# US 2014/0190244 A1 · System and Method for the Determination of Mixture Averaged Molecular Weight of Complex Mixtures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190244 A1 - Document ID: US20140190244A1 - Status: Published application - Kind: A1 - Application number: 14/148,213 - Filed: 2014-01-06 - Published: 2014-07-10 - Earliest claimed: 2013-01-04 - Assignees: The Trustees of Princeton University - Inventors: Frederick L. Dryer; Sang Hee Won; Stephen Dooley - Web page: https://patentgrep.com/patent/US20140190244A1 ## CPC - G01N 7/16: by heating the material - G01N 25/02: by investigating changes of state or changes of phase; by investigating sintering {(investigating or analysing oils or hydrocarbon fluids by measuring cloud point or pour point G01N33/2811)} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract An apparatus and method for determining the average molecular weight of a complex mixture from a plurality of test samples of the complex mixture are disclosed. The method includes a) providing a chamber having two fixed conditions and one variable condition selected from three state variables of temperature, pressure and volume; b) introducing a test sample of known mass into the chamber; c) setting operating conditions of the state variables such that the test sample will be fully vaporized into a gaseous state without decomposition or chemical reaction; and d) measuring the change of the variable condition after full vaporization of the test sample is achieved. Steps b-d are repeated for several test samples having different masses. The average molecular weight of the complex mixture is determined as a linear gradient (slope) of the relationship for the change of variable condition as a function of test sample mass. ## Claims ### Claim 1 A method for determining the average molecular weight of a complex mixture from a plurality of test samples of the complex mixture, the method comprising: a) providing a chamber having two fixed conditions and one variable condition selected from three state variables of temperature, pressure and volume; b) introducing a test sample of known mass into the chamber; c) setting operating conditions of the state variables such that the test sample will be fully vaporized into a gaseous state without decomposition or chemical reaction; d) measuring the change of the variable condition after full vaporization of the test sample is achieved; e) repeating steps b-d for several test samples having different masses; f) determining the average molecular weight of the complex mixture as a linear gradient of the relationship for the change of variable condition as a function of test sample mass. ### Claim 2 (depends on 1) The method of claim 1 wherein the fixed conditions are volume and temperature and the variable condition is pressure. ### Claim 3 (depends on 1) The method of claim 1 wherein the fixed conditions are temperature and pressure and the variable condition is volume. ### Claim 4 (depends on 1) The method of claim 1 wherein determining the average molecular weight comprises performing a linear regression on the measured change of variable condition as a function of test sample mass. ### Claim 5 (depends on 4) The method of claim 4 wherein the linear regression generates a line having a slope equal to the average molecular weight of the fuel under test. ### Claim 6 (depends on 1) The method of claim 1 wherein the fixed conditions are held essentially constant. ### Claim 7 (depends on 1) The method of claim 1 wherein at least one of the fixed conditions is controlled using a proportional-integral-derivative (PID) controller. ### Claim 8 (depends on 1) The method of claim 1 further comprising vacuuming chamber to a target pressure prior to introducing the test sample. ### Claim 9 (depends on 1) The method of claim 1 further comprising purging the chamber with nitrogen prior to intruding the test sample. ### Claim 10 (depends on 1) The method of claim 1 wherein the target pressure is approximately 1.4 kPa. ### Claim 11 An apparatus configured to determine of the average molecular weight of a complex mixture from a plurality of test samples, the apparatus comprising: a chamber having two fixed conditions and one variable condition selected from three state variables of temperature, pressure and volume; at least one sensor configured to the measure variable condition for the plurality of test samples; a controller configured to determine the average molecular weight of the complex mixture as a linear gradient (slope) of the relationship for the change of variable condition as a function of test sample mass. ### Claim 12 (depends on 11) The apparatus of claim 11 wherein the fixed conditions are volume and temperature and the variable condition is pressure. ### Claim 13 (depends on 11) The apparatus of claim 11 wherein the fixed conditions are temperature and pressure and the variable condition is volume. ### Claim 14 (depends on 11) The apparatus of claim 11 wherein average molecular weight is determined by performing a linear regression on the measured mass and change in variable condition associated with the plurality of test samples. ### Claim 15 (depends on 14) The apparatus of claim 14 wherein the linear regression generates a line having a slope equal to the molecular weight of the complex mixture. ### Claim 16 (depends on 11) The apparatus of claim 11 wherein the fixed conditions are held essentially constant. ### Claim 17 (depends on 11) The apparatus of claim 11 further comprising a proportional-integral-derivative (PID) controller configured to control at least one of the fixed conditions. ### Claim 18 (depends on 11) The apparatus of claim 11 further comprising a vacuum pump configured to vacuum the chamber to a target pressure prior to introducing the test sample. ### Claim 19 (depends on 11) The apparatus of claim 11 further comprising a nitrogen supply configured to purge the chamber with nitrogen prior to introducing the test sample. ### Claim 20 (depends on 1) The method of claim 1 wherein the target pressure is approximately 1.4 kPa.