ABSTRACT. In this paper, a conventional SOFC-GT hybrid system and an SOFC-GT hybrid system with cathode gas recirculation system fuelled 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 is heated at the air recuperator and air preheater to meet the required cathode inlet temperature while in the SOFC-GT hybrid system with cathode gas recirculation, in addition to the air recuperator and air preheater, also the recirculation of the cathode exhaust gas is 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%).Keywords: Solid oxide fuel cell, Gas turbine, Cathode gas recirculation, Exergy.

The effect of applying carbon-fibre-reinforced polymer sheets together with a prestress force to strengthen lightweight reinforced concrete slabs was investigated experimentally and numerically. As reported in this paper, load–deflection curves, stiffness, energy-absorption capacity and crack width of the prestressed slabs were examined and a detailed numerical model is presented. Strengthening with polymer layers resulted in a larger lever arm, while prestressing slightly reduced the lever arm of the section. The maximum deflection of prestressed slabs was smaller than that of the control specimen due to a small reduction in energy absorption. Using polymer sheets increased both the strength and maximum ultimate deflection simultaneously due to a higher energy-absorption capacity. The formation and propagation of cracks was postponed due to prestressing, so the ultimate crack width was reduced. Owing to the increase in stiffness, the polymer strengthening reduced crack spacing, crack width and crack growth for all strengthened specimens. In addition, a parametric study revealed that the variations in tendon eccentricity had a significant influence on the force–displacement response of slabs, whereas variations in characteristic strength and dilation angle only had a slight effec/t.

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