Environmental assessment of a hybrid system composed of solid oxide fuel cell, gas turbine and multiple effect evaporation desalination system

2020 ◽  
pp. 0958305X2097357
Author(s):  
Sobhan Jehandideh ◽  
Hasan Hassanzade ◽  
Seyyed Ehsan Shakib
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Solid Oxide ◽  
Nox Emission ◽  
Emission Rates ◽  
Oxide Fuel ◽  
Exhaust Temperature ◽  
Desalination Plant ◽  
Compressor Pressure Ratio

This study deals with a solid oxide fuel cell- gas turbine (SOFC-GT) hybrid system coupled with a multi-effect evaporation desalination plant with steam condensation. The environmental evaluation is also done due to the importance of waste energy recovery especially waste heat in power generation systems. The evaporation desalination plant is studied for using the excess heat to produce freshwater. The thermodynamic relationships governing different components of the system are first provided, including fuel cells, heat exchangers, gas turbine, and desalination plant. Next, given the absence of previous research on the environmental effects of cogeneration systems, despite its necessity, the study system is analyzed from an environmental point of view. Accordingly, the impacts of the system performance parameters, including the fuel consumption coefficients, compressor pressure ratio, fuel pre-reforming percentage, and the steam to carbon ratio are investigated on the CO2, CO, and NOx emission rates. Based on the findings, it is concluded that of different species, the impacts of CO, CO2, and NOx emission rates are significant on the environment. Thus, the impacts of pressure ratio and pre-reforming percentage on their emission rates have been studied. The results revealed with increasing the compressor pressure ratio, increasing the fuel consumption coefficients, and decreasing the fuel cell's exhaust temperature, the CO and NOx emission rates and corresponding social costs diminished. On the other hand, with elevation of the ratio of steam to carbon, the recovery rate, the fuel cell's exhaust temperature, the concerned gas emission rates, and corresponding social costs increased.

The Effect of Size on Optimisation of Solid Oxide Fuel Cell/Gas Turbine Hybrid Cycles

2009 ◽  
Author(s):  
Michael J. Brear ◽  
Michael J. Dunkley
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Solid Oxide ◽  
Total Power ◽  
Oxide Fuel ◽  
Component Size ◽  
System Pressure

The integration of high temperature solid oxide fuel cells with gas turbines to form high efficiency, hybrid generators is receiving significant attention within both the academic and industrial communities. Various systems have been proposed or demonstrated, and which cover a range of sizes from low power generators suitable for domestic power generation through to larger systems in the megawatt size range. The performance of such hybrid systems depends on the matching of the fuel cell and gas turbine through optimisation of the system pressure ratio and reactant flow rates. Losses associated with non-ideal cycle components are significant and vary with component size, and must be taken into account if optimal performance is to be achieved. This paper presents an intentionally very simple numerical model of the hybrid system, so that the effect of key component efficiencies on the overall cycle efficiency can be examined easily. These component efficiencies of course scale with size, and the results presented suggest that hybrid cycles with total power output of order several MW are preferable.

A Comparative Study on the Options in Combining Solid Oxide Fuel Cell With Gas Turbine

2015 ◽  
Author(s):  
Ji Hye Yi ◽  
Ju Hwan Choi ◽  
Tong Seop Kim
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Solid Oxide ◽  
Inlet Temperature ◽  
Oxide Fuel ◽  
System Efficiency ◽  
Turbine Inlet Temperature ◽  
Turbine Inlet

