Thermo-Economic Operation Analysis of SOFC–GT Combined Hybrid System for Application in Power Generation Systems

Author(s):  
Jamasb Pirkandi ◽  
Mohammad Ommian

This study investigated the combination of the direct and indirect hybrid systems in order to develop a combined hybrid system. In the proposed system, a direct solid oxide fuel cell (SOFC) and gas turbine (GT) hybrid system and an indirect fuel cell cycle were combined and exchanged the heat through a heat exchanger. Several electrochemical, thermal, and thermodynamic calculations were performed in order to achieve more accurate results; then, beside the parametric investigation of the abovementioned hybrid system, the obtained results were compared to the results of direct and indirect hybrid systems and simple GT cycle. Results indicate that the efficiency of the combined hybrid system was between those of the direct and indirect hybrid systems. The electrical efficiency and the overall efficiency of the combined hybrid system were 43% and 59%, respectively. The generation power in the combined hybrid system was higher than that of both other systems, which was the only advantage of using the combined hybrid system. The generation power in the combined hybrid system was higher than that of the direct hybrid system by 16%; accordingly, it is recommended to be used by the systems that are supposed to have high generation power.

Author(s):  
Abdulrazzak Akroot ◽  
Lutfu Namli ◽  
Hasan Ozcan

Abstract In this study, two solid oxide fuel cell (SOFC) hybrid systems (anode-supported model (ASM) and electrolyte-supported model (ESM)) is developed in matlab® and compared. The hybrid system model is considered to investigate the impacts of various operating parameters such as SOFC operating temperature and steam/carbon ratio on power production and performance of the hybrid system where it is projected that results can be utilized as guidelines for optimal hybrid system operation. According to the findings, a maximum 695 kW power is produced at 750 °C operating temperature for the anode-supported model, whereas 627 kW power is produced at 1000 °C for the electrolyte-supported model. The highest electrical efficiencies for the anode-supported model and the electrolyte-supported model are 64.6% and 58.3%, respectively. Besides, the lower value of the steam to carbon ratio is favorable for increased power output from the fuel cell and consequently a high SOFC efficiency.


2018 ◽  
Vol 7 (3) ◽  
pp. 263-267
Author(s):  
Vahid Azami ◽  
Mortaza Yari

This study focuses on the effect of the temperature difference at the fuel cell stack (ΔTcell) on the performances of the two types of SOFC–GT hybrid system configurations, with and without cathode gas recirculation system. In order to investigation the effect of matching between the SOFC temperature (TSOFC) and the turbine inlet temperature (TIT) on the hybrid system performance, we considered additional fuel supply to the combustor as well as cathode gas recirculation system after the air preheater. Simulation results show that the system with cathode gas recirculation gives better efficiency and power capacity for all design conditions than the system without cathode gas recirculation under the same constraints. As the temperature difference at the cell becomes smaller, the both systems performance generally degrade. However the system with cathode gas recirculation is less influenced by the constraint of the cell temperature difference. The model and simulation of the proposed SOFC–GT hybrid systems have been performed with Cycle-Tempo software.Article History: Received January 16th 2018; Received in revised form July 4th 2018; Accepted October 5th 2018; Available onlineHow to Cite This Article: Azami, V and Yari, M. (2018) Comparison Between Conventional Design and Cathode Gas Recirculation Design of a Direct-Syngas Solid Oxide Fuel Cell–Gas Turbine Hybrid Systems Part II: Effect of Temperature Difference at The Fuel Cell Stack. International Journal of Renewable Energy Development, 7(3), 263-267.http://dx.doi.org/10.14710/ijred.7.3.263-267


Author(s):  
Francesco Marsano ◽  
Loredana Magistri ◽  
Michele Bozzolo ◽  
Olivier Tarnowski

The design of Solid Oxide Fuel Cell (SOFC) Hybrid Systems (HS) is usually based on the use of natural gas as fuel. However, the possibility of using other fuels such as biomass gasification, pyrolysis, fermentation, and coal gasification could potentially increase the market for SOFC Hybrid Systems. In this paper, the influence of fuel composition on both HS layout and performance is investigated. The analysis is based on a layout and a detailed simulation model of a Hybrid System based on Rolls-Royce Integrated Planar SOFC (IP-SOFC) technology fed with natural gas, previously developed by the authors. Particular attention has been given to the thermal management of the stack, the anode flow recirculation design and the turbine-compressor redesign, including safe surge margin operation conditions.


Author(s):  
Francesco Caratozzolo ◽  
Mario L. Ferrari ◽  
Alberto Traverso ◽  
Aristide F. Massardo

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.


2009 ◽  
Author(s):  
W. J. Sembler ◽  
S. Kumar

The reduction of shipboard airborne emissions has been receiving increased attention due to the desire to improve air quality and reduce the generation of greenhouse gases. The use of a fuel cell could represent an environmentally friendly way for a ship to generate in-port electrical power that would eliminate the need to operate diesel-driven generators or use shore power. This paper includes a brief description of the various types of fuel cells in use today, together with a review of the history of fuel cells in marine applications. In addition, the results of a feasibility study conducted to evaluate the use of a fuel-cell hybrid system to produce shipboard electrical power are presented.


Author(s):  
Y. Haseli

Optimum pressure ratios of a regenerative gas turbine (RGT) power plant with and without a solid oxide fuel cell are investigated. It is shown that assuming a constant specific heat ratio throughout the RGT plant, explicit expressions can be derived for the optimum pressure ratios leading to maximum thermal efficiency and maximum net work output. It would be analytically complicated to apply the same method for the hybrid system due to the dependence of electrochemical parameters such as cell voltage on thermodynamic parameters like pressure and temperature. So, the thermodynamic optimization of this system is numerically studied using models of RGT plant and solid oxide fuel cell. Irreversibilities in terms of component efficiencies and total pressure drop within each configuration are taken into account. The main results for the RGT plant include maximization of the work output at the expenses of 2–4% lower thermal efficiency and higher capital costs of turbo-compressor compared to a design based on maximum thermal efficiency. On the other hand, the hybrid system is studied for a turbine inlet temperature (TIT) of 1 250–1 450 K and 10–20% total pressure drop in the system. The maximum thermal efficiency is found to be at a pressure ratio of 3–4, which is consistent with past studies. A higher TIT leads to a higher pressure ratio; however, no significant effect of pressure drop on the optimum pressure ratio is observed. The maximum work output of the hybrid system may take place at a pressure ratio at which the compressor outlet temperature is equal to the turbine downstream temperature. The work output increases with increasing the pressure ratio up to a point after which it starts to vary slightly. The pressure ratio at this point is suggested to be the optimal because the work output is very close to its maximum and the thermal efficiency is as high as a littler less than 60%.


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