Two-Phase Cryogenic Flowmeter: A Proof of Concept

• Other Authors: Ashmore, Robert H. (authoraut)
• Format: Others
• Language: English; English
• Published: Florida State University
• Subjects: Mechanical engineering
• Online Access: http://purl.flvc.org/fsu/fd/FSU_migr_etd-0245

A new concept for a two-phase flow-metering device has been developed and tested. The concept involves vapor-liquid two-phase flow through narrow, parallel channels which results in a laminar, stratified flow with a slope at the liquid-vapor interface. By measuring the height at various locations in the channel, the mass flow rate can be calculated. Two laminar two-phase flow meter systems were designed and tested. The first is a room temperature apparatus designed to confirm the basic concept. This apparatus, which uses air and water two-phase flow, consisted of 10 rectangular channels, each just over 1 mm wide, 74 mm high, and 305 mm long. To allow for observation of the flow behavior in the device, the channels in the room temperature device are made from borosilicate glass plates and are kept evenly spaced by a machined aluminum spacer plate. The apparatus was tested with water flow rates ranging from 0 to 0.126 liters per second and the air flow rates ranging from 0 to 4.72 standard liters per second. The results show a correlation between the flow quality and the slope of the water-air interface. Following the results from the room-temperature apparatus, a cryogenic two-phase laminar flow meter was designed and constructed. This apparatus, which uses saturated liquid nitrogen as the test fluid, consists of 30 narrow, parallel channels each measuring 2 mm wide, 102 mm tall, and 330 mm long. The liquid height is measured in the channel using capacitance-liquid level devices. The channel walls are made of G10 printed circuit boards (PCBs) with the capacitor conductors electroplated directly on the boards so that they produce minimal intrusion into the channel. The capacitors are wired in parallel to measure the sum of the capacitance across the 30 channels. A mutual capacitance effect was seen when trying to measure the flow-channel capacitors. This effect made it difficult to properly analyze the data. The differential pressure transducer also malfunctioned so that the pressure drop over the channel length could not be measured. This measurement is crucial in determining the fluid velocity in the experiment. Despite these problems, the device still showed the ability to clearly distinguish between liquid and vapor flows. There was also a correlation between the mass flow rate as the liquid level was changed. The room temperature apparatus and the cryogenic apparatus both showed that the laminar two-phase flow meter concept warrants further study. A strong correlation between the vapor and liquid mass flow rates has been seen and improvement of the current system would allow for proper measurement of the flow rates. Suggestions for future work to further the development of the device are given. === A Thesis submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Master of Science. === Degree Awarded: Fall Semester, 2006. === Date of Defense: August 16, 2006. === Two-Phase Flow, Cryogenic, Cryogenic Flow Measurement, Two-Phase Measurement === Includes bibliographical references. === Steven Van Sciver, Professor Directing Thesis; Cesar Luongo, Committee Member; Emmanuel Collins, Committee Member.