VCHP Heat Exchanger for Passive Thermal Management of a Fuel Cell Reforming Process

A key component of the Navy fuel cell system is the reformer, which converts diesel fuel into methane for consumption by the fuel cell. Reaction temperatures are critical to proper function of the reformer. Reaction temperatures are currently regulated by valves in the process gas streams. These valves require power, consume space, increase pressure drop, and are hindering tight integration and packaging of the reformer. In addition, these valves are prone to failure at elevated temperatures. Advanced Cooling Technologies, Inc. (ACT) has proposed a variable conductance heat pipe (VCHP) heat exchanger to provide a passive, valve-less means of regulating process gas temperatures in reformers for fuel cells. The VCHP-based system has the potential to provide nearly constant reformer temperatures despite wide changes in gas flow rate while needing no additional components or control systems and without limiting packaging options for the reformer. In Phase I, ACT successfully demonstrated the feasibility of the proposed technology through analysis and subscale hardware testing. In Phase II, the goal is to fully characterize and evaluate the use of VCHPs in heat exchangers to control gas temperatures, culminating in building a 4kW VCHP heat exchanger for use in a 50kW fuel cell system.