Method and apparatus for pressurizing propellant tanks used in propulsion motor feed syste

Appel, M. A.

Weitzel, D. F.

English

NASA Technical Reports Server

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION 
WASHINGTON. D C. 20546 
J u n e  30, 1971 
MEMORANDUM 
TO : KSI/Scientific & Technical Information Division 
A t t n :  M i s s  Winnie M. Morgan 
FROM : GP/Office of Assis tant  General 
Counsel f o r  Patent Matters 
SUBJECT: Announcement of NASA-Owned U.S, Patents i n  STAR 
I n  accordance with the  procedures contained i n  t h e  Code G P  
t o  Code USE memorandum on t h i s  subjec t ,  dated June 8, 1970, 
the  attached NASA-owned U.S. patent is being forwarded for  
abs t rac t ing  and announcement i n  NASA STAR. 
The following information is provided: 
U.S. Patent N o .  : 3,170,295 
corporate Source North American Avia t ion  
Supplementary 
Corporate Source 
NASA Patent C a s e  No. :  XNP-00650 
Please note t h a t  t h i s  pa ten t  covers an invention made by an 
employee of a NASA contractor. Pursuant  t o  ~ 3 0 5 ( a )  of t h e  
NAS A c t ,  t h e  name of the Administrator of NASA appears on the  
f i r s t  page of t h e  patent ;  however, t he  name of t he  actual 
inventor (author) appears a t  t he  heading of Column N o .  1 of 
t h e  Specif icat ion,  following the  words 'I. . . with respect  t o  
an invention of .  . . . I '  _ _  
N 
0 
9 
Gayle Parker z 
9 
E 
2 
d 
U (NASA CR OR TMX OR AD NUMBER) Enclosure : 
Copy of Patent I 
https://ntrs.nasa.gov/search.jsp?R=19710019453 2020-03-17T03:15:02+00:00Z
Feb. 23, 1965 HUGH L. D R Y D E N  3,170,295 
FUEL 
t 
D E P U T Y  ADMINISTRATOR OF THE N A T I O N A L  
A E R O N A U T I C S  A N D  S P A C E  A D M I N I S T R A T I O N  
PROPELLANT TANK PRESSURIZATION SYSTEM 
OXIDIZCR 
--6 --4 
Filed April 9, 1963 
Patented Feb. 23, 1965 
1 
3,170,295 
PROPELLANT TANK PRlESSU 
Hugh L. Dryden, Deputy Administrator of the Na~ona l  
Aeronautics and Space Adrnhistra~on, with respect 
to an invention of Marsh2111 A. Appel and Donald F. 
Weitzel 
Filed Apr. 9,1963, Ser. No. 271,823 
6 Claims. (CL 60-39.48) 
The invention described herein may be manufactured 
and used by or for the Government of the United States 
of America for governmental purposes without the pay- 
ment of any royalties thereon or therefor. 
This invention relates to propulsion motors. More 
specifically it relates to a method and apparatus for pres- 
wrizing propellant tanks used in the feed system of a pro- 
pulsion motor. 
Propellant tanks have been pressurized in a number of 
ways. One way has been to take liquid oygen from the 
oxygen tank, vaporize it, and use it to pressurize both 
the oxygen and fuel tanks. Some of the vaporized oxygen 
is fed to the oxygen tank. The remainder of the vaporized 
oxygen is used to inflate a bag carried in the fuel tank. As 
the vaporized oxygen iaflates the bag, it forces fuel out 
of the fuel. tank. 
There are a number of disadvantages in the above sys- 
tem. It is dangerous. Oxygen might escape from the 
inflatable bag into the fuel tank. Many propellants are 
hypergolic-will ignite on contact. Also, an inflatable 
bag is bulky, and takes up room in the fuel tank. 
Another approach to pressurizing propellant tanks, has 
been io use a separate gas generator to provide hot com- 
bustion gases. These gases are mixed with an inert gas 
to cool them, and they are then fed to both the oxidizer 
and fuel tanks to pressurize them. 
This system also has disadvantages. It is heavy. Fuel 
necessary for the gas generator, the inert gas, and the 
container for the inert gas, all add weight to the system. 
Further, since the same mixture is fed to the (oxidizer and 
fuel tanks, it is necessary that it be compatible with both 
oxidizer and fuel. It is also necessary that the products 
do not contanminate the propellants. This is also very 
important where the propellants are hypergolic. 
In this invention, hot combustion products and vapor- 
ized oxidizer are used to individually pressurize the pro- 
pellant tanks. The combustion products pressurize the 
fuel tank, and the vaporized oxidizer pressurizes the oxi- 
dizer tank. Fuel and oxidizer are obtained from the 
propellant tanks and are combined in a fuel-rich mixture. 
They are then combusted to completely consume the 
oxidizer and form hot combustion products. The hot 
combustion products are then fed to a heat exchanger. 
Additiond oxidizer is then bled from the oxidizer pro- 
pellant tank and passed through the heat exchanger where 
it is vaporized by the hot combustion products. The 
oxidizer in turn, cools the hot combustion products to a 
temperature that is compatible with the fuel to be pres- 
surized. 
The vaporized oxidizer is then fed back to the oxidizer 
propellant tank to pressurize it. And, the combustion 
