Fuel Cell Calorific Value Estimation via Cell Voltage Segmentation
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Solution Overview
Problem
Existing fuel cell systems inaccurately reflect the actual calorific value when determining coolant flow rates, leading to ineffective coolant flow adjustments, especially during low-temperature operations where power generation reactions do not occur in all cells.
Innovation Solution
A fuel cell system with sensors to detect current and cell voltage, a controller that estimates calorific value by considering the number of cells not generating heat, and adjusts coolant flow rates based on this estimation to accurately reflect the actual calorific value, using a map or ratio to correct the reference calorific value for more precise flow rate control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the calorific value is decided by using the total voltage value and current value of the fuel cell, then the calculation is simple, but the decided calorific value may be significantly different from the actual calorific value
Solution Approach 1:
The patent segments the fuel cell into individual cells and further into active and inactive regions within each cell. By detecting cell voltage at multiple positions and comparing with threshold values, the system identifies which regions are actively generating power versus which are inactive, allowing for a segmented calculation of calorific value that reflects the actual distribution of power generation activity.
Solution Approach 2:
The patent applies local quality by recognizing that different regions of the fuel cell have different operational states. Instead of treating the entire cell as uniform, the system identifies specific local regions where power generation reactions are occurring versus where they are not, based on local voltage measurements. This allows the calorific value calculation to account for spatial variations in activity across the cell surface.
2Device complexity
If the flow rate of coolant is adjusted based on inaccurate calorific value, then the control system is simple, but the coolant flow rate adjustment does not accurately reflect actual heat generation
Solution Approach 1:
The patent implements feedback by continuously monitoring cell voltage at multiple positions and using this information to dynamically adjust the coolant flow rate. The system compares detected voltages with threshold values to determine active versus inactive regions, calculates the actual calorific value based on this segmented information, and then adjusts the coolant flow accordingly. This closed-loop feedback ensures the coolant flow rate accurately reflects real-time heat generation conditions.
Solution Approach 2:
The patent applies dynamics by making the coolant flow rate adjustable and adaptive rather than fixed. The circulation pump's flow rate is dynamically modified based on real-time detection of cell voltage distribution and calculated calorific value. This allows the system to respond to changing operational conditions, ensuring optimal cooling performance under varying load and temperature conditions.
3Use of energy by moving object
If coolant flow rate is reduced to prevent refreezing in low temperature operation, then energy consumption is reduced, but inaccurate calorific value estimation leads to insufficient or excessive flow rate adjustment
Solution Approach 1:
The patent applies preliminary action by proactively identifying inactive cell regions before they cause problems. By continuously monitoring cell voltage and comparing with thresholds, the system detects which regions are not generating power and would otherwise contribute to inaccurate calorific value estimation. This early detection allows the system to pre-adjust the coolant flow rate to match actual heat generation, preventing both refreezing and overheating conditions before they occur.
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 approach ensures accurate coolant flow rate adjustments that reflect the actual calorific value, preventing coolant refreezing and maintaining efficient power generation by accounting for cells not participating in power generation reactions.
Implementation Method 1
a fuel cell in which cells of a plurality of cells are stacked
Implementation Method 2
The circulation pump is disposed in the external flow path and configured to adjust a flow rate of the cooling medium
Implementation Method 3
The circulation flow path of a cooling medium has an internal flow path that is formed inside the fuel cell and an external flow path that is connected to the internal flow path and formed outside the fuel cell
Data Source
AI summary
A fuel cell system includes a fuel cell a current sensor that detects a current of the fuel cell, a plurality of cell voltage sensors that detects a voltage in a unit of one or two or more cells of the fuel cell among the cells, a pump that adjusts a flow rate of the cooling medium, and a controller. The controller estimates, in a first case, a calorific value of the fuel cell using each detected cell voltage value and the detected current value, decides the flow rate of the cooling medium based on the estimated calorific value, and controls the operation of the pump such that the flow rate of the cooling medium is lower than that of a case where the estimated calorific value is the same in a normal operation of the fuel cell.