Evaluation of Cathode Air Flow Transients in a SOFC/GT Hybrid System Using Hardware in the Loop Simulation

2015 ◽  
Vol 12 (1) ◽  
Author(s):  
Nana Zhou ◽  
Chen Yang ◽  
David Tucker
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
Cell System ◽  
Open Loop ◽  
Department Of Energy ◽  
Dynamic Responses ◽  
Cell Component ◽  
Hot Air ◽  
Hardware Component ◽  
And Control

Thermal management in the fuel cell component of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system can be improved by effective management and control of the cathode airflow. The disturbances of the cathode airflow were accomplished by diverting air around the fuel cell system through the manipulation of a hot-air bypass valve in open loop experiments, using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). The dynamic responses of the fuel cell component and hardware component of the hybrid system were studied in this paper.

Evaluation of Cathode Air Flow Transients in a SOFC/GT Hybrid System Using Hardware in the Loop Simulation

2014 ◽  
Author(s):  
Nana Zhou ◽  
Chen Yang ◽  
David Tucker
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Hybrid System ◽  
Mass Flow ◽  
Cell System ◽  
Department Of Energy ◽  
Dynamic Responses ◽  
Partial Recovery ◽  
Fuel Cell System ◽  
Air Mass

Thermal management in the fuel cell component of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system, especially during an imposed load transient, can be improved by effective management and control of the cathode air mass flow. The response of gas turbine hardware system and the fuel cell stack to the cathode air mass flow transient was evaluated using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). The disturbances of the cathode air mass flow were accomplished by diverting air around the fuel cell system through the manipulation of a hot-air bypass valve in open loop experiments. The dynamic responses of the SOFC/GT hybrid system were studied in this paper. The evaluation included distributed temperatures, current densities, heat generation and losses along the fuel cell over the course of the transient along with localized temperature gradients. The reduction of cathode air mass flow resulted in a sharp decrease and partial recovery of the thermal effluent from the fuel cell system in the first 10 seconds. In contrast, the turbine rotational speed did not exhibit a similar trend. The collection of distributed fuel cell and turbine trends obtained will be used in the development of controls to mitigate failure and extend life during operational transients.

Evaluation of Cathodic Air Flow Transients in a Hybrid System Using Hardware Simulation

2006 ◽  
Author(s):  
David Tucker ◽  
Larry Lawson ◽  
Thomas P. Smith ◽  
Comas Haynes
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
Department Of Energy ◽  
Effective Control ◽  
Fuel Cell Stack ◽  
Hybrid Power ◽  
Hot Air ◽  
Bypass Valve ◽  
The Impact ◽  
Flow Transients

Effective control of cathode airflow in a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system is critical to thermal management of a fuel cell stack. Hybrid fuel cell turbine designs often incorporate the use of a valved hot air bypass in parallel with the cathode flow to divert a portion of the compressor effluent around the fuel cell system. The primary objective of this valve in the early development of hybrid power systems was to facilitate system startup. From a system controls perspective, the hot air bypass offers the means to balance and manipulate the level of airflow supplied to the fuel cell stack at a minimal efficiency penalty. Manipulation of this valve has a significant impact on stack performance and reliability, as well as cathodic exhaust airflow conditions. Since the turbine is directly coupled to the fuel cell subsystem through the cathode airflow, non-linear effects are propagated through the system components in response to any hot air bypass valve change. The effect of cathode flow transients on hybrid system performance has been evaluated though the manipulation of a hot air bypass valve on a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). A brief overview of this experimental facility is provided and has been described in more detail previously. Open loop experiments were conducted using the facility, where a perturbation was made to the hot air bypass flow and turbine speed was allowed to change in response. The impact of the transients to both fuel cell and turbine performance are discussed.

