Systems and methods for starting and operating fuel cell systems in subfreezing temperatures

A fuel cell system, comprising:

• a fuel cell stack configured to produce an electrical output from a fuel and an oxidant;
• a thermal management system configured to selectively deliver a heat exchange fluid stream containing a liquid heat exchange fluid to the fuel cell stack, wherein the thermal management system comprises:
• a liquid reservoir;
• a volume of liquid heat exchange fluid within the liquid reservoir;
• a heat exchange circuit fluidly interconnecting the fuel cell stack and the liquid reservoir and including a plurality of fluid conduits, wherein the plurality of fluid conduits includes a delivery conduit through which liquid heat exchange fluid may flow from the liquid reservoir to the fuel cell stack, at least one fuel cell heat exchange conduit through which liquid heat exchange fluid may flow in thermal communication with the fuel cell stack, and a return conduit through which a recycle stream of the liquid heat exchange fluid may flow from the fuel cell stack to the liquid reservoir;
• a delivery mechanism configured to selectively propel the liquid heat exchange fluid within the heat exchange circuit;
• and
• wherein the thermal management system includes a drainage assembly that is configured to automatically withdraw liquid heat exchange fluid from the heat exchange circuit when the thermal management system is not being used to deliver the heat exchange fluid stream to the fuel cell stack, wherein the liquid reservoir is positioned relative to the fuel cell stack so that liquid heat exchange fluid automatically drains from the fuel cell stack to the liquid reservoir when the delivery mechanism is not being used to propel the liquid heat exchange fluid from the liquid reservoir to the fuel cell stack.