Long-distance loop heat pipe for effective utilization of energy

The purpose of this study is to develop a long-distance loop heat pipe (LHP). First, the mathematical model was developed to predict the operating characteristics of the LHP; the model is based on a one-dimensional steady-state flow. Second, three LHPs were fabricated with different distances for heat transport: 2 m, 4 m, and 10 m. The wick was made of a polytetrafluoroethylene porous material, the working fluid was ethanol, and the cooling method was natural convection. All three LHPs operated stably at heat loads up to 160 W. When the maximum heat load of 160 W was applied, the thermal resistances of the 2 m, 4 m, and 10 m LHPs were 0.073 K/W, 0.063 K/W, and 0.13 K/W, respectively. As the heat-transport distance increased, the temperature in the compensation chamber (CC) decreased and the temperature difference between the evaporator and CC increased. Finally, the computational results from the mathematical model were compared with the experimental data; there was a good agreement between the predicted and measured temperature distributions across the LHPs.