Needs and Approaches for Novel Characterization of Direct Hybrid Fuel Cell/Gas Turbines

2015 ◽  
Author(s):  
David Tucker ◽  
Comas Haynes ◽  
Patrick Geoghegan
Keyword(s):  
Fuel Cell ◽  
Hybrid Systems ◽  
Gas Turbines ◽  
Low Cost ◽  
A Priori ◽  
The United States ◽  
Hardware In The Loop ◽  
Operational Flexibility ◽  
Developmental Needs ◽  
Heat Engines

Solid oxide fuel cell (SOFC)/ gas turbine (GT) hybrid systems possess the capacity for unprecedented performances, such as electric efficiencies nearly twice that of conventional heat engines at variable scale power ratings inclusive of distributed generation. Additionally, these hybrids can have excellent operational flexibility with turndowns possibly as great as 85%. There are, however, developmental needs such as turbomachinery characterization and re-design. A leading example is that of greater propensity to have occurrences of stall-surge given the significantly different operating environment in contrast to conventional heat engines. Additionally, dynamic variation in power generation has to be done with significant a priori insight to avoid thermomechanical threats to cell stack and turbomachinery. State-of-the-art approaches involving hardware-in-the-loop simulation and, ultimately, additive manufacturing are being pursued to enable such characterization and re-design considerations given variable and dynamic operability requirements. Compressor performance in hybrid systems has been characterized at the United States National Energy Technology Laboratory (NETL), inclusive of a capability of feed forward hardware-in-the-loop simulation of hybrid systems under dynamic conditions and a capability of replacing turbine and compressor components at a relatively low cost. This paper highlights some of the simulation results, and the net result is an approach that addresses hybrid system developmental needs for accommodating generation transients.

scholarly journals A Real-Time Degradation Model for Hardware in the Loop Simulation of Fuel Cell Gas Turbine Hybrid Systems

2015 ◽  
Author(s):  
Valentina Zaccaria ◽  
Alberto Traverso ◽  
David Tucker
Keyword(s):  
Fuel Cell ◽  
Real Time ◽  
Gas Turbine ◽  
Hybrid Systems ◽  
Current Density ◽  
Gas Turbines ◽  
Hardware In The Loop ◽  
Fuel Utilization ◽  
Time Operation ◽  
The Impact

The theoretical efficiencies of gas turbine fuel cell hybrid systems make them an ideal technology for the future. Hybrid systems focus on maximizing the utilization of existing energy technologies by combining them. However, one pervasive limitation that prevents the commercialization of such systems is the relatively short lifetime of fuel cells, which is due in part to several degradation mechanisms. In order to improve the lifetime of hybrid systems and to examine long-term stability, a study was conducted to analyze the effects of electrochemical degradation in a solid oxide fuel cell (SOFC) model. The SOFC model was developed for hardware-in-the-loop simulation with the constraint of real-time operation for coupling with turbomachinery and other system components. To minimize the computational burden, algebraic functions were fit to empirical relationships between degradation and key process variables: current density, fuel utilization, and temperature. Previous simulations showed that the coupling of gas turbines and SOFCs could reduce the impact of degradation as a result of lower fuel utilization and more flexible current demands. To improve the analytical capability of the model, degradation was incorporated on a distributed basis to identify localized effects and more accurately assess potential failure mechanisms. For syngas fueled systems, the results showed that current density shifted to underutilized sections of the fuel cell as degradation progressed. Over-all, the time to failure was increased, but the temperature difference along cell was increased to unacceptable levels, which could not be determined from the previous approach.

Performance Analysis on SOFC-HCCI Engine Hybrid System

2012 ◽  
Author(s):  
Sung Ho Park ◽  
Young Duk Lee ◽  
Sang Gyu Kang ◽  
Kook Young Ahn
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Gas Turbines ◽  
Waste Heat ◽  
Metal Catalyst ◽  
Molten Carbonate ◽  
Hcci Engine ◽  
Ci Engines

Fuel cell systems are currently regarded as a promising type of energy conversion system. Various types of fuel cell have been developed and investigated worldwide for portable, automotive, and stationary applications. In particular, in the case of large-scale stationary applications, the high-temperature fuel cells known as the molten carbonate fuel cell (MCFC) and the solid oxide fuel cell (SOFC) have been used as a power source due to their higher efficiency compared to low-temperature fuel cells. Because SOFCs have many advantages, including a high power density, low corrosion, and operability without a metal catalyst, many efforts to develop a SOFC hybrid system have been undertaken. SOFC hybrid systems with a gas turbine or engine show improved system efficiency through their utilization of waste heat and unreacted fuel. Especially, the internal combustion engine has the advantage of robustness, easy maintenance, and a low cost compared to gas turbines, this type is more adaptable for use in a hybrid system with a SOFC. However, the engine should be operated stably at a high air fuel ratio because the SOFC anode exhaust gas has a low fuel concentration. The homogeneous charge compression ignition (HCCI) engine has both the advantages of SI and CI engines. Moreover, the lean burn characteristics of the HCCI engine make it a strong candidate for SOFC hybrid systems. The objective of this work is to develop a novel cycle composed of a SOFC and a HCCI engine. In order to optimize the SOFC-HCCI hybrid system, a system analysis is conducted here using the commercial software Aspen Plus®. The SOFC model is validated with experimental data. The engine model is developed based on an empirical equation that considers the ignition delay time. The performance of the hybrid system is compared with that of a SOFC stand-alone system to confirm the optimization of the system. This study will be useful for the development of a new type of hybrid system which uses a fuel cell and an optimized system.

