Throttling process

Throttling process - When a perfect gas is expanded through an aperture of minute dimensions such as a narrow throat or a slightly opened valve, the process is termed as throttling process. During this process, no heat is supplied or rejected and also no external work is done. Moreover, there is no change in temperature, and so the total heat of the fluid remains constant.

During the throttling process, the expansion of a perfect gas is under constant total heat conditions, and resembles with free expansion process. Thus in a throttling process,

Q1-2 = 0, W1-2 = 0 and dU = 0.