A mathematical model of two-stage Solid Oxide Fuel Cell, SOFC, stacks for dynamic simulation of Combined Heat and Power system fed by natural gas

Abstract Zero-dimensional two-stage SOFC stacks dynamic model was developed to investigate the effect of operating parameters on stacks performance. The model resolves spatially thermal and thermo-electrochemical behaviour for electrochemical reactions, Catalytic Partial Oxidation and Steam Reforming processes. Design variables and thermo-electrochemical properties were obtained from in-house-fabricated SOFCs carried out by project partners. The completed SOFCs based Combined Heat and Power, CHP, system model was validated by data18 and numerical results obtained at steady-state mode showing its high-fidelity. A parametric study with respect to key operating parameters including changes in fuel utilization, lambda number and current density values was conducted. The global CHP system dynamic response, in term of the current/voltage delivered by two-stage SOFC stacks, under a fixed fuel utilization, has been determined resulting in greater variations in the voltage of a single cell in the first stack in comparison to the corresponding values in the second stack.

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Numerical analysis of a serial connection of two staged SOFC stacks in a CHP system fed by methane using Aspen TECH

Polish Journal of Chemical Technology ◽

10.2478/pjct-2019-0007 ◽

2019 ◽

Vol 21 (1) ◽

pp. 33-43

Author(s):

Paulina Pianko-Oprych ◽

Mateusz Palus

Keyword(s):

Electrical Performance ◽

Fuel Utilization ◽

Optimal Control Strategy ◽

Two Stage ◽

Performance Simulation ◽

Serial Connection ◽

Funded Project ◽

Chp System ◽

Sofc Stacks ◽

Good Agreement

Abstract The objective of the study was to develop a steady-state system model in Aspen TECH using user-defined subroutines to predict the SOFC electrochemical performance. In order to achieve high overall fuel utilization and thus high electrical efficiency, a concept of Combined Heat and Power system with two-stage SOFC stacks of different number of cells was analyzed. The concept of two-stage SOFC stacks based system was developed in the framework of the FP7 EU-funded project STAGE-SOFC. The model was validated against data gathered during the operation of the proof-of-concept showing good agreement with the comparative simulation data. Following model validation, further simulations were performed for different values of fuel utilization to analyze its influence on system electrical performance. Simulation results showed that the concept of two-stage SOFC stacks configuration was viable and reliable. The model can be useful for development the optimal control strategy for system under safe conditions.

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Study on the operating parameters of the 10 kW SOFC-CHP system with syngas

International Journal of Coal Science & Technology ◽

10.1007/s40789-021-00451-3 ◽

2021 ◽

Author(s):

Biao Li ◽

Zewei Lyu ◽

Jianzhong Zhu ◽

Minfang Han ◽

Zaihong Sun

Keyword(s):

High Efficiency ◽

Operating Parameters ◽

System Efficiency ◽

Generation System ◽

Electrical Efficiency ◽

Fuel Ratio ◽

Distributed Power Generation ◽

Preheating Temperature ◽

Power Generation System ◽

Chp System

AbstractSolid oxide fuel cell combined with heat and power (SOFC-CHP) system is a distributed power generation system with low pollution and high efficiency. In this paper, a 10 kW SOFC-CHP system model using syngas was built in Aspen plus. Key operating parameters, such as steam to fuel ratio, stack temperature, reformer temperature, air flow rate, and air preheating temperature, were analyzed. Optimization was conducted based on the simulation results. Results suggest that higher steam to fuel ratio is beneficial to the electrical efficiency, but it might decrease the gross system efficiency. Higher stack and reformer temperatures contribute to the electrical efficiency, and the optimal operating temperatures of stack and reformer when considering the stack degradation are 750 °C and 700 °C, respectively. The air preheating temperature barely affects the electrical efficiency but affects the thermal efficiency and the gross system efficiency, the recommended value is around 600 °C under the reference condition.

