Fuel Cell Low-Temp Start via Hydrogen Joule-Thomson Heating
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Solution Overview
Problem
Fuel cell vehicles face challenges in low-temperature starting due to insufficient temperature increase of the fuel cell stack, particularly at the anode side, where direct heating is unsafe and inefficient, leading to prolonged starting times and reduced performance.
Innovation Solution
A system and method utilizing a high-pressure hydrogen flow control valve to apply the Joule Thomson effect, increasing hydrogen temperature by depressurizing it through a narrow passage, combined with an air heater to rapidly raise the internal temperature of the fuel cell stack, thereby reducing low-temperature starting time and enhancing output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the opening rate of the high-pressure hydrogen flow control valve decreases, then the pressure of hydrogen decreases and temperature increases, but the amount of hydrogen supplied to the fuel cell stack decreases
Solution Approach 1:
The patent employs dynamic control of the hydrogen flow control valve opening rate based on real-time temperature feedback from the stack. The control system continuously adjusts the valve opening to balance two competing requirements: maintaining sufficient hydrogen supply quantity while achieving the necessary temperature increase through pressure drop. This dynamic adjustment allows the system to adapt to changing operating conditions and resolve the contradiction between temperature and quantity.
Solution Approach 2:
The patent implements a feedback control mechanism where the stack temperature is continuously monitored and used to adjust the hydrogen flow control valve opening rate. When the stack temperature is below the reference value, the valve opening is adjusted to optimize both hydrogen temperature (through pressure drop) and hydrogen supply quantity, ensuring the contradiction is resolved based on actual operating conditions.
2Temperature
If the internal temperature of the fuel cell stack needs to be increased to a target level, then the starting time increases due to insufficient heating efficiency
Solution Approach 1:
The patent segments the heating function into two parallel pathways: air heating for the cathode side and hydrogen flow control for the anode side. This simultaneous dual-sided heating approach significantly reduces the time required to reach the target stack temperature compared to sequential or single-sided heating methods.
Solution Approach 2:
The patent uses high-pressure hydrogen as a thermal intermediary to rapidly heat the anode side. By controlling the pressure drop of hydrogen through the flow control valve, substantial temperature increase occurs in the hydrogen, which then directly heats the anode. This intermediary mechanism provides rapid heating that dramatically reduces the time to reach target stack temperature.
Solution Approach 3:
The patent changes the physical parameters of hydrogen (pressure and temperature) by controlling its flow through a restricted passage. By decreasing the opening rate of the hydrogen flow control valve, the pressure drop increases, which transforms the hydrogen temperature from a low value to a high value, enabling rapid heating of the stack and reduction of starting time.
3Temperature
If direct heating of hydrogen supplied to the anode side is attempted, then heating efficiency increases, but safety issues arise due to explosion risk
Solution Approach 1:
The patent replaces direct thermal heating mechanisms (which would pose explosion risks) with a mechanical pressure control system. By using a flow control valve to regulate hydrogen pressure and induce adiabatic heating through pressure drop, the system achieves hydrogen temperature increase without direct contact between heat sources and hydrogen, eliminating explosion hazards while maintaining heating efficiency.
Solution Approach 2:
The patent changes the pressure parameter of hydrogen as the primary control mechanism, which secondarily affects temperature. By controlling the pressure drop across the flow control valve, the hydrogen temperature increases through thermodynamic relationships rather than direct heating. This parameter transformation approach (pressure to temperature) achieves the desired temperature increase without the safety risks associated with direct heating methods.
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 effectively shortens the low-temperature starting time and improves fuel cell stack output by directly heating hydrogen and air, ensuring rapid temperature increase and maintaining high performance even in low-temperature conditions.
Implementation Method 1
A system and method utilizing a high-pressure hydrogen flow control valve to apply the Joule Thomson effect, increasing hydrogen temperature by depressurizing it through a narrow passage
Implementation Method 2
combined with an air heater to rapidly raise the internal temperature of the fuel cell stack
Data Source
AI summary
A system for controlling low-temperature starting of a fuel cell vehicle includes a high-pressure hydrogen flow control valve controlling a flow of hydrogen supplied to a fuel cell stack. A fuel cell controller is configured to change and control an opening rate of the high-pressure hydrogen flow control valve when an internal temperature of the fuel cell stack is a reference value or less. When the opening rate of the high-pressure hydrogen flow control valve decreases, a pressure of the hydrogen passing through the high-pressure hydrogen flow control valve decreases to increase a temperature of the hydrogen which is supplied to the fuel stack.