Cathode Exhaust Heating for Fuel Reformer Temperature Control

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Solution Overview

Problem

Existing fuel cell devices face challenges in efficiently controlling the temperature of the reformer unit, which is crucial for optimal operation, as they rely on suboptimal methods such as direct heating or using reformed gas mixtures for temperature control, leading to inefficiencies and potential thermal power losses.

Innovation Solution

Incorporating a temperature control unit that utilizes a portion of the cathode exhaust gas from the fuel cell unit to supply thermal energy to the reformer unit through a heat exchanger, allowing for precise temperature regulation via a bypass line and control unit, thereby optimizing the thermal energy transfer and maintaining the required process temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If direct heating or reformed gas mixture is used for temperature control of the reformer unit, then the reformer unit can be heated, but thermal power losses occur and system efficiency decreases

Engineering Contradiction:
Improvereformer unit temperatureVSAvoidthermal power loss
Core Design Contradiction:
TemperatureVSLoss of energy

Solution Approach 1:

The patent converts the waste heat from cathode exhaust gas, which would otherwise be discarded, into a useful heating source for the reformer unit. The cathode exhaust gas contains significant thermal energy that is redirected through a heat exchanger to maintain reformer temperature, transforming a waste stream into a beneficial thermal source and eliminating the need for separate heating systems that would cause additional energy losses.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces a heat exchanger as an intermediary device between the cathode exhaust gas stream and the reformer unit. This intermediary enables efficient thermal energy transfer from the exhaust gas to the reformer without direct contact between the streams, allowing temperature control while maintaining system separation and preventing thermal power losses that would occur with direct heating methods.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If cathode exhaust gas is used to heat the reformer unit, then system efficiency improves, but temperature control precision may be compromised

Engineering Contradiction:
Improvethermal power lossVSAvoidtemperature control precision
Core Design Contradiction:
Loss of energyVSManufacturing precision

Solution Approach 1:

The patent implements a feedback control system with a control unit that monitors the temperature of the reformer unit and adjusts the flow of cathode exhaust gas through the bypass line accordingly. When the reformer temperature deviates from the setpoint, the control unit modulates the exhaust gas flow to restore optimal temperature, ensuring precise temperature control while continuously utilizing the thermal energy from cathode exhaust to maintain high system efficiency.

Inventive Principle:
Principle #23Feedback

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 solution enables improved temperature control of the reformer unit, enhancing the overall efficiency of the fuel cell system by utilizing thermal power losses from the fuel cell unit, ensuring consistent methane concentration and system flexibility, even under varying conditions or component degradation.

Implementation Method 1

a heat exchanger which is designed to transfer thermal energy from the portion of the cathode exhaust gas to the reformer unit

Methodology Applied
Scientific EffectHeat exchanger: Heat Exchanger

Data Source

PatentEP3316371B1Fuel cell system comprising reformer heated by cathode exhaust
Publication Date: 2023.12.20 ROBERT BOSCH GMBH
  • EP3316371B1 patent drawingFigure 1
  • EP3316371B1 patent drawingFigure 2

AI summary

The invention is based on a fuel cell device (10a; 10b) which is intended to be operated with a fluid fuel (12a; 12b), with a fuel cell unit (14a; 14b) and with a reformer unit (16a; 16b) which is provided for generating at least one fuel gas (22a; 22b). It is proposed that the fuel cell device (10a; 10b) has a temperature control unit (18a; 18b) which is provided for the reformer unit (16a; 16b) at least part (26a; 26b) of a cathode exhaust gas (20a; 20b) of the fuel cell unit (14a; 14b) for temperature control of the reformer unit (16a; 16b).