Radial junction thermal flowmeter

A thermal flowmeter to measure the rate of flow of a fluid in a conduit, comprising a first upstream radial junction thermocouple, a second downstream radial junction thermocouple, a heat source to supply substantially constant output heat to at least one of said radial junction thermocouples and to said fluid in said conduit, said heat source being positioned with respect to said first and second radial junction thermocouples to supply more heat to one of said thermocouples than the other, means to detect and measure the differential electrical output between said thermocouples, said differential output being mathematically related to said rate flow of said fluid wherein a conduit of a first metal is uninterrupted and continuous through said flowmeter, a thin sleeve of a second metal, thermoelectrically dissimilar to said first metal, is provided circumferentially around one surface of said conduit, the upstream end of said sleeve comprising said first upstream radial junction thermocouple and the downstream end of said sleeve comprising said second downstream radial junction thermocouple.

A thermal flowmeter to measure the rate of flow of a fluid in a conduit, comprising a first upstream radial junction thermocouple, a second downstream radial junction thermocouple, a heat source to supply substantially constant output heat to at least one of said radial junction thermocouples and to said fluid in said conduit, said heat source being positioned with respect to said first and second radial junction thermocouples to supply more heat to one of said thermocouples than the other, means to detect and measure the differential electrical output between said thermocouples, said differential output being mathematically related to said rate of flow of said fluid wherein a conduit of a first metal is uninterrupted and continuous through said flowmeter, said conduit is circumferentially slightly necked inwardly at both the upstream and downstream ends of said flowmeter, a wire of a second metal, thermoelectrically dissimilar to said first metal, is provided circumferentially around said conduit, in each of said necked inwardly portions of said conduit, each of said circumferential wires forming a radial junction thermocouple with said conduit.

A thermal flowmeter to measure the rate of flow of a fluid in a conduit, comprising a first upstream radial junction thermocouple, a second downstream radial junction thermocouple, a heat source to supply substantially constant output heat to at least one of said radial junction thermocouples and to said fluid in said conduit, said heat source being positioned with respect to said first and second radial junction thermocouples to supply more heat to one of said thermocouples than the other, means to detect and measure the differential electrical output between said thermocouples, said differential output being mathematically related to said rate of flow of said fluid wherein a conduit of a first metal is uninterrupted and continuous through said flowmeter, said conduit is circumferentially reduced in wall thickness from the outside at both the upstream and downstream ends of said flowmeter, a wire of a second metal, thermoelectrically dissimilar to said first metal, is provided circumferentially around said conduit in each of said reduced portions of said conduit, each of said circumferential wires forming a radial junction thermocouple with said conduit.