Analysis of the effect of the heat stabilizer outer surface finning on soil cooling efficiency

Abstract

Relevance. The construction of buildings and structures in permafrost conditions is associated with the problem of soil thawing. To prevent this phenomenon, heat stabilizer have proven themselves good in practice. Their successful use is difficult without preliminary modeling of heat flows in the soil–heat stabilizer system. The most effective design of a passive heat stabilizer is an installation with two-phase of refrigerant. An additional increase in the efficiency of using a two-phase heat stabilizer is possible due to the finning of the outer surface of the outer pipe of it. Aim. To calculate the efficiency of using a heat stabilizer with and without finning of the outer surface. Objects. Heat stabilizer, refrigerant, heat transfer, frozen soil. Methods. The mathematical model for describing the processes of heat and mass transfer in the heat stabilizer–frozen soil system is considered in an axisymmetric formulation. There are three subtasks: the movement of liquid refrigerant in the inner tube of the heat stabilizer, the two-phase convective flow of refrigerant in the gap between the inner and outer tubes and conductive heat exchange in the system of the heat stabilizer–frozen soil. The influence of the finning of the outer surface of the heat stabilizer is considered within the framework of the modified concept of the skin factor. Results and conclusions. The authors have obtained the pressure and temperature distributions along the length of the heat stabilizer. It was found that the presence of fins on the outer surface of the external pipe of the heat stabilizer increases the heat flow from the soil by 10%. It is determined that the soil is effectively cooled within 1 m from the heat stabilizer; this distance is recommended as optimal for the placement of an adjacent heat stabilizer.

Keywords

• heat stabilizer
• thermosiphon
• refrigerant
• frozen soil
• two-phase flow
• heat and mass transfer