Patent attributes
An operating method is provided for a cryopressure tank in which cryogenic hydrogen for supplying a motor vehicle fuel cell can be stored under supercritical pressure at 13 bar or more. In order to compensate the pressure drop resulting from removal of hydrogen from the cryopressure tank, either a heat transfer medium is supplied to a heat exchanger provided in the cryopressure tank via a control valve over a period of time which significantly exceeds the cycle times of a conventional cycle valve or the heat transfer medium is not supplied to the heat exchanger. Depending on the fill level of the cryopressure tank, the control valve is actuated with respect to a desired temperature or a desired pressure of the hydrogen in the cryopressure tank. As long as there is a risk of liquefaction of the residual hydrogen in the cryopressure tank, as is the case when the temperature falls below the critical temperature of 33 K if the pressure drops below the critical pressure of approximately 13 bar, during the removal of cryogenic hydrogen from the cryopressure tank, the temperature is adjusted such that it does not drop below the critical temperature of 33 Kelvin. If the fill state in the cryopressure tank drops further, the pressure in the cryopressure tank is adjusted when there is no longer a risk of liquefaction such that the pressure does not drop below a minimum pressure value which the hydrogen that is removed from the cryopressure tank must have in order to be usable in the consumer without restricting the function thereof.
