SOFC Heat Exchanger Network for Anode Exhaust Recirculation
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Solution Overview
Problem
High-temperature SOFC systems face challenges in efficiently recirculating anode exhaust gas and maintaining optimal temperatures for blower operation due to extreme temperature ranges and varying temperature requirements, which complicates the service life and efficiency of the system.
Innovation Solution
A heat exchanger network is arranged with a first heat exchanger in the fuel supply section and a second heat exchanger in the air supply section, allowing for controlled temperature management of recirculated anode exhaust gas, reducing the need for a hot gas blower and minimizing heat loss, while introducing fresh fuel upstream of the heat exchangers to prevent condensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hot gas blowers are used to recirculate anode exhaust gas in high-temperature fuel cell systems, then fuel utilization is increased, but the service life and technical implementation become problematic due to extreme temperatures between 500°C and 1000°C
Solution Approach 1:
The heat exchanger network is divided into multiple stages with at least two heat exchangers arranged in series. The first heat exchanger performs initial cooling of the anode exhaust gas, and the second heat exchanger performs further cooling, progressively reducing the temperature to a level suitable for blower operation while maintaining efficient heat recovery
Solution Approach 2:
The heat exchanger network acts as an intermediary between the high-temperature anode exhaust gas and the recirculation blower. By introducing these heat exchangers as intermediate components, the system enables the blower to operate at safe temperatures while still handling hot gas recirculation, thus protecting the blower from thermal damage
2Reliability
If heat is extracted from anode exhaust gas to cool it for blower operation, then blower service life is improved, but the temperature control becomes complex due to varying temperature requirements in different system sections
Solution Approach 1:
The heat exchanger network is designed with adjustable parameters that allow dynamic adaptation to varying operating conditions. The system can adjust the degree of cooling and heat extraction based on real-time temperature requirements in different system sections, enabling flexible temperature control without excessive complexity
Solution Approach 2:
The heat exchanger network serves multiple functions simultaneously: it cools the anode exhaust gas for blower protection, recovers heat for system efficiency, and provides adjustable temperature control for different sections. This multi-functionality reduces the need for separate dedicated components for each function
3Measurement precision
If a heat exchanger network with multiple heat exchangers is used to control temperature, then temperature control precision is improved, but the device complexity and heat loss increase
Solution Approach 1:
The system uses at least two heat exchangers arranged in series to achieve the necessary temperature reduction, which provides sufficient cooling capacity and temperature control precision without over-engineering the system. This partial action approach achieves the required temperature precision while limiting the number of components
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
This configuration enables efficient recirculation and temperature control within the system, reducing the risk of blower damage and maintaining high fuel utilization and electrical efficiency, while allowing for flexible temperature adjustment and reduced complexity in the fuel cell system.
Implementation Method 1
a heat exchanger network is provided with at least one first heat exchanger and a second heat exchanger
Implementation Method 2
so much heat is extracted from the anode exhaust gas that the temperature of the anode exhaust gas which is to be recirculated remains at least above a condensate temperature
Implementation Method 3
a heat exchanger network is provided with at least one first heat exchanger and a second heat exchanger
Implementation Method 4
the temperature in the recirculation section and/or in the fuel supply section can be controlled
Data Source
AI summary
The invention relates to a fuel cell system (1), in particular an SOFC system, comprising at least one fuel cell stack (2) with an anode section (3) and a cathode section (4), an air supply section (5), a fuel supply section (6) and a recirculation section (7), wherein a heat exchanger network with at least one first heat exchanger (8) and a second heat exchanger (9) is provided, wherein the second heat exchanger (9) is arranged downstream of the first heat exchanger (8), wherein a cold side of the first heat exchanger (8) is arranged in the fuel supply section (6) and a cold side of the second heat exchanger (9) is arranged in the air supply section (7).The invention further relates to the use of such a fuel cell system (1).