Flow switching of coolant at freeze start to support stack life and quick start

摘要

An auxiliary coolant system for a fuel cell stack system includes a reversible coolant pump, a control valve and piping. The pump allows for reversal of the coolant flow direction in the fuel cell stack system. The auxiliary coolant system is disposed in parallel with the primary coolant system and communicates through valves with the primary coolant system. At startup, as the coolant flow through the fuel cell stack system is right to left, a valve of the primary coolant system is partially open and controls the amount of cold coolant addition from the primary coolant system to the fuel cell stack while the auxiliary coolant system valve measures the temperature difference between the inlet and exhaust ports of the primary coolant system Stack controls.