Device and method for determining the operating parameters of individual fuel cells or short stacks of fuel cells

Abstract

The invention relates to a device and a method for determining the operating parameters of individual cells or short stacks of fuel cells, preferably of medium-temperature or high-temperature fuel cells.

1 - 39 . (canceled) 
     
     
         40 . A method for determining the operating parameters of single fuel cells or of short stacks of fuel cells, wherein in parallel with the fuel cell plane planar heating elements are pressed against one or preferably both exterior surfaces of the single cell or the short stack, a predetermined temperature T H  is set for the fuel cell by means of the heating elements and at least one operating parameter of the fuel cell is measured as a function of the chosen temperature T H . 
     
     
         41 . The method according to  claim 40 , wherein a temperature curve or a temperature gradient over time is applied under which different operational states of the fuel cell, such as start-up, change of load or continuous operation, are simulated. 
     
     
         42 . The method according to  claim 40 , wherein by partitioning of the planar heating elements into individual, separately controllable segments a two-dimensional temperature distribution or temperature gradient is applied. 
     
     
         43 . The method according to  claim 40 , wherein by a cyclical application of extreme temporal and/or areal temperature gradients an accelerated aging process of the fuel cell is simulated. 
     
     
         44 . The method according to  claim 40 , wherein electrochemical parameters of the fuel cell, which are obtained from simulation models or model computations, are compared to measured values of these parameters and the simulation models are adapted accordingly. 
     
     
         45 . The method according to  claim 40 , wherein the temperature T Z  in the fuel cell and the temperature T H  in the heating element or in the individual heating element segments are measured and the temperature T H  in the heating element is regulated in such a way that the heating power of an adjacent neighbour cell is simulated. 
     
     
         46 . The method according to  claim 40 , wherein the temperature T Z  of the fuel cell is additionally set or varied by applying or removing exterior insulating elements or by active cooling elements. 
     
     
         47 . A device for determining the operating parameters of single cells or of short stacks of fuel cells, wherein in parallel with the fuel cell plane planar heating elements are placed at one or preferably both exterior surfaces of the single cell or the short stack, which heating elements are connected to a control and evaluation unit for setting a predetermined temperature. 
     
     
         48 . The device according to  claim 47 , wherein temperature sensors are located in each single cell and in the heating elements, which sensors are connected to a control loop in the control and evaluation unit. 
     
     
         49 . The device according to  claim 47 , wherein each of the heating elements is partitioned into multiple, separately controllable segments. 
     
     
         50 . The device according to  claim 49 , wherein thermally insulating elements are placed between the heating element segments located at an exterior surface of the single cell. 
     
     
         51 . The device according to  claim 47 , wherein the heating elements or their segments are provided with detachable, exterior insulating elements. 
     
     
         52 . The device according to  claim 51 , wherein the exterior insulating elements and/or the insulating elements located between the heating element segments are provided with active cooling elements, for instance heat exchangers for a cooling medium. 
     
     
         53 . The device according to  claim 47 , wherein a thin thermally insulating intermediary layer is placed between the exterior surfaces of the single cell and the heating elements or heating element segments. 
     
     
         54 . The device according to  claim 53 , wherein a current collector with areally distributed contact sites is located in the insulating intermediary layer. 
     
     
         55 . The device according to  claim 54 , wherein the current collector is partitioned into a number of separately contacted segments. 
     
     
         56 . The device according to  claim 47 , wherein a clamping mechanism is provided for pressing the heating elements against the exterior surfaces of the single cell or the short stack and/or against the exterior insulation elements and/or the thermally insulating intermediary layer. 
     
     
         57 . The device according to  claim 56 , wherein the hermetic seal for the gas connections and the electrical connections of the single cell or the short stack are provided by means of the pressure exerted by the clamping mechanism. 
     
     
         58 . The device according to  claim 47 , wherein the control and evaluation unit comprises means for determining at least the temperature, the current and voltage values, the composition of the process gases, the pressure of the process gases, and the useful life of the fuel cell.