Joule-Thomson coefficients of propane and n-butane

<p>Experimental Joule-Thomson measurements were made on gaseous propane at temperatures from 100 to 280ËšF and at pressures from 8 to 66 psia. Joule-Thomson measurements were also made on gaseous n-butane at temperatures from 100 to 280Ëš and at pressures from 8 to 42 psia. For propane, the values of these measurements ranged from 0.07986ËšF/psi at 280ËšF and 8.01 psia to 0.19685ËšF/psi at 100ËšF and 66.15 psia. For n-butane, the values ranged from 0.11031ËšF/psi at 280ËšF and 9.36 psia to 0.30141ËšF/psi at 100ËšF and 41.02 psia. The experimental values have a maximum error of 1.5 percent. </p> <p>For n-butane, the measurements of this study did not agree with previous Joule-Thomson measurements made in the Laboratory in 1935. The application of a thermal-transfer correction to the previous experimental measurements would cause the two sets of data to agree. Calculated values of the Joule-Thomson coefficient from other types of p-v-t data did agree with the present measurements for n-butane.</p> <p>The apparatus used to measure the experimental Joule-Thomson coefficients had a radial-flow porous thimble and was operated at pressure changes between 2.3 and 8.6 psi. The major difference between this and other Joule-Thomson apparatus was its larger weight rates of flow (up to 6 pounds per hour) at atmospheric pressure. The flow rate was shown to have an appreciable effect on non-isenthalpic Joule-Thomson measurements. </p> <p>Photographic materials on pages 79-81 are essential and will not reproduced clearly on Xerox copies. Photographic copies should be ordered.</p>