摘要:
A microsensor system for determining water vapor content of the ambient atmosphere that uses a thin film suspended ceramic diaphragm structure featuring an embedded, patterned thin film heater, temperature sensor and an external film of an hygroscopic salt stabilized in a water-insoluble, crosslinked polymer matrix and contacting a pair of patterned electrodes which are proximate to the heater. The heater controls a selected electrical parameter of the salt to a fixed, predetermined value, as determined by its electrical characteristics. The dew point of the atmosphere is determined based on the dynamic relation with the salt dehydration temperature.
摘要:
A sensor that provides absolute pressure independent of the composition of the measured gas includes a large microbridge used to determine the thermal conductivity and specific heat of the gas and a small microbridge pressure sensor comprising a heated element suspended over a V-groove. Voltages and currents associated with heated elements of both microbridges are measured and used in an equation to provide an absolute pressure value.
摘要:
A leak detector for a valve controlling flow of fuel to a combustion chamber employs a fuel concentration sensor in a sensing chamber placed downstream from the valve seat. The valve has a downstream chamber which is in communication by diffusion through an orifice, with a source of pressurized air. By injecting air into the downstream chamber through this orifice after the valve has closed and then measuring with the sensor the fuel concentration within the sensing chamber, excessive fuel leakage by the valve can be detected.
摘要:
A method for correcting the flow measurement of a gaseous fluid of interest for changes in the composition of that fluid in a flowmeter of the microanemometer class is disclosed in which an uncorrected flow value signal for the fluid of interest in relation to a microanemometer sensor output is corrected by applying a correction factor to the flow value signal based on certain unique physical parameters of the fluid of interest which nominally include thermal conductivity, k, specific heat, c.sub.p, and density, q.
摘要:
A selective gas detecting apparatus for determining the concentration and type of hydrocarbon gas in a gas sample based upon absorption of infrared radiation by the gas sample, the apparatus having at least two infrared radiation absorption channels with the wavelengths for measurement in the two channels selected as 3.2 microns and 3.4 microns, signals in the two channels being processed to formulate an indication of absorbance of hydrocarbons at the selected wavelength, the absorbance signal in one channel being displayed as an indication of concentration of approximately the total hydrocarbon gas in air and the ratio of absorbances being displayed as an indication of the type of hydrocarbon in air and independent of the concentration of the gas.
摘要:
The specific gravity, l, of a fluid of interest is determined based on thermal conductivity, k, and specific heat, c.sub.p, of the fluid of interest. An embodiment uses proximately positioned resistive heater and thermal sensor elements coupled by the fluid of interest. Pulses of electrical energy are applied to the heater of a level and duration such that both a transient change and a substantially steady-state temperature occur in the sensor. The k of the fluid of interest is determined based upon sensor output at steady-state elevated temperature, c.sub.p of the fluid of interest is determined based upon the rate of change of sensor output during a time interval of transient temperature change in the sensor, and l is determined from k and c.sub.p.
摘要:
A method and apparatus for determining both the thermal conductivity, k, and specific heat, c.sub.p, of a fluid of interest are disclosed. An embodiment uses proximately positioned resistive heater and thermal sensor coupled by the fluid of interest. A pulse of electrical energy is applied to the heater of a level and duration such that both a transient change and a substantially steady-state temperature occur in the sensor. The k of the fluid of interest is determined based upon a known relation between the sensor output and k at steady-state sensor temperature; and c.sub.p of the fluid of interest is determined based on a known relation among k, the rate of change of the sensor output during a transient temperature change in the sensor and c.sub.p.
摘要:
With the addition of a conductive means in the form of a grounded ring or member placed at the insulator means of a high voltage spark electrode structure, the required break down voltage of the spark gap can be reduced. The conductive means typically would be a ring encircling the insulator means of the electrode structure and would provide a ground as well as a mechanical support near the end of the insulator means of the electrode structure.
摘要:
An improved detector for combustible gases and which is able to discriminate between natural gas (methane and ethane) and other sources of methane (e.g. swamp gas, petrochemical and automotive) or other combustible gases by measuring the characteristic methane/ethane ratio of natural gas, based on infrared absorption of methane and ethane, in combination with another non-specific combustible gas detector.