Speaker
Description
A novel cycle has been developed using an ejector driven by a compressor. This cycle gives a low quality 2-phase flow similar as the traditional 2PACL system provides. The advantage of this ejector system is that it can go lower in temperature than the liquid pumped 2PACL since there is no limitation with respect to the needed subcooling anymore. Where a 2PACL with CO2 is limited to -45°C, an ejector cycle can go as low as -55°C, and able to work close to the triple point.
The ejector cycle can work with Krypton for the ultra low temperature range (-140°C -55°C) or with CO2 for the temperature range above. The design for a Krypton or CO2 filled system is rather similar so 1 system could be used for both Krypton or CO2. Initial warm operation could be done with CO2, where a refill with Krypton could be applicable for a cold use later.
The concept design was proven in a study carried out by CERN and NTNU. The challenge for the future is the development of a good oil free compressor, A controllable ejector and the qualification for cold temperature use of typical components designed for CO2 refrigeration.