Simulation of an Innovative Startup Phase for SOFC Hybrid Systems Based on Recompression Technology: Emulator Test Rig

2015 ◽  
Vol 12 (4) ◽  
Author(s):  
U. M. Damo ◽  
M. L. Ferrari ◽  
A. Turan ◽  
A. F. Massardo
Keyword(s):  
Fuel Cell ◽  
Hybrid Systems ◽  
Outlet Temperature ◽  
Test Rig ◽  
Control Logic ◽  
Transient Model ◽  
Fuel Flow ◽  
Research Activities ◽  
Surge Margin ◽  
Efficiency Increase

This paper presents a novel startup approach for solid oxide fuel cell (SOFC) hybrid systems (HSs) based on recompression technology. This startup approach shows a novel method of managing a complete plant to obtain better performance, which is always also a difficult task for equipment manufactures. The research activities were carried out using the HS emulator rig located in Savona (Italy) and developed by the Thermochemical Power Group (TPG) of the University of Genoa. The test rig consists of three integrated technologies: a 100 kWe recuperated microturbine modified for external connections, a high temperature modular vessel necessary to emulate the dimensions of an SOFC stack, and, for air recompression, a turbocharger necessary to increase fuel cell pressure (using part of the recuperator outlet flow) as required for efficiency increase and to manage the cathodic recirculation. It was necessary to develop a theoretical model in order to prevent abnormal plant startup conditions as well as motivated by economic considerations. This transient model of the emulator rig was developed using Matlab®-Simulink® environment to study the time-dependent (including the control system aspects) behavior during the entire system (emulator equipped with the turbocharger) startup condition. The results obtained were able to demonstrate that the HS startup phase can be safely managed with better performance developing a new control logic. In detail, the startup phase reported in this paper shows that all important parameters were always inside acceptable operating zones (surge margin kept above 1.1, turbine outlet temperature (TOT), and fuel flow maintained lower than 918.15 K and 7.7 g/s, respectively).

Physical Simulator of Start-Up for Hybrid System Cathode Side

2006 ◽  
Author(s):  
A. Traverso ◽  
M. L. Ferrari ◽  
M. Pascenti ◽  
A. F. Massardo
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Cell Hybrid ◽  
Cathode Side ◽  
Outlet Temperature ◽  
Test Rig ◽  
Start Up ◽  
Fuel Cell Hybrid

A start-up test rig at TPG laboratory at the University of Genoa, Italy, has been designed and built for two main purposes: physically simulating different early start-up layout and procedures of high temperature fuel cell hybrid systems, and validating time-dependent hybrid system models based on TRANSEO software. Since start-up is a critical operating phase for high temperature fuel cell hybrid systems, and it may require specific modifications to the hybrid system layout, the start-up test rig is meant to be very flexible for testing several start-up layouts as well as the coupling of different turbomachines and stacks. Results for cold test, 700°C and 950°C start-up combustor outlet temperature tests are reported. Such results show the pressure and temperature quick rise during the early phase of start-up, which could represent an issue for the mechanical and thermal stress to the stack. A dynamic model of the test rig was built up and validated showing good agreement with the experimental results. This achievement was very useful to increase the confidence with predictive dynamic simulation tools during the start-up phase, where experimental data are hardly available and where the fuel cell materials may undergo risky thermal shocks.

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.

scholarly journals Microturbine-Based Test Rig for Emulation of SOFC Hybrid Systems

2019 ◽  
Vol 113 ◽  
pp. 02004 ◽  
Author(s):  
Mario L. Ferrari ◽  
Matteo Pascenti ◽  
Aristide F. Massardo
Keyword(s):  
Fuel Cell ◽  
Risk Analysis ◽  
Electric Power ◽  
Hybrid Systems ◽  
Experimental Studies ◽  
Component Analysis ◽  
Test Rig ◽  
Dynamic Conditions

This work is devoted to an emulator test rig based on a T100 microturbine (100 kW electric power) and designed for SOFC hybrid systems. Since this facility does not include a real fuel cell, it is mainly used for tests on the SOFC/T100 integration to analyse possible stress and risky operations (e.g. surge) especially in dynamic conditions. The tests performed with this rig range from component analysis, to experimental studies at dynamic conditions and surge risk analysis.

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.

