for drilling mud the datum detected by the first temperature sensor 7 the second temperature sensor 10 the third temperature sensor 11 the fourth temperature sensor 13 the fifth temperature sensor 14 the sixth temperature sensor 16 the eighth temperature sensor 19 and the seventh temperature sensor 20 are real time displayed on a screen of the inspection instrument 22 a forced cooling circulation system or a drilling mud is provided in which an output end of its refrigeration unit 1 is connected with a refrigerant tank 4 via a first valve 3 an output end of the refrigerant tank 4 is connected with an input end of the refrigeration unit 1 via a third valve 6 and a refrigeration unit pump 2 another output end of the refrigerant tank 4 is connected with an input end of a coaxial convection heat exchanger 12 in this way a refrigerant inlet 30 via a first temperature sensor 7 a fourth valve 8 a refrigerant tank pump 9 and a second temperature sensor 10 an output end of the coaxial convection heat exchanger 12 in this way a mud outlet 31 is connected with a mud pond 17 via a fourth temperature sensor 13 an input end of the refrigerant tank 4 is connected with another output end of the coaxial convection heat exchanger 12 in this way a refrigerant outlet.