Palmen an der Ostsee oder was wir gegen den …...Chair of Fluid Dynamics, Hermann-Föttinger-Institute (HFI) C. O. Paschereit Institute of Fluid Mechanics and Acoustics [email protected]

Chair of Fluid Dynamics, Hermann-Föttinger-Institute (HFI)C. O. Paschereit Institute of Fluid Mechanics and Acoustics [email protected] 23 June 2009 1

Palmen an der Ostsee oder was wir gegen den Klimawandel tun können

Christian Oliver Paschereit


Global warming

Glacier in Patagonia, Argentina

1928

2004


Outline

Presentation of the chair

What is global warming?

Evidence for global warming

How is “energy” related to global warming?

What can we do? What are we doing?


Outline







Our missionOur goals

We provide highly trained engineers who comply with the ambitious demands of industry and research

Our basic technology development follows long term goals

We integrate “real world” challenges into the academic fundamental research

Goal: Develop technologies for energy conversion with lowest CO2 impact


Fluid Dynamics Wind Tunnel Test Facility

Building and vehicleaerodynamicsLift and drag controlSeparation control

Plasma assisted controlNoise reduction


Fluid Dynamics – Building AerodynamicsForces, emissions


Fluid Dynamics – Vehicle AerodynamicsAirplanes, cars, trucks, trains, ships


Fluid Dynamics –Active flow control for wind turbines


Fluid Dynamics – Sailing research


Fluid Dynamics – Misc

Fluid dynamics in medical applications

Micro gas turbine


Combustion –Increase efficiency, decrease emissions

Combustion chambers and boilersThermoacoustics, combustion noiseControl & Modelling

New combustion conceptsHydrogenadvanced sensors


Outline







The greenhouse effect


What are greenhouse gases?

Carbon dioxide CO2

Methane CH4

Nitrous Oxide N2O (Lachgas)

Water vapour H2O

Ozone


Outline

Presentation of the department






Reconstructing past climate change


Concentration of green house gases for the last 2000 years


Global warming




Which sector is the first in world wide CO2 emissions?

Transport (cars, trains, airplanes, ships)

Industry (excluding electricity generation)

Electric power generation

Heating (residential and tertiary)


CO2 Emissionen


Outline







How is power generation related to climate change?


What are the consequences?


Outline







Energy and climate change

Continue as before

Fast development and introduction of efficient technologies

Intergovernmental Panel on Climate ChangeFourth Assessment Report


Energy generation now and in thefuture

0

200000

400000

600000

800000

1000000

1990 2000 2010 2020 2030 2040 2050

Year

Prim

ary

Ener

gy (P

J)

SolarWindHydroNuclear

BiomassNat. GasOilCoal


Power generationHydro power plant


Power generationNuclear power plant


Power generationCoal-fired (steam) power plant


Power generationCombined cycle (gas & oil) power plant

Gas Turbine

Control Systems

GeneratorSteam Turbine


Gas turbinesSchematic

ALSTOM GT13E2


Gas turbine Power generation

• Single cycle engine– Base-load power generation

– Engine efficiency ~40 %

Generator

Source: ALSTOM


Gas TurbineControl Systems Generator

Steam Turbine

Gas turbine Power generation (II)

• Combined cycle engine– Cycle efficiency ~60 %

Source: ALSTOM


Brayton cycle (gas turbine cycle)Diagrams

2 3 41 compressorisentropic compression

combustorisobaric heat

addition

turbineisentropicexpansion

ambientisobaric heat loss


Efficiency & specific workInfluencing factors

Efficiency depends on– pressure ratio r = p2 / p1 and gas

properties– increases with r

23QWη =

Specific work -depends on r and t = T3 / T1 with t from metallurgical limit (e.g. T3 = 1650 K)

-maximum when T2=T4

1TcW

p


Effects of turbine and compressor losses


“Greener” power

Efficiency increase– Pressure– Temperature– Cooling– Losses

Carbon capture and storage– Loss in efficiency

• Pre combustion 6 – 10 %

• Post combustion 10 – 14 %

Advanced cycles– Recuperation– Wet cycles– Pressure increased

combustor

20

25

30

35

40

45

50

1960 1970 1980 1990 2000 2010uncooled

Internal cooling

Annular combustorFilm cooling

optimization

effic

ienc

y [%

]


