Experimental investigation of a pulsating heat pipe for hybrid vehicle applications

This paper deals with the experimental results of an unlooped pulsating heat pipe (PHP) developed and tested in an electronic thermal management field with hybrid vehicle applications in mind. The 2.5 mm inner tube diameter device was cooled by an air heat exchanger to replicate the environment of a vehicle.In order to characterize this pulsating heat pipe, four working fluids have been tested. They are acetone, methanol, water, and n-pentane, with applied thermal power ranging from 25 W to 550 W, air temperature ranging from 10 °C to 60 °C and air velocity ranging from 0.25 m s−1 to 2 m s−1. Three inclinations have also been tested according to their horizontal positions: +45° (condenser above the evaporator), 0° and −45° (condenser below the evaporator).Among the different results, some of the most revelatory were obtained with regard to unfavourable inclination (−45°), for which the performances were very interesting considering a terrestrial application. On the other hand, one also observed low temperature limitations for water as a working fluid and degradation of performances for n-pentane tested at 60 °C air temperature. On an overall basis, however, it should be noted that the PHP functioned with high reliability and reproducibility and without any failure during the start-up or working stage.

► An unlooped pulsating heat pipe (PHP) has been tested varying heat power, air velocity and temperature, inclination and fluid.
► Four working fluids have been tested and classified into two groups according to the performances of the PHP.
► Interesting water phenomena have been highlighted in this study.
► The PHP worked with a good reliability and reproducibility.