RESUMO

The objective of this work was to develop a device for cooling electronic elements with a heat power up to 30 W by its rejection and dissipation in the ambient by free air convection. The device specification assigned the temperature range of the ambient conditions from −40 to +105° C and the available space of 30(W) × 120(H) × 200(L) mm. As a result a hybrid scheme based on a loop thermosyphon was proposed, where the evaporator embodied the capillary structure. In such a scheme, the return working fluid flow was ensured by the combined action of the gravity and capillary forces. Several prototypes with different loop and evaporator designs were tested in laboratory conditions. Water and heptane were used as working fluids. The experiments showed that the role of the capillary structure locally placed in the evaporator can be efficiently implemented by both highly porous cellular materials and capillary grooves made on the evaporating surface. It is also shown that heptane can be effectively used as a working fluid which is appropriate for the temperature range requirements. At the same time the device has good mass-and-size characteristics and total thermal resistance under a nominal heat load of about 1.7° C/W.