Design and Testing of Ejectors for High Temperature Fuel Cell Hybrid Systems

2006 ◽  
Vol 3 (3) ◽  
pp. 284-291 ◽  
Author(s):  
Mario L. Ferrari ◽  
Davide Bernardi ◽  
Aristide F. Massardo
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Hybrid Systems ◽  
Fluid Dynamic ◽  
Experimental Tests ◽  
Open Circuit ◽  
Secondary Flows ◽  
Atmospheric Conditions ◽  
Simplified Approach ◽  
Chamber Length

Our goal in this work is the improvement of the ejector performance inside hybrid systems supporting the theoretical activity with experimental tests. In fact, after a preliminary ejector design, an experimental rig has been developed to test single stage ejectors for hybrid systems at different operative conditions of mass flow rates, pressures, and temperatures. At first, an open circuit has been built to perform tests at atmospheric conditions in the secondary duct. Then, to emulate a SOFC anodic recirculation device, the circuit has been closed, introducing a fuel cell volume in a reduced scale. This configuration is important to test ejectors at pressurized conditions, both in primary and secondary ducts. Finally, the volume has been equipped with an electrical heater and the rig has been thermally insulated to test ejectors with secondary flows at high temperature, necessary to obtain values in similitude conditions with the real ones. This test rig has been used to validate simplified and CFD models necessary to design the ejectors and investigate the internal fluid dynamic phenomena. In fact, the application of CFD validated models has allowed us to improve the performance of ejectors for hybrid systems optimizing the geometry in terms of primary and secondary ducts, mixing chamber length, and diffuser. However, the simplified approach is essential to start the analysis with an effective preliminary geometry.

scholarly journals Hardware-in-the-Loop Operations With an Emulator Rig for SOFC Hybrid Systems

2017 ◽  
Author(s):  
Mario L. Ferrari ◽  
Alessandro Sorce ◽  
Aristide F. Massardo
Keyword(s):  
Fuel Cell ◽  
Real Time ◽  
Hybrid Systems ◽  
Control Strategies ◽  
Experimental Tests ◽  
Outlet Temperature ◽  
Hardware In The Loop ◽  
Set Point ◽  
The Real ◽  
System Components

This paper shows the Hardware-In-the-Loop (HIL) technique developed for the complete emulation of Solid Oxide Fuel Cell (SOFC) based hybrid systems. This approach is based on the coupling of an emulator test rig with a real-time software for components which are not included in the plant. The experimental facility is composed of a T100 microturbine (100 kW electrical power size) modified for the connection to an SOFC emulator device. This component is composed of both anodic and cathodic vessels including also the anodic recirculation system which is carried out with a single stage ejector, driven by an air flow in the primary duct. However, no real stack material was installed in the plant. For this reason, a real-time dynamic software was developed in the Matlab-Simulink environment including all the SOFC system components (the fuel cell stack with the calculation of the electrochemical aspects considering also the real losses, the reformer, and a cathodic recirculation based on a blower, etc.). This tool was coupled with the real system utilizing a User Datagram Protocol (UDP) data exchange approach (the model receives flow data from the plant at the inlet duct of the cathodic vessel, while it is able to operate on the turbine changing its set-point of electrical load or turbine outlet temperature). So, the software is operated to control plant properties to generate the effect of a real SOFC in the rig. In stand-alone mode the turbine load is changed with the objective of matching the measured Turbine Outlet Temperature (TOT) value with the calculated one by the model. In grid-connected mode the software/hardware matching is obtained through a direct manipulation of the TOT set-point. This approach was essential to analyze the matching issues between the SOFC and the micro gas turbine devoting several tests on critical operations, such as start-up, shutdown and load changes. Special attention was focused on tests carried out to solve the control system issues for the entire real hybrid plant emulated with this HIL approach. Hence, the innovative control strategies were developed and successfully tested considering both the Proportional Integral Derivative and advanced approaches. Thanks to the experimental tests carried out with this HIL system, a comparison between different control strategies was performed including a statistic analysis on the results The positive performance obtainable with a Model Predictive Control based technique was shown and discussed. So, the HIL system presented in this paper was essential to perform the experimental tests successfully (for real hybrid system development) without the risks of destroying the stack in case of failures. Mainly surge (especially during transient operations, such as load changes) and other critical conditions (e.g. carbon deposition, high pressure difference between the fuel cell sides, high thermal gradients in the stack, excessive thermal stress in the SOFC system components, etc.) have to be carefully avoided in complete plants.

