Fuel Cell Refrigerant Flow Control for Thermal Shock Prevention
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Solution Overview
Problem
Conventional fuel cell systems are prone to thermal shocks due to temperature differences in the refrigerant circulation, leading to potential distortion of the fuel cell separator and flooding caused by condensed water vapor, especially during startup and restart scenarios.
Innovation Solution
A fuel cell system with a refrigerant circulating system that includes flow control means to manage temperature differences by delaying the start of refrigerant flow in the exhaust heat utilization line relative to the cooling line, ensuring that the fuel cell is initially cooled by refrigerant from the cooling line, and gradually increasing the flow rate to minimize temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pump is driven immediately when starting up the fuel cell to circulate refrigerant, then the cooling function is activated quickly, but the thermostat valve switches undesirably to the radiator side due to high-temperature refrigerant from the fuel cell, causing thermal shock to the fuel cell
Solution Approach 1:
The patent applies preliminary action by delaying the pump operation until after a predetermined time has elapsed since the fuel cell started up. This preliminary timing control prevents the thermostat valve from switching to the radiator side due to high-temperature refrigerant, thereby avoiding thermal shock to the fuel cell while still activating cooling when needed
2Adaptability or versatility
If the thermostat valve switches to the radiator side during fuel cell startup, then the refrigerant circulation path is changed, but this causes sudden temperature change in the fuel cell leading to thermal shock and potential separator distortion
Solution Approach 1:
The patent uses preliminary action by controlling the pump start timing to occur after a predetermined time following fuel cell startup. This preliminary timing control prevents the thermostat valve from undesirably switching to the radiator side, thereby preventing sudden temperature changes that could cause thermal shock and separator distortion
Solution Approach 2:
The patent applies feedback by using the thermostat valve's temperature-sensitive switching characteristic and controlling pump operation based on the resulting refrigerant temperature conditions. The system monitors the thermal state through the thermostat valve's position and adjusts pump operation accordingly to maintain fuel cell temperature stability
3Stability of the object's composition
If refrigerant flow is controlled to prevent thermal shock during startup, then the fuel cell temperature stability is improved, but the cooling response time may be delayed
Solution Approach 1:
The patent applies preliminary action by establishing a predetermined time delay after fuel cell startup before activating the pump. This preliminary timing control prevents thermal shock while still providing timely cooling activation, optimizing the balance between temperature stability and cooling response time
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 configuration effectively prevents thermal shocks, protecting the fuel cell from temperature-related damage and ensuring stable operation during startup and restarts by controlling the refrigerant flow to maintain a consistent temperature.
Implementation Method 1
a cooling apparatus for the fuel cell... having a circulation passage through which a refrigerant is circulated between the fuel cell and a radiator
Implementation Method 2
the refrigerant that has passed through the fuel cell is used for heating the interior of the car
Implementation Method 3
a pump, a bypass passage for bypassing the radiator, and a thermostat valve for switching between the radiator and the bypass passage when circulating the refrigerant
Implementation Method 4
The thermostat valve performs a switching operation based on the temperature of the refrigerant flowing through the thermostat valve
Implementation Method 5
a radiator... for cooling the refrigerant
Implementation Method 6
an exhaust heat utilization line having a heater core capable of heat-exchanging the refrigerant with air-conditioning gas
Data Source
AI summary
Disclosed is a fuel cell system capable of restraining a temperature change in a fuel cell caused by a refrigerant. The fuel cell system has a refrigerant circulating system for circulating the refrigerant from the fuel cell to the fuel cell. The refrigerant circulating system has flow control means for restraining the inflow of the refrigerant, which has a predetermined difference in temperature from that of the fuel cell, into the fuel cell.