PURPOSE: To improve the performance limit of the heat pipe due to the limitation to the capillarity and maintain the temperature of the evaporation part at an almost constant level by means of a Clapeyron tube used for the feedback of liquid from the condensation part to the evaporation part.

CONSTITUTION: This heat pipe is composed of a heat pipe body 1, Clapeyron tube 2, a Clapeyron tube evaporation chamber and a working liquid 4. The tube works to convey the liquid by difference in the vapor pressure. In this apparatus, the liquid level is kept the same only if the temperature is the same in the tube and the heat pipe. Under such a condition, even if the heat pipe evaporation part 5 is heated while the condensation part is cooled, the liquid level remains unchanged. On the other hand, when the temperature of the evaporation chamber becomes lower than that of the heat pipe body with the cooling of the tube evaporation chamber 3, a difference in the vapor pressure is yielded and the working liquid moves up through the tube.