scholarly journals Study of 10kW molten carbonate fuel cell power generation system and its performance test

2020 ◽  
Author(s):  
Chengzhuang Lu ◽  
Ruiyun Zhang ◽  
Hao Li ◽  
Jian Cheng ◽  
Shisen Xu ◽  
...  
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Current Density ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Molten Carbonate Fuel Cell ◽  
Operating Voltage ◽  
Molten Carbonate ◽  
Fuel Cell Stack ◽  
Carbonate Fuel Cell

Abstract High-temperature fuel cells are a power technology that can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide. The present work explores the performance of the 10kW high-temperature molten carbonate fuel cell (MCFC). The key materials of the molten carbonate fuel cell single cell were characterized and analyzed by X-ray diffraction(XRD) and scanning electron microscope (SEM). The results show that the pore size of key electrode material was 6.5 μm and the matrix material is α-LiAlO 2 .The open circuit voltage of the single cell is 1.23 V in experiment. The current density is greater than 100 mA / cm^2 when the operating voltage is 0.7 V. The 10 kW fuel cell stack was constitutive of 80 pieces single fuel cells with area of 2000 cm 2 . The open circuit voltage of the stack reaches above 85 V. The fuel cell stack power and current density can reach 11.7 kW and 104.5 mA/cm^2 when the operating voltage is 56 V. The influence and long-term stable operation of the stack were also analyzed and discussed. The successful operation of 10kW high temperature fuel cell promotes the scale of domestic fuel cell and provides the research basis of fuel cell capacity enhancement and distributed generation in the next step.

scholarly journals Performance of Pulverized Coal Combustion under High Temperature Air Diluted by Steam

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mohsen Saffari Pour ◽  
Yang Weihong
Keyword(s):  
High Temperature ◽  
Coal Combustion ◽  
Fluid Dynamic ◽  
Flame Temperature ◽  
Experimental Tests ◽  
Injection Rate ◽  
Pulverized Coal ◽  
Injection Velocity ◽  
Pulverized Coal Combustion ◽  
Injection Speed

The high temperature air combustion (HiTAC) is an advanced promising technology for heat recovery, energy saving, and stability improvement of flame. Computational fluid dynamic (CFD) is known as an applied tool to execute HiTAC modeling. In this paper, performances of pulverized coal combustion under the high preheated and oxygen deficient air are studied by both experimental and numerical methodology. The experimental facilities have been accomplished in a HiTAC chamber with coal injection velocity that ranges from 10 to 40 m/s. In order to achieve different preheated temperatures, the combustion air in such system is diluted by variable steam percentages from 0 to 44%. Results of mathematical simulation and experimental tests present convincible agreement through whole region. It is concluded that NOX emission is reduced by increasing the steam percentage in the oxidizer due to decreasing the flame temperature. Besides, graphical contours show that by adding more steam to oxidizer composition, the oxygen concentration decreased. Additionally, results show that when the injection speed of fuel is increased, NOX emission is also increased, and when the injection rate of preheated air is increased, NOX emission shows decreasing trend. Further contribution in future is needed to investigate the performance of such technologies.

Experimental Test Facility for the Analysis of Transient Behavior of High Temperature Fuel Cell/Gas Turbine Hybrid Power Plants

2006 ◽  
Vol 3 (3) ◽  
pp. 234-241 ◽  
Author(s):  
Rodolfo Taccani ◽  
Diego Micheli
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Power Systems ◽  
Gas Turbine ◽  
Power Plants ◽  
Fluid Dynamic ◽  
Transient Behavior ◽  
Combustion Products ◽  
Test Facility ◽  
Operational Conditions

