In these systems cryogenic LN2 is transported to the customer’s application where the cold fluid extracts energy from the system, by heating up and/or by evaporation. The warmer fluid/vent gas is collected and, in a closed loop, fed to (a) Cryogenerator(s) where the energy is removed and the gas re-liquefied again.
These systems tend to be very efficient: Normally, in cases where an application is cooled with bulk LN2, cold vent gas going to waste. With that, a lot of effort (energy), which was required to produce and cool it, is wasted. However by collection, re-using and re-liquefying the gas the cold is saved and less energy is required to produce liquid Nitrogen again. In case the customer does not require any cooling the system will switch to stand-by mode to keep itself cold by switching the cooler on and off.
As a minimum, these systems comprise of one or more cryocoolers, a LN2 storage tank and (vacuum insulated) lines towards customers application and return lines. More often the system will have some kind of pump (to get the liquid flowing), cryogenics valves, connections and instrumentation. Within our more than 50 years of experience, we have developed the know-how and expertise to design and size these kind of set ups.
All Stirling’s Cryogenerators (one and two stage) can be considered for integration in these kind of closed loop systems. Systems with multiple coolers are possible and common. A Stirling’s SPC-1 and SPC-4 cryogenerators (cryocooler) provide cryogenic cooling power in the range of 500 – 4,000 Watt at 77K. They can be used in an operating range of 150 – 50 Kelvin. Stirling’s two stage Cryogenerators SPC-1T and SPC-4T provide cryogenic cooling power in the range of approx. 20 -800 Watt from 15-40K.
Stirling Cryogenics is able to assist you with design a process set up and selecting the right equipment.
For more information on how cold is produced, see:
The Stirling Cycle