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.

Fuel Composition Transients in Fuel Cell Turbine Hybrid for Polygeneration Applications

2014 ◽  
Vol 11 (6) ◽  
Author(s):  
Nor Farida Harun ◽  
David Tucker ◽  
Thomas A. Adams
Keyword(s):  
Fuel Cell ◽  
Hybrid Systems ◽  
Carbon Deposition ◽  
Dynamic Performance ◽  
Sudden Change ◽  
Department Of Energy ◽  
Test Facility ◽  
Fuel Composition ◽  
Hardware In The Loop ◽  
Fuel Flexibility

Transient impacts on the performance of solid oxide fuel cell/gas turbine (SOFC/GT) hybrid systems were investigated using hardware-in-the-loop simulations (HiLSs) at a test facility located at the U.S. Department of Energy, National Energy Technology Laboratory. The work focused on applications relevant to polygeneration systems, which require significant fuel flexibility. Specifically, the dynamic response of implementing a sudden change in fuel composition from syngas to methane was examined. The maximum range of possible fuel composition allowable within the constraints of carbon deposition in the SOFC and stalling/surging of the turbine compressor system was determined. It was demonstrated that the transient response was significantly impact the fuel cell dynamic performance, which mainly drives the entire transient in SOFC/GT hybrid systems. This resulted in severe limitations on the allowable methane concentrations that could be used in the final fuel composition when switching from syngas to methane. Several system performance parameters were analyzed to characterize the transient impact over the course of 2 h from the composition change.

Hybrid Power: A 2003 Perspective for the Decade

2003 ◽  
Author(s):  
Richard Dennis ◽  
Gary Burch ◽  
Mark Williams ◽  
Pat Hoffman ◽  
Robert Gross ◽  
...  
Keyword(s):  
Power Generation ◽  
Fuel Cells ◽  
Hybrid Systems ◽  
Gas Turbines ◽  
High Efficiency ◽  
Electric Energy ◽  
Hybrid Power ◽  
Distributed Power Generation ◽  
Heat Engines ◽  
The Individual

Hybrid power generation systems are evolving as attractive candidates for high-efficiency production of electric energy and a near-zero emission of primary pollutants. Hybrids, by definition, are a combination of two or more power generation technologies that create a synergistic value greater than the sum of the individual parts. Examples include fuel cells integrated with gas turbines, fuel cells integrated with photovoltaics, and heat engines integrated with wind generation. This paper describes the evolution of hybrid systems for both distributed power generation and central power generation as anticipated for this decade, the development requirements and application opportunities, and strategies that utilize both fossil and renewable fuels to achieve the dramatic increase in electrical efficiency that hybrid systems portend.

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.

Fuel Composition Transients in Fuel Cell Turbine Hybrid for Polygeneration Applications

2014 ◽  
Author(s):  
Nor Farida Harun ◽  
David Tucker ◽  
Thomas A. Adams
Keyword(s):  
Fuel Cell ◽  
Hybrid Systems ◽  
Carbon Deposition ◽  
Dynamic Performance ◽  
Sudden Change ◽  
Department Of Energy ◽  
Test Facility ◽  
Fuel Composition ◽  
Hardware In The Loop ◽  
Fuel Flexibility

Transient impacts on the performance of solid oxide fuel cell / gas turbine (SOFC/GT) hybrid systems were investigated using hardware-in-the-loop simulations (HiLS) at a test facility located at the U.S. Department of Energy, National Energy Technology Laboratory. The work focused on applications relevant to polygeneration systems which require significant fuel flexibility. Specifically, the dynamic response of implementing a sudden change in fuel composition from syngas to methane was examined. The maximum range of possible fuel composition allowable within the constraints of carbon deposition in the SOFC and stalling/surging of the turbine compressor system was determined. It was demonstrated that the transient response was significantly impact the fuel cell dynamic performance, which mainly drives the entire transient in SOFC/GT hybrid systems. This resulted in severe limitations on the allowable methane concentrations that could be used in the final fuel composition when switching from syngas to methane. Several system performance parameters were analyzed to characterize the transient impact over the course of two hours from the composition change.

