Which thermodynamic property of steam does NOT change in throttling calorimeter?

Explanation:

Throttling calorimeter:

• A throttling calorimeter is a device used to measure the quality of steam, which is the measure of the percentage of vapor in a wet steam mixture. The throttling calorimeter takes advantage of the principle that enthalpy remains constant during a throttling process.
• First, high-pressure steam is allowed to flow through a throttling device into a lower pressure region. Throttling devices can take several different forms, such as a small orifice or a partly opened valve.
• According to the First Law of Thermodynamics, the energy entering a system should equal the energy leaving it, meaning the enthalpy (the total heat content) of the steam should not change as a direct result of the throttling.
• If the steam is superheated before throttling, it remains superheated but at a lower pressure and usually a lower temperature after the throttle.
• If the steam is wet, however, something interesting happens: As the steam pressure drops after the throttle, some of the wet steam flashes into dry steam, causing the steam temperature to lower (due to the latent heat of vaporization). Therefore, by measuring the temperature and pressure after the throttle, the quality of the incoming steam can be determined.
• It's important to remember that, while enthalpy stays constant, other properties (such as pressure and temperature) can and do change during the throttling process. This is why the Throttling Calorimeter can work: by looking at these changes, we can learn about the initial quality of the steam.

In summary, in a throttling calorimeter, the enthalpy value remains constant while other properties such as pressure and temperature change, which helps in determining the initial quality of the steam.