Temperature changes in LNG products
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In the LNG liquefaction stage, the gas exits the cryogenic tank at a temperature of -160 degrees and a pressure of 4.6 MPA; after passing through the step valve, the pressure drops to 0.085 MPA while the temperature remains at -158.5 degrees. Why does the temperature rise after passing through the step valve?
In actual operation, such a situation has occurred; let’s analyze it. The throttling process is an isenthalpic process, with H=U+PV. After throttling, the liquid does not vaporize, which means the volume of the material remains unchanged while the pressure decreases. According to 0=△U+△PV, if △PV is negative, then U increases and the temperature rises. Hope this can help you
#Here’s a quick reply: #Natural gas, in gaseous or gas-liquid state, experiences a decrease in temperature when the pressure drops. If it remains liquid after pressure reduction, the temperature rises. When the pressure is reduced from a liquid state to a gas-liquid state, the temperature drops as a phase change occurs, which is a form of evaporative cooling