How comes the frost into the ground?
No question about it, there is much energy necessary in ground freezing technology. Freezing can be realized especially for smaller jobs with open systems i.e. evaporation of liquid nitrogen (= LN2), but in shaft sinking closed pipe systems with brine (= watery saline solution) are used. Brine freezing is more than ten times more used than LN2-technology. Here exclusively those systems with double concentric pipes are discussed, not using LN2 but circulating brine as cooling liquid. By this the freeze pipes distributed on a so-called freezing circle the heat of the surrounding ground is absorbed. A frozen cylinder is formed which may be totally frozen in dependence of time (see Figure 1).