Pressurized high temperature fuel cells and gas turbine integrated power systems are receiving growing attention as capable of reaching very high electrical conversion efficiency even in small size power plants. In this system the fuel and the oxidant (air) enter the cell after being compressed. The fuel oxidation reaction occurs predominantly within the fuel cell. The reaction is completed in a combustion chamber and the pressurized combustion products are exhausted through a turbine. The dynamic interdependences related to the integration of the fuel cell and the gas turbine are not completely understood and unexpected complications and dangers might arise. In fact as a consequence of both the relatively large volume of the pressurized portion of the plant and the shape of the stalled characteristic of available compressors, the plant could be affected by the inception of fluid-dynamic instabilities. In particular, surge could be detected in the transient off-design operational conditions occurring during plant regulation, start up and shut down. The paper presents a new experimental fuel cell gas turbine simulation facility that has been constructed at the Mechanical Engineering Department of the University of Trieste, Italy. The facility was designed to examine the effects of transient events on the dynamics of these systems. The theoretical analysis of the plant is completed using a dynamic model of the system purposely developed.

A New Concept for High Temperature Fuel Cell Hybrid Systems Using Supercritical Carbon Dioxide

2009 ◽  
Vol 6 (2) ◽  
Author(s):  
D. Sánchez ◽  
R. Chacartegui ◽  
F. Jiménez-Espadafor ◽  
T. Sánchez
Keyword(s):  
Carbon Dioxide ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Supercritical Carbon Dioxide ◽  
Hybrid Systems ◽  
Cell Hybrid ◽  
Gas Turbines ◽  
Solid Oxide ◽  
Molten Carbonate

Hybrid power systems based on high temperature fuel cells are a promising technology for the forthcoming distributed power generation market. For the most extended configuration, these systems comprise a fuel cell and a conventional recuperative gas turbine engine bottoming cycle, which recovers waste heat from the cell exhaust and converts it into useful work. The ability of these gas turbines to produce useful work relies strongly on a high fuel cell operating temperature. Thus, if molten carbonate fuel cells or the new generation intermediate temperature solid oxide fuel cells are used, the efficiency and power capacity of the hybrid system decrease dramatically. In this work, carbon dioxide is proposed as the working fluid for a closed supercritical bottoming cycle, which is expected to perform better for intermediate temperature heat recovery applications than the air cycle. Elementary fuel cell lumped-volume models for both solid oxide and molten carbonate are used in conjunction with a Brayton cycle thermodynamic simulator capable of working with open/closed and air/carbon dioxide systems. This paper shows that, even though the new cycle is coupled with an atmospheric fuel cell, it is still able to achieve the same overall system efficiency and rated power than the best conventional cycles being currently considered. Furthermore, under certain operating conditions, the performance of the new hybrid systems beats that of existing pressurized fuel cell hybrid systems with conventional gas turbines. From the results, it is concluded that the supercritical carbon dioxide bottoming cycle holds a very high potential as an efficient power generator for hybrid systems. However, costs and balance of plant analysis will have to be carried out in the future to check its feasibility.

A unified model of high-temperature fuel-cell heat-engine hybrid systems and analyses of its optimum performances

2014 ◽  
Vol 39 (4) ◽  
pp. 1811-1825 ◽  
Author(s):  
Xiuqin Zhang ◽  
Yuan Wang ◽  
Juncheng Guo ◽  
Tien-Mo Shih ◽  
Jincan Chen
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Hybrid Systems ◽  
Heat Engine ◽  
Unified Model

Parametric Analysis and Optimization of a High Temperature Fuel Cell: Supercritical CO2 Turbine Hybrid System

2008 ◽  
Author(s):  
D. Sa´nchez ◽  
R. Chacartegui ◽  
A. Mun˜oz ◽  
T. Sa´nchez
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Operating Temperature ◽  
Inlet Temperature ◽  
Brayton Cycle ◽  
Molten Carbonate ◽  
Turbine Inlet Temperature

