An integrated process configuration of solid oxide fuel/electrolyzer cells (SOFC‐SOEC) and solar organic Rankine cycle (ORC) for cogeneration applications

In the present study, the effects of the fuel reforming process and bottoming cycle steam parameters on the design point: energy efficiency/power output of large-scale solid oxide fuel cell (SOFC) combined systems are investigated. The fuel reforming processes considered in this study are adiabatic steam reforming (ASR), partial oxidation reforming (POX), and autothermal reforming (ATR). For the bottoming cycles, subcritical (SubC), supercritical (SupC), ultrasupercritical (USC), and advanced ultrasupercritical (A-USC) steam cycles are considered. The results show that the efficiency of the ASRcombined system, which varies from 72.60% to 75.07% lower heating value (LHV) depending on the bottoming cycle, is the highest, followed by ATR (61.54%-65.65% LHV) and POX (56.81%-61.91% LHV) systems. On the other hand, the net power produced by the combined systems for a fixed SOFC cell area is in the reverse order, POX being the highest, followed by ATR and ASR systems. Even though the efficiency of the standalone A-USC cycle is 10.25% points higher than the SubC steam cycle, the net efficiencies of the SOFC combined systems are less sensitive to the bottoming cycles, that is, 2.46% points difference between SubC and A-USC for the ASR-combined system, 5.11% points difference for the POX, and 4.11% points difference for the ATR systems. Parametric studies are also conducted for the oxygen to carbon ratio (O/C) and steam to carbon ratio (S/C) to investigate the suitable values in achieving the highest efficiency of the SOFC-steam cycle combined system and minimum carbon deposition in the anode of SOFC.

Section: Mathematical Descriptionmentioning

confidence: 99%

Design point analyses of solid oxide fuel cell‐steam cycle combined system: Effects of fuel reforming and bottoming cycle steam parameters

Selvam

Rokni

Komatsu

et al. 2022

“…Ex w is the exergy of work which is the shaft work performed by the system. Ex Q represents the exergy of thermal energy which depends on the temperature and heat of the system and can be determined as following Equation (24).…”

Section: Solution Approachmentioning

confidence: 99%

“…In addition, the hightemperature waste heat released from an SOFC stack can be used as a heat source for cogeneration applications and bottoming cycles. 23,24 Currently, there are a few researchers who focused on SOFCs fuelled by glycerol. [25][26][27] Seabae et al 25 studied the performance of an SOFC integrated with a steam reformer using different renewable fuels (ie, glycerol, ethanol, and biogas).…”

mentioning

confidence: 99%

Performance assessment of a 10 kW pressurized solid oxide fuel cell integrated with glycerol supercritical water reforming

Patcharavorachot

Chatrattanawet

Saebea

et al. 2022

Summary In this work, the integrated system of pressurized solid oxide fuel cell (SOFC) and supercritical water reforming of glycerol was proposed. The syngas from the reforming process has high temperature and pressure and thus, it can be used as fuel for the SOFC. The performance of an integrated system was determined through the Aspen Plus simulator in which the electrochemical equations were also included. The developed model was employed to examine the performance of the integrated system with respect to the wider ranges of operation of the reformer and SOFC. In this work, the desired power output of an SOFC stack is set as 10 kW and thus, the area of an SOFC is determined. A smaller area is required as it normally leads to a lower fabrication cost for the SOFC. The simulation results revealed that the smallest SOFC area can be provided when the reformer is operated at 800°C and 240 atm with a ratio of supercritical water to glycerol as 50 whereas the SOFC operation is at 900°C and 4 atm with the current density as 7000 A/m2. Under these operating conditions, the integrated system can provide the cell voltage, required area, fuel utilization, and SOFC efficiency as 1 V, 1.42 m2, 75% and 61%, respectively. From the exergy analysis, it was found that the compressor, heater, and turbine are the highest exergy destruction units whereas the reformer has the lowest exergy destruction, followed by the SOFC stack.

“…The R-113 has been proven to be a good candidate for the ORP cycles. 33,34 Khalili et al 35 suggested an integrated process architecture of SOFC/SOEC combination and solar ORP unit used for cogeneration usage. The fuel cell unit's energy and exergy efficiencies could achieve 51.71% and 49.63% under design conditions.…”

Section: Introductionmentioning

confidence: 99%

An innovative hybrid system for the polygeneration of power, heat, and liquid carbon dioxide using solid oxide fuel cell/electrolyzer technology and oxyfuel power generation cycle

Ghorbani

Manesh

2022

Summary An innovative polygeneration structure is proposed based on the oxyfuel power generation (OPG) system integration with carbon dioxide (CO2) capture, CO2 power system, NH3/H2O absorption refrigeration (AR) unit, and organic Rankine power (ORP) cycle. In this regard, a combination of solid oxide electrolysis cell (SOEC) and solid oxide fuel cell (SOFC) is applied to produce the required pure oxygen for the OPG system. The proposed system simultaneously produces 7204 kmol/h hot water, 149.3 kmol/h liquid CO2, and 102.4 MW power in different cycles. Energy and exergy analyses are performed to evaluate the proposed system. The thermodynamic modeling and simulation of power and refrigeration cycles are performed in Aspen HYSYS software, and verified with high accuracy. Also, an integrated SOEC/SOFC simulation has been done using developed computer code in MATLAB programming. The overall electrical efficiency and the AR coefficient of performance are calculated at 31.55% and 0.4803, respectively. In addition, the thermal and exergy efficiencies of the proposed system are 65.10% and 70.60%, respectively. The exergy analysis indicates the combustion chamber's highest exergy destruction with a share of 35.26%. In the next rank, the heat exchangers (26.42%) and turbines (16.98%) have the largest share of degraded exergy among other devices. The sensitivity analysis demonstrates that when the oxygen productivity increases from 9050 to 9275 kg/h, the electrical efficiency in the total integrated structure and the liquid CO2 productivity rise to 34.57% and 6480 kg/h, respectively. Also, by increasing the natural gas entering the proposed structure from 2375 to 2550 kg/h, the exergy efficiency of the structure increases to 71.19% and its thermal efficiency decreases to 58.70%. Highlights A novel polygeneration system to produce power, liquid CO2, and heat is introduced. Integration of oxyfuel/ORC/CO2 power plants and absorption cooling unit is applied. A solid oxide fuel cell/electrolyzer technology is used to produce pure oxygen. The electrical and exergy efficiencies of the overall system are 31.55% and 70.60%. The exergy analysis indicates the combustion chamber has the highest exergy destruction.