Method and apparatus for controlling a combined heat and power fuel cell system
View Patent ↗A cogeneration fuel cell system and associated methods of operation are provided that accommodate a demand for heat as well as a demand for electric power. The system is operated among various modes to balance heat and power demand signals. In general, a fuel cell system is coupled to a power sink and a heat sink, and a controller is adapted to respond to data signals from the power sink and the heat sink. As examples, such data signals from the heat sink may include a temperature indication or a heat demand signal (such as from a thermostat), and such data signals from the power sink may include a voltage or current measurement, an electrical power demand signal, or an electrical load.
1. A method of operating a fuel cell system, comprising:
providing a fuel flow and an oxidant flow to a fuel cell stack to produce electricity;
providing the electricity to an electrical load;
transferring heat from the fuel cell stack to a heat sink by circulating a first coolant through a first coolant circuit, wherein the first coolant circuit is adapted to remove heat from the fuel cell stack and is further adapted to transfer heat to the heat sink;
measuring a thermal parameter of the heat sink;
generating a heat demand signal when the thermal parameter of the heat sink is below a predetermined level; and
shorting at least one fuel cell in the fuel cell stack in response to the heat demand signal.
2. The method of claim 1 , wherein the heat sink comprises a water tank, and wherein the thermal parameter is a temperature of water in the water tank.
3. The method of claim 1 , wherein the heat sink comprises air contained in a building, and wherein the thermal parameter comprises a temperature of the air contained in the building.
4. The method of claim 1 , wherein the heat sink comprises a generator portion of an adsorption cooling system and wherein the thermal parameter is a temperature of the generator portion.
5. A method comprising:
providing a reactant flow to a fuel cell stack to produce electricity;
selectively shorting at least one fuel cell of the fuel cell stack to increase a thermal output from the fuel cell stack;
transferring heat from the fuel cell stack to a heat sink;
measuring a thermal parameter of the heat sink; and
generating a heat demand signal to control shorting of said at least one fuel cell stack in response to the thermal parameter of the heat sink.
6. The method of claim 5 , wherein the heat sink comprises air contained in a building, and wherein the thermal parameter comprises a temperature of the air contained in the building.
7. The method of claim 5 , wherein the heat sink comprises a generator portion of an adsorption cooling system and wherein the thermal parameter is a temperature of the generator portion.
8. A method comprising:
providing a reactant flow to a fuel cell stack to produce electricity; and
based on a thermal parameter of a heat sink that is thermally coupled to the fuel cell stack, selectively shorting at least one fuel cell of the fuel cell stack.
9. The method of claim 8 , wherein the heat sink comprises air contained in a building, and wherein the thermal parameter comprises a temperature of the air contained in the building.
10. The method of claim 8 , wherein the heat sink comprises a generator portion of an adsorption cooling system and wherein the thermal parameter is a temperature of the generator portion.