Fuel Cell Water Circulation Pump Control for Air Bubble Removal
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Solution Overview
Problem
The existing fuel cell systems face difficulties in ensuring a stable circulation flow rate of storage water due to air bubbles formed in the water circulation line, especially when water pressure decreases, leading to inefficient heat exchange and potential corrosion of the heat exchanger.
Innovation Solution
The system includes an air bubble detection mechanism that controls the storage water circulation pump to stop temporarily, allowing air bubbles to rise and collect at the pump's upper portion, then resumes operation to push out the enlarged air bubbles, ensuring a stable flow rate and preventing deposition and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the water circulation pump operates at maximum power output to push out air bubbles, then the air bubbles are pushed out, but the water pressure at the pump inlet and impeller periphery decreases, causing dissolved air to easily become air bubbles
Solution Approach 1:
The pump operates periodically: first at maximum power output to push out existing air bubbles, then stops to allow pressure recovery and prevent new bubble formation. This periodic operation pattern resolves the contradiction by alternating between the two conflicting requirements.
Solution Approach 2:
The pump stops operation in advance before water pressure decreases too much, allowing pressure to recover. This preliminary action prevents dissolved air from becoming air bubbles before the next maximum power output phase, maintaining pressure stability while still enabling bubble removal.
2Object-generated harmful factors
If the water circulation pump increases rotation speed to push out air bubbles, then the air bubbles are pushed out, but the air bubbles are stirred by the pump operation, leading to idle running and difficulty in pushing out bubbles
Solution Approach 1:
The pump operates at maximum power only for brief intervals to push out bubbles, then stops to allow bubbles to settle and coalesce. This periodic action avoids continuous stirring that would keep bubbles dispersed and prevent idle running, thereby maintaining pump efficiency while still removing bubbles.
Solution Approach 2:
During pump stop periods, buoyancy forces cause air bubbles to rise and collect at the upper portion of the pump. This natural upward movement counteracts the downward pumping action, allowing bubbles to accumulate in a controllable location without requiring continuous pump operation.
3Productivity
If the storage water circulation pump operates continuously, then the circulation flow rate is maintained, but air bubbles are stirred and remain dispersed, making it difficult to push them out
Solution Approach 1:
The pump alternates between operating and stopping states. During operation, circulation flow rate is maintained; during stop periods, bubbles rise and coalesce due to buoyancy. This periodic pattern ensures both continuous overall circulation and effective bubble removal.
Solution Approach 2:
The pump operation is temporarily suspended to allow air bubbles to be extracted from the circulation system. By stopping the pump, bubbles are allowed to separate from the water and collect at the upper portion, where they can be pushed out when the pump resumes operation.
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 removes air bubbles, maintains the circulation flow rate, and inhibits deposition and corrosion in the heat exchanger, enhancing the system's efficiency and longevity.
Implementation Method 1
the air bubbles which are stirred are raised by buoyancy to be collected at an upper portion of an inside of the storage water circulation pump
Data Source
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AI summary
A fuel cell system includes a fuel cell module (20) performing a power generation and discharging an exhaust combustion gas generated by the power generation, a water storage tank (31) storing water that serves as a storage water, a storage water circulation line (32) at which the storage water circulates, a storage water circulation pump (32a) provided at the storage water circulation line and driven by an electric motor, a heat exchanger performing a heat exchange (33) between the exhaust combustion gas and the storage water, an air bubble detection portion (S102) detecting a generation of air bubbles at the storage water circulation line and a control unit (60) controlling the storage water circulation pump to stop operating for a predetermined time period in response to an air bubble detection signal generated by the air bubble detection portion and to resume the operation of the storage water circulation pump.