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SUBLIN Subcooler

Liquid nitrogen is used as a cost effective coolant for industrial applications. In many cases, it is necessary to supply the liquid to the application under elevated pressure conditions, and to de-pressurise it subsequently without any significant formation of gas, or to allow adequate heat-absorption before the liquid reaches its boiling point.

Typical Subcooler Applications:

  • spray cooling of large spaces, machines or plants via nozzle manifolds that require an even distribution of the liquid nitrogen within the nozzle manifold, such as
    • spray-cooling in tunnel freezers, mixers, kneading machines mainly in the food industry
    • high capacity cooling processes, precise temperature control in freeze-drying for chemical & pharmaceutical production processes
    • deburring of rubber and plastic parts, e.g. in the automotive industry
  • high efficiency cooling processes, especially at high differential temperature, such as mold or die-plate cooling in aluminium or other metal extrusion processes
  • generation of high-pressure cryogenic liquid jets
  • fast filling of pressure-less vessels, dewars and transport containers without the
    formation of fog for transport & general production purposes
  • liquid conditioning for high pressure pumps
  • liquid transfer to systems susceptible to the formation of gas bubbles, such as oscillating or rotary pumps, MBE cryogenic pumps
  • HT super conductors cooling loops


Inside a SUBLIN subcooler, the operating medium is conducted through a heat exchanger that is surrounded by boiling liquid nitrogen. The vacuum-insulated nitrogen bath is pressure-less at a temperature of -196°C. The liquid inside the heat exchanger is under tank pressure. Depending on the throughput of liquid, it cools down to near bath temperature while the bath partially evaporates due to the absorption of heat. An electronic level control with an actuated fill valve maintains the pre-set bath level automatically. If the medium is also nitrogen, the bath is fed by the pressurised part of the system via an internal bypass. Subcoolers for media other than nitrogen need to be supplied with nitrogen (acting as coolant) from the outside.

For special applications, SUBLIN VAC super-coolers are available that operate at a coolant bath temperature of about -209°C.

Design features

  • vacuum-insulated vessel of horizontal or vertical design
  • top-mounted gas vent and valves
  • liquid inlet and outlet connections located at the bottom (vertical version) or on the side (horizontal version)
  • non-insulated connections with welded ends or metal sealed threaded connections (flanged connections are feasible, if requested), alternatively vacuum-insulated Johnston-type or welded couplings

Technical Data

Coolant: liquid nitrogen
Operating medium: liquid nitrogen; optional: LOX; LAr and LNG (only with pressurised coolant bath)
Operating temperature: coolant bath: -196°C (at ambient pressure)
outlet on pressure side: 0.5 to 2°C above bath temperature
Operating pressure: coolant bath: ambient pressure
medium: 2 to 25 bar(g)

  • elevated bath / outlet temperature by means of pressurised coolant bath via a pressure retaining valve at the gas outlet;
  • bath operating pressure 150 mbar(a) for cooling down to -208°C
Control: ON-OFF level control via KRYTEM level sensor and solenoid inlet valve;
Low exhaust gas temperature trip

  • steady level control via capacitive level sensor and pneumatic steady control valve
  • outlet temperature control / monitoring by means of continuous level adjustment via an outlet temperature sensor / phase sensor
  • level control without auxiliary energy with float valve (e.g., for operation in explosive atmosphere)
  • integrated vacuum-insulated inlet valve (electric or electro-pneumatic)
Insulation: vacuum max. 10-4 mbar at operating temperature
Current: 230 VAC / 24 VDC
Materials: 1.4541, 1.4571, copper, PTFE