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Problem $03\mathrm{.}067-$ A piston$-$cylinder device contains steam

A piston$-$cylinder device initially contains steam at $3\mathrm{.}5$ MPa $,$ superheated by $5C.$ Now, steam loses heat to the

surroundings and the piston moves down, hitting a set of stops, at which point the cylinder contains saturated liquid water.

The cooling continues until the cylinder contains water at $190\mathrm{.}0C.$ Use data from the steam tables.

Problem $03\mathrm{.}067.$b $-$ Enthalpy change in superheated steam

Determine the enthalpy change per unit mass of the steam by the time the piston first hits the stops.

The enthalpy change is $,k\frac{J}{k}g.$