Fuel Cell Cold Start Compressor Control and Heating Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fuel cell assemblies face performance issues and potential damage due to water vapor condensation and ice formation during starting operations in subzero temperatures, and there is a concern about hydrogen emission above the lower flammability limit, which can lead to increased airflow and drying out of the fuel cell assembly.
Innovation Solution
A fuel cell system that includes a compressor to compress and heat a fluid, a heat exchanger to regulate the fluid's temperature, and a flow control mechanism to direct the heated fluid to the fuel cell assembly, mitigating vapor condensation and ice formation, and managing hydrogen emissions by diluting it below the flammability limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fuel cell assembly operates in subzero temperatures during starting operation, then the system can be started, but water vapor condenses and ice forms in the fuel cell assembly causing performance issues and potential damage
Solution Approach 1:
The compressor heats the air before it enters the fuel cell assembly during cold start operation. This preliminary heating action raises the air temperature above freezing point, preventing water vapor condensation and ice formation in the flow channels before they can occur, thus protecting the fuel cell assembly during the critical starting phase in subzero temperatures
Solution Approach 2:
The system changes the temperature parameter of the air by using the compressor to heat the air from subzero temperatures to above freezing point before it enters the fuel cell assembly. This parameter change prevents the harmful phase transition of water vapor to liquid or ice, eliminating the root cause of performance degradation and damage
2Reliability
If a bypass valve is used to reduce fluid flow to the fuel cell assembly to mitigate compressor surge, then compressor surge is reduced, but hydrogen concentration in the exhaust stream increases above the lower flammability limit
Solution Approach 1:
Instead of reducing airflow (which would concentrate hydrogen), the system changes the temperature parameter by heating the air with the compressor. This allows maintaining higher airflow rates needed for hydrogen dilution while still preventing compressor surge through controlled heating, thus keeping hydrogen concentration below the lower flammability limit
Solution Approach 2:
The system replaces the traditional bypass valve mechanical flow restriction method with a thermal control approach using the compressor. Instead of mechanically reducing flow to prevent surge, the system uses thermal heating to modify air density and temperature, achieving surge mitigation while maintaining adequate airflow for safe hydrogen emissions
3Object-generated harmful factors
If increased airflow is used to dilute hydrogen in the exhaust stream, then hydrogen emission safety is improved, but the fuel cell assembly dries out
Solution Approach 1:
The system changes the temperature parameter of the air using compressor heating. This thermal parameter change allows the air to hold more moisture capacity while maintaining adequate flow rates for hydrogen dilution, preventing fuel cell assembly drying out even at higher airflow rates needed for safe hydrogen emissions
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 effectively reduces the warm-up time of the fuel cell system, prevents damage from ice formation, and ensures hydrogen emissions remain below the flammability limit, enhancing the system's efficiency and safety.
Implementation Method 1
The compressor increases the pressure of a fluid flowing therethrough by reducing a volume of the fluid within the compressor. Increasing the pressure of the fluid increases the temperature of the fluid.
Implementation Method 2
a heat exchanger disposed between and in fluid communication with said compressor and said fuel cell assembly
Implementation Method 3
In subzero temperatures, water vapor in the fuel cell assembly may condense in the flow channels.
Implementation Method 4
Further, the condensate may form ice in the fuel cell assembly.
Data Source
AI summary
A fuel cell system is disclosed, wherein the fuel cell system is heated by a fluid during a starting operation to mitigate against vapor condensation and ice formation in a fuel cell assembly and to decrease a warm up time of the fuel cell system.