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The Joule expansion, treated as a thought experiment involving ideal gases, is a useful exercise in classical thermodynamics. It provides a convenient example for calculating changes in thermodynamic quantities, including the resulting increase in entropy of the universe ( entropy production ) that results from this inherently irreversible process.
This scientific paper provided a substantial challenge to established theories of heat and began the 19th century revolution in thermodynamics. The experiment inspired the work of James Prescott Joule in the 1840s. Joule's more exact measurements on equivalence were pivotal in establishing the kinetic theory at the expense of the caloric theory.
Between 1840 and 1843, Joule carefully studied the heat produced by an electric current. From this study, he developed Joule's laws of heating, the first of which is commonly referred to as the Joule effect. Joule's first law expresses the relationship between heat generated in a conductor and current flow, resistance, and time. [1]
Charles Haldat made some penetrating criticisms of the reproducibility of Rumford's results [15] and it is possible to see the whole experiment as somewhat tendentious. [16] However, the experiment inspired the work of James Prescott Joule in the 1840s. Joule's more exact measurements were pivotal in establishing the kinetic theory at the ...
In thermodynamics, the Joule–Thomson effect (also known as the Joule–Kelvin effect or Kelvin–Joule effect) describes the temperature change of a real gas or liquid (as differentiated from an ideal gas) when it is expanding; typically caused by the pressure loss from flow through a valve or porous plug while keeping it insulated so that no heat is exchanged with the environment.
The inversion temperature in thermodynamics and cryogenics is the critical temperature below which a non-ideal gas (all gases in reality) that is expanding at constant enthalpy will experience a temperature decrease, and above which will experience a temperature increase.
Using these values, Joule was able to determine the mechanical equivalent of heat. Joule estimated a mechanical equivalent of heat to be 819 ft•lbf/Btu (4.41 J/cal). The modern day definitions of heat, work, temperature, and energy all have connection to this experiment. In this arrangement of apparatus, it never happens that the process runs ...
These various states and kinetics determine the heat transfer, i.e., the net rate of energy storage or transport. Governing these process from the atomic level (atom or molecule length scale) to macroscale are the laws of thermodynamics, including conservation of energy.