Investigation of a compact copper–water loop heap pipe with a flat evaporator

A compact copper–water loop heat pipe (LHP) with an effective length of 310 mm equipped with a flat–oval evaporator measuring 80 (L) × 42 (W) × 7 (H) has been tested. The vapor line and the condenser had the same internal diameter of 5.4 mm. The internal diameter of the liquid line was 3.4 mm. Tests were conducted with a heat source which had a heating surface of 30 mm × 30 mm. The condenser was cooled by running water with a temperature of 20 °C. In the horizontal position the device has exhibited serviceability in the heat load range from 5 W to 1200 W at vapor temperatures from 26.5 °C to 103.4 °C. The maximum capacity was achieved at a heat source temperature of 143.5 °C, when the LHP thermal resistance was equal to 0.044 °C/W. The corresponding values of thermal resistance for the evaporator and the condenser were at a level of 0.006 °C/W and 0.038 °C/W. A minimum thermal resistance of 0.097 °C/W for the “heat source–LHP–cooling water” system was obtained at a heat load of about 700 W, at which the temperature of the heat source was 87 °C.