Simulation of a Natural Gas Solid Oxide Fuel Cell System Based on Rated Current Density Input
Abstract
1. Introduction
2. Materials and Methods
2.1. SOFC Electrochemical Model
2.1.1. SOFC Output Current
- is the molar flow rate of hydrogen actually participating in the electrochemical reaction (mol/h)
- is the rated current density of the system (A/m2)
- is the number of single SOFC cells
- is the total activation area for the electrochemical reaction in the SOFC (m2)
- is Faraday’s constant, valued at 96,485 C/mol
- is the number of electrons transferred per mole of hydrogen undergoing electrochemical oxidation
- is the total molar flow rate of the inlet fuel (mol/h)
- is the mole fraction of each gaseous component X in the inlet fuel
- is the specified fuel utilization rate
2.1.2. SOFC Output Voltage
- is the output voltage of the SOFC under actual operating conditions (V)
- is the baseline voltage of the SOFC under specific reference conditions (V). In this study, the reference operating conditions are based on experimental data from the literature: inlet fuel composition of 67% H2, 22% CO, and 11% H2O; fuel utilization of 0.85; air utilization of 0.25; stack operating temperature of 1000 °C; and stack operating pressure of 1 bar. Under these reference conditions, is taken as 0.7 V.
- is the voltage loss due to the deviation of the actual operating temperature from the reference temperature (V)
- is the voltage loss due to the deviation of the actual operating pressure from the reference pressure (V)
- is the voltage loss due to the deviation of the anode-side fuel composition from the reference state (V)
- is the voltage loss due to the deviation of the cathode-side oxidant composition from the reference state (V)
- is the absolute operating pressure of the SOFC under actual working conditions (bar)
- is the absolute operating pressure under reference conditions (1 bar)
- is the operating temperature of the SOFC under actual working conditions (°C)
- is the operating temperature under reference conditions (1000 °C)
- is the input current density to the SOFC (mA/cm2)
- is the ratio of the partial pressure of H2 to the partial pressure of H2O in the anode stream under actual SOFC operating conditions. In this model, this value is taken as the arithmetic mean of the corresponding ratios at the anode inlet and outlet.
- is the ratio of the partial pressure of H2 to the partial pressure of H2O in the anode stream under reference conditions (0.15)
- is the average partial pressure of O2 on the cathode side under actual SOFC operating conditions (bar). In this model, this value is taken as the arithmetic mean of the O2 partial pressures at the cathode inlet and outlet.
- is the average partial pressure of O2 on the cathode side under reference conditions (0.164 bar)
2.1.3. SOFC Output Power
- is the DC output power of the SOFC power generation system (W)
- is the input current density to the SOFC (A/m2)
- is the total activation area for the electrochemical reaction in the SOFC (m2), which is set to 96.1 m2 in this study
- is the output voltage of the SOFC under actual operating conditions (V)
- is the electrical efficiency of the SOFC
- is the total molar flow rate of the inlet fuel (mol/h), the calculation of which is detailed in Equation (2)
- is the average lower heating value of the inlet fuel (J/mol). In this study, this value is calculated as the weighted average of the standard LHV of each gaseous component in the inlet fuel, based on their respective mole fractions.
- The factor “3600” in the denominator is used to convert the hourly molar flow rate () to a per-second basis, to align with the unit of power (W, J/s).
