Fuel Cell Cooling System Ion Control via Segmented Flow Paths
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Solution Overview
Problem
In fuel cell systems, prolonged shutdowns lead to increased ion elution from the heat exchanger into the cooling medium, enhancing its electrical conductivity and potentially causing electric leakage when reintroduced, which existing cooling medium circulation systems fail to effectively manage.
Innovation Solution
A fuel cell system with a cooling medium circulation system that includes a radiator, a bypass flow path with an ion exchanger, and a controller to regulate the flow rate ratio by adjusting the flow dividing valve's opening position based on conductivity measurements to maintain the electrical conductivity of the supply cooling medium below a target level, thereby preventing electric leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cooling medium is circulated through the radiator for cooling, then the fuel cell temperature is maintained, but ions are eluted from the heat exchanger into the cooling medium, increasing electrical conductivity and causing electric leakage
Solution Approach 1:
The cooling medium circulation system is divided into two separate flow paths: a first flow path for cooling (through the radiator) and a second flow path for ion removal (through the ion exchanger). This segmentation allows the system to independently address temperature control and ion removal, preventing ion elution from causing electric leakage while maintaining effective cooling.
Solution Approach 2:
The ion exchanger acts as an intermediary component in the second flow path, specifically removing ions from the cooling medium that have been eluted from the heat exchanger. This intermediary mechanism addresses the harmful effect of ion elution without interfering with the primary cooling function, thereby preventing electric leakage while maintaining system reliability.
2Reliability
If a preliminary washing process is performed on the radiator to remove ions, then electric leakage is prevented, but system complexity and cost increase
Solution Approach 1:
Instead of performing a one-time preliminary washing process, the system continuously removes ions from the cooling medium through the ion exchanger in the second flow path. This continuous action ensures ions are removed as they are eluted, maintaining reliable operation without requiring additional complexity from preliminary washing procedures.
Solution Approach 2:
The ion exchanger automatically removes ions from the cooling medium as it flows through the second flow path, providing self-service ion removal without requiring external intervention or complex preliminary washing processes. The system maintains itself by continuously treating the cooling medium.
3Temperature
If the flow rate through the radiator is increased for better cooling, then temperature control improves, but more ions are eluted into the cooling medium
Solution Approach 1:
The system segments the cooling medium flow into two paths, allowing the first flow path to handle high flow rates for effective cooling while the second flow path independently removes the ions that are inevitably eluted. This segmentation decouples the relationship between cooling efficiency and ion concentration.
Solution Approach 2:
The ion exchanger serves as an intermediary that specifically targets and removes ions from the cooling medium, allowing the system to increase flow rates through the radiator for better cooling without concern for ion elution, as the ions are continuously removed by the ion exchanger in the parallel second flow path.
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 effectively reduces the risk of electric leakage by controlling the electrical conductivity of the cooling medium supplied to the fuel cell, even after prolonged shutdowns, without requiring a preliminary washing process for the radiator, thus reducing costs and maintaining system efficiency.
Implementation Method 1
an ion exchanger provided in the bypass flow path
Implementation Method 2
a radiator configured to release heat of a cooling medium that is used to cool down the fuel cell
Data Source
AI summary
When a time period from a stop to a start of a fuel cell system exceeds a predetermined time period, a controller of the fuel cell system obtains a first electrical conductivity of a cooling medium that is placed from a radiator to before a connecting location of one end portion in a cooling medium circulation flow path and a second electrical conductivity of the cooling medium that is placed on a downstream side of an ion exchanger in a bypass flow path, and uses the obtained first electrical conductivity and second electrical conductivity and a predetermined target electrical conductivity of a supply cooling medium to control the operation of a flow dividing valve such that the electrical conductivity of the supply cooling medium becomes equal to or less than the target electrical conductivity and thereby regulate a flow rate ratio.