Fuel Cell Recirculation Heat Exchanger Segmentation
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Solution Overview
Problem
Existing fuel cell systems face challenges in increasing efficiency and extending the service life of components, particularly in the reforming process and heat management.
Innovation Solution
The integration of a recirculation heat exchanger to preheat oxidant gas for both the fuel cell and reformer, combined with a residual gas burner to utilize unconverted fuel gas, and the use of heat exchangers to optimize heat transfer and component protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the recirculation heat exchanger is integrated into the first oxidizer line, then the oxidant gas fed to the fuel cell is preheated, but the reformer process efficiency is not optimized
Solution Approach 1:
The oxidizer supply system is segmented into two separate lines: the first oxidizer line supplies preheated oxidant gas to the fuel cell, while the second oxidizer line supplies oxidant gas to the reformer. This segmentation allows independent optimization of each process, enabling the reformer to receive oxidant gas at the appropriate temperature for efficient reforming while the fuel cell receives preheated oxidant gas.
Solution Approach 2:
Different temperature qualities of oxidant gas are provided to different components: the fuel cell receives preheated oxidant gas through the first oxidizer line, while the reformer receives oxidant gas through the second oxidizer line at a temperature suitable for the reforming process. This local quality differentiation optimizes both processes simultaneously.
2Productivity
If the recirculated anode waste gas is not cooled, then the reforming process can utilize the hot gas, but heat-sensitive components downstream are damaged
Solution Approach 1:
The recirculation heat exchanger acts as an intermediary between the hot anode waste gas and the components downstream in the recirculation line. It transfers heat from the anode waste gas to the oxidant gas in the first oxidizer line, thereby cooling the anode waste gas to protect heat-sensitive components while maintaining the reforming process efficiency.
3Productivity
If the oxidant gas for the reformer is not preheated, then the reforming process efficiency decreases, but the system complexity increases
Solution Approach 1:
The recirculation heat exchanger serves multiple functions: it preheats the oxidant gas for the fuel cell, cools the recirculated anode waste gas, and indirectly supports the reforming process by enabling efficient heat recovery. This multi-functionality achieves reformer oxidant gas preheating without adding significant system complexity.
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 enhances the efficiency of the fuel cell system by improving the reforming process, protecting heat-sensitive components, and increasing energy yield through effective heat management and gas recirculation.
Implementation Method 1
a recirculation heat exchanger, which is integrated on the one hand in the first oxidizer line and on the other hand in a recirculation line
Implementation Method 2
the oxidizer gas fed to the fuel cell being preheated and the recirculated anode waste gas being cooled at the same time via the recirculation heat exchanger
Implementation Method 3
the oxidizer gas fed to the fuel cell being preheated and the recirculated anode waste gas being cooled at the same time via the recirculation heat exchanger
Implementation Method 4
The residual gas burner can be used to convert fuel gas that is present in the anode waste gas and has not been converted in the fuel cell
Implementation Method 5
a heat exchanger or main heat exchanger can be arranged in the fuel cell exhaust gas line downstream of the residual gas burner, which heat exchanger is also integrated into the first oxidizer line. With the help of this main heat exchanger, the heat contained in the exhaust gas of the residual gas burner can be used to heat up the oxidizer gas fed to the fuel cell
Data Source
Figure 1
Figure 2
AI summary
The system has a fuel cell (2) for producing electric current from oxidizer gas and fuel gas, and a reformer (3) for producing a fuel gas from an oxidizer and a fuel. A fuel cell exhaust gas line (30) is attached to a cathode outlet (7) and an anode outlet (5) over a cathode exhaust gas line (27) and an anode exhaust gas line (28), respectively. A recirculation heat-exchanger (35) is integrated into an oxidizer line (20) or into a common oxidizer supply line (22) for supply of oxidizer lines (18, 20) with oxidizer gas.