Metal hydride-hydrogen tank system with a frost-start capability
A cold start device for an exothermic hydrogen consumer such as a fuel cell, as well as a method for operating an exothermic hydrogen consumer with a metal hydride storage system. An exothermic hydrogen consumer such as a fuel cell with an efficient cold start device which can be brought into operation rapidly and. does not require a pressure tank is provided. The cold start device is available for an unlimited number of start-up procedures. At least one starter tank is filled with a metal hydride which has an equilibrium pressure for desorption of at least 100 kPa at a temperature of −40° C., as well as at least one operating tank which is filled with at least one metal hydride, which has an equilibrium pressure of <100 kPa at temperatures of <0° C., and wherein the starter tank is incorporated into the operating tank.
1. A device for operating an exothermic hydrogen consumer, wherein the device comprises the exothermic hydrogen consumer, at least one starter tank and at least one operating tank, wherein the at least one starter tank comprises a container which is pressure-tight to hydrogen filled with a first metal hydride which is incorporated into the operating tank, wherein the first metal hydride has an equilibrium pressure for the desorption of hydrogen of at least 100 kPa at a temperature of −40° C., and wherein the at least one operating tank comprises a container which is pressure-tight to hydrogen filled with a second metal hydride, wherein the second metal hydride has an absolute value for the reaction enthalpy for the hydrogen absorption reaction (|ΔH abs |) of less than 65 kJ/mol H 2 and has an equilibrium pressure for the desorption of hydrogen of less than 100 kPa at a temperature of −40° C.
2. The device as claimed in claim 1 , wherein the exothermic hydrogen consumer is a fuel cell.
3. The device as claimed in claim 1 , wherein the starter tank is completely encased by the operating tank.
4. The device as claimed in claim 1 , wherein the starter tank comprises a metal hydride which has an equilibrium pressure for desorption of hydrogen of at least 300 kPa at a temperature of −40° C.
5. The device as claimed in claim 4 , wherein the starter tank comprises a metal hydride which has an equilibrium pressure for desorption of hydrogen of at least 1000 kPa at a temperature of −40° C.
6. The device as claimed in claim 5 , wherein the starter tank comprises a metal hydride which has an equilibrium pressure for desorption of hydrogen of at least 1300 kPa at a temperature of −40° C.
7. The device as claimed in claim 1 , wherein the metal hydride of the starter tank is a titanium-chromium-manganese-based alloy.
8. The device as claimed in claim 1 , wherein the second metal hydride of the operating tank has an absolute value for the reaction enthalpy for the hydrogen absorption reaction (|ΔH abs |) of between 20 kJ/mol H 2 and less than 65 kJ/mol H 2 .
9. The device as claimed in claim 1 , wherein cooling of the starter tank is carried out by means of a Peltier element or by means of compressor-based cooling.
10. A method for operating an exothermic hydrogen consumer, wherein the exothermic hydrogen consumer is initially supplied with hydrogen from at least one starter tank and which comprises a first metal hydride which has an equilibrium pressure for desorption of hydrogen of at least 100 kPa at a temperature of −40° C., and after reaching the operating temperature, the fuel cell is supplied with hydrogen from at least one operating tank which comprises at least one second metal hydride which has an absolute value for the reaction enthalpy (|ΔH abs |) for the hydrogen absorption reaction of less than 65 kJ/mol H 2 and has an equilibrium pressure for the desorption of hydrogen of less than 100 kPa at a temperature of −40° C., and the starter tank is cooled when the supply for the exothermic hydrogen consumer from a second operating tank commences, and the starter tank is recharged with hydrogen from the at least one operating tank, wherein the starter tank is incorporated into the at least one operating tank and is separated therefrom by a wall which is pressure-tight to hydrogen, so that the first metal hydride is insulated from environmental heat as soon as the starter tank is charged with hydrogen from the at least one operating tank.
11. The method as claimed in claim 10 , wherein the exothermic hydrogen consumer is a fuel cell.
12. The method as claimed in claim 10 , wherein the starter tank comprises a metal hydride which has an equilibrium pressure for desorption of hydrogen of at least 300 kPa at a temperature of −40° C.
13. The method as claimed in claim 10 , wherein the metal hydride of the starter tank is a titanium-chromium-manganese-based alloy.
14. The method as claimed in claim 10 , wherein cooling of the first metal hydride storage system is carried out by a Peltier element or by compressor-based cooling.
15. The method as claimed in claim 10 wherein, when supplying the exothermic hydrogen consumer by means of the at least one operating tank, the exhaust heat from the exothermic hydrogen consumer is used to maintain the at least one operating tank at the desorption temperature.
16. The device as claimed in claim 1 , wherein the exothermic hydrogen consumer is a PEM fuel cell.
17. The method as claimed in claim 10 , wherein the exothermic hydrogen consumer is a PEM fuel cell.