Vapor composition and flow sensor
First Claim
1. An apparatus for providing gaseous vapor output signals indicative of the composition and flow of the gaseous vapor traveling through a duct, the apparatus comprising:
- a first sensing pattern including a first heater positioned equidistant between an upstream detector and a downstream detector, the first heater as well as the upstream and downstream detectors positioned transversely within the duct and responsive to temperature;
a second sensing pattern including a second heater positioned equidistant between a first detector and a second detector, the second heater as well as the first and second detectors positioned longitudinally within the duct and responsive to temperature; and
means for exciting the first and second heaters to generate sinusoidal thermal waves which propagate through the gaseous vapor to the upstream and downstream detectors and the first and second detectors, respectively, resulting in temperature variations and corresponding responses by the upstream, downstream, first and second detectors, wherein the responses of the upstream and downstream detectors are dependant upon the composition and flow of the gaseous vapor and the responses of the first and second detectors are dependant upon only the composition of the gaseous vapor.
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Abstract
The present invention is directed to a single solid state thermal diffusion sensor capable of measuring both the composition and flow of gaseous vapors traveling through a duct. The sensor comprises two orthogonal sensing patterns, each having a heating element positioned equidistant between two thermistor elements. The heaters and thermistors are made from thin film platinum deposited on a thermally insulating polyimide layer having low thermal diffusivity. A sinusoidal voltage is applied to each heating element for generating oscillating thermal waves which propagate through the gaseous vapor to their respective thermistors. The thermistors of a first, transversely positioned sensing pattern are responsive to both the composition and flow of the gaseous vapor, while the thermistors of a second, longitudinally positioned sensing pattern are responsive only to the composition of the gaseous vapor. Appropriate electronic circuitry utilizes the responses of the thermistor pairs for determining the composition and flow of the gaseous vapor.
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Citations
6 Claims
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1. An apparatus for providing gaseous vapor output signals indicative of the composition and flow of the gaseous vapor traveling through a duct, the apparatus comprising:
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a first sensing pattern including a first heater positioned equidistant between an upstream detector and a downstream detector, the first heater as well as the upstream and downstream detectors positioned transversely within the duct and responsive to temperature; a second sensing pattern including a second heater positioned equidistant between a first detector and a second detector, the second heater as well as the first and second detectors positioned longitudinally within the duct and responsive to temperature; and means for exciting the first and second heaters to generate sinusoidal thermal waves which propagate through the gaseous vapor to the upstream and downstream detectors and the first and second detectors, respectively, resulting in temperature variations and corresponding responses by the upstream, downstream, first and second detectors, wherein the responses of the upstream and downstream detectors are dependant upon the composition and flow of the gaseous vapor and the responses of the first and second detectors are dependant upon only the composition of the gaseous vapor. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification