Calculating the System Efficiency of the NETL Gas-Turbine/Fuel-Cell Hybrid System Using a Fully Coupled Lumped Parameter System Model

2006 ◽  
Author(s):  
John VanOsdol ◽  
Dave Tucker
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
System Performance ◽  
Operating Conditions ◽  
System Model ◽  
Model Parameters ◽  
System Efficiency ◽  
Simple Method ◽  
System Models

Thermodynamic efficiency must be considered in the effective analysis of gas turbine fuel cell power generation system performance. In most numerical simulations of hybrid systems, the use of compressor maps and turbine maps are neglected. It is assumed that the design criterion generated by the system model can be met by the manufacturer of these items. These system models may use partial information from a compressor map, or a turbine map, but they fail to match all the operating conditions of both maps in a hybrid configuration. Also, to simplify the calculations that are performed by the complex hybrid system models, the effects of heat transfer and fluid dynamic drag are often decoupled. When system calculations are done in this way, the resulting calculations for system efficiency may suffer error. Hybrid system designers need a simple method to calculate the system performance directly from the maps of real compressors and real turbines that currently exist, and that would be part of a hybrid system. In this work, a simple procedure is illustrated where a coupled analysis of the various system components is performed and included as part of the system model. This analysis is done using the compressor and turbine maps of the hybrid performance project hardware at the U.S. Department of Energy, National Energy Technology Laboratory (NETL). Model parameters are tuned using experimental conditions and results are obtained. The results show the importance of aerodynamic coupling in system models, and how this coupling affects the system efficiency calculations. This coupling becomes important especially for the variable density flows that are typically found in combustors, heat exchangers and fuel cells.

Performance Study of Hybrid Solid Oxide Fuel Cell–Gas Turbine Power System

2010 ◽  
Vol 171-172 ◽  
pp. 319-322
Author(s):  
Hong Bin Zhao ◽  
Xu Liu
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Cell Model ◽  
Research Work ◽  
Atmospheric Condition ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Oxide Fuel

The simulation and analyses of a “bottoming cycle” solid oxide fuel cell–gas turbine (SOFC–GT) hybrid system at the standard atmospheric condition is presented in this paper. The fuel cell model used in this research work is based on a tubular Siemens–Westinghouse–type SOFC with 1.8MW capacity. Energy and exergy analyses of the whole system at fixed conditions are carried out. Then, comparisons of the exergy destruction and exergy efficiency of each component are also conducted to determine the potential capability of the hybrid system to generate power. Moreover, the effects of operating conditions including fuel flow rate and SOFC operating temperature on performances of the hybrid system are analyzed.

Compressor Instability Analysis Within a Hybrid System Subject to Cycle Uncertainties

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Alessandra Cuneo ◽  
Alberto Traverso ◽  
Aristide F. Massardo
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Stochastic Analysis ◽  
High Speed ◽  
Operating Conditions ◽  
Operational Parameters ◽  
Surge Margin ◽  
Speed Range ◽  
Compressor Surge

The dynamic modeling of energy systems can be used for different purposes, obtaining important information both for the design phase and control system strategies, increasing the confidence during experimental phase. Such analysis in dynamic conditions is generally performed considering fixed values for both geometrical and operational parameters such as volumes, orifices, but also initial temperatures, pressure. However, such characteristics are often subject to uncertainty, either because they are not known accurately or because they may depend on the operating conditions at the beginning of the relevant transient. With focus on a gas turbine fuel cell hybrid system (HS), compressor surge may or may not occur during transients, depending on the aforementioned cycle characteristics; hence, compressor surge events are affected by uncertainty. In this paper, a stochastic analysis was performed taking into account an emergency shut-down (ESD) in a fuel cell gas turbine HS, modeled with TRANSEO, a deterministic tool for the dynamic simulations. The aim of the paper is to identify the main parameters that impact on compressor surge margin. The stochastic analysis was performed through the response sensitivity analysis (RSA) method, a sensitivity-based approximation approach that overcomes the computational burden of sampling methods. The results show that the minimum surge margin occurs in two different ranges of rotational speed: a high-speed range and a low-speed range. The temperature and geometrical characteristics of the pressure vessel, where the fuel cell is installed, are the two main parameters that affect the surge margin during an emergency shut down.

Control Strategies for Start-Up and Part-Load Operation of Solid Oxide Fuel Cell/Gas Turbine Hybrid System

2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Wei Jiang ◽  
Ruixian Fang ◽  
Jamil Khan ◽  
Roger Dougal
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Control Strategies ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Electrical Characteristics ◽  
Part Load ◽  
Start Up

Control strategy plays a significant role in ensuring system stability and performance as well as equipment protection for maximum service life. This work is aimed at investigating the control strategies for start-up and part-load operating conditions of the solid oxide fuel cell/gas turbine (SOFC/GT) hybrid system. First, a dynamic SOFC/GT hybrid cycle, based on the thermodynamic modeling of system components, has been successfully developed and simulated in the virtual test bed simulation environment. The one-dimensional tubular SOFC model is based on the electrochemical and thermal modeling, accounting for voltage losses and temperature dynamics. The single cell is discretized using a finite volume method where all the governing equations are solved for each finite volume. Two operating conditions, start-up and part load, are employed to investigate the control strategies of the SOFC/GT hybrid cycle. In particular, start-up control is adopted to ensure the initial rotation speed of a compressor and a turbine for a system-level operation. The control objective for the part-load operation regardless of load changes, as proposed, is to maintain constant fuel utilization and a fairly constant SOFC temperature within a small range by manipulating the fuel mass flow and air mass flow. To this end, the dynamic electrical characteristics such as cell voltage, current density, and temperature under the part load are simulated and analyzed. Several feedback control cycles are designed from the dynamic responses of electrical characteristics. Control cycles combined with control related variables are introduced and discussed.

scholarly journals Performance Analysis of a Hybrid System Consisting of a Molten Carbonate Direct Carbon Fuel Cell and an Absorption Refrigerator

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 357 ◽  
Author(s):  
Houcheng Zhang ◽  
Jiatang Wang ◽  
Jiapei Zhao ◽  
Fu Wang ◽  
He Miao ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
Current Density ◽  
System Performance ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Molten Carbonate ◽  
Direct Carbon Fuel Cell ◽  
Operating Current ◽  
Absorption Refrigerator

By integrating an Absorption Refrigerator (AR), a new hybrid system model is established to reuse the waste heat from a Molten Carbonate Direct Carbon Fuel Cell (MCDCFC) for additional cooling production. Various irreversible losses in each element of the system are numerically described. The operating current density span of the MCDCFC that allows the AR to work is derived. Under different operating conditions, the mathematical expressions for equivalently evaluating the hybrid system performance are derived. In comparison with the stand-alone MCDCFC, the maximum attainable power density of the proposed system and its corresponding efficiency are increased by 5.8% and 6.8%, respectively. The generic performance features and optimum operating regions of the proposed system are demonstrated. A number of sensitivity analyses are performed to study the dependences of the proposed system performance on some physical parameters and operating conditions such as operating temperature, operating current density, and pressure of the MCDCFC, cyclic working fluid internal irreversibility inside the AR, thermodynamic losses related parameters and the anode thickness of the MCDCFC. The obtained results may offer some new insights into the performance improvement of an MCDCFC through a reasonable heat management methodology.

scholarly journals Gas turbine advanced power systems to improve solid oxide fuel cell economic viability

2017 ◽  
Vol 1 ◽  
pp. U96IED ◽  
Author(s):  
Valentina Zaccaria ◽  
David Tucker ◽  
Alberto Traverso
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Economic Performance ◽  
Economic Feasibility ◽  
Solid Oxide ◽  
Economic Viability ◽  
Oxide Fuel ◽  
System Efficiency

Abstract Coupling a solid oxide fuel cell (SOFC) with a gas turbine provides a substantial increment in system efficiency compared to the separate technologies, which can potentially introduce economic benefits and favor an early market penetration of fuel cells. Currently, the economic viability of such systems is limited by fuel cell short lifetime due to a progressive performance degradation that leads to cell failure. Mitigating these phenomena would have a significant impact on system economic feasibility. In this study, the lifetime of a standalone, atmospheric SOFC system was compared to a pressurized SOFC gas turbine hybrid and an economic analysis was performed. In both cases, the power production was required to be constant over time, with significantly different results for the two systems in terms of fuel cell operating life, system efficiency, and economic return. In the hybrid system, an extended fuel cell lifetime is achieved while maintaining high system efficiency and improving economic performance. In this work, the optimal power density was determined for the standalone fuel cell in order to have the best economic performance. Nevertheless, the hybrid system showed better economic performance, and it was less affected by the stack cost.

Effect of Fuel Cell Operating Parameters on the Performance of a Multi-MW Solid Oxide Fuel Cell/Gas Turbine Hybrid System

2007 ◽  
Author(s):  
Georgia C. Karvountzi ◽  
Joe Ferrall ◽  
James D. Powers
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
System Performance ◽  
Cell Voltage ◽  
Leakage Rate ◽  
Solid Oxide ◽  
System Efficiency ◽  
Optimum Pressure ◽  
Average Cell ◽  
Internal Reforming

The principal planar solid oxide fuel cell operating parameters are pressure, stack temperature and temperature gradient, cell voltage, fuel utilization, leakage rate and percentage of internal reforming. This paper shows the effects of these parameters on overall fuel cell/gas turbine hybrid system performance. The baseline conceptual system used to investigate these parameters is a 500MW hybrid system. The system performance was simulated using ASPEN Plus and GateCycle™ commercial software platforms and a GE developed FORTRAN code to simulate the fuel cell performance. Parameter choices for the baseline case are: 15atm pressure, 725°C average cell temperature, 150°C stack temperature rise, 0.75V average cell voltage, 80% fuel utilization, 1% leakage rate and 70% internal reforming. At these conditions, the system efficiency is predicted at approximately 65.8%. The addition of a steam turbine bottoming cycle, increases the hybrid system efficiency by 4% to 70%. Increasing the average cell voltage to 0.8V or the percentage of internal reforming to 90% also increases the hybrid system efficiency to nearly 70%. The optimum pressure for maximum efficiency is 8 atm for the hybrid system; the optimum pressure for the hybrid with a steam turbine bottoming cycle is 9 atm. While increasing the SOFC temperature rise, cell voltage, and percentage of internal reforming improve system efficiency, they may adversely affect stack cost and reliability; these competing effects must be traded when designing a practical system.

Performance Simulation of a Hybrid Micro Gas Turbine Fuel Cell System Based on Existing Components

2011 ◽  
Author(s):  
D. P. Bakalis ◽  
A. G. Stamatis
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
System Performance ◽  
Cell System ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Utilization Factor ◽  
Micro Gas Turbine ◽  
Wide Range ◽  
Using Data

The objective of this work is the development of a simulation model for a hybrid Solid Oxide Fuel Cell (SOFC)/Micro Gas Turbine (MGT) system, flexible and robust enough, capable to predict the system performance under various operating conditions. The hybrid system consists of a high temperature SOFC, based on a tubular configuration developed by Siemens Power Generation Inc, and a recuperated small gas turbine (GT) validated using data for the Capstone C30. The design and off-design performance of the system is examined by means of performance maps. Moreover, operating parameters such as fuel utilization factor, steam to carbon ratio and current density are varied over a wide range and the influence on system performance is studied. The optimum operating conditions are discussed with regard to overall system performance under part load operation. The results show that high electrical efficiencies can be achieved making these systems appropriate for distributed generation applications.

A Solid Oxide Fuel Cell-Gas Turbine Hybrid System for a Freight Rail Application

2019 ◽  
Author(s):  
Philipp Ahrend ◽  
Ali Azizi ◽  
Jacob Brouwer ◽  
G. Scott Samuelsen
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Lithium Ion ◽  
Economic Feasibility ◽  
Solid Oxide ◽  
System Model ◽  
Oxide Fuel ◽  
Particulate Matter Emissions

Abstract The simulation of a Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT) hybrid system for a locomotive application is presented. Using Matlab Simulink, a 2.8 MW SOFC system was combined with a 500 kW GT and simulated to travel the route from Bakersfield to Mojave in California. Elevation data was imported using the Google API Console and smoothed in order to calculate the dynamic power demand for the SOFC-GT system, assuming 480 tons of freight per 120 ton locomotive traveling at an average speed of 45 mph. The SOFC-GT system model follows this demand without causing a significant disruption to the speed of the locomotive. A lithium-ion battery was included into the system model to improve the net system efficiency and make the operation smooth enough for the highly dynamic route. The overall efficiency along the simulated route has been calculated as 57% operating on partially pre-reformed natural gas fuel. These results suggest the development of a physical prototype of the simulated system and are very promising for the future of freight rail transportation throughout the US. CO2 and particulate matter emissions are significantly reduced compared to current diesel-electric locomotives and it is also possible to operate the system on hydrogen, i.e., completely emission-free. A techno-economic analysis to assess the economic feasibility of this system is currently being prepared.

Compressor Instability Analysis Within an Hybrid System Subject to Cycle Uncertainties

2018 ◽  
Author(s):  
Alessandra Cuneo ◽  
Alberto Traverso ◽  
Aristide F. Massardo
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Stochastic Analysis ◽  
Energy Systems ◽  
Operating Conditions ◽  
Transient Dynamic ◽  
Surge Margin ◽  
Speed Range ◽  
Compressor Surge

The transient/dynamic modeling of energy systems can be used for different purposes. Important information can be obtained and used for the design phase. The control system and strategies can be safely tested on transient/dynamic models in simulation, increasing the confidence during experimental phase. Furthermore, these models can be used to acquire useful information for safety case. The analysis of energy systems in dynamic conditions is generally performed considering fixed values for both geometrical and operational parameters such as volumes, orifices, but also initial temperatures, pressure, etc. However, such characteristics are often subject to uncertainty, either because they are not known accurately or because they may depend on the operating conditions at the beginning of the relevant transient. With focus on a micro-gas turbine fuel cell hybrid system, compressor surge may or may not occur during transients, depending on the aforementioned cycle characteristics; hence compressor surge events are affected by uncertainty. In this paper, a stochastic analysis was performed taking into account an emergency shut-down in a fuel cell gas turbine hybrid system, modelled with TRANSEO, a deterministic tool for the transient and dynamic simulations of energy systems. The aim of the paper is to identify the main parameters that impact on compressor surge margin. The stochastic analysis was performed through the RSA (Response Sensitivity Analysis) method, a sensitivity-based approximation approach that overcomes the computational burden of sampling methods such as MCS (Monte-Carlo Simulation). The results show that the minimum surge margin occurs in two different ranges of rotational speed: a high-speed range and a low-speed range, the latter being more sensitive for surge occurrence. The temperature and geometrical characteristic of the outer pressure vessel, where the fuel cell is installed, are the two main parameters that affect the surge margin during an emergency shut down.

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