Fazle Hussain

advertisement
Energy Advancement Leadership Conference GEMI, UH
Engines with no
gaseous emission
Fazle Hussain, Valery Zimin and Dhoorjaty Pradeep
[email protected]
Institute of Fluid Dynamics and Turbulence
University of Houston
Motivation
• Improved performance from inherently high-efficiency
cycles
• Carnot cycle: impractically high compression ratios for
even realistic temperature ranges
Two cycles with Carnot efficiency:
• Stirling cycle (isochoric heat regeneration/isothermal expansion
and compression) : also impractical due to very high
pressures
• Ericsson cycle (isobaric heat regeneration/isothermal expansion
and compression) : modest pressure ratios deliver high
efficiency; e.g. 87.5% with 2400 K.
Alleviating Pollution
• Hydrocarbon combustion  H20 + CO2
• Chief problem: NOx
• Solution: combustion with pure Oxygen
Advantages:
• No NOx
• Temperature restricted by materials alone
• Handling of exhausts far easier
(a) lower mass flow rate
(b) fewer chemical components
Cost:
• Energy for air separation (not very large)
Key features
Applications: local power plants, large vehicles, ships
Environment: no NOx & CO, CO2 sequestration
Thermodynamics: Ericsson cycle, near-Carnot
efficiency, high-temp combustion
Technology: • separation of N2 and O2 from air,
ceramic expansion chamber & heat
regenerator
• variable torque without gearbox
Economics: low construction and maintenance costs,
use of low-grade fuels
Ericsson cycle
p(bar)
100
(1  2) Isothermal compression
with water spray injection
3
2
T=300K
50
T=2400K
) g k/ m( v
3
6 3. 5 4
2 7. 0 9
1
4 3. 1 1 7 6. 5
0
1
4
05
K0 0 4 2 = T
4
K0 0 3 = T
3
2
001
) r a b( p
0
5.67 11.34
90.72
45.36
3
v( m /kg)
(2  3) Isobaric expansion in heat
regenerator: compressed gas
heated by counter-flowing exhaust
(3  4) Isothermal expansion
achieved by proper timing of fuel
injection during combustion in the
expansion chamber
(4  1) Isobaric compression in heat regenerator due to cooling of
the exhaust flow
Power plant schematics
CH4 , gas
1kg/sec
N2 , gas
15kg/sec
Air
19kg/sec
CO 2 ,liquid
2.75/kg/sec
O 2 , gas
4kg/sec
Oxygen
plant
CO2
Engine
Liquifyer
H2O, liquid
2.25kg/sec
CO 2 ,liquid
2.75/kg/sec
H2O
Less than
0.1%
Mass balance is shown for 1kg/sec flux of fuel (CH4)
Two emisionless-engine
designs:
• Vortex Engine: for low-grade fuels (e.g.
biomass)
• Rotary Engine: for high-grade fuels (e.g.
natural gas)
Vortex engine for
low-grade fuels
• Steady-flow combustion engine
• Centrifugal forces support pressure difference
• Density stratification suppresses turbulence,
decreasing thermodynamic irreversibility
• No moving parts in high-temp zone ceramics
possible
• High efficiency direct-contact radiative heat transfer
between counter-flowing fluids at different pressures
• Intense flow driven by centrifugal convection
• Continuous removal of slag from combustion zone
• Efficient energy conversion using MHD generator
Key components of rotary
engine
•
•
•
•
•
•
Air separator
Isothermal liquid ring compressor
Ceramic heat exchanger & expander
High-temp isothermal combustor
CO2 liquefier
Water-spray cooler
Liquid-ring compressor
5
6
4
1 - casing
2 – water ring
7
3 – expanding cavity
4 – low pressure
3
8
2
9
10
1
5 – intake port
6 – intake manifold
7 – collapsing cavity
8 – high pressuure
11
9 – stationary collector
10 – exhaust port
11 - exhaust manifold
New combustor/expander
1
2
1 - stationary core
3
4
2 - ceramic lining of
core
3 – rotor
4 - ceramic lining of
rotor
5
5 - sliding vane
6 - stationary cam.
6
Expander operation
Back end
Front end
Beginning
of Exhaust
Beginning
of Intake
same
time
same
time
End of
Expansion
End
of Exhaust
Innovative heat exchanger
High-temperature part
Key features:
• Use of high
conductivity ceramics
• Designed for only
compressive loading on
the ceramic components
Energy balance
• Power from combustion of 1kg/s CH4
at 87.5% thermodynamic efficiency: 43.75 MW
• Amount of O2 consumed: 4 kg/s
• Power consumed by N2 – O2 separator: 4 MW
• Losses due to leakage in expander (estimated at 0.6%): 0.26MW
• Loss due to heat flux through ceramic layers of expander (1.1%):
0.48MW
• Losses due to leakage in compressor (estimated at 1.2%): 0.53 MW
• Power consumed by CO2 liquefier (with recuperation)
0.15 MW
• Estimated losses in heat regenerator:
1.8 MW
• Other losses (frictional, incomplete combustion…):
0.85 MW
• Total available work:
35.68 MW
• Energy density of CH4 combustion:
50 MW
• Overall plant efficiency:
71.4 %
Experimental 10 kW set-up
Cool water
Rejected water
Temperature
measurements
and control
Water
pump
2
Electro
motor
3
1
Electro
motor/
generator
Rotary
expander
Heat
exchanger
Compressor
Electric
measurements
and control
U, V, P, rpm,...
4
CO2
liquifyer
Flow measurement & control
liquid CO2
Oxygen
Methane
Carbon
Dioxide
Summary
1. Use of the Ericsson cycle provides high thermodynamic efficiency
2. Isothermal combustion occurring in this cycle is the most
thermodynamically beneficial way to heat the working fluid
3. Cooling by a water spray provides effective isothermal compression
4. Separation of O2 and N2 (from air by an energy-efficient O2 plant) and
release of N2 to atmosphere before combustion ensures no NOx in the
engine exhaust
5. Use of CO2 as the working fluid allows us to exhaust liquefied CO2.
This feature drives down the cost of CO2 separation and permits CO2
sequestration.
6. Use of ceramic tiles (for the inner surface of the combustion chamber and
other high-temperature zones of the engine) that makes the engine feasible.
7. The high temperature of combustion and multiple returns of
combustion products to the combustion zone prevents CO pollution.
Download
Related flashcards
Thermodynamics

61 Cards

Thermodynamics

57 Cards

Thermodynamicists

27 Cards

Thermodynamics

22 Cards gattwik

Create flashcards