118 research outputs found
Development of Next Generation micro-CHP System:Based on High Temperature Proton Exchange Membrane Fuel Cell Technology
Gas turbine modeling using adaptive fuzzy neural network approach based on measured data classification
Experimental and theoretical evidence for control requirements in solid oxide fuel cell gas turbine hybrid systems
Hybrid fuel cell gas turbine sensitivity to ambient perturbations is analyzed using experimental and dynamic simulation results. Experimental data gathered from the world's first pressurized hybrid SOFC-GT system tested at the University of California, Irvine, capture performance variations due to diurnal temperature oscillations. A dynamic modeling methodology demonstrates accuracy, robustness, and clearly identifies critical system sensitivities that require additional control systems development. Simulation results compare favorably with dynamic experimental responses. Predictions of component temperatures, pressures, voltage and system power exhibited 5 °C, 2 kPa, 2 mV, and 0.5% error respectively. Moderate ambient temperature fluctuations, 15 °C, caused variations in stack temperature of 30 °C, and system power of 5 kW. Small to moderate changes in fuel composition produced 30 °C shifts in stack temperature and 25% changes in system power. Simple control loops manipulating fuel cell air flow through SOFC bypass and inlet temperature through recuperator bypass are shown to effectively mitigate internal temperature transients at the expense of reduced system output. The observed temperature fluctuations resulting from typical environmental perturbations are of concern for performance loss and diminished longevity. Experiments and dynamic simulation results indicate the importance of integrated control systems development for hybrid fuel cell gas turbine systems. © 2012 Elsevier B.V. All rights reserved
Advancements and prospects of thermal management and waste heat recovery of PEMFC
Despite that the Proton Exchange Membrane Fuel Cell (PEMFC) is considered to be an efficient power device; around half of the energy produced from the electrochemical reaction is dissipated as heat due to irreversibility of the cathodic reaction, Ohmic resistance, and mass transport overpotentials. Effective heat removal from the PEMFC, via cooling, is very important to maintain the cell/stack at a uniform operating temperature ensuring the durability of the device as excessive operating temperature may dry out the membrane and reduces the surface area of the catalyst hence lowering the performance of the cell. In addition to cooling, capturing the produced heat and repurposing it using one of the Waste Heat Recovery (WHR) technologies is an effective approach to add a great economic value to the PEMFC power system. Global warming, climate change, and the high cost of energy production are the main drivers to improve the energy efficiency of PEMFC using WHR. This paper presents an overview of the recent progress concerning the cooling strategies and WHR opportunities for PEMFC. The main cooling techniques of PEMFCs are described and evaluated with respect to their advantages and disadvantages. Additionally, the potential pathways for PEMFC-WHR including heating, cooling, and power generation are explored and assessed. Furthermore, the main challenges and the research prospects for the cooling strategies and WHR of PEMFCs are discussed
Thermoeconomic modeling and parametric study of hybrid SOFC-gas turbine-steam turbine power plants ranging from 1.5 to 10 MWe
Thermoeconomic Modeling and Parametric Study of a Photovoltaic-Assisted 1 MWe Combined Cooling, Heating, and Power System
In this study a small-scale, completely autonomous combined cooling, heating, and power (CCHP) system is coupled to a photovoltaic (PV) subsystem, to investigate the possibility of reducing fuel consumption. The CCHP system generates electrical energy with the use of a simple gas turbine cycle, with a rated nominal power output of 1 MWe. The nominal power output of the PV subsystem is examined in a parametric study, ranging from 0 to 600 kWe, to investigate which configuration results in a minimum lifecycle cost (LCC) for a system lifetime of 20 years of service. The load profile considered is applied for a complex of households in Nicosia, Cyprus. The solar data for the PV subsystem are taken on an hourly basis for a whole year. The results suggest that apart from economic benefits, the proposed system also results in high efficiency and reduced CO2 emissions. The parametric study shows that the optimum PV capacity is 300 kWe. The minimum lifecycle cost for the PV-assisted CCHP system is found to be 3.509 million €, as compared to 3.577 million € for a system without a PV subsystem. The total cost for the PV subsystem is 547,445 €, while the total cost for operating the system (fuel) is 731,814 € (compared to 952,201 € for a CCHP system without PVs). Overall, the proposed system generates a total electrical energy output of 52,433 MWh (during its whole lifetime), which translates to a unit cost of electricity of 0.067 €/kWh
Thermoeconomic Optimization of a Hybrid Photovoltaic-Solid Oxide Fuel Cell System for Decentralized Application
A small-scale, decentralized hybrid system is proposed for autonomous operation in a commercial building (small hotel). The study attempts to provide a potential solution, which will be attractive both in terms of efficiency and economics. The proposed configuration consists of the photovoltaic (PV) and solid oxide fuel cell (SOFC) subsystems. The fuel cell subsystem is fueled with natural gas. The SOFC stack model is validated using literature data. A thermoeconomic optimization strategy, based on a genetic algorithm approach, is applied to the developed model to minimize the system lifecycle cost (LCC). Four decision variables are identified and chosen for the thermoeconomic optimization: temperature at anode inlet, temperature at cathode inlet, temperature at combustor exit, and steam-to-carbon ratio. The total capacity at design conditions is 70 and 137.5 kWe, for the PV and SOFC subsystems, respectively. After the application of the optimization process, the LCC is reduced from 1,203,266 to 1,049,984 USD. This improvement is due to the reduction of fuel consumed by the system, which also results in an increase of the average net electrical efficiency from 29.2 to 35.4%. The thermoeconomic optimization of the system increases its future viability and energy market penetration potential
Modeling and simulation of a 100 kWe HT-PEMFC subsystem integrated with an absorption chiller subsystem
Thermodynamic modeling and parametric study of a small-scale natural gas/hydrogen-fueled gas turbine system for decentralized applications
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