The integration of high temperature fuel cells — molten carbonate and solid oxide — and gas turbine engines for efficient power generation is not new. Different strategies for integrating both systems have been proposed in the past ten years and there are some field tests being run presently. However, the commercial availability of such power systems seems to be continuously delayed, probably due to cost and reliability problems. The materials used in high temperature fuel cells are expensive and their cost is not decreasing at the expected pace. In fact, it looks as if they had reached stabilization. Therefore, there seems to be agreement that operating at a lower temperature might be the only way to achieve more competitive costs to enter the market, as metallic materials could then be used. From the point of view of conventional hybrid systems, decreasing the operating temperature of the cell would affect the efficiency of the bottoming cycle dramatically, as long as turbine inlet temperature is a critical parameter for the performance of a Brayton cycle. This is the reason why hybrid systems perform better with solid oxide fuel cells operating at 1000 °C than with molten carbonate cells at 650 °C typically. This work presents a hybrid system comprising a high temperature fuel cell, either SOFC or MCFC, and a bottoming Brayton cycle working with supercritical carbon dioxide. A parametric analysis is done where all the parameters affecting the performance of the hybrid system are studied, with emphasis in the bottoming cycle. For the Brayton cycle: pressure ratio, expansion and compression efficiencies, recuperator effectiveness, pressure losses, turbine inlet temperature... For the fuel cell: fuel utilization, current density, operating temperature, etc. From this analysis, optimum operating point and integration scheme are established and, after this, a comparison with conventional hybrid systems using similar fuel cells is done. Results show that, although the fuel cell is not pressurized in the CO2 based system, its performance is similar to the best conventional cycle. Furthermore, if lower operating temperatures are considered for the fuel cell, the new system performs better than any of the conventional.

scholarly journals Study and performance test of 10 kW molten carbonate fuel cell power generation system

2021 ◽  
Author(s):  
Chengzhuang Lu ◽  
Ruiyun Zhang ◽  
Guanjun Yang ◽  
Hua Huang ◽  
Jian Cheng ◽  
...  
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Molten Carbonate Fuel Cell ◽  
Operating Voltage ◽  
Molten Carbonate ◽  
Fuel Cell Stack ◽  
Carbonate Fuel Cell

AbstractThe use of high-temperature fuel cells as a power technology can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide. This work explores the performance of a 10 kW high-temperature molten carbonate fuel cell. The key materials of a single cell were characterized and analyzed using X-ray diffraction and scanning electron microscopy. The results show that the pore size of the key electrode material is 6.5 µm and the matrix material is α-LiAlO2. Experimentally, the open circuit voltage of the single cell was found to be 1.23 V. The current density was greater than 100 mA/cm2 at an operating voltage of 0.7 V. The 10 kW fuel cell stack comprised 80 single fuel cells with a total area of 2000 cm2 and achieved an open circuit voltage of greater than 85 V. The fuel cell stack power and current density could reach 11.7 kW and 104.5 mA/cm2 at an operating voltage of 56 V. The influence and long-term stable operation of the stack were also analyzed and discussed. The successful operation of a 10 kW high-temperature fuel cell promotes the large-scale use of fuel cells and provides a research basis for future investigations of fuel cell capacity enhancement and distributed generation in China.

scholarly journals Study of 10kW molten carbonate fuel cell power generation system and its performance test

2020 ◽  
Author(s):  
Chengzhuang Lu ◽  
Ruiyun Zhang ◽  
Hao Li ◽  
Jian Cheng ◽  
Shisen Xu ◽  
...  
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Current Density ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Molten Carbonate Fuel Cell ◽  
Operating Voltage ◽  
Molten Carbonate ◽  
Fuel Cell Stack ◽  
Carbonate Fuel Cell

Abstract High-temperature fuel cells are a power technology that can improve the efficiency of electricity generation and achieve near-zero emissions of carbon dioxide. The present work explores the performance of the 10kW high-temperature molten carbonate fuel cell (MCFC). The key materials of the molten carbonate fuel cell single cell were characterized and analyzed by X-ray diffraction(XRD) and scanning electron microscope (SEM). The results show that the pore size of key electrode material was 6.5 μm and the matrix material is α-LiAlO2.The open circuit voltage of the single cell is 1.23 V in experiment. The current density is greater than 100 mA / cm^2 when the operating voltage is 0.7 V. The 10 kW fuel cell stack was constitutive of 80 pieces single fuel cells with area of 2000 cm2. The open circuit voltage of the stack reaches above 85 V. The fuel cell stack power and current density can reach 11.7 kW and 104.5 mA/cm^2 when the operating voltage is 56 V. The influence and long-term stable operation of the stack were also analyzed and discussed. The successful operation of 10kW high temperature fuel cell promotes the scale of domestic fuel cell and provides the research basis of fuel cell capacity enhancement and distributed generation in the next step.

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