The expansion of a gas through a small opening or a porous plug with the pressure on either side being maintained is called Joule-Kelvin expansion. The pressures are maintained by the flow of gases. T...The expansion of a gas through a small opening or a porous plug with the pressure on either side being maintained is called Joule-Kelvin expansion. The pressures are maintained by the flow of gases. The values of the pressures on the two sides of the plug are not the same. The gas undergoes a decrease in volume on one side as the molecules move through the opening to the other side. The volume on the other side increases as molecules move in. The whole system is under adiabatic condition.
