Experimental study on loop heat pipe with flat evaporator at different tilt angles

To realize highly efficient heat dissipation of electronics, a loop heat pipe (LHP) with a flat evaporator was designed to study its operation characteristics at the tilt angles of 0°, 30°, 45°, 60°, 90° with an improved evaporator structure and a well arranged pipes which can reduce heat loss due to back conduction and improve inner flow performance. The results show that the LHP with inclination has a lower power to start up than the horizontal one, and at the same heat load, the operation temperature of the evaporator is much lower and the system is easier to reach a steady state with less temperature oscillations. However, there is slight difference in operating performance for the LHP at different title angles. The thermal resistance decreases with an increase in the heat load and a steady state occurs at last. The thermal resistance is larger for the horizontal case than that for the inclination case at the same heat load. The thermal resistances are very different at different tilt angles at low heat load, but the difference is small at high heat load.