  An experimental effort was conducted to measure the change in internal energy
of non-ideal carbon dioxide as its volume rapidly expanded with the sudden
opening of a valve from one to two compressed gas cylinders. This was achieved
by measuring the mass heat capacity of the gas cylinders and the
manifold-valve, and measuring the change in temperature from the sudden
doubling of volume of the non-ideal carbon dioxide. It was determined that an
empirical equation for the change in internal energy of a non-ideal fluid was
more accurate than previous methods used for estimating the change in internal
energy by estimating the change in entropy. With this empirical equation, a
theoretical ideal Stirling cycle heat engine that exceeds the Carnot efficiency
was realized by utilizing non-ideal carbon dioxide as a working fluid.

Statistical Mechanics;Chemical Physics