Measurement of heat release rate for liquid phase reaction of nitrogen tetroxide and hydrazin

Lawver, B. R.

Tkachenko, E. A.

English

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HEAT RELEASE RATE FOR THE L 
REACTION BY SOMOGYI AND FEILER'S METHOD 
-. 
(Subcontract under NASA Contract No.  NAS7-100) 


nitrogen tetroxide and hydrazine was measured. The basic met 
of the apparatus as employed in the present study consists of a n  arrangement 
to measure directly the driving piston velocity, Prior to carrying out measure- 
ments for the system N20 /N H 
was utilized to  check out t h e  apparatus, 
the propellant combination HNO /N H 
2 4' 3 2 4  
The heat release rate values for N 2 0  /N2H4 obtained in this  study 
were found to  depend on injection velocity. %he range of heat release rate 
values for the system N 0 /N H found in this study is very nearly the 
same as that determinecfby Somogyi and Feiler for HNO /N H 4 2 4  3 2 4' 
model yielding separation criteria by utilizing the heat release rate as 
An empirical mixing/separation criterion, agreeing well with the Kushida- 
Houseman results , has  been determined by W. Lawver, and B. Breen (Ref. 2 .) . 
The object of the present study was to measure the heat release rate 
for the liquid phase reaction of Nz04/NzH4 and compare it to  the rate for 
the system HN03/N2H4 
The apparatus employed was that of Somogyi and Feiler (Ref, 3.) 
Fundamentally, the apparatus is a constant volume calorimeter, at the 
same t i m e  serving as a rapid-mixing injection device. The two liquid 
reactants are  injected through a fixed mixing chamber, and then through 
variable length mixing cups into the calorimetric fluid, which also serves 
as a reaction quenching medium. Measurement of the temperature rise 
i n  the calorimetric fluid, and of the injection velocity, and knowledge 
of the mixing cup lengths makes possible calculation of the effective heat 
release rate. 
assumptions for the present study are described i n  Ref. 3 ,  The subsequent 
discussion treats the experimental modification, measur 
interpretation of measured results obtained in this study 
A, Apparatus and Procedure 
In Figure 1 is depicted the original heat re lease measurement 
apparatus of Somogyi and Feiler with one important modification. The 
change consis ts  of a device to  measure the actual travel distanc? and t i m e  
of the driving piston, in  order to obtain directly values of the liqcid injection 
velocity. The necessity for this modification became clear during the check 
out tests with HNO /N H During these tests it was found that u se  of the 
jet velocity-driving pressure calibration curve (Figure 3 ,  Ref. 3 .) yielded 
excessive scatter of heat  release values as functions of driving pressure. 
This difficulty was diagnosed as stemming from mechanical factors such 
as irregular driving piston travel and related pressure guage recordings. 
In order to eliminate such inconsistencies, a system recording the actual 
piston travel was devised . * 
3 2 4' 
For the modified apparatus , piston travel was recorded (oscilloscope) 
by means of electrical signals actuated upon passage of the driving piston 
past a known initial and final station in  the piston housing, 
The minimum mixing cup length was 0.36 inches and the maximum, 
1.36 inches for both the check out test and the N 0 /N H measurements. 
Driving piston velocity values ranging between 4 %thec2an% 21 ft/sec were 
obtained. In all tests 1 .O m l  of each reactant was employed; and in  the case 
of N204, chilling of the fluid as well as reactant block was used to prevent 
evaporative l o s s ,  because of the high vapor pressure of N 0 near room 
temperature. For the study of the effect of reactant temperature on heat 
re lease (N2O4/NzH4) the temperature of the reactant block was  monitored 
by .means of a thermocouple. 
2 4  
* .According to Dr. 
. r  
(3) Preliminary tests using N ~ O * / N ~ H ~ ,  
(4) Heat release measurements for N 0 /N H , varying mixing cup 
lengths, piston velocit ies,  and ?ea&an% timperatures . 
Figures 2 through 5 summarize the resul ts  obtained with the modified 
apparatus (enabling piston velocity measurement) . 
Figures 2 shows the relationship of experimental heat re lease as a 
function of mixing cup length, at different driving piston velocities Both 
HNO /N H and N 0 /N H data points are included. The  shortest  
expe?ime%th mixing cup ength has  the dimension 0.36 inches,  and the 
largest 1.35 inches. A t  the hypothetical 0.0 mixing cup length,is plotted 
the heat release value obtained when first, one reactant is mixed separately 
with the calorimetric fluid (H 0) , and second, the other reactant is intro- 
duced into the water solution of the first.  This heat  release value for 
zero mixing cup length obtained is in  excellent agreement with that cited 
by Somogyi and Feiler (Figure 4 . ,  Ref . 3 .) . 
2 4  8 4  
2 
It is evident in  Figure 2 that  at constant mixing cup length, the heat  
re lease first increases with piston velocity, and then fal ls  to lower values 
when velocity is increased further. T 
with Somogyi and Feiler's resul ts  , 
In Figure 3 is depicted the var 
velocity at constant values of mixing cup length, The extremes of minimum 
and maximum mixing cup lengths are shown, however, in each case the 
Figure 4 shows the effect of propellant temperature on the heat 
release for several constant pistbn velocities At  all values of piston 
velocity the heat release decreases with increasing propellant temperature 
Derived values of heat release rate as functions of driver piston 
velocity are presented i n  Figure 5. The general behavior indicates an  
initially increasing heat release rate with increasing driver piston velociy , 
eventually reaching a plateau, or a tendency to fall in  value 
The results described above and the conclusions drawn from th 
must  be viewed from the standpoint that the present study (a) does not 
constitute a n  exhaustive effort to map i n  detail the heat release rate-jet 
velocity relationship for N 0 /N H 8 and (b) cannot directly be compared 
to Somogyi and Feiler's reported 8ata, because of the modification of the 
velocity measurement method. Nevertheless since heat release values for 
both systems, N 0 /N H and HNO /N H were measured in the present 
study under the zan?e c8nc&tionsf comparatfve results for these two systems 
should be valid. The general heat release characteristics obtained in  this 
study f i t  Somogyi and Feiler's suggested combustion mechanism a s  well as 
aspects of Breen and Lawver's mix/separate concepts. 
2 4  4 
3 2  
In brief, phenomena operative in the heat release process charac- 
teristic of the apparatus used are: 
(1) degree of mixing as a function liquid velocity, 
(2) degree of mixing as a function of reactant temperature. 
At a given initial propellant temperature, the increase i n  heat release rate 
with injection velocity (at low velocities) can be attributed to an increase 
i n  contact, or interfacial area. At  relatively high velocities gas evolution 
may become so large that separation of the liquid reactants occurs resulting 
i n  a decreasing heat release . 
In suumary, 
1. The systems N 2 0  /N2H4 and HNO /N2H4 yielded nearly 
identical heat release rate--pfston velocity re 3 ationship a s  determined by 
Somogyi and Feiler' s apparatus modified to make possible direct measurement 
of driving piston velocity. 
2. The maximum measured heat release rate value for N 
65K cal/mole N 2 0 4  sec . 
temperature a t  constant piston velocity for the system N 0 /N H 
3 * Heat release values decreased with increasing propellan 
2 4  2 4 '  
4. A t  constant mixing cup length heat release increases initially 
with piston velocity reaching a maximum, and then decreases. Extent of 
interfacial area heat dissipation and gag formation can be 
4 
Streams of Hypergolic Propellants, 
Pasadena California, presented at the Combustion Institute 
Western States Section, Paper WSCI-67-38. 
B. P. Breen and B. R,  Lawver, "Unlike Hypergolic Impingement 
Model, I' in Quarterly Report SN-95 (NAS7-4671, October 1967 
Dynamic Science Monrovia, California . 
Somogyi, Dezso and C. E. Feiler, "Liquid-Phase Heat Release 
Rates of the Systems Hydrazine-Nitric Acid and Unsymmetrical 
Dimethyllydrazine-Nitric Acid, I' NASA Tech. Note D-469 
September 19 6 0 . 
Jet Propulsion Laboratory 
2. 
3 .  
,360" 
Driving piston 
Dfam., 1.184 in. 
Quenching midi 
1.6 
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1.2 
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\ 0 4 a 12 16 ZQ ' 24 
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Driver Piston Vela 
Figure 3.  Heat Release vs . Piston Velocity.. 
1' . .  
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Heat release rate for the liquid nitrogen tetroxide/hydrazine reaction by Somogyi and Feiler's method Final report, 19 Jan. - 12 Apr. 1968

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