Demonstration of Simultaneous Temperature and Power Control in a Simulation Facility for a SOFC Hybrid System

2012 ◽  
Author(s):  
Francesco Caratozzolo ◽  
Mario L. Ferrari ◽  
Alberto Traverso ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Fuel Cell ◽  
Real Time ◽  
Hybrid System ◽  
Thermal Response ◽  
Experimental Plant ◽  
Outlet Temperature ◽  
Test Rig ◽  
Time Model ◽  
The University

This study is based on a complete hybrid system emulator test rig developed at the University of Genoa (Savona laboratory) by the Thermochemical Power Group (TPG). The plant is mainly composed of a 100 kW recuperated micro gas turbine coupled with both anodic and cathodic vessels for high temperature fuel cell emulation. The test rig was recently equipped with a real-time model for emulating components not physically present in the laboratory (SOFC block, reformer, anodic circuit, off-gas burner, cathodic blower). This model is used to fully evaluate thermodynamic and electrochemical performance related to solid oxide fuel cell systems. Using a UDP based connection with the test rig control and acquisition software, it generates a real-time hardware-in-the-loop (HIL) facility for hybrid system emulation. Temperature, pressure and air mass flow rate at the 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 into the machine control system and the turbine electric load is moved to match the model TOT values. In this study various 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 provided the dynamic response of the system. The control system proved to be fast, compared to the slow thermal response of the SOFC stack, and also reliable. The hybrid systems operated at 90% of nominal power with electrical efficiency of about 56% based on natural gas LHV.

T100 Micro Gas Turbine Converted to Full Humid Air Operation: Test Rig Evaluation

2014 ◽  
Author(s):  
Ward De Paepe ◽  
Marina Montero Carrero ◽  
Svend Bram ◽  
Francesco Contino
Keyword(s):  
Energy Transfer ◽  
Gas Turbines ◽  
Water Injection ◽  
Test Rig ◽  
Humid Air ◽  
Limited Energy ◽  
Surge Margin ◽  
Heat Demand ◽  
Compressor Surge ◽  
Efficiency Increase

Micro Gas Turbines (mGTs) are very cost effective in small-scale Combined Heat and Power (CHP) applications. By simultaneously producing electric and thermal power, a global CHP efficiency of 80 % can be reached. However the low electric efficiency of 30 % makes the mGT profitability strongly dependent on the heat demand. This makes the mGT less attractive for applications with a non-continuous heat demand like domestic applications. Turning the mGT into a micro Humid Air Turbine (mHAT) is a way to decouple the power production from the heat demand. This new approach allows the mGT to keep running with water injection and thus higher electric efficiency during periods with no or lower heat demand. Simulations of the mHAT predicted a substantial electric efficiency increase due to the introduction of water in the cycle. The mHAT concept with saturation tower was however never tested experimentally. In this paper, we present the results of our first experiments on a modified Turbec T100 mGT. As a proof of concept, the mGT has been equipped with a spray saturation tower to humidify the compressed air. The primary goal of this preliminary experiments was to evaluate the new test rig and identify its shortcomings. The secondary goal was to gain insight in the mHAT control, more precisely the start-up strategy. Two successful test runs of more than 1 hour with water injection at 60 kWe were performed, resulting in stable mGT operation at constant rotation speed and pressure ratio. Electric efficiency was only slightly increased from 24.3 % to 24.6 % and 24.9 % due to the limited amount of injected water. These changes are however in the range of the accuracy on the measurements. The major shortcomings of the test rig were compressor surge margin reduction and the limited energy transfer in the saturation tower. Surge margin was reduced due to a pressure loss over the humidification unit and piping network, resulting in possible compressor surge. Bleeding air to increase surge margin was the solution to prevent compressor surge, but it lowers the electric efficiency by approximately 4 % absolute. The limited energy transfer was a result of a low water injection temperature and mass flow rate. The low energy transfer causes the limited efficiency increase. The first experiments on the mHAT test rig indicated its shortcomings but also its potential. Stable mGT operation was obtained and electric efficiency remained stable. By increasing the amount of injected water, the electric efficiency can be increased.

Micro Gas Turbine Based Test Rig for Hybrid System Emulation

2007 ◽  
Author(s):  
Matteo Pascenti ◽  
Mario L. Ferrari ◽  
Loredana Magistri ◽  
Aristide F. Massardo
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Gas Turbine ◽  
Experimental Facility ◽  
Test Rig ◽  
Transient Model ◽  
Micro Gas Turbine ◽  
Preliminary Experimental Data ◽  
Critical Phases ◽  
And Control

The Thermochemical Power Group (TPG) is building at the laboratory of the University of Genoa, Italy, a new high temperature fuel cell - micro gas turbine physical emulator based on commercial machine technology. The aim of this new test rig is the experimental analysis of the coupling of commercial machines with fuel cell stacks focusing the attention on the critical phases of start-up, shutdown and load changes. The experimental facility is composed of a Turbec T100 micro gas turbine package modified for the fuel cell emulator connection, a set of pipes designed for by-pass, measurement or bleed reasons, and a high temperature volume designed for the RRFCS stack dimension physical emulation. This experimental approach is essential for model validations, and to test different transient operative procedures and control systems without any risk for an expensive real fuel cell stack. This paper shows the preliminary experimental data obtained with the machine in stand alone configuration, focusing the attention on the comparison of these results with the tests performed with the external pipes. Furthermore, a theoretical transient model of this new experimental facility has been developed with the TRANSEO tool. It is essential for the rig design and to perform preliminary results necessary to prevent dangerous conditions during the tests. This paper reports a preliminary verification of this model performed with the facility.