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A Small Gas Turbine Plant for Cogeneration of Electricity, Thermal and Cooling Thermal Energy With an Absorption Unit

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/97-gt-174 ◽

1997 ◽

Author(s):

Maurizio De Lucia ◽

Carlo Lanfranchi ◽

Antonio Matucci

Keyword(s):

Gas Turbine ◽

Thermal Energy ◽

Operating Conditions ◽

Hot Water ◽

Plant Performance ◽

Cooling Power ◽

Operating Parameters ◽

The European Union ◽

Cogeneration Plant ◽

Two Stage

A cogeneration plant with a small gas turbine was installed in a pharmaceutical factory and instrumented for acquiring all the values necessary to appraise both its energetic and cost advantages. The plant was designed and built as a demonstrative project under a program for energy use improvement in industry, partially financed by the European Union. The system comprises as its main components: 1) a gas turbine cogeneration plant for production of power and thermal energy under the form of hot water, superheated water, and steam; 2) a two-stage absorption unit, fueled by the steam produced in the cogeneration plant, for production of cooling thermal energy. The plant was provided with an automatized control system for the acquisition of plant operating parameters. The large amount of data thus provided made it possible to compare the new plant, under actual operating conditions, with the previously existing cooling power station with compression units, and with a traditional power plant. This comparative analysis was based on measurements of the plant operating parameters over nine months, and made it possible to compare actual plant performance with that expected and ISO values. The analysis results reveal that gas turbine performance is greatly affected by part-load as well as ambient temperature conditions. Two-stage absorber performance, moreover, turned out to decrease sharply and more than expected in off-design operating conditions.

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Thermodynamic Analysis of Minimum Extraction Ratio for Coal-Fired CHP Plants

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.472.1052 ◽

2014 ◽

Vol 472 ◽

pp. 1052-1056

Author(s):

Chun Hui Liao ◽

Zhi Gang Zhou ◽

Jia Ning Zhao

Keyword(s):

Energy Efficiency ◽

Thermodynamic Analysis ◽

District Heating ◽

Combined Heat And Power ◽

Exergy Efficiency ◽

Extraction Ratio ◽

Dual Purpose ◽

Heat Demand ◽

Chp System ◽

Minimum Heat

For evaluating the performance of combined heat and power district heating (CHP-DH) system, some thermodynamic indicators of CHP system, include energy efficiency, exergy efficiency, RPES and RAI, are introduced in this paper. Based on two condensed and heating dual purpose plants, the values of these indicators are calculated with different extraction ratio. The results show that RAI and RPES are more reasonable to be used to assess CHP-DH system and there is a minimum extraction ratio for each unit, which is 0.4 for given plants in this paper, to keep CHP-DH beneficial compared with separate heat and power (SHP) system. Besides, the minimum heat demand of CHP-DH system should be larger than the supplied heat correspond to minimum extraction ratio.

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The application of the TES technology in CHP heating system with Chinese demand profiles——A techno-economic feasibility case study

E3S Web of Conferences ◽

10.1051/e3sconf/201911106010 ◽

2019 ◽

Vol 111 ◽

pp. 06010

Author(s):

Ruoyu Zhang ◽

Haichao Wang ◽

Xiaozhou Wu ◽

Xiangli Li ◽

Lin Duanmu

Keyword(s):

Mathematical Model ◽

Heating System ◽

Combined Heat And Power ◽

Economic Benefits ◽

Economic Feasibility ◽

Electricity Pricing ◽

Peak Shaving ◽

Optimum Type ◽

Chp System

The thermal energy storage (TES) technology is an effective method to enhance the planning and the economy of the combined heat and power (CHP) plants, while it has still not been broadly promoted in China. In this paper we firstly establish a mathematical model for a Chinese CHP plant with TES. Then the EnergyPRO software is used to find the optimum type of the TES tank in a three-tariff electricity pricing market and the operation strategy of the CHP plant with the selected TES tank is studied. Thirdly, the economic benefits of the system with/without TES is evaluated. The results show that adding a TES tank with volume of 24000m3 can significantly increase operational profits of the CHP system and reduce the use of peak-shaving heat source.

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Techno-Economic Optimal Design of Solid Oxide Fuel Cell Systems for Micro-Combined Heat and Power Applications in the U.S.

