperature variation in PHP was observed over a
wider range, signifying the periodic motion in the fluid flow of the liquid slug and vapour plug. This characteristic
frequency corresponded to the characteristic time for a couple of adjacent vapour plug and liquid slug passing
through a specific local wall surface in a PHP
