Fuel Cell Thermal Management via Flow Balancing
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Solution Overview
Problem
In high-power fuel cells, heat imbalances between stacks can compromise the integrity of electrochemical membranes due to increased head losses and uneven cooling, leading to temperature fluctuations that damage materials and reduce efficiency.
Innovation Solution
A fuel cell system with a heat management system that includes an inside and outside coolant circuit, featuring a heat exchanger and a secondary circuit that allows coolant to bypass the exchanger, with valves controlling flow to maintain close or equal head losses between subcircuits, using thermostatic valves and diaphragms to regulate coolant flow and ensure balanced cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the valve opens to the first cooling subcircuit provided with the heat exchanger to cool the first stack, then the temperature of the first stack is reduced, but the head loss increases and the flow rate of coolant in the first stack decreases
Solution Approach 1:
A flow balancing device is introduced as an intermediary element in the second cooling subcircuit to create artificial head loss, balancing the head losses between the two subcircuits. This mediator ensures equal coolant flow distribution without requiring complex active control systems, resolving the contradiction between cooling effectiveness and flow balance.
Solution Approach 2:
The invention changes the head loss parameter in the second cooling subcircuit by adding flow balancing means, thereby equalizing the head losses in both subcircuits. This parameter modification ensures balanced coolant flow distribution while maintaining effective temperature control in both stacks.
2Productivity
If the flow rate of coolant in the first stack decreases due to passage through the heat exchanger, then the head loss increases, but the flow rate in the second stack increases causing uneven cooling
Solution Approach 1:
The flow balancing device acts as a mediator in the second subcircuit to compensate for the head loss difference caused by the heat exchanger. By introducing this intermediary element, the system achieves balanced coolant flow distribution, ensuring uniform temperature control across both stacks while maintaining high cooling efficiency.
Solution Approach 2:
The invention creates equipotential conditions for coolant flow by equalizing the head losses in both cooling subcircuits through the flow balancing device. This ensures that both stacks receive equal coolant flow rates, eliminating temperature imbalances and achieving uniform thermal management across the fuel cell system.
3Volume of moving object
If multiple stacks are connected in parallel to restrict overall height space and head losses, then the electrical voltage level decreases, but heat imbalances between stacks can compromise membrane integrity
Solution Approach 1:
The cooling system is segmented into multiple independent subcircuits, each serving a specific stack. Flow balancing devices are installed in each subcircuit to independently control and equalize coolant flow distribution. This segmentation approach maintains the compact parallel stack configuration while ensuring reliable temperature control and membrane protection in each individual stack.
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 heat imbalances between stacks, maintaining optimal temperature ranges and preventing damage to the fuel cell components, thereby enhancing the overall efficiency and longevity of the fuel cell.
Implementation Method 1
a subcircuit provided with a heat exchanger in order to cool the coolant
Implementation Method 2
valves are directly implanted at the outlet of each cell and are controlled as a function of the coolant temperature
Data Source
AI summary
A fuel cell including at least two stacks of electrochemical cells, a heat management system including a circuit for flowing a coolant into each of the stacks fed in parallel, and an outside circuit for flowing the coolant outside the stacks. The outside circuit includes a first subcircuit including a heat exchanger and a second subcircuit directly connected to an inlet of the inside circuit, and controlling valves for controlling flow of the coolant toward either or both subcircuits as a function of temperature of the coolant at an output of each of the stacks. The second outside subcircuit includes a mechanism increasing its head loss such that it is close or equal to that of the first outside subcircuit.