Dew point and bubble point measurement
AssigneeHeriot-Watt University
InventorsRhoderick William Burgass, Adrian Christopher Todd, Sayed Ali Danesh, Bahman Tohidi Kalorazi
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Abstract
Apparatus and method for detecting the dew point or bubble point phase transition in fluid. The apparatus used comprises a piezoelectric crystal sensor and a signal analyser. The phase transition of the fluid is measured by monitoring, directly or indirectly, change in the resonant frequency of the piezoelectric crystal sensor while said one of the temperature and pressure is varied, so as to detect a substantial change in said resonant frequency and/or in the rate of change in resonant frequency with change in the varying one of the temperature and pressure.
Claims30
A phase transition detection apparatus for detecting the dew point and bubble point phase transition in a fluid, the apparatus comprising:
- a pressure chamber for holding said fluid;
- a piezoelectric crystal sensor mounted in said pressure chamber and in contact with said fluid, said crystal sensor being formed and arranged to resonate at a variable resonant frequency which is dependent upon physical properties of the fluid in contact with the crystal sensor;
- and
- means for directly or indirectly monitoring, in use of the apparatus, changes in the resonant frequency of the piezoelectric crystal sensor consequent upon variations of one of the temperature and pressure of said fluid in contact with said sensor, whereby to detect a substantial change in said resonant frequency and/or a substantial change in the rate of change with respect to time of said resonant frequency consequent upon variations of the varying one of the temperature and pressure, said substantial change occurring at the dew or bubble point phase transition of the fluid, whereby the said dew or bubble point phase transition may be detected;
- the pressure chamber being adapted to hold a sufficient amount of said fluid to contact or surround the piezoelectric crystal sensor;
- and
- means for controllably varying the pressure and/or temperature of said fluid in the pressure chamber.
A method for detecting a dew point or bubble point phase transition in a fluid, the method comprising the steps of:
- a) providing a pressure chamber for holding said fluid;
- b) providing a piezoelectric crystal sensor which is formed and arranged to resonate at a variable resonant frequency which is dependent upon physical properties of any fluid in contact therewith;
- c) placing a sample of fluid to be tested in said pressure chamber;
- d) immersing at least one surface of the sensor in the sample of a fluid in the pressure chamber, so that said sensor surface is in contact with said sample;
- e) varying one of the temperature and pressure of the fluid sample in said pressure chamber so as to cause a dew point or bubble point phase transition to occur in the fluid, while maintaining the other one of the temperature and pressure substantially constant;
- and
- f) directly or indirectly monitoring changes in the resonant frequency of the piezoelectric crystal sensor while said one of the temperature and pressure is varied, so as to detect a substantial change in said resonant frequency and/or a substantial change in the rate of change with respect to time of said resonant frequency consequent upon variations of the temperature and pressure, said substantial change occurring at the dew point or bubble point phase transition in the fluid, thereby to detect the said dew point or bubble point phase transition.
Dependencies are inferred from the claim text.