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CATALYST HEAT KNIFE FOR GAS GENERATE
V.M. Khanaev, Е.S. Borisova and N.N.Kundo
Boreskov Institute of catalysis Novosibirsk, Russia
Problems
Solid – fuel composition
A new approach to controlling the combustion of solid propellants on the basis of structured catalysts (porous materials and honeycomb blocks) was proposed by Kundo N.N.
H2
CO
O2
N2
Energy(Heat, electricity, chemical energy)
The use of Catalyst allows :• To create a low-temperature compositions with a
combustion temperature of 300-1000° C without using of coolant with a high burning rate
• To obtain a gas containing oxidizers or combustible components (H2, CO) or a neutral gas (N2, CO2)
• To control operatively the combustion rate and combustion chamber pressure
The use of catalysts in combustion of solid fuels
Peculiarities of catalytic solid fuels combustion
• Small residence Time of catalyst particles in the flame zone 0.0001 - 0.00001 sec
• The temperature of 300 oC - 1000 oC
Action • increase the increase the combustion ratecombustion rate • providing a providing a given burning given burning rate dependence rate dependence on pressureon pressure
Catalysts • iron oxide, copper iron oxide, copper chromite, lead oxideschromite, lead oxides • Plasticizers Plasticizers (ferrocene (ferrocene derivatives)derivatives)
Reaction zone •low-low-temperature zonetemperature zone of the flame of the flame •on the surface on the surface of the of the burning sampleburning sample
Form •the form the form of dispersed of dispersed powderspowders
1 – body, 2 – water jacket , 3 - catalyst block ,4 – powdered gunpowder, 5 – propellant , 6 –
shaft , 7 - safety valve, 8 – pressure sensor.
The model gas generator scheme with the operating burning rate control
Combustion solid high energy compositions with catalytic knife
Pressure in the combustor verses the displacement of the propellant charge with respect to a fixed block catalyst curves 1 - the displacement of the propellant charge 2 - the pressure in the combustor.
the regime with combustion termination
the regime with variation of the burning rate
displacement
pressure pressure
displacement
Mathematical modelMathematical model
inf
f
inf
ThT
TThz
TTz
0
0
:0
:
:
1. Propellant
02
2
ffffffff Tz
Tz
GCpTCp
ssgsg
ggsgg
g
,TcρΩwccSk
cc,ccSkρdz
dcG
2
00
4
0
1
;0
1
TLzdz
dT
TThz
Tz
Rs
S
se
ss
gTTSzgTcu
cgcgpg
0:0 TTz
g
2. Structured catalyst
Conservation of energy
3.Contact area
Conservation of mass
01100 TTh
QTCpTCpTz s
egfff
ff GTh
01 gg GTh
01
sgss
Ssss TTSTwQz
TTCp
222
2
11
KineticsHNO3*NH2]-NH-C(NH)-[H2N
222
x222357
H CO OH CO
OtNt)H(1.5Ot)H-(2COxt)/2N-(5 ONCH
222
x222357
H CO OH CO
OtNt)H(1.5Ot)H-(2COxt)/2N-(5 ONCH
aminoguanidine nitrate decomposing
21x
02t
ON x
x
Catalyst combustion
222
22x2
H CO OH CO
OHN2
ONH
x
222
22x2
H CO OH CO
OHN2
ONH
x
Effect of catalyst activity Pre-exponential factor
of the reaction rate constant
• 1 –1.35*108 1/s, • 2 – 5*108 1/s, • 3 - 1.35*109 1/s , • 4 – 5*109 1/s, • 5 - 1.35*1010 1/s. Block thermal conductivity –
10 W/(m К).
0.4 0.5 0.6 0.7U, m m / sec
200
400
600
800
Blo
ck e
ntr
ance
tem
per
atu
re,
C
12
34
5
T0
Entrance gas flow
temperature
Effect of homogeneous combustion
0.5 1.0 1.5 2.0U, m m / sec
0
200
400
600
800
1000
1200
Blo
ck e
ntr
ance
tem
per
atu
re,
C
T0
t = 2
t = 1.5
t = 1
t = 0.8
T0 – gas flow temperature
at the block entrance. Catalyst thermal conductivity λ = 5 W/m K
Effect of catalyst thermal conductivity
Catalyst thermal conductivity:
•1 – 2 W |m K,
•2 - 5 W/m К,
•3 - 10 W/m К,
•4 - 15 W/m К,
•5 - 20 W/m К.
