In order to improve the heat transfer characteristics of pulsating heat pipes

a type of two-diameter pulsating heat pipe structure was proposed

and the applicable physical and mathematical model was developed based on the mass

momentum

and energy conservation equations. This two-diameter pulsating heat pipe adopted different pipe diameters between the evaporation section and the condensation section. The ratio of the two was defined as the diameter ratio. The above theoretical model was used to analyze the effect of the diameter ratio on the pulsating heat pipe motion and heat transfer characteristics. Results show that the two-diameter structure can effectively improve the self-excited oscillation mechanism of the pulsating heat pipe

especially when diameter ratio is less than 1. In terms of heat transfer characteristics

compared with the traditional equal-diameter pulsating heat pipe (diameter ratio equals to 1)

using the structure of diameter ratio less than 1 can significantly reduce the thermal resistance of the pulsating heat pipe

but using the structure of diameter ratio more than 1 instead can decrease the heat transfer characteristics.