Fuel Cell Humidifier Warm-Up Using Off-Gas Heat Control
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Solution Overview
Problem
Existing fuel cell systems face challenges in efficiently humidifying reaction gases without increasing the number of system components, particularly due to the need for additional parts like heaters in traditional humidifiers.
Innovation Solution
A fuel cell system that includes a reaction gas supply unit, a humidifier, and a controller to regulate gas supply based on the humidifier's temperature, allowing for warm-up control to increase gas flow and heat the humidifier efficiently, eliminating the need for a separate heater and reducing the number of parts by estimating the humidifier's temperature using refrigerant temperature data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heater is provided in the humidifier to increase the temperature of the reaction gas, then the saturated vapor pressure increases and the amount of moisture the reaction gas can contain increases, but the number of parts and the weight increase
Solution Approach 1:
The humidifier uses the off-gas discharged from the fuel cell stack as a heat source to warm itself and the reaction gas. The off-gas, which contains waste heat, flows through the humidifier to transfer heat to the reaction gas, eliminating the need for an external heater. This self-warming mechanism reduces the number of parts while achieving the required temperature increase for effective humidification
Solution Approach 2:
The off-gas acts as an intermediary heat transfer medium between the fuel cell stack and the reaction gas. By introducing the off-gas as a thermal mediator, the system transfers heat from the exhaust stream to the incoming reaction gas through the humidifier structure, avoiding the need for direct electrical heating components
2Productivity
If the temperature of the humidifier is low, then the humidifier cannot efficiently humidify the reaction gas, but increasing temperature requires additional heating components
Solution Approach 1:
The system performs preliminary warming of the humidifier by controlling the flow of off-gas through it before the reaction gas enters. The controller regulates the off-gas flow rate to ensure the humidifier reaches an appropriate temperature early in the operation, preparing it for efficient humidification without requiring active heating components during normal operation
3Temperature
If the supply amount of reaction gas is increased to warm up the humidifier, then the humidifier temperature increases and humidification efficiency improves, but the power generation amount of the fuel cell stack decreases
Solution Approach 1:
The controller dynamically adjusts the supply amount of reaction gas based on the humidifier temperature and target power generation requirements. By changing the flow rate parameter of the reaction gas, the system balances the need to warm the humidifier with the need to maintain adequate power generation, optimizing both thermal and electrical performance
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 enables efficient humidification of reaction gases without adding extra components, quickly heating the humidifier and maintaining optimal conditions for fuel cell operation, thus preventing deterioration and reducing system complexity.
Implementation Method 1
a humidifier (46) configured to transfer moisture from an off-gas discharged from the fuel cell stack to the reaction gas
Implementation Method 2
a humidifier (46) configured to transfer moisture from an off-gas discharged from the fuel cell stack to the reaction gas
Implementation Method 3
When the warm-up control is executed, the amount of the off-gas supplied to the humidifier increases, and thus the amount of heat supplied to the humidifier increases
Data Source
AI summary
A fuel cell system includes: a reaction gas supply unit configured to supply a reaction gas to a fuel cell stack; a humidifier configured to transfer moisture from an off-gas discharged from the fuel cell stack to the reaction gas; and a controller configured to control the reaction gas supply unit so as to regulate a supply amount of the reaction gas, wherein the controller is configured to acquire a temperature of the humidifier and set the supply amount of the reaction gas based on a target power generation amount of the fuel cell stack, and in a case where the temperature of the humidifier is equal to or lower than a prescribed warm-up determination value, the controller executes warm-up control to increase the supply amount of the reaction gas as compared with a case where the temperature of the humidifier is higher than the warm-up determination value.