Method and apparatus for controlling a combined heat and power fuel cell system

Abstract

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 comprising: 
 operating a fuel cell stack to generate fuel cell heat;    circulating a coolant between a fuel cell stack and a coolant reservoir to remove a    portion of the fuel cell heat;    circulating the coolant through a heat sink to transfer heat from the coolant to the heat sink when a temperature of the coolant is greater than a temperature of the heat sink;    fixing an end plate of the fuel cell stack to a surface of the coolant reservoir; and    transferring heat from the end plate to the coolant reservoir when a temperature of the end plate is greater than a temperature of the coolant reservoir.    
   
   
       2 . The method of  claim 1 , wherein the coolant reservoir comprises a thermally insulated portion and a thermally isolated portion, and the act of fixing comprises fixing the fuel cell plate to the thermally conductive portion.  
   
   
       3 . A method comprising: 
 operating a fuel cell stack to generate fuel cell heat;    circulating a coolant between a fuel cell stack and a coolant reservoir to remove a    portion of the fuel cell heat;    circulating the coolant through a heat sink to transfer heat from the coolant to the heat sink when a temperature of the coolant is greater than a temperature of the heat sink;    fixing a water tank to a surface of the coolant reservoir; and    transferring heat from the water tank to the coolant reservoir when a temperature of the fuel cell plate is greater than a temperature of the coolant.    
   
   
       4 . The method of  claim 3 , wherein the coolant reservoir comprises a thermally insulated portion and a thermally isolated portion, and the act of fixing comprises fixing the water tank to the thermally conductive portion.  
   
   
       5 . A method comprising: 
 operating a fuel cell stack to generate fuel cell heat;    circulating a coolant between a fuel cell stack and a coolant reservoir to remove a    portion of the fuel cell heat;    circulating the coolant through a heat sink to transfer heat from the coolant to the heat sink when a temperature of the coolant is greater than a temperature of the heat sink;    fixing a blower to a surface of the coolant reservoir; and    transferring heat from the blower to the coolant reservoir when a temperature of the fuel cell plate is greater than a temperature of the coolant.    
   
   
       6 . The method of  claim 5 , wherein the coolant reservoir comprises a thermally insulated portion and a thermally isolated portion, and the act of fixing comprises fixing the blower to the thermally conductive portion.