O-design analysis Jarosªaw Milewski Instytut Techniki Cieplnej Politechnika Warszawska Slide 1 of 24
Fuel cells generate electricity through electrochemical processes. There are many types of fuel cells, two of which molten carbonate fuel cell (MCFC) and solid oxide fuel cell (SOFC) are high-temperature fuel cells. The high-temperature range of outlet gases allows the development of a hybrid (HS) by opening the possibility of adding a gas turbine sub, which improves total eciency to an ultrahigh level: 70% based on Lower Heating Value (LHV). Results presented in this paper concern a larger (3 MW) which can be utilized for oce building applications. Slide 2 of 24
An axial turbine can replace radial turbine for this range of power. Slide 3 of 24
Molten Carbonate Fuel Cell Gas Turbine The Molten Carbonate Fuel Cell Hybrid System consists of the following elements: Air Compressor Fuel Compressor Gas Turbine MCFC module Air Heater Fuel Heater MCFC Module Slide 4 of 24
Figure: The model of created in HYSYS environment software Slide 5 of 24
MCFC O-design analysis η HS = P MCFC η DC/AC + (P T P C,air ) η g η m P C,fuel η e ṅ fuel HHV fuel (1) MCFC Air compressor Gas turbine Slide 6 of 24
MCFC O-design analysis Molten Carbonate Fuel Cell Power P MCFC = ( m I j n j=1 i=1 E MCFC,i,j ) (2) MCFC Air compressor Gas turbine Stack current Voltage I = 2 F ṅ H2,equivalent η f (3) E MCFC = E max i max r 1 η f r 1 r 2 (1 η f ) + 1 (4) Slide 7 of 24
Air compressor O-design analysis MCFC Air compressor Gas turbine Figure: Experimental and simulations data at dierent H 2 molar fractions, experimental data from [? ] Slide 8 of 24
Gas turbine O-design analysis Air compressor MCFC Air compressor Gas turbine Figure: Air compressor map [? ] Slide 9 of 24
Gas turbine m m 0 = A p α p α,0 T α,0 T α E E 0 Maps of performance Slide 10 of 24
Maps of performance O-design The operator can control the following input parameters: 1. fuel mass ow by a methane valve 2. MCFC current by external resistance 3. rotational speed of the compressor-turbine sub by a special electric generator. A triple layer control is proposed for controlling. Slide 11 of 24
Maps of performance Figure: Triple-layer control ṁ fuel = f (P HS ) Slide 12 of 24
n = f (P HS ) Maps of performance I MCFC = f (P HS ) Slide 13 of 24
Maps of performance Figure: eciency layers for two dierent fuel utilization factors Approximately, 16,000 points (state Slide 14 of 24
Maps of performance O-design analysis points) were found. Maps of performance Slide 15 of 24
Maps of performance O-design analysis Maps of performance Maps of performance Figure: Stack temperature dierence, (reduced to the nominal value of 214 C) for η f = 0.9 Slide 16 of 24
Maps of performance O-design analysis Maps of performance Figure: Turbine Inlet Temperature (reduced to the nominal value of 623 C) for η f = 0.9 Slide 17 of 24
Maps of performance O-design analysis Maps of performance Figure: System eciency (reduced to the nominal value of 63%) for η f = 0.9 Slide 18 of 24
Maps of performance O-design analysis Maps of performance Figure: Fuel cell temperature (reduced to the nominal value of 770 C) for η f = 0.9 Slide 19 of 24
Maps of performance O-design analysis Maps of performance Figure: Gas turbine pressure ratio (reduced to the nominal value of 8.16) for η f = 0.9 Slide 20 of 24
Maps of performance O-design analysis Maps of performance Figure: eciency chart, main limitations and line are indicated Slide 21 of 24
Shaft speed, rpm 31 000 30 500 30 000 29 500 29 000 28 500 28 000 27 500 27 000 26 500 26 000 1 500 2 000 2 500 3 000 3 500 4 000 4 500 Power, kw Figure: Shaft speed as a function of Power Slide 22 of 24
The presented results indicate that the analyzed possesses a high and control exibility while at the same time maintaining stable thermal eciency. Operation of the is possible over a wide range of parameter changes. The control strategy given by line in o-design conditions was indicated. A triple-layer control is proposed. Adequate maps of performance during o-design were generated by a simulator using 0D mathematical modeling. Slide 23 of 24
The can be kept within safe ranges by controlling the compressor-turbine shaft speed. Slide 24 of 24