Exergy Analysis of a Hybrid Micro Gas Turbine Fuel Cell System Based on Existing Components

2012 ◽  
Author(s):  
D. P. Bakalis ◽  
A. G. Stamatis
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
Exergy Analysis ◽  
Cell System ◽  
System Component ◽  
Utilization Factor ◽  
Fuel Cell Stack ◽  
Micro Gas Turbine ◽  
Partial Load ◽  
Set Up

A hybrid system based on an existing recuperated microturbine and a pre-commercially available high temperature tubular solid oxide fuel cell is modeled in order to study its performance. Individual models are developed for the microturbine and fuel cell generator and merged into a single one in order to set up the hybrid system. The model utilizes performance maps for the compressor and turbine components for the part load operation. The full and partial load exergetic performance is studied and the amounts of exergy destruction and efficiency of each hybrid system component are presented, in order to evaluate the irreversibilities and thermodynamic inefficiencies. Moreover, the effects of various performance parameters such as fuel cell stack temperature and fuel utilization factor are investigated. Based on the available results, suggestions are given in order to reduce the overall system irreversibility. Finally, the environmental impact of the hybrid system operation is evaluated.

Avoiding Compressor Surge During Emergency Shutdown Hybrid Turbine Systems

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Paolo Pezzini ◽  
David Tucker ◽  
Alberto Traverso
Keyword(s):  
Fuel Cell ◽  
System Analysis ◽  
Risk Mitigation ◽  
Dynamic Effect ◽  
Transient Behavior ◽  
Open Loop ◽  
Department Of Energy ◽  
Mitigation Strategies ◽  
Emergency Shutdown ◽  
Compressor Surge

A new emergency shutdown procedure for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle (IGFC), implemented through the Hybrid Performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test, and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide a means of quantifying risk mitigation strategies. An open-loop system analysis regarding the dynamic effect of bleed air, cold air bypass, and load bank is presented in order to evaluate the combination of these three main actuators during emergency shutdown. In the previous Hybrid control system architecture, catastrophic compressor failures were observed when the fuel and load bank were cut off during emergency shutdown strategy. Improvements were achieved using a nonlinear fuel valve ramp down when the load bank was not operating. Experiments in load bank operation show compressor surge and stall after emergency shutdown activation. The difficulties in finding an optimal compressor and cathode mass flow for mitigation of surge and stall using these actuators are illustrated.

Proton Exchange Membrane Fuel Cell System Identification and Control: Part I — System Dynamics, Modeling and Identification

2006 ◽  
Author(s):  
Yee-Pien Yang ◽  
Fu-Cheng Wang ◽  
Hsin-Ping Chang ◽  
Ying-Wei Ma ◽  
Chih-Wei Huang ◽  
...  
Keyword(s):  
Fuel Cell ◽  
System Identification ◽  
Proton Exchange Membrane ◽  
Cell System ◽  
Proton Exchange ◽  
Time Varying ◽  
Fuel Cell System ◽  
And Control ◽  
Exchange Membrane ◽  
Auxiliary Input

This paper consists of two parts to address a systematic method of system identification and control of a proton exchange membrane (PEM) fuel cell. This fuel cell is used for communication devices of small power, involving complex electrochemical reactions of nonlinear and time-varying dynamic properties. From a system point of view, the dynamic model of PEM fuel cell is reduced to a configuration of two inputs, hydrogen and air flow rates, and two outputs, cell voltage and current. The corresponding transfer functions describe linearized subsystem dynamics with finite orders and time-varying parameters, which are expressed as discrete-time auto-regression moving-average with auxiliary input models for system identification by the recursive least square algorithm. In experiments, a pseudo random binary sequence of hydrogen or air flow rate is fed to a single fuel cell device to excite its dynamics. By measuring the corresponding output signals, each subsystem transfer function of reduced order is identified, while the unmodeled, higher-order dynamics and disturbances are described by the auxiliary input term. This provides a basis of adaptive control strategy to improve the fuel cell performance in terms of efficiency, transient and steady state specifications. Simulation shows the adaptive controller is robust to the variation of fuel cell system dynamics.

