Zarz dzanie Energi i Teleinformatyka

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1 O-design analysis Jarosªaw Milewski Instytut Techniki Cieplnej Politechnika Warszawska Slide 1 of 24

2 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

3 An axial turbine can replace radial turbine for this range of power. Slide 3 of 24

4 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

5 Figure: The model of created in HYSYS environment software Slide 5 of 24

6 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

7 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

8 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

9 Gas turbine O-design analysis Air compressor MCFC Air compressor Gas turbine Figure: Air compressor map [? ] Slide 9 of 24

10 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

11 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

12 Maps of performance Figure: Triple-layer control ṁ fuel = f (P HS ) Slide 12 of 24

13 n = f (P HS ) Maps of performance I MCFC = f (P HS ) Slide 13 of 24

14 Maps of performance Figure: eciency layers for two dierent fuel utilization factors Approximately, 16,000 points (state Slide 14 of 24

15 Maps of performance O-design analysis points) were found. Maps of performance Slide 15 of 24

16 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

17 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

18 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

19 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

20 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

21 Maps of performance O-design analysis Maps of performance Figure: eciency chart, main limitations and line are indicated Slide 21 of 24

22 Shaft speed, rpm Power, kw Figure: Shaft speed as a function of Power Slide 22 of 24

23 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

24 The can be kept within safe ranges by controlling the compressor-turbine shaft speed. Slide 24 of 24