| 摘要 |
<p>A cryogenic gas is liquefied using a refrigeration system [ 101 ] thermally coupled at an evaporator [ 125 ] to a cold end of a gas supply system [ 103 ] within a dewar [ 116 ]. The refrigerator has a minimum temperature at an evaporator [ 125 ] above the boiling point of the gas at atmospheric pressure but below the boiling point of the gas at a high pressure. Thus, the gas is compressed [ 128 ] to high pressure so it condenses when cooled by the evaporator [ 125 ]. As it expands at a flow restrictor [ 148 ], a portion evaporates and cools a fraction to the temperature of the boiling point of the gas at atmospheric pressure, producing liquefied gas. Opening a purge valve [ 142 ] sends warm gas upward through heat exchange section [ 146 ] and out through a three-way valve [ 138 ] for defrosting. To reduce clogging, the gas supply valve [ 138 ] is controlled by a gas purity sensor [ 158].</p> |