products are fed to the fuel propellant tank to pressurize 
this tank. 
It is, therefore, an object of this invention to use the 
propellants themselves to pressurize the propellant tanks, 
thereby eliminating the need for extra pressurant con- 
tainers and accompanying equipment. 
l t  is also an object of this invention to directly pres- 
surize propellant tanks with products that are completely 
compatible with the contents of each individual tank and 
that can be fed directly to the tanks. 
2 
5 
10 
15 
20 
25 
30 
35 
40 
45 
50 
55 
60 
65 
bustion products are fed by means in the form of duct 46 
to its respective tank 4. To control the flow of the pro- 
Other objectives and advantages will appear from the 
specification and claims taken in connection with the 
drawing wherein in the single figure there is illustrated 
the propellant tank pressurization system in one type of 
propulsion system. 
A preferred embodiment of the invention is shown in 
the figure. There is provided propulsion motor 2 and 
propellant tanks 4 and 6 containing propellant for the 
motor. Propellant tank 4 contains fuel such as RP-1 
(kerosene-base fuel) or similar propellant. Propellant 
tank 6 contains oxidizer such as liquid oxygen or similar 
propeilant. 
Generally, depending on conditions to be encountered, 
either a gravity flow or positive feed means are used to 
feed the propellant from the tanks to the propulsion 
m)otor. In the embodiment disclosed, a positive propel- 
lant feed means is illustrated. 
The propellant feed means includes: ducts 8, 10 con- 
nected to tanks 4 and 6; valves 12, 14 in the ducts; pmpel- 
lant pumps 16, 18 to feed the propellant; and gas turbine 
2dB to operate the propellant pumps. The output of tur- 
bine 20 passes through duct 29 to thrust chamber 2. 
To initially start the flow of propellant to the propul- 
sion motor, it is necessary to first start the turbine operat- 
ing so it will in turn operate the propellant pumps. TO 
start the turbine initially, a combustor means or gas gen- 
erator 22 is used. The gas generator is made with a start- 
ing supply of a liquid or solid propellant (not shown). 
The combustion products from the generator are fed 
through duct 24 to turbine 20. 
The hot coinbustion products from the gas generator 
operate the ttlrbine and it in turn operates propellant 
pumps 16, Zf? to feed fuel and oxidizer through ducts 8, 
10 to propulsion motor 2. Once the propellant pumps 
start operating, they will take over and also feed fuel 
and oxidizer to gas generator 22 through ducts 26, 28 
and valves 30,32. 
Valves 50, 32 in ducts 26,28 are adjusted so the propel- 
lants are fed to the gas generator in a fuel-rich mixture. 
The reason for this will be explained below. It is pointed 
out that once the system is started, it sustains itself to 
the depletion of the propellants. 
The propellant tank pressurization system will now be 
explained. 
A heat transfer means 34 is provided, in the form of a 
heat exchanger. A small quantity of hot combustion 
products is fed to heat transfer means 34 by means in 
the form of bleed duct 36 connected to dud  24 upstream 
of turbine 20. Also, a small quantity of oxidizer is fed 
to heat transfer means 34 by means in the form of bleed 
duct 38 connected to duct 10. 
In heat transfer means 34, the combustion gases are at 
a high temperature and contain excess heat. The heat 
transfer means is constructed so that the hot combustion 
gases will be cooled by the oxidizer, to a temperature 
that is compatible with the fuel being pressurized, and 
the overall system. The excess heat from the combustion 
gases in turn is used to vaporize the oxidizer and raise its 
temperature to enable it to be used as a pressurant gas. 
Heat transfer means 34 is constructed so the hot com- 
bustion gases from duct 36 pass through tubing 40. The 
relatively cold oxidizer is circulated on the outside 42 
of tubing 40. This is done so the oxidizer will act as 
a shield to protect contiguous parts of the system from 
the heat of the combustion gases. 
The vaporized oxidizer and cooled combustion products 
are then fed from the heat transfer means to their re- 
spective tanks 4, 6. The vaporized oxidizer is fed by 
means in the form of duct 44 to tank 6. The cooled com- 
3,170,205 
3 
pellants, each duct 44, 46 contains a check valve 48, ad- 
justable orifice valve 50 and relief valve 52. 
A fuel-rich mixture is used in gas generator 22 to insure 
that the oxidizer will be completely consumed in the com- 
bustion process. This is to eliminate any danger of 
oxidizer being fed to the fuel propellant tank with the 
combustion products and contaminating the fuel. Also, 
as mentioned previously, if the propellants are hypergolic, 
the fuel would ignite on contact with any unconsumed 
oxidizer. The desired ratio of oxidizer to fuel feed can 