Influence of the Control Logic on Gas Turbine Operation

1997 ◽  
Author(s):  
R. Bettocchi ◽  
P. R. Spina
Keyword(s):  
Gas Turbine ◽  
Thermal Power ◽  
Maximum Efficiency ◽  
Outlet Temperature ◽  
Control Parameters ◽  
Control Logic ◽  
Surge Margin ◽  
Power Turbine ◽  
Variable Power ◽  
And Control

This paper presents an analysis of the influence of control logic on gas turbine operation, when machine load adjustments are carried out. An examination is made of the control logics that are possible for a two-shaft gas turbine with variable power turbine nozzle in order to reach the following objectives: - operation in maximum efficiency conditions; - operation in the conditions of maximum thermal power of exhaust gases at the turbine outlet; - operation at constant turbine outlet temperature; - operation with the maximum Surge Margin. The control logics necessary for reaching the predetermined objectives in the part-load operation are provided by the map of gas turbine’s main performance, thermodynamic and control parameters.

Comparison of a Heat Soakage Model With Turbofan Transient Engine Data

2017 ◽  
Author(s):  
Maximilian Vieweg ◽  
Florian Wolters ◽  
Richard-Gregor Becker
Keyword(s):  
Test Data ◽  
Thermal Effects ◽  
Sampling Rate ◽  
Inlet Temperature ◽  
Outlet Temperature ◽  
Time Step ◽  
Transient Model ◽  
Engine Control System ◽  
Fuel Flow ◽  
Lumped Parameter

In the present paper, a transient performance code is employed to predict on-wing test data of the IAE-V2500 engine mounted on an Airbus A320-232. The test data was recorded by the engine control system and may serve as an open basis for validation of future transient studies. For the current investigation, the employed code considers the fundamental equations of the constant mass flow method as well as heat transfer effects by a lumped parameter approach. The study focuses on seven accelerations and one deceleration. Engine test data was gathered with 10Hz sampling rate, imprinting the applied time step of the model. First, the steady-state matching of the test data was conducted. Subsequently, the measurement quantities fuel flow, inlet temperature and inlet pressure were prescribed as time-varying boundary conditions to the transient model. The results of the standard transient model and the model including thermal effects were compared with temperatures, pressures and shaft speeds. The LPT outlet temperature and the working line excursion in the booster map were examined in detail. The outcome concurs with the original statement that thermal effects are mandatory to enhance model accuracy. Lastly, a sensitivity analysis of the thermal input parameters was accomplished and its influence on model prediction investigated.

Investigation of Different Surge Handling Strategies and its Impact on the Cogeneration Performance for a Single-Shaft Gas Turbine Operating on Syngas

2015 ◽  
Author(s):  
Javier Beltran Montemayor ◽  
Lars-Uno Axelsson
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Rate ◽  
Outlet Temperature ◽  
Advantages And Disadvantages ◽  
Fuel Flow ◽  
Surge Margin ◽  
Compressor Surge ◽  
Increasing Demand

The increasing demand for decentralized power has led to a growing interest in smaller gas turbines for cogeneration applications. One benefit of decentralized power generation is the possibility to utilize fuels that are locally available. One example is syngas, which has gained increasing interest during the recent years. Compared to natural gas the syngas fuels have a large amount of dilutants, such as nitrogen and carbon dioxide, which results in a very low energy density. Hence, significant larger fuel flow is required. However, the added fuel flow will decrease the compressor surge margin and eventually drive the compressor towards surge. Several methods exist to address this issue including variable inlet guide vanes, increased turbine throat area, compressor bleeding and decreased combustor outlet temperature. This paper examines the operability of a generic all-radial single-shaft gas turbine in the 2 MW power range when running on syngas with different heating values. The above methods to combat the decreased surge margin will be analyzed using detailed cycle simulations and their advantages and disadvantages will be discussed. It was found that the increased throat area is the most beneficial of the four methods. The net power output is nearly the same as for natural gas operation and the heat rate is the lowest of the four methods.

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