Fuel Cell Coolant Valve Resistance Temperature Sensing
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Solution Overview
Problem
Existing fuel cell cooling systems face challenges in maintaining optimal coolant temperatures within fuel cell stacks due to the high operating temperatures, requiring efficient cooling systems that often rely on multiple sensors and complex valve mechanisms, which can be costly and space-intensive.
Innovation Solution
A method that determines the coolant temperature by correlating the ohmic resistance of a wax expansion element in a coolant flow valve, allowing the valve to control coolant flow through either a chiller or bypass loop to maintain optimal temperatures without the need for a stack inlet temperature sensor, using a performance-map thermostat and heating system to adjust the expansion element's state based on measured resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple temperature sensors and complex valve mechanisms are used to maintain optimal coolant temperatures, then temperature control reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the temperature sensing function from a separate sensor component and integrates it into the expansion element of the coolant flow valve. The expansion element's resistance directly indicates coolant temperature, eliminating the need for a dedicated stack inlet temperature sensor while maintaining temperature control reliability.
Solution Approach 2:
The patent merges the temperature sensing function with the expansion element's electrical resistance property. The expansion element serves dual purposes: mechanically controlling coolant flow through expansion/contraction and electrically indicating temperature through resistance changes, thereby reducing overall system complexity.
2Measurement precision
If multiple temperature sensors are installed in the coolant circuit, then temperature measurement accuracy is improved, but manufacturing cost and assembly complexity increase
Solution Approach 1:
The patent removes the stack inlet temperature sensor from the coolant circuit by utilizing the expansion element's inherent resistance-temperature relationship. This extraction eliminates sensor assembly costs and potential defect sources while maintaining sufficient temperature measurement accuracy for control purposes.
Solution Approach 2:
The patent employs the expansion element's electrical resistance as a low-cost temperature indication mechanism. Instead of using expensive dedicated temperature sensors, the system leverages the existing expansion element's electrical properties, which are already part of the valve assembly, thereby reducing manufacturing costs.
3Reliability
If a stack inlet temperature sensor is used, then coolant temperature monitoring is improved, but available space for other components is reduced
Solution Approach 1:
The patent combines the temperature monitoring function with the existing expansion element in the coolant flow valve. By utilizing the expansion element's resistance-temperature relationship, the system eliminates the need for a separate stack inlet temperature sensor, thereby freeing up space for other components while maintaining reliable coolant temperature monitoring.
4Reliability
If conventional cooling systems with multiple sensors are used, then temperature control is reliable, but system cost and sensor assembly defects increase
Solution Approach 1:
The patent extracts the temperature sensing function from separate sensor components and integrates it into the expansion element. This eliminates the need for additional sensors and their associated assembly processes, reducing both system cost and potential defect sources while maintaining reliable temperature control.
Solution Approach 2:
The patent makes the expansion element multi-functional by utilizing both its mechanical expansion/contraction property for coolant flow control and its electrical resistance property for temperature indication. This universality eliminates the need for separate temperature sensors, thereby reducing system cost and complexity while maintaining reliable temperature control.
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 method effectively maintains coolant temperatures within optimal ranges for fuel cell operation, reducing costs and sensor-related issues while providing additional space for other components, and ensures reliable temperature control even if sensors fail.
Implementation Method 1
The density and volume of the expansion element change depending on the temperature of the element. Therefore, when it is unheated, the expansion element is in a contracted configuration and blocks flow of coolant from the chiller to the stack
Implementation Method 2
The heating system which induces heating of the expansion element is controlled by the stack inlet and stack outlet temperature sensors. Since heating of the expansion element acts through a linear (ohmic) resistance, the ohmic resistance of the expansion element is correlated with the valve outlet or stack inlet temperature of the coolant.
Data Source
AI summary
A method of determining a temperature of a coolant in a coolant circulation system is disclosed. The coolant circulation system includes a coolant flow valve having a valve housing and an expansion element provided in the valve housing for controlling flow of the coolant through the valve housing. According to the method, an ohmic resistance of the expansion element is measured. The temperature of the coolant is determined by correlating the ohmic resistance of the expansion element with the temperature of the coolant.