Thermal management subsystem

Figure 1 provides a schematic of the gasoline fuel cell power plant. The major subsystems include the Fuel Processing Subsystem, the Power Subsystem and the Balance of Plant. The Balance of Plant includes the Thermal Management Subsystem, the Air and Water Subsystems and the Controller and associated electrical equipment. 

Thermal management subsystem The subsystem consists of a number of heat exchangers/recuperators (including steam generators) and combustors/burners to maintain the SOFC stack temperature at the required level and to control heat supply/removal for efficient operation of the fuel processor. Insulation is also an important element in thermal management of the system to contain heat losses. 

The thermal management subsystem of a SOFC system consists of (i) those components downstream of the stack whose primary functions are to react any remaining combustibles in the anode exhaust and to preheat the various streams that eventually find their way to tlie stack inlets [8, 40-42] and (ii) insulation. The primary components of this subsystem may include, but are not limited to. 

Asghari S, Akhgar H, Imani BF (2011) Design of thermal management subsystem fin a 5kW polymer electrolyte membrane fuel cell system. J Power Sources 196 3141-3148... 

Thermal Management Subsystem - Provides the heat rejection, thermal isolation, and supplemental heating needed to keep the different Reactor Module elements within temperature limits. The thermal management subsystem would include insulating materials (insulation, multi-layer blankets, spacers), surface thermo-optical materials (paints, coatings, treatments, etc), conductive and isolating materials, and probably more active elements such as heaters, temperature sensors and heat pipes. 

Mass estimates do not include the Aerothermal Protection Segment or Thermal Management Subsystem masses... 

The Thermal Management and Micrometeoroid Protection Subsystem masses are not yet known and are not included in the overall Reactor Module mass. Reference 4-10 estimates the Thermal Management Subsystem mass at 75 kg. 

The preliminary plant design assumes a thermal management subsystem which maintains the temperature of the plant components at 250-300 K from launch until startup of the power plant. 

The Project shall comply with the Prometheus Single Point Failure Policy as documented in the Prometheus Project Policies Document 982-00057. (Level 2 Requirement) Structure and thermal management subsystems must be designed with fault tolerant capacity. This would include features such as ability to react flight loads in presence of element failure (with reduced margin) and redundant heaters and temperature sensors. Micrometeoroid and orbital debris protection reduce the risk in areas where single point failure can not be eliminated, such as the pressure boundaries. 

Provide support for the thermal management subsystem (Derived from segment functional requirements) The structure subsystem must provide radiative surfaces, or accommodate external radiators. Other thermal control elements such as heaters, temperature sensors and blankets must also be accommodated. 

The reactor l C equipment would be distributed over many regions of the spacecraft, such that interrelated elements of its subsystems would often be subjected to very different thermal conditions. An understanding of the thermal elements within each zone would guide tile design and development of the l C system components and the local thermal management subsystems to ensure that the l C component thermal requirements would be met. This section presents the initial efforts to identify the thermal environments within the various regions of the spacecraft to allow the development of a rational set of requirements for the l C equipment that reside within them. 

FCS water management is the key factor for an efficient and reliable operation of a PEMFC stack. Membrane hydration control and water balance for a durable operation of FCS are the main objectives of this sub-system, whose design and control issues, strictly connected to thermal management but also to reactant subsystem components, are discussed in Sect. 4.5. The possibility of interactions between the wet and warm cathode outlet stream and the components of thermal and water management sub-systems is also discussed. 

Research, develop, assemble, and test a 50 kW net polymer electrolyte membrane (PEM) fuel cell stack system comprised of a PEM fuel cell stack and the supporting gas, thermal, and water management subsystems. The PEM fuel cell stack system will be capable of integration with at least one of the fuel processors currently under development by Hydrogen Burner Technology (HBT) and Arthur D. Little, Inc. 

In summary, each of the four subsystems described above are critical in the automotive Li-ion RESS design as all operate and function in conjunction with the other subsystems. For instance, a battery design that has an effective thermal management... 

In addition, a fuel cell power plant, depending on size, type, and sophistication, may require an oxidant subsystem, thermal and fluid management subsystems, and ether ancilliary subsystems. 

Fuel cell power systems contain an assembly of electrochemical cells, which oxidize a fuel to generate direct current electricity. Balance-of-plant subsystems may include controls, thermal management, a fuel processor, and a power conditioner. Some fuel cell power systems may contain additional power generating equipment such as steam generators, gas turbine generators, or micro-turbine generators. The net power output and all the fuel input to the system shall be taken into account in the performance test calculations. 

The next important parameter of SOFC-M operation is the temperature difference between the fuel cell stack inlet and outlet. Good thermal management of the stack is very important for the dynamic operation of the whole system—mainly start-up and shutdown of the unit. There should be little difference between those temperatures. An adequate map of performance is presented in Fig. 5.64. The stack temperature differences are relatively high (reaching values above 300°C) for low rotational speed of the gas turbine subsystem. This is due to the lower quantity of air delivered, resulting in worse cooling of the stack. 

The Plant Structure and Environmental Protection Segment provides structural support, micrometeoroid protection, and thermal management for the Space Nuclear Power Plant arrangement. It consists of three subsystems ... 

While different developers are addressing improvements in individual components and subsystems in automotive fuel cell propulsion systems (e.g., cells, stacks, fuel processors, balance-of-plant components), we are using modeling and analysis to address issues of thermal and water management, design-point and part-load operation, and component-, system-, and vehicle-level eificiencies and fuel economies. Such analyses are essential for effective system integration. 

The PEM fuel cell stack system consists of the fuel cell stack and supporting gas, thermal and water management systems as shown in Figure 1. Overall system performance depends on the careful integration of these subsystems. The system developed under this contract was designed to accept reformed gasoline from a fuel processor. Development of the fuel processor was not part of this program. 

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