System for protecting a fuel cell from cold temperatures
A protection system for a fuel cell is provided that has two different modes of operation. The protection system includes a fuel cell, a cooling system for the fuel cell that controls the temperature of the fuel cell responsive to a controller. The controller is operable in a first mode of operation when a time T for the next start-up is not known and a second mode of operation when the time T for the next start-up is known. In the first mode, a time T F is the time an estimated future ambient temperature is estimated to fall to near freezing wherein at T F the cooling system purges the fuel cell. In the second mode, at T F the cooling system turns on without starting the fuel cell. The controller turns of the cooling system when the fuel cell stack is warmed to a nominal temperature.
1 . A protection system for a fuel cell comprising:
a fuel cell stack;
a cooling system for the fuel cell stack that controls a temperature of the fuel cell; and
a controller operable when a time T for a next start-up is known and a time T F that an estimated future ambient temperature is estimated to fall to near freezing before T, at T F the cooling system is turned on without starting the fuel cell stack, wherein the controller is programmed to estimate a time Y 1 required for a fuel cell stack temperature to fall to near freezing, and estimate a time Y 2 required for the fuel cell stack to drop from fully warmed to near freezing, and wherein T must be less than sum of Y 1 +Y 2 , before the cooling system is turned on without starting the fuel cell.
2 . The protection system for a fuel cell of claim 1 , wherein the controller is operable in a second mode when the time T of the next start-up is not known, wherein when T F is estimated to fall to near freezing, at T F the cooling system purges the fuel cell stack.
3 . The protection system for a fuel cell of claim 2 wherein the cooling system purges the fuel cell stack by blowing heated air through the fuel cell stack to remove water from the fuel cell stack.
4 . The protection system for a fuel cell of claim 1 , wherein T F is selected from one of the following sources:
a temperature sensor;
a temperature data source; and
a manual input from a user.
5 . The protection system for a fuel cell of claim 1 , wherein the controller turns off the cooling system after the cooling system is turned on without starting the fuel cell stack and coolant is warmed to a predetermined level.
6 . A protection system for a fuel cell comprising:
a fuel cell stack;
a cooling system for the fuel cell that controls a temperature of the fuel cell; and
a controller operable in a first mode of operation when a time T for a next start-up is not known and a second mode of operation when the time T for the next start-up is known, wherein in the first mode and a time T F is the time an estimated future ambient temperature is estimated to fall to near freezing, at T F the cooling system purges the fuel cell, and in the second mode at T F the cooling system turns on without starting the fuel cell, wherein the controller is programmed to estimate a time Y 1 required for a fuel cell stack temperature to fall to T F , and estimate a time Y 2 required for the fuel cell stack temperature to drop from fully warmed to T F , and wherein T must be less than a sum of Y 1 +Y 2 , before the cooling system is turned on without starting the fuel cell.
7 . The protection system for a fuel cell of claim 6 wherein the cooling system purges the fuel cell by blowing heated air through the through the fuel cell stack to remove water from the fuel cell stack.
8 . The protection system for a fuel cell of claim 6 wherein T F is based upon one of the following sources:
a temperature sensor;
a temperature data source; and
a manual input from a user.
9 . A protection system for a fuel cell comprising:
a fuel cell stack;
a cooling system for the fuel cell that controls a temperature of the fuel cell stack when operating and warms the fuel cell stack for start-up, and
a controller programmed to—
shutdown the fuel cell stack when requested,
store a predicted start-up time T,
store an ambient temperature value;
estimate a time Y 1 required for the fuel cell stack temperature to fall to a selected near freezing fuel cell temperature,
estimate a time Y 2 required for the fuel cell stack to drop from fully warmed to the selected near freezing fuel cell temperature, and
start the cooling system when T is known and Y 1 <T and T<Y 1 +Y 2 .
10 . The protection system for a fuel cell of claim 9 , wherein the controller is operable in a second mode when the time T of the next start-up is not known, the controller estimates a time T F that is an estimated time that an ambient temperature is estimated to fall to near freezing, the cooling system purges the fuel cell.
11 . The protection system for a fuel cell of claim 9 wherein the cooling system purges the fuel cell by blowing heated air through the through the fuel cell stack to remove water from the fuel cell stack.
12 . The protection system for a fuel cell of claim 9 wherein T F is estimated based upon one of the following sources:
a temperature sensor;
a temperature data source; and
a manual input from a user.
13 . The protection system for a fuel cell of claim 9 wherein the controller turns the cooling system off when a nominal temperature is reached.
14 . The protection system for a fuel cell of claim 9 wherein the controller turns the cooling system off when T<Y 1 +Y 2 .