Is the throttling expansion of an ideal gas the same as adiabatic free expansion?
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The book states that \"the throttling process occurs very rapidly and can be considered adiabatic, meaning Q=0; no work is done on or by the system, so Ws=0. Therefore, throttling expansion is an adiabatic process with no work done, and it is a typical irreversible process.\" It seems like this is the same as adiabatic free expansion. Check with Haiyou.
Throttling expansion applies to flowing systems, while free adiabatic expansion applies to closed systems; volume work must be done in the latter case
Isn’t self-expansion expansion into a vacuum? Doesn’t it require no work?
Free expansion into a vacuum involves no work; according to the first law of thermodynamics, the internal energy of the gas remains unchanged. As its volume increases, its pressure decreases, while its temperature stays constant. Entropy and enthalpy increase. During adiabatic throttling, the enthalpy remains constant; the temperature may increase or decrease depending on the Joule coefficient. Entropy increases, and internal energy may increase or decrease depending on changes in temperature.
1. When an ideal gas expands freely into a vacuum, no work is done. According to the first law of thermodynamics, the internal energy of the gas remains unchanged, as does its temperature. Since enthalpy is a function of temperature alone, it also remains constant. As the volume increases, entropy increases. 2. During adiabatic throttling, the enthalpy remains constant, the temperature remains constant, the internal energy remains constant, and entropy increases. In summary, for an ideal gas, it’s a different matter.