be obtained by adjusting valves 30 and 32 in ducts 26,28. 
The system does not require separate tanks or storage 
of pressurant gas. 
Operation 
To initially start turbine 20 operating, gas may be 
generated in gas generator 22 by either a solid fuel (not 
shown) or from propellant (not shown) first obtained 
from the propellant tanks 4, 6. 
The high temperature, high pressure combustion prod- 
ucts from gas generator 22, then flow through duct 24 
to gas turbine 20 which operates propellant pumps 16, 
18. Simultaneously, propellant pumps 16, 18 start to 
build up pressure. As pressure increases, propellant valves 
12, 14 open to feed fuel and oxidizer through ducts 8, 18 
into thrust chamber 2. 
In a boot strap type of operation, fuel and oxidizer are 
then fed to gas generator 22 from propellant tanks 4, 6; 
through conduits 8,10; propellant pumps 16,18; conduits 
26,28; and valves 32,36. The propellants are combusted 
in gas generator 22 at high temperature and pressure and 
hot combustion products fed through duct 24 to turbine 
20. 
The pressurants are fed to heat transfer means 34 from 
bleed ducts 36, 38. Bleed duct 36 is connected to hot 
gas duct 24 just up stream of the turbine 20 and directs a 
flow of a small quantity of hot gases tu heat transfer 
means 34, and bleed duct 38 is connected in feed line 
10 to feed oxidizer to be vaporized to heat transfer means 
34. 
As oxidizer passes through heat transfer means 34 it 
adsorbs heat from the hot combustion gases and is va- 
porized. n e  oxidizers' temperature is raised to the de- 
gree required for use. The temperature of the hot gases 
is in turn lowered to a usable temperature. 
After passing through heat transfer means 34, the pres- 
surants pass through their respective ducts 44, 46, check 
valves 48, valves 50 that are made adjustable to provide 
a variable restriction in the line, and then into their re- 
spective tanks 4.6. Relief valves 52 are adjusted to main- 
tain a selected pressure in the system. 
The following is an example of some of the tempera- 
tures that may be encountered in a system using RP-1 
as fuel, and liquid oxygen as an oxidizer. The tempera- 
ture of the hot combustion gases in duct 24 going into 
the heat exchanger would be about 1700" F. The tem- 
perature of the liquid oxygen in duct 38 going into the 
heat exchanger would be around -292" F. Leaving the 
heat exchanger, both pressurization gases will be at ap- 
proximately +575" F. 
The specific design of the heat exchanger is dependent 
upon a number of factors. For example, the propellants 
used, and exit temperatures of the pressurants required. 
If the heat available in the combustion gases is higher 
than required to pressurize the fuel tank, additional cool- 
ing of the combustion gases may he attempted through a 
second heat exchanger in the oxidizer feed line 38, or 
even in the oxidizer tank itself. 
Conversely, when required, additional heating of the 
vaporized oxidizer may be obtained. A second heat ex- 
changer may be placed in duct 21 leading from turbine 
20 to thrust chamber 2; or through the use of additional 
hot gases obtained directly from thrust chamber 2. 
Although but a single embodiment out of the present 
invention has been illustrated and described, it will be ap- 
parent to one skilled in the art that various changes and 
4 
modifications may be made therein without departing from 
the invention as defined in the appended claims. 
What is claimed is: 
1. In a propulsion system a method of pressurizing 
5 propellant tanks, wherein one of said tanks contains 
oxidizer and one of said tanks contains fuel, comprising 
the steps of: 
providing a portion of oxidizer and a portion of fuel 
in a fuel-rich mixture from said propellant tanks; 
combusting said mixture to completely consume said 
oxidizer and produce hot combustion products; 
providing additional oxidizer from said oxidizer pro- 
pellant tank; 
transferring heat from said hot combustion products 
to said additional oxidizer to vaporize said oxidizer 
and lower the temperature of said combustion prod- 
ucts; 
feeding said vaporized oxidizer back to said oxidizer 
propellant tank to increase the pressure in said tank; 
and 
feeding said relatively cooled combustion products to 
said fuel propellant tank to increase the pressure in 
said tank. 
2. In a propulsion system a method of pressurizing pro- 
25 pellant tanks wherein one of said tanks contains oxidizer 
and one of said tanks contains fuel, comprising the 
stem of: 
10 
15 
2o 
30 
35 
40 
45 
providing a portion of oxidizer and a portion of fuel 
in a fuel-rich mixture from said propellant tanks; 
combusting said mixture to completely consume said 
oxidizer and produce hot combustion products; 
providing additional oxidizer from said oxidizer pro- 
pellant tank; 