Hybrid Gas Turbine and Fuel Cell Systems in Perspective Review

1999 ◽  
Author(s):  
David J. White
Keyword(s):  
Carbon Dioxide ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid Systems ◽  
Gas Turbines ◽  
Energy Output ◽  
Net Energy ◽  
Cell Systems

The concept of hybrids combining fuel cell and gas turbine systems is without question neoteric, and probably is less than eight years old. However, this concept is in a sense a logical development derived from the many early systems that embodied the key features of rotating machinery to compress air. It was the introduction of high temperature fuel cells such as the solid oxide fuel cell (SOFC) that allowed the concept of hybrid gas turbine fuel cell systems to take root. The SOFC with an operating temperature circa 1000° C matched well with small industrial gas turbines that had firing temperatures on the same order. The recognition that the SOFC could be substituted for the gas turbine combustor was the first step into the realm of fuel cell topping systems. Fuel cells in general were recognized as having higher efficiencies at elevated pressures. Thus the hybrid topping system where the gas turbine pressurized the fuel cell and the fuel cell supplied the hot gases for expansion over the turbine promised to provide a high level of synergy between the two systems. Bottoming systems using the exhaust of a gas turbine as the working fluid of a fuel cell such as the molten carbonate fuel cell (MCFC) have been identified and are potential future power generation hybrid systems. The MCFC is especially well suited to the bottoming role because of the need to have carbon dioxide present in the inlet air stream. The carbon dioxide in the gas turbine exhaust allows the high temperature blower, normally used to recirculate and inject exhaust products into the inlet air, to be eliminated. Hybrid systems have the potential of achieving fossil fuel to electricity conversion efficiencies on the order of 70% and higher. The costs of hybrid systems in dollars per kilowatt are generally higher than say an advanced gas turbine that is available today but not by much. The net energy output over the life of a hybrid topping system is similar to that of a recuperated gas turbine but possibly lower than a high-efficiency simple-cycle machine, depending on the efficiency of the hybrid. Methodologies to aid in the selection of the hybrid system for future development have to be developed and used consistently. Life cycle analyses (LFA) provide a framework for such selection processes. In particular the concept of net energy output provides a mechanism to assign relative worth to competing concepts.

Real-Time Hardware-in-the-Loop Tool for a Fuel Cell Hybrid System Emulator Test Rig

2011 ◽  
Author(s):  
Francesco Caratozzolo ◽  
Mario L. Ferrari ◽  
Alberto Traverso ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Real Time ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Solid Oxide ◽  
Outlet Temperature ◽  
Hardware In The Loop ◽  
Test Rig ◽  
Time Model

The Thermochemical Power Group of the University of Genoa built a complete Hybrid System emulator test rig constituted by a 100 kW recuperated micro gas turbine, an anodic circuit (based on the coupling of a single stage ejector with a stainless steel vessel) and a cathodic modular volume (located between the recuperator outlet and combustor inlet). The system is sized to consider the coupling of the commercial micro turbine, operated at 62 kW load, and a planar Solid Oxide Fuel Cell (SOFC) to reach the overall electrical power output of 450 kW. The emulator test rig has been recently linked with a real-time model of the SOFC block. The model is used to simulate the complete thermodynamic and electrochemical behavior of a high temperature fuel cell based on solid oxide technology. The test rig coupled with the model generates a real-time hardware-in-the-loop (HIL) facility for hybrid systems emulation. The model is constituted by a SOFC module, an anodic circuit with an ejector, a cathodic loop with a blower (for the recirculation) and a turbine module. Temperature, pressure and air mass flow rate at recuperator outlet (downstream of the compressor) and rotational speed of the machine are inputs from the plant to the model. The turbine outlet temperature (TOT) calculated by the model is fed to the machine control system and the turbine electric load is moved to match the model TOT value. In this work different tests were carried out to characterize the interaction between the experimental plant and the real-time model; double step and double ramp tests of current and fuel characterized the dynamic response of the system. The mGT power control system proved to be fast enough, compared to the slow thermal response of the SOFC stack, and reliable. The hybrid systems was operated at 90% of nominal power with about 56% of electrical efficiency based on natural gas LHV.

Solid Oxide Fuel Cell Hybrid Systems Fed by Liquid Fuels for Distributed Power Generation

2008 ◽  
Author(s):  
Marco Santin ◽  
Alberto Traverso ◽  
Aristide Massardo
Keyword(s):  
Power Generation ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Hybrid Systems ◽  
Gas Turbines ◽  
Solid Oxide ◽  
Design Parameters ◽  
Oxide Fuel ◽  
Distributed Power ◽  
Distributed Power Generation

Solid oxide fuel cell hybridization with micro gas turbines is an attractive option for distributed power generation up to a few MW, allowing to obtain high efficiency and low pollutant emission. In this publication, a comparative thermoeconomic analysis of SOFC hybrid systems with methanol and kerosene fuel processors is presented. Methanol can be produced from renewable sources. Also, hybrid systems fuelled by methanol can achieve high efficiencies due to effective heat recovery from the exhaust gases in the low temperature reformer. Kerosene is representative of conventional liquid fossil fuels, and it is also a typical fuel for aerospace applications. A 500 kW class hybrid system was chosen for this analysis and the performance was calculated based on macroscopic component models. The results were obtained with WTEMP software, developed by the Thermochemical Power Group of the University of Genoa. The choice of the fuel processing strategy and the influence of the main design parameters on the thermoeconomic characteristics of hybrid systems were investigated.

Sign in / Sign up

Export Citation Format

Share Document