Fuel Cell Pump Speed Control for Low-Temp Warm-Up
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Solution Overview
Problem
Conventional fuel cell systems face challenges when operating at low temperatures, particularly below freezing, as the high viscosity of the cooling medium leads to uneven temperature distribution, fluctuating temperature increase speeds, and potential water freezing, which can hinder oxidizing gas supply and hydrogen generation.
Innovation Solution
A fuel cell system with a control unit that monitors the stack temperature and adjusts the cooling medium circulation pump's rotational speed by executing a warm-up operation, setting a smaller decrease speed after a specific temperature change point to maintain stable flow and prevent water freezing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the cooling medium circulation pump is driven to circulate high viscosity cooling medium at low temperatures, then the cooling medium can be circulated, but the temperature distribution in the cooling medium circulation path increases significantly
Solution Approach 1:
The patent applies dynamics by making the pump rotational speed adjustable and variable over time. The control unit dynamically changes the rotational speed based on temperature measurements, transitioning from a static operating mode to a dynamic one that adapts to changing thermal conditions during warm-up and steady-state operation.
Solution Approach 2:
The patent changes the operational parameters of the cooling medium circulation pump, specifically the rotational speed, as a function of temperature. By monitoring temperature and adjusting the pump speed accordingly, the system optimizes cooling medium circulation to maintain uniform temperature distribution while preventing water freezing in the fuel cell.
2Reliability
If the rotational speed of the cooling medium circulation pump is increased to prevent water freezing, then water freezing is prevented, but the temperature of the fuel cell may drop significantly
Solution Approach 1:
The patent implements a feedback control mechanism where the control unit continuously monitors the temperature of the fuel cell and the cooling medium, and adjusts the pump rotational speed based on these measurements. This closed-loop feedback system ensures that the pump speed is optimized to prevent water freezing while maintaining appropriate fuel cell temperature.
Solution Approach 2:
The system dynamically adjusts the pump rotational speed based on real-time temperature conditions. During warm-up phases, the speed is controlled to prevent excessive cooling, while during steady-state operation, it is adjusted to maintain temperature uniformity and prevent freezing, creating a adaptive response to changing operational conditions.
3Stability of the object's composition
If the cooling medium circulation pump operates at variable speeds to maintain temperature uniformity, then temperature distribution is improved, but the complexity of the control system increases
Solution Approach 1:
The control system uses temperature feedback from sensors positioned in the cooling medium circulation path to automatically adjust pump rotational speed. This feedback mechanism simplifies the control logic by using direct temperature measurements to determine pump speed requirements, avoiding the need for complex predictive models or multiple control parameters.
Solution Approach 2:
The system performs self-regulation by using its own temperature measurements to control its cooling medium circulation. The control unit automatically adjusts the pump speed based on measured temperature conditions, enabling the system to self-optimize its thermal management without external intervention or complex external control systems.
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 stabilizes the fuel cell temperature, reduces the risk of water freezing, and ensures consistent oxidizing gas supply, thereby preventing the generation of pumping hydrogen and maintaining efficient power generation.
Implementation Method 1
a fuel cell stack (116), a cooling medium circulation path (79) allowing a cooling medium to flow into the fuel cell stack (116)... executes warm-up operation processing of the fuel cell stack to raise the temperature of the fuel cell stack by use of heat generated by the fuel cell stack
Implementation Method 2
a cooling medium circulation pump (74) disposed on the cooling medium circulation path (79) and configured to regulate the circulation flow rate of the cooling medium
Implementation Method 3
In general, when the temperature of the cooling medium is low, for example, −30° C. (Celsius), the cooling medium has high viscosity... the temperature increase speed of the fuel cell fluctuates frequently
Data Source
AI summary
A fuel cell system includes a fuel cell stack, an oxidizing gas supply system, a cooling medium circulation pump, a stack temperature acquisition unit, and a control unit. After a first time point when a change in an acquisition temperature turns from downward to upward after the change in the acquisition temperature turns from upward to downward for the first time after the start of the warm-up operation processing, the control unit sets a decrease speed in cases of decreasing a rotational speed of the cooling medium circulation pump to a smaller value than a value set before the first time point.