Various options in combining a solid oxide fuel cell (SOFC) with a gas turbine (GT) were compared in this study. The combination of an SOFC with either a simple gas turbine or a gas/steam turbine combined cycle was investigated. For each combined system, the effect of using a recuperative heat exchanger was examined. The design parameters of a state-of-the-art gas turbine for central power stations were used. The GT modeling included modulation of turbine coolant flow depending on turbine working conditions. An SOFC temperature of 900°C was used. Given a currently available reference voltage, pressure-dependent SOFC cell voltage was used. The analysis was divided into two parts. In the first part, the turbine inlet temperature of the reference gas turbine was given and the influence of pressure ratio was analyzed. In the second part, the influence of varying turbine inlet temperature was analyzed to search for optimal design conditions. The results showed that the SOFC/GTCC systems would provide considerably higher efficiencies than the SOFC/GT systems. The optimal pressure ratio in terms of system efficiency is over 30 for non-recuperated systems but is around 10 for recuperated systems. Reducing the extra fuel to the gas turbine combustor improves system efficiency, especially in the SOFC/GT systems. With zero extra fuel, efficiencies of all of the four systems exceed 70%, the highest of which is obtained by the recuperated SOFC/GTCC layout.

The Effect of Size on Optimization of Solid Oxide Fuel Cell/Gas Turbine Hybrid Cycles

2010 ◽  
Vol 132 (9) ◽  
Author(s):  
Michael J. Brear ◽  
Michael J. Dunkley
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Solid Oxide ◽  
Total Power ◽  
Specific Power ◽  
Oxide Fuel ◽  
Secondary Importance ◽  
Power Outputs

The coupling of solid oxide fuel cells (SOFCs) and recuperated gas turbines (GTs) in a hybrid system has the potential to lead to efficiencies exceeding 60%. SOFC/GT hybrids have been proposed at power outputs from 20 MW down to power outputs as low as 25 kW. The optimum configuration for high and low power outputs is therefore likely to be significantly different. This paper proposes a simple model of the SOFC/GT hybrid to investigate the desired flow rate and pressure ratio for optimum hybrid efficiency with varying component performance and, hence, varying inferred size. The overall hybrid specific power will be dominated by the fuel cell and is therefore of secondary importance when matching with a gas turbine. The results presented suggest that hybrid cycles with total power output of the order MW or greater are preferable.

Surge Prevention Techniques for a Turbocharged Solid Oxide Fuel Cell Hybrid System

2021 ◽  
Author(s):  
L. Mantelli ◽  
M. L. Ferrari ◽  
A. Traverso
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Rotational Speed ◽  
Pressure Ratio ◽  
High Energy ◽  
Cell System ◽  
Solid Oxide ◽  
Pollutant Emissions ◽  
Inlet Temperature ◽  
Oxide Fuel

Abstract Pressurized solid oxide fuel cell (SOFC) systems are one of the most promising technologies to achieve high energy conversion efficiencies and reduce pollutant emissions. The most common solution for pressurization is the integration with a micro gas turbine, a device capable of exploiting the residual energy of the exhaust gas to compress the fuel cell air intake and, at the same time, generating additional electrical power. The focus of this study is on an alternative layout, based on an automotive turbocharger, which has been more recently considered by the research community to improve cost effectiveness at small size (< 100 kW), despite reducing slightly the top achievable performance. Such turbocharged SOFC system poses two main challenges. On one side, the absence of an electrical generator does not allow the direct control of the rotational speed, which is determined by the power balance between turbine and compressor. On the other side, the presence of a large volume between compressor and turbine, due to the fuel cell stack, alters the dynamic behavior of the turbocharger during transients, increasing the risk of compressor surge. The pressure oscillations associated with such event are particularly detrimental for the system, because they could easily damage the materials of the fuel cells. The aim of this paper is to investigate different techniques to drive the operative point of the compressor far from the surge condition when needed, reducing the risks related to transients and increasing its reliability. By means of a system dynamic model, developed using the TRANSEO simulation tool by TPG, the effect of different anti-surge solutions is simulated: (i) intake air conditioning, (ii) water spray at compressor inlet, (iii) air bleed and recirculation, and (iv) installation of an ejector at the compressor intake. The pressurized fuel cell system is simulated with two different control strategies, i.e. constant fuel mass flow and constant turbine inlet temperature. Different solutions are evaluated based on surge margin behavior, both in the short and long terms, but also monitoring other relevant physical quantities of the system, such as compressor pressure ratio and turbocharger rotational speed.

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