| Summary: | How to effectively release excess ground heat to cool permafrost by using renewable ambient cool energy is an important issue because many environmental and engineering problems are associated with permafrost degradation. Two-phase closed thermosyphons (TPCTs) are widely used in many heat transfer applications. In this paper, a field experiment was conducted to evaluate the cooling performance of an air-L-shaped TPCT-ground (ALTG) cooling system used in permafrost embankments. We then developed a coupled model to describe the energy process of the ALTG cooling system, including the coupled ALTG heat transfer and the heat conduction with phase change for the permafrost ground. The model was validated by the field experiment. Both experimental and numerical results indicate that the cooling system can improve the heat releasing from ground to atmosphere, especially in the first four years. Finally, an improved ALTG system was proposed to enhance the absorption of ambient cool energy for a wider high-grade highway based on series of numerical simulations. Simulation results showed that the improved system could sufficiently extend the horizontal cooling extent under the embankment. This specially designed ALTG system will contribute to the control of ground heat using ambient cool energy in cold regions. Ambient cool energy; Ground heat control; Cooling system; System modeling; Cold region;
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