Boiling point cryogenic fluids

The refrigerator in Fig. 4a produces a cold gas, which absorbs heat from 4-5 and provides a method of refrigeration for obtaining temperatures other than those at the boiling points of cryogenic fluids. 

For cryogenic temperature measurements, furnaces consist of thermally conductive jackets filled with liquid nitrogen (boiling point 77.35 K) or liquid helium (boiling point 4.215 K). The heat dissipation from resistance heating elements competes with the cooling effects of these fluids to permit stable temperature control down to near absolute zero [10]. 

Table 1. Normal boiling points of common cryogenic fluids...

NORMAL BOILING POINTS OF COMMON CRYOGENIC FLUIDS... 

Most of the experiments discussed below require the ability to vary the temperature continuously from a little above room temperature down to about 4 K. The simplest Dewar flask of course is an immersion Dewar where the sample sits in the cryogenic fluid. They are inexpensive and easy to use but permit studies only at the boiling points of commonly available cryogenic liquids, and thus their utility is limited in this field. 

The commercial distribution of liquid neon, an inert cryogenic fluid with a boiling point of 27.2°K, began in 1960. The slow but steady usage growth since that time is due to three basic advantages possessed by liquid neon ... 

Aside from differences in heat capacity and boiling points, the cryogenic fluids showed no great apparent differences from water during boiling heat transfer. 

Two-Phase Systems. The combination of low boiling point and low heat of vaporization increases the possibility that cryogenic fluids become boiling, two phase systems. The influence of this fact upon pumping, liquid density, and level determination are obvious. Any sensor adding energy to the system is in fact creating a vapor-liquid interface at the very point of measurement. 

Therefore, for the purpose of this monograph, we have adopted the definition of a cryogenic liquid as one with a normal boiling point below the triple point of water at 0.13 °C, or 273 K. The application of cryogenic fluid dynamics is then developed to describe and predict the behaviour of LNG, LPG and other hydrocarbon mixtures with NBPs below 273 K [4, 5]. 

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