surrounding said hot combustion products with said ad- 
ditional oxidizer propellant to act as a heat shield 
land to also transfer heat from said hot combustion 
products to said additional oxidizer to vaporize said 
additional oxidizer and lower the temperature of 
said combustion products; 
feeding said vaporized oxidizer back to said oxidizer 
propellant tank to increase the pressure in said tank; 
and 
feeding said relatively cooled combustion products to 
said fuel propellant tank to increase the pressure in 
said tank. 
3. In a propulsion system, a construction for pressuriz- 
ing propellant tanks, wherein one of said tanks-contains 
oxidizer and one of said tanks contains fuel, the combina- 
tion comprising: 
means to provide a portion of oxidizer and a portion 
of fuel in a fuel-rich mixture from said propellant 
tanks; 
means to combust said mixture to completely consume 
said oxidizer and produce hot combustion products; 
means to provide additional oxidizer from said oxidizer 
propellant tank; 
heat transfer means to transfer heat from said hot 
combustion products to said additional oxidizer to 
vaporize said oxidizer and lower the temperature 
means to feed said vaporized oxidizer from said heat 
transfer means back to said oxidizer propellant tank 
to increase the pressure in said tank; and 
means to feed said relatively cooled combustion prod- 
ucts from said heat transfer means to said fuel pro- 
pellant tank to increase the pressure in said tank. 
4. In a propulsion system a construction for pressuriz- 
ing propellant tanks, wherein one of said tanks contains 
oxidizer and one of said tanks contains fuel, the combi- 
10 nation comprising: 
a gas generator; 
means to bleed a portion of oxidizer and a portion of 
fuel in a fuel-rich mixture from said propellant 
tanks to said gas generator, said gas generator com- 
busting said mixture to completely consume said 
60 
65 
60 of said combustion products; 
65 
76 
3,170,295 
5 6 
oxidizer and produce hot combustion products; 
heat transfer means; 
means to feed oxidizer from said oxidizer tank to said 
heat transfer means; 
means to feed said hot combustion products from said 5 
gas generator to said heat transfer means in sufficient 
quantities to vaporize said oxidizer and to lower the 
temperature of said combustion products; 
means to feed said vaporized oxidizer to said oxidizer 
propellant tank to increase the pressure in said tank; 10 
and 
means to feed said relatively cooled combustion prod- 
ucts to said fuel propellant tank to increase the pres- 
sure in said tank. 
5. In a propulsion system a construction for pressuriz- 15 
ing propellant tanks wherein one of said tanks contains 
fuel and one of said tanks contains oxidizer, the combi- 
nation comprising: 
to said turbine to feed combustion products from 
said gas generator to said turbine; 
heat transfer means; 
bleed duct means to feed oxidizer from said first pro- 
pellant pump to said heat transfer means; 
bleed duct means upstream of said turbine to feed hot 
combustion products from said gas generator to said 
heat transfer means; 
means to adjust the feeds of said oxidizer and hot com- 
bustion products to said heat transfer means in an 
amount sufficient to vaporize said oxidizer and lower 
the temperature of said hot combustion products; 
duct means to feed vaporized oxidizer from said heat 
transfer means to said oxidizer propellant tank to in- 
crease the presesure in said tank; and 
dnct means to feed said combustion products from said 
heat transfer means to said fuel tank to increase the 
pressure in said fuel tank. 
first and second propellant pumps; 6. A device as set forth in claim 5 wherein said heat 
duct means connecting said oxidizer tank to the inlet 20 transfer means is a heat exchanger, and said heat exchang- 
of said first propellant pump; er is constructed with tubing through which the hot com- 
duct means connecting said fuel tank to the inlet of said bustion products pass, and the oxidizer is circulated on 
second propellant pump; the outside of said tubing to act as a heat shield. 
a turbine connected to drive said propellant pumps; 
a gas geiierator; 25 References Cited by the Examiner 
individual duct means connecting the outlets of said 
first and second propellant pumps to the inlet of said 
gas generator; 
valve means to adjust the feeds of said oxidizer and 
said fuel to said gas generator to provide a fuel-rich 30 
UNITED STATES PATENTS 
2,408,111 9/46 Truaxeta l .____________ 60-35.6 
2,930,187 3/60 Chillson et al. _ _ _ _ _ _ _ _ _ _  60-35.6 
3,102,388 9/63 Abild ____-_______ 60-39.48 XR 
SAMUEL LEVINE, Primary Examiner. mixture; duct means connecting the outlet of sai,d gas generator 


Propellant tank pressurization system Patent

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server