Fuel Cell Refrigerant Flow Rate Estimation Using Outlet Temperature
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Solution Overview
Problem
The existing fuel cell systems face inaccuracies in estimating the refrigerant flow rate to each fuel cell group due to variations in pressure and temperature, leading to uneven cooling and calorific value estimation across the groups.
Innovation Solution
A fuel cell system with a refrigerant distribution passage, pre-distribution flow rate sensors, and outlet temperature sensors that calculate individual supply flow rates for each fuel cell based on voltage, current, and outlet temperature, allowing for precise refrigerant flow rate estimation and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a refrigerant supply system distributes refrigerant to multiple fuel cell groups in parallel, then the fuel cells can be cooled effectively, but the flow rate of refrigerant varies among distribution passages due to pressure and temperature differences, leading to uneven cooling and inaccurate calorific value estimation
Solution Approach 1:
The patent divides the refrigerant distribution system into individual measurement segments by installing outlet temperature sensors in each refrigerant distribution passage. This segmentation allows independent monitoring of temperature changes in each fuel cell group, enabling accurate calculation of refrigerant flow rates and calorific values for each segment despite variations in pressure and temperature across the system.
Solution Approach 2:
The system implements feedback by using detected outlet temperatures and known inlet temperatures to calculate actual refrigerant flow rates, then using this information to determine calorific values. This feedback loop compensates for flow rate variations caused by pressure and temperature differences, maintaining accurate measurements across all fuel cell groups.
2Measurement precision
If outlet temperature sensors are installed in each refrigerant distribution passage to measure individual temperatures, then accurate calorific value estimation is achieved, but the number of sensors and system complexity increases
Solution Approach 1:
The patent segments the measurement system by placing outlet temperature sensors in each refrigerant distribution passage corresponding to each fuel cell group. This segmentation enables independent temperature measurement for each group, which is necessary for accurate calorific value estimation of individual groups while maintaining overall system coordination.
Solution Approach 2:
Each refrigerant distribution passage serves itself by having its own outlet temperature sensor that independently measures its local temperature conditions. This self-service approach allows each fuel cell group to be characterized independently without relying on assumptions about uniform flow distribution, thereby achieving accurate local measurements.
3Ease of operation
If the system assumes uniform refrigerant flow distribution to simplify calculations, then the calculation process is easier, but the estimation accuracy deteriorates due to actual flow rate variations
Solution Approach 1:
The system replaces the simplified uniform flow assumption with actual flow rate measurements obtained through feedback. By detecting outlet temperatures in each distribution passage and comparing them with inlet temperatures, the system calculates actual refrigerant flow rates for each passage, thereby eliminating errors introduced by assuming uniform distribution.
Solution Approach 2:
The patent replaces the mechanical assumption of uniform flow distribution with a thermal measurement-based calculation system. Instead of relying on mechanical symmetry or uniform pressure distribution assumptions, the system uses temperature measurements and heat balance calculations to determine actual flow rates, substituting thermal sensing for mechanical simplification.
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 enhances the accuracy of refrigerant flow rate estimation and temperature control across fuel cell groups, reducing the need for multiple outlet temperature sensors and lowering system costs while maintaining precise power generation control.
Implementation Method 1
a refrigerant supply system that supplies a refrigerant to a fuel cell group including a plurality of fuel cells and cools the fuel cell by heat conduction
Implementation Method 2
a refrigerant supply system that supplies a refrigerant to a fuel cell group including a plurality of fuel cells and cools the fuel cell
Implementation Method 3
an outlet temperature sensor that detects a temperature of the discharged refrigerant
Data Source
AI summary
A fuel cell system including: a fuel cell group; a refrigerant distribution passage; a pre-distribution refrigerant flow rate acquiring unit configured to acquire a first outlet temperature flow rate; a first outlet temperature detecting unit that is configured to detect a first outlet temperature; a voltage acquiring unit configured to acquire at least a first voltage that is a voltage of the first fuel cell; a current acquiring unit configured to acquire at least a first current; and a controller that calculates a first individual supply flow rate of the first fuel cell on the basis of the first voltage, the first current, and the first outlet temperature, and calculates a second individual supply flow rate of at least one second fuel cell other than the first fuel cell on the basis of the first individual supply flow rate and the pre-distribution refrigerant flow rate.