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International Compressor Engineering Conference
School of Mechanical Engineering
1986
Comparison of Various Dampers Effect on the
Reciprocating Compressor Work the Pressure
Pulsations Quantity in an Discharge Pipeline
M. Luszczycki
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Luszczycki, M., "Comparison of Various Dampers Effect on the Reciprocating Compressor Work the Pressure Pulsations Quantity in
an Discharge Pipeline" (1986). International Compressor Engineering Conference. Paper 591.
http://docs.lib.purdue.edu/icec/591
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COMPARISON OF VARIOUS DAMPERS EFFECT ON THE RECIPROCATING
COMPRESSOR WORK AND THE PRESSURE PULSATION QUANTM IN AN
DISCHARGE PIPELINE.
Marian
~ezczycki,
Docent of Mechanica l Engineeri ng
The Institute of Industria l Apparatus and Energetic s,
Politechn ika Krakowska , Krak6w, Poland
AllSTRACT
Tbe paper presents the pressure pulsation dampers of small
hydraulic resistanc e and the most coomon criteria for the
evaluatio n of their damping efficienc y. The results of experiments on the effect of the location and the inside structure of
dampers on damping efficienc y in a disoharge pipeline on the work
of the reciproca ting compresso r have been presented . Some of
these experimen ts were done on an electric analoge, others on
a specially prepared laboratory stand. Tbe results of the tests
have been listed and discussed , on the basis of which some
practical cone lusions were drawn.
INTRODUCTION
Pressure pulsation s of high amplitude s occur in the
reciproca ting compresso r installati ons as a result of the cyclic
work of these machines. E:rcessive pressure pulsation s effect
unfavoura bly both the work of the compresso rs and the compresse d
gas installati ons. In order to eliminate such negative effects
the resonance phenomena in the installati ons should be prevented
and the absolute values of pressure pulsation s should be reduced.
The reduction of the absolute values of pressure pulsation s can
be achieved by a proper configu.ra t ion and dimension ing of the
installati on and a proper choice and location of pressure
pulsation dampers (1], [4], [51.
1116
PRESSURE PULSATION DAMPERS
For pressure pulsation damping in the compressed gas
installati ons the pulsation dampers are applied. There are
various designs of many types of dampers and patents attached
but they exist with no full scientific grouds for their development and applicatio n. That is why· many disappoin tments arise
when the dampers which operate efficient ly with one installati on
are completel y unreliabl e and have the opposite effect in a case
of some other installati ons. A damping effect much depends on
a location of the damper in the installati on as well as a
character istic impedance of the technolog ical elements and
fittings incorpora ted in the pipeline beyond the damper.
A proper selection of a pressure pulsation damper for
a given installati on is condition ed by taking into account the
influence of all those parameter s upon the operation efficienc y
of the damper. Additi.ona .lly, the considera tions should include
the influence of the damper itself upor1 pressure pulsation rune
both before and beyond it because the damper constitut es
a certain concentra ted inclusion in a homogeneous pipeline
section. Such a complex examinati on of a pressure pulsation
damper selection for a reciproca ting compresso r installati on
requires solving tbe partial different ial equations which
describe a pulsating gas flow a.long with the boundary condition s
adequate for the examined installati on. This task may be solved
eithes by means of the electro-ac oustic analogies using a.n analog
or by the numerical methods on a digital computer [2), 131, [5).
A damper designed for the eliminatio n of the excessive
pressure pulsation s in the reciproca ting compresso r pipelines
should meet the follo~ing requireme nts:
• simple design, ease of making and assemblin g
• smell overall dimension s
• reduction of pressure pulsation absolute values as much as
possible
• small hydraulic resistance
• no harmful reverse effect upon compresso r work.
A coefficie nt o£ pressure fluctuatio ns in the pipeline behind
the damper must not exceed the quantitie s aclalowledged
permissib le.
The presented requireme nts are well satisfied by chamber
damper single chamber and two-chamber resonance damper with
a perforated central pipe. and a resonance chamber damper /Fig.1/.
These types of dampers are recommended by the author to be
applied for pressure pulsation damping in the gas compresso r
station installati ons.
