In this experimental study, a specific flat plate pulsating heat pipe (FPPHP) with ethanol as working fluid has been tested. The experimental test bench consists of a copper block at the surface of which a single 10 turns groove has been machined. A transparent glass pressed in front of the top surface and two high speed cameras allow the fluid flow patterns to be visualized during the operations. Thus, the analysis of the synchronized recorded images permits to link the hydraulic behavior of the fluid inside the PHP to its thermal response as regards operating conditions (heat power applied, cooling temperature, inclination). A quantitative and qualitative analysis of the results show that in vertical position the flow pattern are almost always annular whatever the heat power applied, with liquid storage in some adjacent channels; in horizontal position, the evaporator is progressively dried out with some oscillations for specific heat powers. Lastly by putting the PHP in an original orientation with the gravity, named edge orientation, the fluid motion is transmitted from one branch to another sequence, induced by the pressure difference increased by the gravity forces between channels.
VISUALISATION OF FLOW PATTERNS IN FLAT PLATE PULSATING HEAT PIPE: INFLUENCE OF HYDRAULIC BEHAVIOUR ON THERMAL PERFORMANCES
FILIPPESCHI, SAURO
2013-01-01
Abstract
In this experimental study, a specific flat plate pulsating heat pipe (FPPHP) with ethanol as working fluid has been tested. The experimental test bench consists of a copper block at the surface of which a single 10 turns groove has been machined. A transparent glass pressed in front of the top surface and two high speed cameras allow the fluid flow patterns to be visualized during the operations. Thus, the analysis of the synchronized recorded images permits to link the hydraulic behavior of the fluid inside the PHP to its thermal response as regards operating conditions (heat power applied, cooling temperature, inclination). A quantitative and qualitative analysis of the results show that in vertical position the flow pattern are almost always annular whatever the heat power applied, with liquid storage in some adjacent channels; in horizontal position, the evaporator is progressively dried out with some oscillations for specific heat powers. Lastly by putting the PHP in an original orientation with the gravity, named edge orientation, the fluid motion is transmitted from one branch to another sequence, induced by the pressure difference increased by the gravity forces between channels.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