2.2. System Process Modeling in Aspen Plus
2.2.1. Model Hypothesis
2.2.2. System Flow
2.3. Simulation Input Parameters
3. Results and Discussion
3.1. Simulation Results and Validation
3.1.1. Simulation Results
3.1.2. Simulation Verification
3.2. Sensitivity Analysis of SOFC Unit Parameters
3.2.1. Fuel Utilization
3.2.2. Water-Carbon Ratio
3.2.3. Current Density
3.3. Multi-Unit SOFC Configuration Optimization
4. Conclusions
Author Contributions
Funding
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Assumed Input Parameters | Input Parameter Value |
---|---|
Inlet fuel components | 81.3%CH4, 2.9%C2H6, 0.4%C3H8, 0.2%C4H10, 14.3%N2, 0.9%CO |
Cell operation temperature | 910 °C |
Cell operation pressure | 1.08 atm |
Input current density | 180 mA/cm2 |
Activating reaction area | 96.1 m2 (1152 sets of mono-cells) |
Cell outlet temperature | 910 °C |
Inlet air temperature | 630 °C |
Inlet fuel temperature | 200 °C |
Afterburner reaction rate | 100% |
Air use ratio | 19% |
DC-AC conversion efficiency | 92% |
Overall fuel utilization | 85% |
Water-carbon ratio | 2.5 |
Commingler fresh fuel-pressure ratio | 3 |
SOFC internal pressure drop | 0 |
SOFC heat loss | 2% |
Stream | Temperature (℃) | Pressure (atm) | Mol Flow | Mole Fraction (%) | ||||||
---|---|---|---|---|---|---|---|---|---|---|
(kmol/h) | H2 | CH4 | H2O | CO | CO2 | O2 | N2 | |||
1 | 200.00 | 3.28 | 1.07 | - | 81.30 | - | 0.90 | - | - | 14.30 |
2 | 745.29 | 1.09 | 5.82 | 9.42 | 15.01 | 41.55 | 6.15 | 20.39 | - | 6.83 |
3 | 536.25 | 1.09 | 5.82 | 9.42 | 15.01 | 41.55 | 6.15 | 20.39 | - | 6.83 |
4 | 537.27 | 1.09 | 6.45 | 27.19 | 9.94 | 27.87 | 5.68 | 23.17 | - | 6.16 |
5 | 910.00 | 1.09 | 7.73 | 11.55 | - | 50.96 | 7.34 | 25.01 | - | 5.14 |
6 | 910.00 | 1.09 | 4.74 | 11.55 | - | 50.96 | 7.34 | 25.01 | - | 5.14 |
7 | 910.00 | 1.09 | 2.99 | 11.55 | - | 50.96 | 7.34 | 25.01 | - | 5.14 |
8 | 910.00 | 1.09 | 41.19 | - | - | 4.50 | - | 2.33 | 15.88 | 77.29 |
9 | 630.00 | 1.09 | 40.10 | - | - | - | - | - | 21.00 | 79.00 |
10 | 822.37 | 1.09 | 40.10 | - | - | - | - | - | 21.00 | 79.00 |
11 | 822.37 | 1.09 | 1.61 | - | - | - | - | - | 1.0000 | - |
12 | 822.37 | 1.09 | 38.78 | - | - | - | - | - | 17.72 | 82.28 |
13 | 910.00 | 1.09 | 38.78 | - | - | - | - | - | 17.72 | 82.28 |
14 | 1011.25 | 1.09 | 41.49 | - | - | 4.50 | - | 2.33 | 15.88 | 77.29 |
15 | 833.85 | 1.09 | 41.49 | - | - | 4.50 | - | 2.33 | 15.88 | 77.29 |
Indicators | Lab Data | Reference [24] Simulation Results | Simulation Results | Simulation Errors |
---|---|---|---|---|
Cell power | - | - | 119.059 kW | - |
Cell voltage | - | 0.685 V | 0.689 V | 5.8% |
Current density | 180 mA/cm2 | 179.5 mA/cm2 | - | - |
Anode gas output component | 48%H2O/28%CO2/ 14%H2/5%CO/5.0%N2 | 50.8%H2O/25%CO2/ 11.7%H2/7.3%CO/5.0%N2 | 51.0%H2O/25.0%CO2/ 11.5%H2/7.3%CO/5.1%N2 | - |
Fuel cell electric efficiency | 50% | 50% | 49.8% | 0.4% |
System Output | Method 1 Output Value | Method 2 Output Value |
---|---|---|
SOFC Anode Inlet Total Fuel Flow Rate (kmol/h) | 18.64 | 15.05 |
SOFC Cathode Inlet Total Oxygen Flow Rate (kmol/h) | 6.40 | 5.80 |
SOFC Maximum Power Output (kW) (DC) | 498.38 | 471.21 |
SOFC Maximum Power Output (kW) (AC) | 458.51 | 433.51 |
SOFC Single Cell Voltage (V) | 0.70 | 0.64/0.73 |
System Net Electrical Efficiency (%) | 54 | 59 |
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Hu, W.; Sun, X.; Qin, Y. Simulation of a Natural Gas Solid Oxide Fuel Cell System Based on Rated Current Density Input. Energies 2025, 18, 4456. https://doi.org/10.3390/en18164456
Hu W, Sun X, Qin Y. Simulation of a Natural Gas Solid Oxide Fuel Cell System Based on Rated Current Density Input. Energies. 2025; 18(16):4456. https://doi.org/10.3390/en18164456
Chicago/Turabian StyleHu, Wenxian, Xudong Sun, and Yating Qin. 2025. "Simulation of a Natural Gas Solid Oxide Fuel Cell System Based on Rated Current Density Input" Energies 18, no. 16: 4456. https://doi.org/10.3390/en18164456
APA StyleHu, W., Sun, X., & Qin, Y. (2025). Simulation of a Natural Gas Solid Oxide Fuel Cell System Based on Rated Current Density Input. Energies, 18(16), 4456. https://doi.org/10.3390/en18164456