Projects
Liquid Neon closed-loop cooling for HTS Motor
CryoZone has designed and produced a CryoFlow system based on a liquid neon convection loop for an HTS motor.
The transfer pipe is vacuum insulated and sticks into the cryogenic HTS rotor through a rotating ferrofluid seal. The liquid neon flows through a thin pipe into the inner vessel of the rotor. Here it spreads over the cylindrical wall and cools the HTS coils mounted on the outside. The resulting vapor is transferred back to the cryocooler through the second tube. The insulating vacuum tube starts within the rotor and acts as the thermal resistance to the warm ferrofluid seal.
Cooling power is provided by a Cryomec AL330, to which a CryoZone designed neon re-liquefier is mounted. This is placed in a small neon buffer, collecting the re-liquefied gas. From the buffer, liquid flows to the rotor and gas flows back.
Since the cooling power of the cryocooler is fixed, the system is regulated by evaporating LNe in the buffer using small heaters. These are regulated with a PID controller that measures the neon system pressure. This is set at e.g., 1316 mbara to keep the liquid and the rotor at 28K.
Explanation of pictures:
Picture 2 shows the part of the system to be placed in the vacuum cryostat before being thermally insulated.
Picture 3 shows a FEM model of the copper neon re-liquefier situated between the cryocooler and the neon buffer. Shown is the temperature variation, which was proven to be very small. This is necessary because the relatively warm copper parts will not participate in the liquefaction process.
