摘要:
A refrigerant liquid flows through congelation probes (S1, S2, . . . ). The temperature of the liquid supplied to each probe is regulated as a function of the rate of congelation of the ground around the various probes and/or is progressively increased as the congelation progresses.
摘要:
The injection of liquid nitrogen into the probe (2) is regulated in an on-off manner so as to maintain the temperature of the ground at the coldest point above a value within the range of between -140.degree. C. and -160.degree. C. so as to cause calefaction of the liquid nitrogen. The liquid nitrogen is alternately injected into the central passage (9) and into the annular passage (11) of the probe, these passages being thermally insulated from each other.