1117
DAMPING EFFECT EVALUATION CRITERIA
The measure of pressu re fluctu ation in the pipeli ne
is a
coeffi cient of pressu re fluctu ation determ ined as a ratio
pressu re pulsat ion absolu te va.lue .1pa and mean pressu .re of a
p0 in
the pipeli ne
e =~~
0
Po
··························~··············· I 1I
To evalua te the effect of pressu re pu.lsa tion reduct ion
Qy
means of a damper it is necess ary to find a criter ion
this effect may be e:xpressed in a numer ical form. SuchQy which
a
criter ion should also be a basis for comparing the effect
s of
opera tion of variou s dampers in a given instal lation
as well as
indica te which damper is the best to be used under the
given
condi tions.
Damping Ratio,
MOst freque ntly used for measu ring the effect of pressu
re
pulsat ion reduc tion in the pipeli ne is the damping ratio
Kt
descri bed as the ratio of pressu re pulsat ion coeffi cients
in the pipeli ne before and behind the damper.
Kt
s1
=~
2
•••••••••••••••••••••••••••••••••••••••••• /z/
In case of a damper with small hydrau lic resist
the
damping ratio is descri bed as the ratio of pressu re,ance,
,PUlsa tion
absolu te values before and behind the damper /Fig, 21.
·~····································· /3/
A damping ra.tjo define d in this way is conve nient to
use
in experi menta l testin g of dampers to compare their constr
and evalua te the influe nce of differ ent struct ural eleme uction
nts
on a degree of pressu re pulsat ion reduct ion, It shoud
be
remembered that damping ratio is oha.:r acteris tic of
damping
effect of dampers mere~ under certai n ideali sed
tions,
extrem ely rare in practi ce, It is assumed that incondi
the
pipeli
ne
sectio ns before and behind the damper only the progre
pressu re waves of consta nt amplit udes are propag ated ssive
/Fig.2 /,
1118
Total Rate of Pressure Pulsation Damping.
The most general evaluation criterion of damper effective
operation is the total rat.e of pressure pulsation damping K
which determines lowering of a general pressure pulsation g
level along the whole length of piping. It includes the effect
of reducing the pressure pulsation absolute ·~ra.1ues both before
and behind the damper [ 1). If .6pam denotes a maximum pressure
pulsation absolute values along the pipeline in the installatio n
without dwnper /Fig.}a/ and this maximum is denoted as Apamt
after having installed the damper /Fig.3b/, then the total rate
of pressure p\tlsation damping can be defined a.s the ratio or·
those maximum values.
bp
K
g
=~
........... ........... ........... ....... /4/
6p'!!Jllt
The evaluation of damper effective operation by means of
a. total rate of pressure pulsation damping Kg must be based
on tbe knowledge of how pressure pulsation absolute values run
along the pipeline. First, pressure pulsation absolute values
along the pipeline without damper should be calculated including all the installed elements of equipment and fittings /coolers, oil separators, valves, etc./. Next, the a.:na.logical
pulsation can be used after developing a way of calculating the
pulsation absolute values along the pipeline including the
installed elements. The total rate of pressure pulsation damping
illustrates fully tbe reduction of the general level of pr.:tssure
pulsations in the installatio n owing to the use of damper.
The Aim a.nd Methodology of Research,
The aim of the experiments wa.s to define the effect of the
location and the inside structure of a damper on the efficiency
of pressure pulsation damping in a discharge pipeline and on
the work of a reciprocati ng compressor.
The experiments were carried out on a discharge pipeline of
a laboratory compressed air insta.Uatio n and on its equivalent
electrical model. The air was pressed by a single stage, single
cylinder, single acting air compressor with the cylinder of
160 [ mm] diameter and piston stroke of 150 [ mm I • The compressor
was driven by a d.c. electrical motor whose rotational speed
was regulated steplessly in the range 200- 1500 [rev/mini •
Fig. 4 presents a. three-dimen sional diagram of the discharge
pipeline with the given dimensions. The discharge pipeline
81,5 lmml in diameter and 10,2 (m] length was terminated by a.
severely throttled valve. It was assumed that such a terminal
meets the conditione of complete acoustic closure /z =co/.
1119
The experim ents on the effect of the damper locatio n on
the effich ncy of pressu re pulsat ion dampin g in a discha
rge
pipelin e and on the work of a recipro cating compre ssor
were
carried out on an electr ical model of a discha rge pipelin
e.
The efficie ncy of the damper operat ion was measur ed by
total
rate of pressu re pulsat ion dampin g K , and the effect
of the
g
damper on the compre ssor work vas measur ed by the absolu
te
value of pressu re pulsat ion ~P in the pipelin e behind
the
a
compre ssor.
