Literature Review on Heat Transfer Characteristics of Closed Loop Pulsating Heat Pipe and Thermal Performance

Closed loop pulsating heat pipes (CLPHPs) are complex heat transfer devices having a strong thermo hydrodynamic coupling governing the thermal performance. A wide range of pulsating heat pipes is experimentally studied thereby providing vital, information on the parameter dependency of their thermal performance. Bubble generation and growth in the evaporator and simultaneous collapse in the condenser. The internal diameter is a parameter which necessarily affects the very definition of a pulsating heat pipe. CLPHP design is to make the thermal performance. To take data accuracy of heat transfer by measuring the volume flow rate. And the inlet and out let temperature of coolant flowing through the condenser section. Try to make close loop in between condenser and evaporator. Thermal performance report within ±30% accurate. Controlling the input heat flux and the condenser temperature evaporator temperature is a dependent variable. There are some important data to evaluate the thermal performance of PHPs, such as heat load, heat flux, and average evaporator temperature. In this paper, a wide range of pulsating heat pipes is experimentally studied thereby providing vital information on the parameter dependency of their thermal performance. The influence characterization has been done for the variation if internal diameter, number of turns, working fluid and inclination angle (from vertical bottom heat mode to horizontal orientation mode) of the device. CLPHPs are made of copper tubes of internal diameters 2.0 and 1.0 mm, heated by constant temperature water bath and cooled by constant temperature water-ethylene glycol mixture (50% each by volume). The number of turns in the evaporator is varied from 5 to 23. The working fluids employed are water, ethanol and R-123. The results indicate a strong influence of gravity and number of turns on the performance.