Steam Ejector Fuel Cell Stack Heat Recovery for Anode Gas Reuse
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Solution Overview
Problem
Existing fuel cell systems face inefficiencies in using energy from raw fuels due to the need for auxiliary motive power sources and wastage of combustion heat when using steam as a drive fluid.
Innovation Solution
A fuel cell system that includes a reformer, a fuel cell stack, an ejector using steam as a drive fluid, and a vaporizer generating steam through heat exchange with anode exhaust gas, optimizing energy use and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a source gas pump is used to suck anode exhaust gas, then the gas can be circulated and reused, but an auxiliary motive power source is needed which decreases system efficiency
Solution Approach 1:
The anode exhaust gas itself is used to drive the ejector, creating a self-service system where the waste gas provides the motive power needed for its own circulation and reuse, eliminating the need for external auxiliary power sources
Solution Approach 2:
The mechanical source gas pump is replaced with a thermodynamic ejector system that uses steam generation and expansion to achieve gas suction and circulation, substituting mechanical work with thermal energy conversion
2Quantity of substance
If combustion heat of anode exhaust gas is used to generate steam as drive fluid, then steam can be produced for the ejector, but the combustion heat is wasted and energy utilization decreases
Solution Approach 1:
The waste heat in the anode exhaust gas, which would normally be discarded, is converted into a useful resource by using it to generate steam that drives the ejector, transforming a harmful waste product into a beneficial drive fluid
Solution Approach 2:
The temperature parameter of the anode exhaust gas is utilized by passing it through the vaporizer where its thermal energy is transferred to water, changing the water from liquid to steam phase while cooling the exhaust gas
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively uses energy from raw fuels, enhancing efficiency by generating steam through heat exchange with anode exhaust gas, thereby reducing the need for auxiliary power and minimizing heat wastage.
Implementation Method 1
a vaporizer which generates the steam by vaporizing water, wherein an operation temperature of the fuel cell stack is higher than a boiling point of water at an operation pressure, and the vaporizer generates the steam through heat exchange with the anode exhaust gas
Implementation Method 2
the vaporizer generates the steam through heat exchange with the anode exhaust gas
Implementation Method 3
an ejector which, using, as a drive fluid, steam to be used as the moisture, sucks either a raw fuel containing the hydrocarbon or a recycled gas recovered from an anode exhaust gas, and supplies a resultant gas to the reformer
Implementation Method 4
a fuel cell stack which generates electric energy through electrochemical reaction of the reformed gas and an oxidant separated from each other at an anode and a cathode
Implementation Method 5
a reformer which generates a reformed gas containing hydrogen by reacting hydrocarbon and moisture with each other
Data Source
AI summary
A fuel cell system includes: a reformer which generates a reformed gas containing hydrogen by reacting hydrocarbon and moisture with each other; a fuel cell stack which generates electric energy through electrochemical reaction of the reformed gas and an oxidant; an ejector which, using steam as a drive fluid, sucks either a raw fuel containing the hydrocarbon or a recycled gas recovered from an anode exhaust gas, and supplies a resultant gas to the reformer; and a vaporizer which generates the steam by vaporizing water, wherein an operation temperature of the fuel cell stack is higher than a boiling point of water at an operation pressure, and the vaporizer generates the steam through heat exchange with the anode exhaust gas.