A Joule-Thomson Loop to Study High-Pressure Fluid Expansion

A specialized facility was constructed to investigate the Joule-Thomson (JT) effect during fluid expansion over a valve. The flow loop facility consists of 1.5 m long, 1 in. outer diameter test sections located up- and downstream of an expansion valve, supported by process equipment to control and monitor local pressures and temperatures. The loop features a 1 m removable section after the expansion valve, enabling postexperiment visual inspection of the pipe. Pressure and temperature sensors are instrumented along the 3 m test section, giving spatially resolved information on the dynamic response of a fluid experiencing JT expansion. The expansion and cooling of dry and wet nitrogen, and dry methane were studied with the facility through experiments conducted in pressure-driven batch mode. A dynamic model incorporating thermodynamic predictions of the fluid’s JT coefficient was used to calculate the temperature drop across the valve for a range of experiments. The dynamic model calculations for dry gas systems were consistent to within 10% during the period of experiments where the assumption of isenthalpic expansion is reasonable. However, significant deviations were observed for wet gas systems even though the JT coefficients of both vapor and liquid phases in the mixture were considered. To build a more accurate dynamic model for systems comprising both a gas and aqueous phase, further JT expansion measurements are needed across a variety of water loadings. The facility reported here is ideal for studying the dynamic response of JT cooling for both subsea applications, and in the relief systems of process facilities.