Entrance gas flow
temperature
0.2 0.4 0.6U, mm/sec
0
200
400
600
800
1000
1200
Blo
ck
en
tra
nc
e t
em
pe
ratu
re,
C
1 2 3 4
5
T0
Dependence of maximal fuel burning rate
on the catalyst thermal conductivity
0 5 10 15 20 25
0.1
0.2
0.3
0.4
0.5
0.6
0.7
U m
ax, m
m/s
ec
1
2
λ, W / (m K)
Block sizes (for square cannel):•1 – cannel diameter = 1.2 mm, wall thickness = 0.255 mm•2 – cannel diameter = 5 mm, wall thickness = 2 mm
0 2 4 6 8time, sec
0.0
0.2
0.4
0.6
0.8
1.0
h, m
m
1
2
3
Effect of catalyst initial heating
Initial catalytic block temperature:
• 1 – 12000C,• 2 – 9500C,• 3 – 9000C (stationary
combustion regime couldn’t be obtained).
h is the distance between catalyst and burning fuel. The initial distance was 1 mm for all cases.Catalyst thermal conductivity λ = 10 W/m K, t = 1, U = 0.9 mm/s
Effect of the initial distance between catalytic block and the surface of burning
fuel •h is the distance between catalyst and fuel. Initial distance was 0.5 mm (curve 1), 1 mm (curve 2) and 2 mm (curve 3, steady state regime couldn’t be obtained).•The initial catalyst temperature was 10000C for all cases.
Catalyst and fuel (the part close to contact zone)
temperature profiles in various time moments
0 – t = 0 s, 1 – t = 0.001 s,2 – t = 0.005 s, 3 – t = 0.01 s,4 – t = 0.05 s, 5 – t = 0.1 s,6 – t = 0.4 s, 7 – t = 1 s,8 – t = 36 s (steady state regime)
0 – t = 0, 1 – t = 1.5 s,
2 – t = 2 s, 3 – t = 4 s
4 - t = 7 s, 5 – t = 10 s,
6 – t = 36 s (steady state regime).
Gas generation process dynamics
(decreasing of the fuel burning rate)
0 10 20 30time, sec
0.0
0.4
0.8
1.2
G, k
g/(
m2
sec)
0 200 400 600 800 1000time, sec
0.0
0.1
0.2
0.3
G, k
g/(
m2
sec)
0 200 400 600time, sec
0.0
0.4
0.8
1.2
G, k
g/(
m2
sec)
Gas generation process dynamics (increasing of the fuel burning rate)
0 2 4 6 8 10time, sec
0.0
0.4
0.8
1.2
G, k
g/(
m2
sec)
Conclusions• Catalytic knife ensures controlled combustion
and forms the basis for the development of low-temperature gas generators.
• Mathematical modeling of combustion of a typical condensed substance heated to high temperatures by a catalyst block is performed.
• The proposed model can be used to describe correctly steady-state and dynamic regimes. An increase in the catalytic activity, as well as an increase in the thermal conductivity of the catalyst, is found to increase the range of real-time control of the burning rate of the condensed substance.
Конверсия на различных блоках (с учетом теплопотерь
излучением)
0.0 0.2 0.4 0.6 0.8 1.0
0.0
0.2
0.4
0.6
0.8
1.01
3
Безразмерная длина блока
Кон
верс
ия
• Диаметр канала – 1.2 мм, толщина стенки – 0.255 мм; (кривые 1, 3)
• Диаметр канала – 5 мм, толщина стенки – 2 мм (кривые 2, 4).
Возможности применения контактного каталитического горения твердых топлив
1. Создание низкотемпературных газогенераторов с оперативным (командным) управлением газопроизводительностью и давлением. Применение для наддува емкостей, трапов, спасательных средств.
2. Применение газогенератора с регулируемым давлением и высокой производительностью (1,0-1,5 нм3 газа на 1 кг топлива) для установок аварийного всплытия, вытеснения воды.
3. Использование газогенератора с регулируемым газорасходом и давлением для регулируемой подачи топлива и окислителя в системе ЖРД.
4. Применение длительно хранимых стабильных ТРТ контактного каталитического горения для двигателей ориентации, стыковки, перемещения в космосе с возможностью многократного включения и выключения двигателя.
5. Использование каталитического газогенератора в пусковых устройствах для запуска газотурбинных двигателей, для раскрутки коленчатого вала ДВС, при аварийной остановке основного двигателя.
6. Применение составов, генерирующих горючий восстановительный газ для комбинированных РД.7. Применение газогенераторов, обеспечивающих получение окислительного газа для
комбинированного РД.8. Получение горячего топливного газа для обеспечения работы двигателя (например,
газотурбинного) с применением дожигания воздухом.9. Получение водородного топливного газа для обеспечения работы прямоточного реактивного
двигателя.10.Создание объектов на основе комбинации порометаллического носителя, обладающего
каталитическими свойствами, с твердым топливом для использования их в качестве ложных целей, которые интенсивно излучают в инфракрасной области.