Patent ID: 7854164

Claim:
A flowmeter to determine a flow direction of a fluid, comprising: a measurement element around which the fluid flows, the measurement element comprising: an optical waveguide to carry an electromagnetic wave, the electromagnetic wave being influenced by the temperature of the optical waveguide; and at least two electrical heating elements arranged adjacent to the optical waveguide, each heating element producing a respective heat flow when activated, the heating elements being positioned such that the respective heat flows proceed in opposite directions from the respective heating elements toward the optical waveguide, the amount of heat reaching the optical waveguide from the individual heating elements correlating to the flow direction of the fluid; a control unit to successively in time supply electrical power to the at least two heating elements so as to alternate the electrical power from one heating element to another; and an evaluation unit to monitor temperature influences from the individual heat flows on the electromagnetic wave, and thereby determine the flow direction of the fluid.