Modeling heat transfer between a freeze pipe and the surrounding ground during artificial ground freezing activities

The artificial ground freezing method (AGF) is widely used in civil and mining engineering. In AGF numerical models, the thermal boundary conditions at the freeze pipe wall, whether they be expressed in temperature or in flux, are generally determined based on in situ measurements, which are not readily available. The purpose of this paper is to study the complete heat transfer problem in order to develop a thermal model that can be easily used in field applications. In this numerical model, the freeze pipe and the surrounding ground are considered in a coupled way. External data of temperature or flux at the pipe wall is therefore not needed to predict the temperature evolution in the ground. Moreover, the developed model can be used to conduct parametric studies on operating conditions, refrigerant type, system geometry or ground properties. Indeed, the reduction of the heat transfer problems in the ground and in the pipe into highly time-saving 1D problems allows the rapid resolution of many calculations. Then, the developed model can also find its use in the optimization and the design of AGF systems.