Exergy and economic investigation of different strategies of hybrid systems consisting of gas turbine (GT) and solid oxide fuel cell (SOFC)

Gas turbines and solid oxide fuel cells can be combined in two different strategies to create a new high-efficiency hybrid system. In most hybrid systems, the fuel cell is located directly before the combustion chamber (pressurized type) or after the turbine (atmospheric type). The indirect hybrid system is another compound that has been less studied. In this system, the fuel cell and the gas turbine cycle are located in two separate cycles and heat exchange was done by a heat exchanger. The main purpose of this article is to compare the exergy and economic performance of direct and indirect hybrid systems. The results show that the direct hybrid system with pressurized fuel cell has better performance than the other two types of hybrid system. High electrical efficiency, low rate of irreversibility and pollution, and low cost of electricity generation, as well as appropriate cost of purchase, installation and system setup, are the characteristics of this type of hybrid systems. Analyzes of this study showed that the only positive feature of direct atmospheric fuel cell systems is high production capacity and indirect hybrid systems are less efficient than direct systems

An exergoeconomic-based parametric study to examine the effects of active and passive energy retrofit strategies for buildings

The paper describes a systematic framework that uses exergoeconomic theory integrated into ‘building energy retrofit’ (BER) design. An exergoeconomic module, based on the SPECO method, has been embedded into ‘EXRETOpt’, a recently developed retrofit-oriented exergy simulation tool based on EnergyPlus. Both active and passive technologies were analysed using two calibrated archetype non-domestic buildings as case studies (an office and a primary school). A novel cost-benefit indicator which accounts for building exergy destruction cost, retrofit annual capital cost, and project annual revenue is presented. This indicator is employed to account for best exergoeconomic performance technologies and to further develop deep BER packages. Compared to typical practice, exergoeconomics combined with cost-benefit provides a powerful tool for exploration and design improvement of building energy systems. In both cases, final product cost for heating and cooling processes were substantially reduced. In addition, the office case presented improvements in energy use by 67%, CO2 emissions by 53%, thermal comfort by 22%, exergy destructions by 42%, and the overall building exergy efficiency was improved from 14.8% to 20.0%. The school case presented similar results with an improvement of building exergy efficiency from 8.2% to 11.1%, and the potential to generate income due to current government incentives

Parametric Simulation of a CHP System Based on Industrial Micro Turbine from Exergy and Economic Viewpoints

The present paper deals with the parametric simulation and economic analysis of a CHP system based on an industrial microturbine to produce combined electricity and heat energy. The compressor pressure ratio and turbine inlet gas temperature have been chosen as design and optimization parameters for the current CHP system. In the present investigation, the simple and TRR model have been applied for estimation of the electricity price and other costs. The results show that the optimal performance of the system is obtained by the compressor pressure ratio in the range of 5 to 7 bar and decreasing of the turbine inlet temperature causes the reduction of the optimal pressure ratio. Also, the economical investigation results confirms that the system electricity price in an optimum case is about 20 to 25 cents, while the installation and preparation cost is about 500- 600 dollar per kilowatt. Comparative analysis between two applied economical models proves that the TRR model shows the better accurate results in comparison to simple model with about 9-12 percent

Exergy and economic investigation of different strategies of hybrid systems consisting of gas turbine (GT) and solid oxide fuel cell (SOFC)

Gas turbines and solid oxide fuel cells can be combined in two different strategies to create a new high-efficiency hybrid system. In most hybrid systems, the fuel cell is located directly before the combustion chamber (pressurized type) or after the turbine (atmospheric type). The indirect hybrid system is another compound that has been less studied. In this system, the fuel cell and the gas turbine cycle are located in two separate cycles and heat exchange was done by a heat exchanger. The main purpose of this article is to compare the exergy and economic performance of direct and indirect hybrid systems. The results show that the direct hybrid system with pressurized fuel cell has better performance than the other two types of hybrid system. High electrical efficiency, low rate of irreversibility and pollution, and low cost of electricity generation, as well as appropriate cost of purchase, installation and system setup, are the characteristics of this type of hybrid systems. Analyzes of this study showed that the only positive feature of direct atmospheric fuel cell systems is high production capacity and indirect hybrid systems are less efficient than direct systems

DEVELOPMENT OF A DYNAMIC MODEL FOR SIMULATION OF REAL-TIME TRANSIENT TURBOJET ENGINE PERFORMANCE IN SIMULINK

This study deals with developing a dynamic model with capacity for use in aero-Thermodynamic real-time performance modeling of turbojet engines in MATLAB/Simulink environment. The elements of the engine are modeled by means of non-linear equations and using the inter component volume dynamics method. Through the use of the design point variables in the simulation, the model is capable to adapting with the characteristics of a particular engine. The three factors including, rotor dynamic, volume dynamic and heat soakage are considered in the dynamic model. To validate the modeling approach, the rotational speed and net thrust are compared with the results of the GSP program. The results show the ability of the model to simulate the transient performance such that the maximum error is estimated less than 4 percent. Then a new method to reduce the computational time and create a real-time performance capabilities, was studied. The results indicate that it is possible to select a fixed time step for solver and time scaling the smallest volume (from specified control volumes in the model), the real-time ability to be achieved. In these circumstances, the error in calculation of basic parameters of the engine is less than 0.5 percent