Humid Gas Turbine Cycle

In the Humid Gas Turbine (HGT) cycle, water or steam is introduced into the working fluid of the gas turbineTwo different approaches are possible:– Injection of steam or water, e.g. Steam Injected Gas Turbine (STIG)

or Cheng Cycle– Use of humidification towers to evaporate the water, e.g. Humid Air

Turbine (HAT) or Evaporative Gas Turbine (EvGT)

Different versions of these technologies are being developed, using intercooling, recuperation or reheat


Higher efficiency at reduced NOx

Advantages:– Higher efficiency (10 – 15 %):

• Use of exhaust gas heat– Significantly increased power density (>100 %)– Reduced NOx emissions:

• The moisture lowers the flame temperature – CO2-sequestration:

• The flue gases have a high concentration of CO2 after condensation of the steam– Hydrogen combustion:

• Steam injection allows for H2 combustion at low NOx emission levelsDisadvantages:

– Need for purified water– Increased complexity of the power plant


Ultra wet cycles

With increased degree of humidity:– NOx emissions decrease

The operating range (ΔΦ) is extendedNOx emissions can be reduced by 90% (Ω=0.3, at constant power output)

air

steam

mm&

&=Ω

air

steam

mm&

&=Ω

H2

Natural gas Hydrogen


Pressure increase combustor

Constant volume combustionEfficiency increase by > 10 %


What else are we doing already?


Fundamental ThermoacousticsPossible Consequences

TA instabilities result in high-amplitude pressure pulsationsConsequences– increased pollutant emissions– reduced lifetime & system failure– increased noise emissions

deterioration of system performance

by courtesy of T. C. Lieuwen Sewell et al. GT2004-54310


Atmospheric combustion test rigSet-Up


0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.2

0.4

0.6

0.8

1

Abs

(T22

)

Frequency [Hz/Hz]

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-3

-2

-1

0

1

2

3

Phs

(T22

)

Frequency [Hz/Hz]

Flame transfer matrix measurement

Analytic models

Fit unknown coefficients

•Stability analysis•Frequency response•Time-domain simulation

Full 3-D acoustic model

gas turbine

Hybrid approach:steady CFD analysis for flame model parameterssteady CFD analysis of the burner transfer function

Thermoacoustic simulation strategy


Application of Helmholtz dampers Simulation of engine spectra

multiple burner silo combustor– non uniform arrangement

non-uniform arrangement of Helmholtz dampersdifferent dampers for different frequencies

suppression ofinstability byadditional Helmholtz dampers

stronginstability

23 24 25 2622 10 11 12 27

21 9 3 4 13 28

GT 20 8 2 1 5 14 29 VD37 19 7 6 15 30

36 18 17 16 3135 34 33 32


Impedance Tuning – Motivation

Different acoustic boundary conditions of engine and test rigdifferent dynamicsassessment of new burner technologies in test rig not transferable toengine performancereliable prediction of thermoacoustic stability and emissions not possible

HFI test rig


Change of test rig geometry

Approach: adjustment of acoustic BC’s by means of geometry changes or active control

Mongia et al., JPP 2003 Lieuwen & Neumeier, PCI 2002

TUB approachactively tune test rig to engine acoustics

– partially tunable (laboratory scale) test rigs– degree of reflectivity remains the same (limit-cycle amplitude)– application to more complex industrial test rigs difficult

(high mass flows & elevated pressure)


Impedance tuning at discrete frequencies

: baseline w/ orifice

◊: baseline w/o orifice


Impedance tuning at discrete frequencies

o : @ f = 78 Hz


Conclusions

Concentration of green house gases are increasingThese may lead to climate changeSolving this problem demands leap advencedtechnologiesTU Berlin provides Research and Development in these areasExcellent time to study engineering

Documents

Palmen an der Ostsee oder was wir gegen den …...Chair of Fluid Dynamics, Hermann-Föttinger-Institute (HFI) C. O. Paschereit Institute of Fluid Mechanics and Acoustics [email protected]