Fuel Cell Stack Drying with Recirculation to Prevent Local Dry-Out
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Solution Overview
Problem
Existing fuel cell systems face challenges in minimizing local drying out during preparation for freeze starts due to limited operating temperature and cooling capacity, leading to uneven moisture distribution and potential damage.
Innovation Solution
A fuel cell system with a recirculation path and actuators that circulate and distribute moisture evenly within the fuel cell stack, using a computing unit to manage actuator states and an air system to create a homogeneous mixture, minimizing local moisture differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a drying operation is performed to prepare fuel cells for freeze start, then moisture is removed from the fuel cells, but local drying out occurs leading to uneven moisture distribution and potential damage
Solution Approach 1:
The system dynamically switches between two actuator states: a first state where fluid circulates through the fuel cell stack via the recirculation path, and a second state where fluid is discharged. This dynamic switching creates alternating wetting and drying cycles that prevent localized overheating and ensure uniform moisture distribution during the drying operation
Solution Approach 2:
The computing unit controls actuators to periodically switch between circulation and discharge modes, creating a periodic action pattern. This periodic switching ensures that different regions of the fuel cell stack experience alternating wet and dry phases, preventing permanent local drying out while achieving overall moisture removal necessary for freeze start preparation
2Stability of the object's composition
If the recirculation path is activated to distribute moisture evenly, then moisture distribution uniformity is improved, but system complexity increases due to additional actuators and control logic
Solution Approach 1:
The existing actuators in the fuel cell system are made multi-functional by programming them to perform both normal operational functions and drying operation functions. The computing unit reconfigures the actuators to control fluid circulation through the recirculation path during drying, eliminating the need for dedicated drying actuators and reducing overall system complexity
Solution Approach 2:
The system uses its own existing fluid circulation infrastructure and actuators to perform the drying function, rather than requiring external or dedicated drying equipment. The computing unit leverages the already-present recirculation path and actuators, making the system self-sufficient for moisture distribution control during drying operations
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
The solution ensures uniform moisture distribution, preventing local drying out and enhancing system robustness during freeze starts by maintaining consistent moisture levels across the fuel cells.
Implementation Method 1
a recirculation path (105) fluidically connected to a cathode tract (103) of the fuel cell stack (101)... the at least one actuator (107) is configured to allow a fluid in the recirculation path (105) to circulate through the fuel cell stack (101)
Implementation Method 2
fluids flowing in the recirculation path and the fuel cell stack, such as air, hydrogen, and water, mix together to a homogeneous mixture. Repeated or continuous permeating of fuel cells of the fuel cell stack by means of the homogeneous mixture causes a homogeneous distribution of water or moisture in the fuel cells
Data Source
AI summary
The present invention relates to a fuel cell system (100) for converting energy. The fuel cell system (100) comprises a fuel cell stack (101) having a plurality of fuel cells, a recirculation path (105) fluidically connected to a cathode tract (103) of the fuel cell stack (101), an air system (111) for supplying air to the fuel cell system (100), at least one actuator (107, 123), and a computing unit (109).