Why is enthalpy conserved in steady flow processes? A helium liquefier in its final stage of liquefaction takes in compressed helium gas at 14 K, liquefies a fraction α, and rejects the rest at 14 K and atmospheric pressure. Use the values of enthalpy H of helium gas at 14 K as a function of pressure p in the table below to determine the input pressure which allows α to take its maximum value, and determine what this value is.
[table — see PDF]
[Enthalpy of liquid helium at atmospheric pressure =10.1 kJ kg−1].