Method and apparatus for providing an indication of the composition of a fluid particularly useful in heat pumps and vaporizers
AssigneeA.T.C.T. Advanced Thermal Chips Technologies Ltd.
InventorsGady Golan, Zeev Shavit
Life of this patent
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Abstract
A method and apparatus for providing an indication of the composition of an examined fluid by using an electrical resistor, particularly a positive temperature coefficient thermistor, for measuring the thermal conductivity of the examined fluid with the known thermal conductivity of different fluid compositions. The method and apparatus are particularly described for indicating the relative proportions of a working fluid in the liquid and vapor phases in one or more stages of a heat pump. Another described application is for indicating the liquid level in a liquid vaporizer.
Claims28
A method of providing an indication of the composition of an examined fluid, comprising:
- immersing an electrical resistor within the examined fluid;
- applying electrical current through the electrical resistor to heat it to a temperature above that of the examined fluid;
- controlling the electrical current applied through the electrical resistor to maintain the electrical resistor substantially at a predetermined temperature while the electrical resistor is immersed in said fluid;
- measuring the electrical current applied through the electrical resistor to maintain it substantially at said predetermined temperature, to provide a measurement of the rate of heat dissipation from the electrical resistor via said examined fluid and, thereby, a measurement of the thermal conductivity of the examined fluid;
- and comparing the measured thermal conductivity of the examined fluid with the known thermal conductivities of different fluid compositions to provide an indication of the composition of the examined fluid.
A method of providing an indication of the composition of an examined fluid, comprising:
- immersing within the examined fluid a positive temperature coefficient (PTC) thermistor having a predetermined maximum temperature above the temperature of the examined fluid;
- applying electrical current through the thermistor to heat it to, and to maintain it, at said predetermined maximum temperature;
- measuring the current applied through the PTC thermistor, to maintain the thermistor at said maximum predetermined temperature such as to provide thereby a measurement of the thermal conductivity of the examined fluid;
- and comparing the measured thermal conductivity of the examined fluid with the known thermal conductivities of different fluid compositions to provide an indication of the composition of the examined fluid.
Apparatus for providing an indication of the composition of an examined fluid, comprising:
- an electrical resistor having a mounting device for mounting the electrical resistor immersed in the fluid to be examined;
- a power supply for supplying electrical current to the electrical resistor to heat it to a temperature above that of the examined fluid;
- and a processor for:
- (a) controlling the heating current applied to the electrical resistor to maintain the electrical resistor substantially at a predetermined temperature;
- (b) measuring the electrical current applied to the electrical resistor to maintain it substantially at said predetermined temperature;
- and (c) producing an output, based on the measured electrical current, indicating the composition of the examined fluid.
Dependencies are inferred from the claim text.