Cryocoolers

Our line of cryogenic cryocoolers offer quiet, non-wearing, oil-free, low-vibration, long-life cooling which is, as a recent customer said, "Better for the long run.”

Qdrive cryocooler models operate at temperatures ranging from 40–200K with rated capacities of a few Watts to over 1000 Watts at 80K. Our most popular models, the 2S102K and 2S132K, are readily available in single or OEM quantities. Their acoustic coldhead design, with no moving parts, make them compact and more adaptable for vibration sensitive applications such as radiation and infrared detectors, instrumentation cooling and small liquid cryogen dewars. The larger cryocooler models—2s226K, 2S241K, 2S297K, 2S362K— are ideally suited for high temperature superconductor (HTS) and liquefaction (LNG, LN2, LOX) applications. Detailed specifications, drawings and available options can be found by browsing the product links at the bottom of the page.

How It Works - The Thermoacoustic Operating Principle

The base cryocooler unit consists of a PWG driven by patented STAR™ linear reciprocating motors and a thermoacoustic Stirling (pulse-tube) coldhead. The acoustic Stirling coldhead consists of a warm heat exchanger, a regenerator, a cold heat exchanger, a thermal buffer tube, a hot heat exchanger, an inertance tube, and an inertance tank. The figure below shows an inline cryocooler configuration for clarity, but the actual coldhead is “folded over” at the cold heat exchanger to create a cryocooler with an accessible, exposed cold zone.

PWG Motor Schematic

 

  1. Pressurized helium gas is cyclically compressed and expanded relative to the mean pressure (charge pressure) by the pistons of the PWG.
  2. With each forward stroke of the pistons, the gas moves through the aftercooler, or warm heat exchanger, where heat is removed. The gas parcel continues through the regenerator, which precools it before reaching the cold heat exchanger.
  3. As the gas moves toward the cold heat exchanger, gas in the thermoacoustic network (thermal buffer tube (sometimes called a pulse tube), hot heat exchanger, reservoir) also moves in the same direction. Even as the driven gas stops advancing, when the pistons reach their upper limits, the network’s gas continues moving, driven by its own inertia in the high-speed inertance tube. This acts like a virtual piston, moving away from the cold exchanger, which expands the gas in that area. As it expands, it gathers heat from surroundings (the area or substance to be cooled).
  4. The pistons begin withdrawing and helium then moves back through the regenerator and aftercooler. Still delayed by its inertia, the gas in the network follows and the cycle begins again.
  5. The heat exchangers are cooled by local water, or an optional closed water loop that consists of a reservoir, a pump, and a liquid-to-air heat exchanger. If an air-cooled cryocooler is desired, the motors and warm heat exchangers are cooled by a fan which blows over the motor enclosures and a heat sink connected to the aftercooler. It is recommended that the PWG be convectively cooled during operation to assure optimal performance from the cryocooler.

 

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