Pulsating heat pipe working with nono fluids

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A Pulsating heat pipe is a simple device used to transfer the heat from one place to the other i.e., from evaporator to condenser .
Pulsating  heat pipes was first proposed and patented by Akachi as a passive cooling device.
Pulsating  heat pipes (PHPs) are one of the latest developments in the area of heat transfer.
Heat pipe can have an extremely high thermal conductivity in steady state operation. 
There is also no pump; therefore, the PHP is passive and needs no power for operation.
Literature survey:
Asirvatham using silver water nanofluid on the heat transfer performance of a heat pipe and showed a substantial reduction in thermal resistance of 76.2% and an enhancement in the evaporation heat transfer coefficient of 52.7% for 0.009% silver nanofluid.
Yousefi  experimentally investigated the effects of inclination angle and nanofluids on the performance of a heat pipe used for CPU cooling. With the CPU in the horizontal position. Their results indicated that using 0.5% Al2O3-water nanofluid as the heat pipe’s working fluid, the thermal resistance can be decreased by 15% and 22%, when the heat generated at the CPU was at 10 W and 25 W respectively. 

 Working principle;
                  PHP works on the principle of fluid pressure oscillations that are created by means of differential pressure across vapour plugs from Evaporator to condenser and back. 
The vapour formed at the evaporator is pushed towards the condenser in the form of discrete vapour bubbles amidst packets of fluid.
 The vapour gets condensed at the condenser releasing the latent heat of vaporization and returns to the evaporator to complete the cycle. 
The thermal performance of an actual PHP depends upon the temperature gradient exists between the evaporator and the condenser section.

Procedure;   Before filling the fluid in the PHP it is ensured that no traces of working fluid used in previous cycle of experimentation is available
 The required amount of working fluid is then filled using a syringe by opening the one end of the non- return valve such that fluid directly enters the evaporator section.
  It is reported in the literature (Khandekar) that the PHP develops true pulsating motion when the fill ratio is between 20%-80%and it is also stated that 50% is the optimum fill ratio. Hence we can  conduct for fill ratios ranging from 50% to 80%,
  Now the air is filled through the filling valve provided on the brass tube using another Syringe. This is done to ensure simultaneous formation of liquid slug and vapor bubbles.
 The display unit is ON and required wattage is set using the power supply unit in the present experimentation. The cooling water is allowed to pass  the condenser section of PHP  for condensing vapour.
The transient experiments are conducted and  the temperatures at  various  locations  of the PHP are recorded from the temperature data logger. The experiments are continued  till steady state is reached. 
                                                                                         

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