Comparison Between Conventional Design and Cathode Gas Recirculation Design of a Direct-Syngas Solid Oxide Fuel Cell–Gas Turbine Hybrid Systems Part I: Design Performance

In this paper, a conventional SOFC–GT hybrid system and a SOFC–GT hybrid system with cathode gas recirculation system fueled with syngas as the main source of energy were analyzed and their performances were compared. In the conventional SOFC–GT hybrid system, the incoming air to the cathode was heated at air recuperator and air preheater to meet the required cathode inlet temperature. In the SOFC–GT hybrid system with cathode gas recirculation, besides air recuperator and air preheater, the recirculation of the cathode exhaust gas was also used to meet the required cathode inlet temperature. The system performances have been analyzed by means of models developed with the computer program Cycle–Tempo. A complete model of the SOFC–GT hybrid system with these two configurations evaluated in terms of energy and exergy efficiencies and their performance characteristics were compared. Simulation results show that the electrical energy and exergy efficiencies achieved in the cathode gas recirculation plant (64.76% and 66.28%, respectively) are significantly higher than those obtained in the conventional plant (54.53% and 55.8%). Article History: Received Feb 23rd 2017; Received in revised form May 26th 2017; Accepted June 1st 2017; Available onlineHow to Cite This Article: Azami, V, and Yari, M. (2017) Comparison between conventional design and cathode gas recirculation design of a direct-syngas solid oxide fuel cell–gas turbine hybrid systems part I: Design performance. International Journal of Renewable Energy Development, 6(2), 127-136.https://doi.org/10.14710/ijred.6.2.127-13

Energy and Exergy Analyses of a New Combined Cycle for Producing Electricity and Desalinated Water Using Geothermal Energy

A new combined cogeneration system for producing electrical power and pure water is proposed and analyzed from the viewpoints of thermodynamics and economics. The system uses geothermal energy as a heat source and consists of a Kalina cycle, a LiBr/H2O heat transformer and a water purification system. A parametric study is carried out in order to investigate the effects on system performance of the turbine inlet pressure and the evaporator exit temperature. For the proposed system, the first and second law efficiencies are found to be in the ranges of 16%–18.2% and 61.9%–69.1%, respectively. For a geothermal water stream with a mass flow rate of 89 kg/s and a temperature of 124 °C, the maximum production rate for pure water is found to be 0.367 kg/s