Abstract: Methods and system for operating a thermal storage device of a vehicle system are provided. In one example, a method comprises determining a state of charge of the thermal battery based on an accurate estimation of a melting temperature of one or more phase change materials (PCMs) at a specific aggregate pressure inside the thermal storage device. Variation in melting temperature of the PCM may be minimized by reducing pressure variation inside the thermal storage device by regulating a position of one or more pressure relief valves of the thermal storage device.

Abstract: Fuel-cell thermal management systems and control schemes therefore are disclosed. In one embodiment, the system may include a fuel-cell stack, a heat-exchanger, a thermal battery including a material having a melting temperature of 50-120° C., a first coolant loop including the fuel-cell stack and the thermal battery and excluding the heat-exchanger, and a second coolant loop including the fuel-cell stack, the thermal battery, and the heat-exchanger. The first and second coolant loops may be configured to heat and cool the fuel-cell stack, respectively. The system may include a controller or processor configured to direct coolant to transfer heat from the thermal battery to the fuel-cell stack based on a negative heat rejection status of the fuel-cell stack and to transfer heat from the fuel-cell stack to the thermal battery based on a positive heat rejection status of the fuel-cell stack when the thermal battery is below a target temperature.

Abstract: Methods and system for operating a thermal storage device of a vehicle system are provided. In one example, a method comprises estimating a temperature of a thermal battery after the battery and coolant included therein have reached thermal equilibrium, and determining a state of charge of the battery based on the estimated temperature and one or more chemical properties of two phase change materials included within the battery. Specifically, the thermal battery may include two phase change materials with different melting points for providing thermal energy to warm coolant in a vehicle coolant system.

Abstract: Methods and systems are provided for regulating the temperature of rear axle lubrication oil. In one example, a rear axle coolant system may include a coolant loop with a plurality of valves and sensors, regulating the coolant flow in heat exchange relationship with an exhaust gas heat recovery and storage system to deliver warm coolant to a rear axle heat exchanger to warm the rear axle lubrication oil. The method may regulate the components of the rear axle coolant system through a controller, receiving sensor input from the components of the coolant system.