The experim ents on the effect of the inside structu re
of a damper on the efficie ncy of pres~~re pulsat ion dampin g
in a discha rge pipelin e a,nd on the work of a recipro cating
compre ssor were carried out on a labora tory stand. The
efficiency of the damper operat ion was evalua ted by means
of
dampin g ratio Kt, and the effec·t of the damper on the
compre ssor work by means of the power delive red to the electr
ical
driving motor Nel and the overal l volume tric efficie ncy
which was define d as
A,
m
Ill
A.= --:- -mt
V8 n 60 r;d
······· ··8··· ······· ······· /5/
where: m- the real delive ry of the compre ssor measur
ed in
a discha rge pipelin e, m,t - theore tical delive ry of the
compre ssor, V - swept volume of cylind er,
rotatio nal Speed of the
s
compre ssor shaft, qd. - density of auction medium.
n-
THE P.ESULTS OF EXPERIMENTS
The Effect od Pressu re fulsati on ::Jamper Loca.tic •n,
The experir uent.s on the effect, of the locatio n of a damper
on
the efficie ncy of pressu re pu leat .ion dampin g in a discha
pipelin e and on t.he work of a recipro cating compre ssor rge
were
carried out a.t consta. nt absolu te pressu re of 3 [bar) of
the
outlet and rQtat.i onal speBds varyin g in the range )00
1300 [rev/m in] • Below are presen ted some exampl es of
the
reS'..lH s •)f the tests in case wl1en a chambe r damper was
used for
pressu re pu 1 s<>.t ion d<nnring.
Fig. 5 and 6 ah:::-w in dh.gr.arJJs of fortnul a l::!.pa = f/1/ the
result s of tests on the effect r:..•f locatio n of a. chambe
r damper
on its efficie ncy a.t rot,aUo nal speed of 500 and 900
I
rev/mi ni.
Tbe chamber- damper of o.09)6 !m3I of \f(\lUnte was plaeed
at the
distanc e of 0,3, 1,875 and 5,325 !ml from the Mmpre t!sor.
In
Table 1 are shown, for beth rota.tit mal speeds a.nd partic
ular
distan ces, absolu te values (•f presau_ re pulsat ion D.p
in the
a
pipeHn e b€-hind the oompre Mor a.s wel1 as the valves
of total
ll20
rate of preasure pu"isa1;ion
of pressure fluctuatio n
pressor.
K and trlfi.Ximum ~~o!i>fficient
in the g :.;•i;')eline behind 'the com-
d~unping
am
'!'able 1
!'J P,,.
Distance between (·!'.1<'>1nber
damper and compresso r [ m]
K
g
sm
(bar)
')OO [rev/min]
0,3
1,875
0,19
3,00
0,027
0,355
1.61
o,o:;z
5,325
1,58
o,;6
o.197
0,34
1,53
0!033
0,56
0,93
o,053
1,09
0,48
o,oe
900 [rev/min]
0
'I
'"'
1, 875
5,325·
From the diagrams of formula t. p a = r/1/ p:t•esented in
Fig. 5 and 6 the significan t effeqt of the 1ocat ion c;f'' r..
chamber damper on the efficieno y of its (.•pera.tion becomes
evident. Placing it at, the dieta.nce of ;,325 [ml from the compressor caused a signif!can ! rise in pressure p1Jtlsatit>n absolute
values immediate ly behind the compresso r in compariso n wit.h those
in the pipeline witl:l¢ut a damper. 'l'he effect of a chamber d<iJl~Per
location on the pressure puls~tion rate numeric~lly character izes
the total rate of p~esw.re pulsation damping. The sma1ler the
distance between the c.ompresso r and damp&I'• the weaker the
influence of air pulsa.t 1ng stream on the compresso: t· wo~k and
lower tbe pressure pula.ation absolute va.luea in the pipeline
behind the damper. When this distance is longer, the press-J.re
pulsation absolute values or~ t.he ecmpreaso: r--damper and behind
the damper sections rise.
The Effect of the 1'res:aure Pulsation Damper Inside Structure .
