Abstract: A throttle device provides a large number of small flow channels generally in parallel rather than a single flow path. The throttling device, a porous cartridge within a tube, may be porous metal, packed ferrous spheres or other particles, packed fibrous material, a plurality of smaller capillaries joined together in parallel, etc. The number and size of the channels provide proper pressure drop performance of the throttle, and flow is laminar with a Reynolds number less than 2,000. Vibrations are low. With certain refrigerant components, and small openings in the porous throttle device, refrigerant flow resistance increases until all flow ceases below selected and repeatable temperature levels. Thus, a temperature-dependent, variable on to off throttle device is provided without moving parts. This self adjusting throttle device can operate in parallel with a fixed throttle device.

Abstract: A precooled vapor-liquid refrigeration cycle includes a basic vapor-liquid cycle and an auxiliary regenerative vapor-liquid cycle having a heat exchange relationship between them. The basic cycle includes a compressor connected in series with a condenser, throttle device, and evaporator. The auxiliary cycle includes a compressor, condenser, throttle device, and a counterflow heat exchanger, successively connected. The cycles each have condensers that are cooled by ambient air; the basic cycle is able to operate independently of the auxiliary cycle. To maximize the coefficient of performance, the basic cycle operates with a small pressure differential between compressor discharge and return. In the heat exchanger, refrigerant flow from the basic cycle condenser is further cooled in a counterflow arrangement by the low temperature refrigerant from the auxiliary cycle until the refrigerant in the basic cycle has been precooled from near ambient temperature to near the intended refrigeration temperature.

Abstract: Mixed refrigerants provide refrigeration at cryogenic temperatures with throttling cycles operating with a one-stage compressor. The refrigerants include noncondensable gases such as helium, neon, or hydrogen to increase the overall cooling capacity of a refrigeration system at the same refrigeration temperature which is attainable without such noncondensable gases. More refrigeration can be produced with existing systems at temperatures above the normal boiling point of nitrogen or argon by adding, for example, helium, than for refrigerant blends without helium. By increasing the return pressure value of the refrigeration cycle in relation to the molar percent of helium present in the refrigerant, a constant refrigeration temperature may be maintained which exhibits greater stability than prior systems operating at the same temperature without helium enrichment.