Heat exchanger

Abstract

A heat exchanger (50) is provided for transferring heat between first and second fluids (52) and (54) having a maximum operating mass flow rate through the heat exchanger (50) and mass flow rates that are substantially proportional to each other. The heat exchanger (50) provides essentially constant outlet temperatures for the first and second fluids (52,54) for all of the flow rates within the operating spectrum of the heat exchanger (50) without the use of an active control system. The heat exchanger (50) is of particular use in the fuel processing system (36) of proton exchange membrane type fuel cell systems.

Description

FIELD OF THE INVENTION [0001] This invention relates to heat exchangers in general and in more particular applications, to recuperative heat exchangers which find many uses in industry, including in fuel cell systems. BACKGROUND OF THE INVENTION [0002] Heat exchangers that transfer heat from one fluid flow to another fluid flow and wherein the mass flow rates of each of the fluid flows are substantially proportional to each other are known. Perhaps the most common example of such heat exchangers are recuperative heat exchangers that recoup or recover useful heat from the working fluid of a system as the working fluid flows through the system. One example of such a recuperative heat exchanger can be found in the fuel processing system of proton exchange membrane (PEM) type fuel cell systems. In typical fuel cell systems, a fuel, such as methane or a similar hydrocarbon, is used as the source of hydrogen for the fuel cell. This hydrocarbon must be reformed within the system prior to r...

AI Technical Summary

Benefits of technology

"The invention provides a new and improved heat exchanger for use in fuel cell systems. The heat exchanger is designed to transfer heat between two fluids with specific mass flow rates through the exchanger. The first and second fluids have mass flow rates that are proportional to each other. The heat exchanger includes a stack of heat exchange units or a plurality of tubes, plates, or fins. The method of operating the heat exchanger involves flowing the fluids through the heat exchanger in a specific order to achieve the desired temperature ranges for the system without the need for an active control system. The invention also includes a recuperative heat exchanger that is integrated with an auto-thermal reformer and a water-gas shift reactor, providing a more efficient and compact fuel processing system for fuel cell systems."

Problems solved by technology

For example, the use of an active control system may add cost and complexity to such systems, while reducing the reliability of such systems.

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