A polymer is flowed through a slim tube including porous media until steady state is achieved. A temperature of the porous media with the polymer is adjusted to emulate a reservoir temperature. A slug of a gel solution is flowed through the porous media in the slim tube. The gel solution includes the polymer and a crosslinker. The gel solution is configured to at least partially solidify at the temperature. Multiple pressure drops across the porous media in the slim tube are measured at corresponding locations along a length of the slim tube while the slug flows through the porous media in the slim tube. The slug at least partially solidifies within the slim tube, causing an increase in pressure. A location of gelation of the slug of gel solution within the slim tube is determined based on the increase in pressure.

A system to measure the flow rate of a liquid in a microfluidic circuit. The system includes a vessel that is partially filled with the liquid, a gaseous ceiling above the vessel and a pressure regulator to maintain the pressure of the gas in the gaseous ceiling at a predetermined value P1. A capillary pipe to extract the liquid from the vessel and to output the liquid at a pressure P2 lower than P1. A first inlet of the pressure sensor is connected to the gaseous ceiling, a second inlet of the pressure sensor is connected to the capillary pipe, and the outlet of the pressure sensor outputs a signal as a function of the pressure difference (P1P2), which is a measurement representing the flow rate of pressurized P2 liquid supplied to the microfluidic circuit.

A system to measure the flow rate of a liquid in a microfluidic circuit. The system includes a vessel that is partially filled with the liquid, a gaseous ceiling above the vessel and a pressure regulator to maintain the pressure of the gas in the gaseous ceiling at a predetermined value P1. A capillary pipe to extract the liquid from the vessel and to output the liquid at a pressure P2 lower than P1. A first inlet of the pressure sensor is connected to the gaseous ceiling, a second inlet of the pressure sensor is connected to the capillary pipe, and the outlet of the pressure sensor outputs a signal as a function of the pressure difference (P1P2), which is a measurement representing the flow rate of pressurized P2 liquid supplied to the microfluidic circuit.

A reference volume for use with pressure change flow rate measurement apparatus has an internal structure comprising elements with cross section and length comparable to the cross section and length of adjacent interstitial fluid regions. The reference volume may have one or more heat conduction elements exterior to and in good thermal contact with a corrosion resistant material that defines the internal fluid holding region.

A reference volume for use with pressure change flow rate measurement apparatus has an internal structure comprising elements with cross section and length comparable to the cross section and length of adjacent interstitial fluid regions. The reference volume may have one or more heat conduction elements exterior to and in good thermal contact with a corrosion resistant material that defines the internal fluid holding region.

A self-correcting pressure-based mass flow control apparatus includes outlet pressure sensing to enable correction for non-ideal operating conditions. Further the mass flow control apparatus having a fluid pathway, a shutoff valve in the fluid pathway, a reference volume in the fluid pathway, a first pressure measuring sensor in fluid communication with the reference volume, a first temperature measuring sensor providing a temperature signal indicative of the fluid temperature within the reference volume, a proportional valve in the fluid pathway, and a second pressure measuring sensor in fluid communication with the fluid pathway.

A system comprises a flow restrictor connected to a fluid flow path and located upstream from a chamber. The flow restrictor comprises an adjustable flow restriction aperture defined by the flow path region between a first element and a second element of the flow restrictor, and a drive unit configured to adjust the relative positions of the first element, second element or both to modify the fluid flow path across the aperture. The first or second element provides a curved boundary in the aperture flow path to form a converging region, a region of closest approach and a diverging region, within the flow path. Flow rate may be determined using a reference volume upstream from the flow restrictor.

A flow rate ratio control device is provided with a main flow path, a plurality of branch flow paths that branch off from a terminus of the main flow path, a plurality of fluid control devices that are provided respectively on each branch flow path, and that are each equipped with a valve and a pressure-based flow rate sensor that is disposed downstream of the valve, and an operation setting unit that establishes settings such that, based on the target flow rate ratio, any one fluid control device from among the plurality of fluid control devices is made to operate in a flow velocity control mode in which the flow velocity of a fluid is controlled upstream of each valve, and the remaining fluid control devices are made to operate in a flow rate control mode in which the flow rate is controlled based on the target flow rates.

A flow rate ratio control device is provided with a main flow path, a plurality of branch flow paths that branch off from a terminus of the main flow path, a plurality of fluid control devices that are provided respectively on each branch flow path, and that are each equipped with a valve and a pressure-based flow rate sensor that is disposed downstream of the valve, and an operation setting unit that establishes settings such that, based on the target flow rate ratio, any one fluid control device from among the plurality of fluid control devices is made to operate in a flow velocity control mode in which the flow velocity of a fluid is controlled upstream of each valve, and the remaining fluid control devices are made to operate in a flow rate control mode in which the flow rate is controlled based on the target flow rates.

To provide a flow rate control valve that can improve responsiveness of flow rate control of a pressure differential type of a flow rate control device. The flow rate control valve is so configured to comprise a pair of valve members each of which has a seat surface being in contact with each other, to provide an internal flow channel that opens toward the seat surfaces and that passes through the inside of at least one of the valve members, and to control a flow rate of a fluid flowing out through the internal flow channel to the outside by adjusting a separation distance between the seat surfaces. And a restricted flow channel is formed in the internal flow channel so that a differential pressure is generated between an upstream side and a downstream side of the restricted flow channel.