Thermo-economic modeling of an atmospheric SOFC/CHP cycle: an exergy based approach

¹ Department of Energy Engineering, College of Energy and Environment, Tehran Science and Research Branch, Islamic Azad University, Tehran, Iran
² Department of Energy, Materials and Energy Research Center (MERC), P.O. Box 14155-4777, Tehran, Iran
³ Department of Machine Design, Royal Institute of Technology (KTH), SE 10044 Stockholm, Sweden

^a Corresponding author: h.ghadamian@merc.ac.ir

Received: 2 November 2013
Accepted: 2 January 2014

Abstract

Sustainability is one of the challenging issues in electricity production systems. Recently, solid oxide fuel cell (SOFC) has been suggested for use in combined heat and power (CHP) systems. This application is introduced as a promising environmentally-friendly system according to the thermodynamic and electrochemical models. In this paper, an atmospheric SOFC/CHP cycle was analysed based on integrating exergy concepts, energy and mass balance equations. In this regard, a zero-dimensional energy and mass balance model was developed in engineering equation solver (EES) software. Two dimensionless parameters (the exergetic performance coefficient (EPC) for investigating the whole cycle, and exergetic efficiency for investigating the exergy efficiency of the main component of this cycle) were applied. Results show that efficiencies of the system have been increased substantially. The electrical efficiency, total efficiency and EPC of this cycle were ~54%, ~79% and ~58% respectively. Moreover, the CO₂ emission is 19% lower than when compared with a conventional combined power cycle fed by natural gas. In addition, a dynamic economic evaluation was performed to extract the most sensitive parameters affecting the outputs: electricity sales price (ESP), equipment purchase cost and fuel cost. Furthermore, an electricity production cost of ~125 $ MW.h^-1 was attributed to our model, resulting in yet further cost reduction for widespread applications of this cycle.