Method for model-based operation of a coolant system, control unit and fuel cell system

A non-transitory, computer-readable medium comprising instructions which, when executed by a computer, cause the computer to control operation of an electrochemical energy converter or an electrolyzer, by

• determining a temperature range (T1(i), T2(i)) for at least one subsystem of a coolant system (10),
• approximating a temperature-dependent specific heat capacity (cp(T)) of a coolant in the at least one subsystem of the coolant system (10) for the determined temperature range (T1(i), T2(i)),
• determining a specific enthalpy (h) of the coolant as a function (h(T)) of a temperature (T) based on the approximation, and
• operating the coolant system (10) based on the determination.

A control unit (110), comprising a memory in which a code is stored, and a computer, wherein when the code is executed by the computer, the computer controls operation of an electrochemical energy converter or an electrolyzer, by

• determining a temperature range (T1(i), T2(i)) for at least one subsystem of a coolant system (10),
• approximating a temperature-dependent specific heat capacity (cp(T)) of a coolant in the at least one subsystem of the coolant system (10) for the determined temperature range (T1(i), T2(i)),
• determining a specific enthalpy (h) of the coolant as a function (h(T)) of a temperature (T) based on the approximation, and
• operating the coolant system (10) based on the determination.