Impact of Different Volume Sizes on Dynamic Stability of a Gas Turbine Fuel Cell Hybrid System

2019 ◽  
Author(s):  
Alessio Abrassi ◽  
Alberto Traverso ◽  
David Tucker ◽  
Eric Liese
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Cell System ◽  
Open Loop ◽  
Operating Conditions ◽  
Micro Gas Turbine ◽  
Performance Pressure ◽  
Lumped Parameter ◽  
Turbine Shaft ◽  
And Performance

Abstract A dynamic model is developed for a Micro Gas Turbine (MGT), characterized by an intrinsic free-spool configuration, coupled to large volumes. This is inspired by an experimental facility at the National Energy Technology Laboratory (NETL) called Hyper, which emulates a hybrid MGT and Fuel Cell system. The experiment and model can simulate stable and unstable operating conditions. The model is used to investigate the effects of different volumes on surge events, and to test possible strategies to safely avoid or recover from unstable compressor working conditions. The modelling approach started from the Greitzer lumped parameter approach, and it has been improved with integration of empirical methods and simulated components to better match the real Hyper plant layout and performance. Pressure, flow rate, and frequency plots are shown for the surge behavior comparing two different volume sizes, for cases where gas turbine shaft speed is uncontrolled (open loop) and controlled (closed loop). The ability to recover from a surge event is also demonstrated.

scholarly journals Fuel cell–gas turbine hybrid system design part II: Dynamics and control

2014 ◽  
Vol 254 ◽  
pp. 126-136 ◽  
Author(s):  
Dustin McLarty ◽  
Jack Brouwer ◽  
Scott Samuelsen
Keyword(s):  
Fuel Cell ◽  
System Design ◽  
Gas Turbine ◽  
Hybrid System ◽  
Dynamics And Control ◽  
And Control

A novel reconfigurable hybrid system for fuel cell system

2015 ◽  
Vol 40 (43) ◽  
pp. 14963-14977 ◽  
Author(s):  
K. Latha ◽  
B. Umamaheswari ◽  
K. Chaitanya ◽  
N. Rajalakshmi ◽  
K.S. Dhathathreyan
Keyword(s):  
Fuel Cell ◽  
Hybrid System ◽  
Cell System ◽  
Fuel Cell System

Dynamic Analysis and Control of a Planar IT-SOFC System

2009 ◽  
Author(s):  
A. Salogni ◽  
P. Iora ◽  
S. Campanari
Keyword(s):  
Steady State ◽  
Fuel Cell ◽  
Dynamic Model ◽  
Characteristic Curve ◽  
Cell System ◽  
Internal Reforming ◽  
Internal Cell ◽  
Layer Region ◽  
Air Channels ◽  
And Control

This paper analyzes the dynamic behaviour of a 5 kW fuel cell system based on planar co-flow Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) stack, with internal reforming. The system is composed by the SOFC stack, a combustor of the cell exhausts, two heat exchangers for fuel and air preheating and the related control valves, where the air temperature at the stack exit and the fuel utilization is controlled by means of a PI (proportional integral) device. The model of the stack is based on a lumped parameters dynamic model of a single cell, which is composed of the fuel and air channels, the electrochemically active three layer region representative of the anode, the cathode and the electrolyte. The stack model is first used here for a qualitative steady-state validation, reproducing the cell characteristic curve. Then it is presented the dynamic model of the system, which has been implemented using an a-causal software based on the open-source Modelica modelling language, which allows for future integration in complex power-plant configurations. After a description of the plant layout and of the dynamic model, we present and discuss the results obtained by applying the PI controls to different load changes and with different tuning of the controller parameters, evidencing the amplitudes of load changes, the extent of the transient phase to the new steady-state conditions, the internal cell temperature distribution and the thermal gradients along the PEN structure, giving the possibilities to adapt the control system to the requirements of specific SOFC technologies.

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