Device and method for determining the thermal conductivity of a gas, tank arrangement and vehicle
View Patent ↗A device for determining a hydrogen concentration or hydrogen mixture concentration includes: an electrical conductor arrangement which is designed such that it can be brought into contact with the fluid mixture at least in part and is realized in the form of a voltage divider having two elements, the first element being a first conductor which, at least in a current-carrying state, has a resistance value which is different from that of the second element, a measuring bridge comprising two voltage dividers connected in parallel, one of the voltage dividers being formed by the electrical conductor arrangement, a control unit for applying an AC voltage to the measuring bridge, a voltage detection unit for detecting a bridge voltage, and an evaluation unit configured so as to determine the thermal conductivity of the hydrogen or hydrogen mixture by evaluating the bridge voltage using the 3-Omega method.
1 . A device for determining a leakage of hydrogen from a hydrogen tank, the device configured to be arranged outside a tank space of the hydrogen tank, comprising:
an electrical conductor arrangement which is configured to be brought into contact with a fluid mixture, the conductor arrangement including a voltage divider having first and second elements, the first element being a first conductor which, in a current-carrying state, has a resistance value which is different from that of the second element, the second element being a second conductor, wherein a conductor path corresponding to the first conductor is arranged in a meandering manner between two middle legs of a conductor path corresponding to the second conductor,
a measuring bridge comprising two voltage dividers connected in parallel, one of the voltage dividers being formed by the electrical conductor arrangement,
a control unit, for applying an AC voltage to the measuring bridge,
a voltage detection unit for detecting a bridge voltage, and
an evaluation unit configured to:
determine a hydrogen concentration in the fluid mixture based on a thermal conductivity of the fluid mixture, the thermal conductivity being determined by evaluating the bridge voltage using the 3-Omega method,
determine the leakage of hydrogen from the hydrogen tank based on the determined hydrogen concentration in the fluid mixture, and
output a signal upon determining the leakage.
2 . The device according to claim 1 , wherein
the first conductor and the second conductor have an equal resistance value in a currentless state, and
the first conductor reaches a higher temperature than the second conductor in the current-carrying state as the first conductor has a higher resistance value than that of the second conductor in the current-carrying state.
3 . The device according to claim 2 , wherein
the first conductor and the second conductor are arranged in the form of two conductor paths on a circuit board in a meandering manner, and
each of the conductor paths includes a plurality of legs and connecting portions between the legs.
4 . The device according to claim 1 , wherein
the second element is a fixed resistor, and the first conductor has, in the current-carrying state, a resistance value which is different from that of the fixed resistor,
the other of the voltage dividers of the measuring bridge is formed by two adjustable resistors, and
the evaluation unit is configured to adjust the two adjustable resistors before an application of the AC voltage in such a way that the measuring bridge is balanced.
5 . A tank arrangement comprising at least one device according to claim 1 and at least one fluid tank which is filled with a fluid, wherein the conductor arrangement of the device is in contact with a gas at least partially surrounding the fluid tank.
6 . The tank arrangement according to claim 5 , wherein the fluid tank is the hydrogen tank which is filled with hydrogen.
7 . The tank arrangement according to claim 5 , wherein a plurality of the devices are provided, which are arranged spaced apart from each other outside the tank space of the hydrogen tank.
8 . A vehicle comprising a hydrogen propulsion unit and the tank arrangement according to claim 5 .
9 . A method for determining a leakage of hydrogen from a hydrogen tank by means of the tank arrangement according to claim 5 , comprising the following steps:
applying the AC voltage to the measuring bridge,
detecting the bridge voltage,
determining the hydrogen concentration in the fluid mixture based on the thermal conductivity of the fluid mixture, the thermal conductivity being determined by evaluating the bridge voltage using the 3-Omega method,
determining the leakage of hydrogen from the hydrogen tank based on the determined hydrogen concentration in the fluid mixture, and
outputting the signal upon determining the leakage.
10 . A method for determining a leakage of hydrogen from a hydrogen tank by means of the device according to claim 1 , comprising the following steps:
applying the AC voltage to the measuring bridge,
detecting the bridge voltage,
determining the hydrogen concentration in the fluid mixture based on the thermal conductivity of the fluid mixture, the thermal conductivity being determined by evaluating the bridge voltage using the 3-Omega method,
determining the leakage of hydrogen from the hydrogen tank based on the determined hydrogen concentration in the fluid mixture, and
outputting the signal upon determining the leakage.
11 . The device according to claim 1 , wherein
a cross-sectional area of the conductor path corresponding to the first conductor is smaller than that of the conductor path corresponding to the second conductor, and
the conductor path corresponding to the first conductor is longer than the conductor path corresponding to the second conductor.