Measuring method and measuring apparatus for determining the recirculation rate

Abstract

The invention relates to a measuring method for determining the recirculation rate (RR) in the anode gas circuit (50) of a fuel cell system (1) having a fuel cell (10), wherein anode gas (52) from ananode chamber (13) is supplied to the fuel cell (10) using an anode gas recirculation line (51) by means of a gas conveying device (70) and is thermostated in an anode gas heat exchanger (60) arrangedin the anode gas recirculation line (51). The following method steps are carried out for this purpose: - measuring a first differential pressure loss (DELTA P1_2) along a first line section (101) ofthe anode gas recirculation line (51), through which line section a first mass flow (M1_2) flows in the operating state of the fuel cell system (1); - measuring a second differential pressure loss (DELTA P3_4; DELTA P2_3) along a second line section (102; 103) of the anode gas recirculation line (51), through which line section a second mass flow (M3_4; M2_3) different to the first mass flow (M1_2) flows in the operating state; - calculating the differential pressure loss ratio (RDELTA P) by forming a quotient of the second measured differential pressure loss (DELTA P3_4; DELTA P2_3) and the first measured differential pressure loss (DELTA P1_2); - determining the recirculation rate (RR) in the anode gas circuit (50) on the basis of a characteristic system characteristic curve (S) as a function of the differential pressure loss ratio (R DELTA P) calculated in each case.

Description

technical field [0001] The invention relates to a measuring method for determining the recirculation rate in the anode gas cycle of a fuel cell system comprising at least one fuel cell with at least one cathode arranged in the cathode chamber, at least one anode arranged in the anode chamber an anode in the chamber and an electrolyte present between the cathode chamber and the anode chamber, wherein anode gas is supplied from the anode chamber to the at least one fuel cell by means of at least one gas delivery mechanism by means of the anode gas recirculation line, and the anode The gas is tempered in at least one anode gas heat transfer element arranged in the anode gas recirculation line. The invention also relates to a measuring device for carrying out the measuring method according to the invention. Background technique [0002] Fuel cell systems used in particular as auxiliary power supplies in motor vehicles or as “static power plants” usually comprise at least one fu...

AI Technical Summary

Problems solved by technology

The disadvantage here, however, is that the additional pressure gauge or Venturi introduces a considerable additional pressure loss into the recirculation line of the anode exhaust gas

Especially when you want to cover a large measuring range with a single pressure gauge: In order to achieve reliable measurement of the pressure gauge even at very low mass flows, at least a small measurable differential pressure must be obtained, which needs to be Small free-flow cross-section in the flow orifice or venturi of the piezometer, but causes considerable pressure loss in the recirculation line at large mass flows

It is also disadvantageous that such additional manometers cause additional costs and increase the space requirements of the recirculation line, especially since in most cases there is a long inflow path, which is used to ensure that the recirculation line As uniform as possible directional inflow of the manometer required to obtain reliable differential pressure measurement with the help of the Venturi tube

[0005] Another important disadvantage when using additional piezometers such as Venturi tubes is that for reliable determination of the recirculation rate in the anode cycle by means of differential pressure readings an actual knowledge of the anode exhaust gas flow through the piezometer is also required composition

Since the gas composition can only be determined with difficulty during operation, an exact determination of the recirculation rate can only be achieved with difficulty

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