In order to meet the requirements for fast cooling speeds and low temperatures, it is sometimes necessary to switch from conventional thermostat cooling to liquid gas cooling. KGWISOTHERM has developed a new KALTGAS application for this application. Here, a test chamber is cooled using cryogenic nitrogen gas, thus enabling rapid cooling speeds.
KALTGAS is a temperature control system based on the low temperature of liquid nitrogen as a refrigerant. The liquid nitrogen is vaporized in a cryogenic tank by means of a heater (jet). This generates a constant, cryogenic gas flow. By varying the heater (jet), both the cooling capacity and the gas flow volume can be changed, and the LN2 consumption can also be reduced to a minimum by varying the jet output. The cryogenic gas flow is then fed through a vacuum-insulated, flexible metal pipe to a heat exchanger (heater). The heat exchanger has the task of heating the cold gas flow to the desired temperature. This means that a predefined gas flow with a predefined temperature is available as cooling gas at the outlet of the heat exchanger. A KALTGAS system can generate a -170°C cold gas flow within a few minutes. The use of different temperature controllers enables the optimum customized design of a KALTGAS system. Depending on the customer’s requirements, temperature stability of up to +/-0.1°C can be achieved by using an optimized controller. With a standard safety controller (SC5), a temperature stability of less than +/-0.2°C is achieved.