FLUID TEMPERATURE DIFFERENTIAL FLOW METER

• US 3,802,264 A
• Filed: 07/10/1972
• Issued: 04/09/1974
• Est. Priority Date: 07/10/1972
• Status: Expired due to Term

• Current Assignee: Cullen M. Sabin, Heinz F. Poppendiek
• Original Assignee: Cullen M. Sabin, Heinz F. Poppendiek
• Inventors: Poppendiek, Heinz F., Sabin, Cullen M.
• Primary Examiner(s): Goldstein, Herbert
• Application Number:
  US05/271,262
• Time in Patent Office: 638 Days
• Field of Search: 73/204
• US Class Current: 73/204.24
• CPC Class Codes: G01F 1/002 wherein the flow is in an open channel
• CPC Class Codes: G01F 1/68 by using thermal effects
• CPC Class Codes: G01F 1/6847 where sensing or heating elements are not disturbing the fluid flow, e.g. elements mounted outside the flow duct
• CPC Class Codes: G01F 1/6888 Thermoelectric elements, e.g. thermocouples, thermopiles

Abstract

A fluid temperature differential flow meter involves a thin wall tube through which a liquid flows either alone or accompanied by the presence or flow of a gas. Heat is supplied from an external location through the tube to such liquid; and the resulting rise in temperature of the liquid in its flow between two spaced regions in such tube is measured using a series of cold and hot junctions in a thermopile also located externally of the tube. The electrical output of such thermopile serves as an indication of the rate of flow of the fluids. The source of heat and thermopile are located with respect to the tube to avoid or minimize so-called entrance region effects so that the relationship of the electrical output of the thermopile to flow rate is substantially linear although in inverse relationship. The thermopiles may in some instances be located inside of the flow tube. The flow tube may be a straight tube or in the form of a spiral tube or in other cases as a bent tube in which more thermocouples may then be used to advantage. A servo system may be incorporated to maintain the measured temperature constant while varying the amount of heat.

Claims

1. A flow meter system including a conduit for the flow of material being metered;

heater means arranged to produce heat uniformly along said conduit from one region thereon to a second region thereon spaced in the direction of material flowing in said conduit to heat said material flowing through said conduit whereby the temperature of the material is increased progressively from said one region to said second region;

a first section of the conduit extending from said one region upwardly in the direction of incoming material flow and a second section extending downwardly from said one region in a space between said one and said first and second sections having progressively lower non-linear temperatures and defining an entrance region wherein said material is initially heated;

thermopile means mounted externally of said conduit and having a first series of upstream cold junctions spaced longitudinally along said conduit from a second series of downstream hot junctions; and

means connected to said thermopile and indicating the electrical output of said hot and cold junctions;

said first and said second series of junctions each being between said one region and said second region with said series of cold junctions being positioned sufficiently downstream from said first region to be outside of said entrance region and with the temperature of such conduit between said regionS increasing linearly.

2. A system as set forth in claim 1 in which said conduit is a tube.

3. A system as set forth in claim 2 in which said tube is a thin wall of metal.

4. A system as set forth in claim 1 in which said heater means is the electrical resistance of said conduit.

5. A system as set forth in claim 1 in which said conduit is a spiral conduit with the series of cold junctions being on one convolution of the spiral conduit and the series of hot junctions being on another convolution.

6. A system as set forth in claim 5 in which the spacing between different pairs of each corresponding cold and hot junction pair as measured along the path of fluid flow in the spiral conduit is substantially the same.

7. A system as set forth in claim 1 in which said conduit is a bent tube defined by two leg portions thereof with the series of cold junctions being on one of said leg portions and with the series of hot junctions being on the other of said leg portions.

8. A system as set forth in claim 7 in which the spacing between different pairs of each corresponding cold and hot junction pair as measured along the path of fluid flow in the bent tube is substantially the same.

9. A system as set forth in claim 1 including a servo system responsive to the output of said thermopile means and functioning in response thereto to control said heater means such that the output of said thermopile means is maintained substantially constant.