Journal of Fuel Cell Science and Technology ◽

10.1115/1.3211099 ◽

2010 ◽

Vol 7 (3) ◽

Cited By ~ 40

Author(s):

Robert J. Braun

Keyword(s):

Life Cycle ◽

Fuel Cell ◽

Life Cycle Cost ◽

Combined Heat And Power ◽

Solid Oxide ◽

Oxide Fuel ◽

Chp System ◽

System Configurations ◽

System Designs ◽

The U.S

A techno-economic optimization study investigating optimal design and operating strategies of solid oxide fuel cell (SOFC) micro-combined heat and power (CHP) systems for application in U.S. residential dwellings is carried out through modeling and simulation of various anode-supported planar SOFC-based system configurations. Five different SOFC system designs operating from either methane or hydrogen fuels are evaluated in terms of their energetic and economic performances and their overall suitability for meeting residential thermal-to-electric ratios. Life-cycle cost models are developed and employed to generate optimization objective functions, which are utilized to explore the sensitivity of the life-cycle costs to various system designs and economic parameters and to select optimal system configurations and operating parameters for eventual application in single-family, detached residential homes in the U.S. The study compares the results against a baseline SOFC-CHP system that employs primarily external steam reforming of methane. The results of the study indicate that system configurations and operating parameter selections that enable minimum life-cycle cost while achieving maximum CHP-system efficiency are possible. Life-cycle cost reductions of over 30% and CHP efficiency improvements of nearly 20% from the baseline system are detailed.

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A modeling approach for low-temperature SOFC-based micro-combined heat and power systems

International Journal of Modern Physics B ◽

10.1142/s0217979219500012 ◽

2019 ◽

Vol 33 (04) ◽

pp. 1950001 ◽

Cited By ~ 7

Author(s):

Fida Hussain ◽

M. Ashfaq Ahmad ◽

Saeed Badshah ◽

Rizwan Raza ◽

M. Ajmal Khan ◽

...

Keyword(s):

Power Systems ◽

Energy Use ◽

Economic Assessment ◽

Combined Heat And Power ◽

Hydrogen Gas ◽

Energy Resources ◽

Efficient System ◽

Operating Strategies ◽

End Use ◽

Chp System

The world’s challenge is to determine a more efficient, economical and environmental-friendly energy source to compete and replace the ongoing conventional energy resources. Solid oxide fuel cells (SOFCs) provide a highly efficient system to use divergent energy resources and have proved to provide the cleanest energy, least energy use, and lowest emissions. A techno-economic study is required to investigate the model design for SOFC-based micro-combined heat and power (m-CHP) systems for applications in terms of educational and commercial buildings. This work models and explores the optimized application of hydrogen gas-fueled SOFC-based m-CHP systems in educational buildings. Two educational departments’ loads are presented and model of SOFC-based m-CHP system against the different electric power demands is performed, in order to provide a techno-economic assessment of the technology. For successful development of the technology, results are related to system rightsizing, operating strategies, thermal to electric ratios, and match between end-use, with an aim towards classifying the overall feasibility and essential application requirements.

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Optimum Microturbine Sizing in Small Scale CHP Systems

ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C ◽

10.1115/es2011-54585 ◽

2011 ◽

Author(s):

Mehdi Aghaei Meybodi ◽

Masud Behnia

Keyword(s):

Power Systems ◽

Carbon Tax ◽

Combined Heat And Power ◽

Small Scale ◽

Optimum Number ◽

Prime Mover ◽

Present Worth ◽

Prime Movers ◽

Chp System ◽

The Impact

Microturbines are ideally suited for distributed generation applications due to their flexibility in connection methods. They can be stacked in parallel for larger loads and provide stable and reliable power generation. One of the main applications of microturbines is operating as the prime mover in a combined heat and power (CHP) system. CHP systems are considered to be one of the best ways to produce heat and power with efficient fossil fuel consumption. Further, these systems emit less pollution compared to separate productions of the same amount of electricity and heat. In order to optimally benefit from combined heat and power systems, the proper sizing of prime movers is of paramount importance. This paper presents a technical-economic method for selecting the optimum number and nominal power as well as planning the operational strategy of microturbines as the prime movers of small scale combined heat and power systems (capacities up to 500 kW) in three modes of operation: one-way connection (OWC) mode, two-way connection (TWC) mode, and heat demand following (HDF) mode. In the proposed sizing procedure both performance characteristics of the prime mover and economic parameters (i.e. capital and maintenance costs) are taken into account. As the criterion for decision making Net Present Worth (NPW) is used. In our analysis we have also considered the impact of carbon tax on the economics of generation. The proposed approach may also be used for other types of prime movers as well as other sizes of CHP system.

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