The investiga tion on the effect of the damper inside
structure on its damping efficienc y in a discharge pipeline and
on the work of a reo.ipr.oca ting compresso r was carried out at the
constant absolute pressure of 3 [bar] of the outlet and rotational speeds between 500 and 1300 [rev/min I .. A single chamber
damper and double chamber resonance dampers with perforate d
central pipe were tested as well as resonance chamber damper
and chamber resonance damper. In the double chamber resonance
1121
i
damper the proportio n of chamber volwnens was changed. All the
tested dampe~a had the same inside diameter of 0 9 499 [ml and
length of 0,604 lml • The perforatio ns of the central pipeline
of the resona.r1ce dampers were 11 [mm) in diameter. The dampers
were placed at 0,3 lml from the compresso r.
On the basis of the experiment.li! it was found that the
change of the inside structure of tbe damper placed in a
discharge pipeline at o,; lml from the compresso r does not
practical ly affect the overall volumetri c efficienc y X • The
effect of the damper inside structure on the electric power
N required for compressi ng 11nd dampi.ng ratio was shown in
e1
•
•
Fig. 7 and 8 as diagrams of formulae N , .. £/D/ and Kt = f/n/.
8«
From the diagrams it is evident that the inside structure of
the damper placed at this distance from the compresso r affects
significa ntly the damping .ratio and has a. negligibl e effect
on the electrica l power necessary for compressi ng. On the whole,
the best l"estdts were obt.ained in case of a single chamber
resonance damper.
CONCI.O"SIONS
On the basis of the invest.iga tion it wa.a found that the
location of a damper in a. discharge pipeline has an essential
effee:t on the effic1ene y of pressure pulsa.Uon damping a.nd the
work of a. compresso r. The in.eide structure of a. damper placed
at an optimum point of a di.scharge pipeline does not have any
practical effect
t.he V()lumet.ri c effi~iency, .s. minor effect
on the power f()r compressi on and a signific-a nt effect on the
damping ratio. By changing the inside stru.ct.ure of a. damper the
damping of particular . harmon.lc coiii)Xmente of a pulsating gas
flow can be a.ffe,::ted.
'm
1. M. ht.szozyck i, Oritericm!' l for the Evaluatio n of the Effecti-
veness of t!"!e PresBl.U"e -Pulsa.tion -Damper. Pro<!eedin gs of the
1976 Purdue C0mpresso r Technology Conferenc e, West Lafayette
1976.
2. M. I.uszczyck i, Electrbh:L i'-'.ade: of a. Single Resonance Chamber
Damper of Pressure Pulsation . l'roc.eedin gs of Conferenc e
Design ani Operation of Indust.ria l Compresso ra, I10ndon 1978.
). M. tuszezyc,k i, R<~~ona.toro-wy H'"<.llll.ik pu.lsacji ciSnienia gazu.
Patent PRL nr 128640.
4.
w.
5.
R. :")ingh. 'tl. 3oedelt A Review of Compl:{;>ssor Lines Pulsation
Analysis 'lnd Muffler Design. Research - Fart I : Pulsation
"Sffecta s.nd l'fu !'fler Crit er.ia, Part II : Analysis of Pulsating
Nimitz, Pltls.iJ<.t.ion a.tld Vibr<ttion . "PiJ:le Line Industry" 1968,
Augu_st - l"cn•t I, ::;..,.ptembet• - Fa.x·~ H.
1122
Flows.
ProceedirJg~ of the 1974 ?urd;.~.e
Lafay~tte 197~.
Corapreusor Technology
Conference, West
a
Fig. 1,
~~~~
c
pulsation dampers: a- chamber, b-
e~ngl.­
ohallber reeonance, c - tw-chamber reaonanoe,
d - reeonance-ohaaber.
Fig. 2. DiagrBII to detemine damping rate:
s-
co~r..eor,
T- damper.
\
',
.ll.pom'----
-----..
........
',
a
ds
. . . , - - .... ,
u ------- . . -T-...--""'. -\j~Po~-.,.....
b
Fig. 3. Diagram to determine the tota.l rate of pr.~eu;re
pula&tiODII damping..
1123
6270
,-+-------------------------~~~~--------------------------i~
II
gl
521
I-'
I-'
N
.,.
Fig. 4. Three - dimensional scheme of discharge pipe1ine1
S - compressor, P- points of pressure pulsation
recording, Z - throttle valve, T - damper.
liPa
[bar]
1[bar] = 14,503 [psi]
fJ
.s";.
3
"'
_l]Il
I\
\
500[rev/min]
\
1.2
1,L
0.9
//
'
01
-....;;;:
\
1\
-. r-
2.30
_1
..........
,... / ~
/
t:/
3/.5
kl
;:::;-. ...-
r~
\II
---
[\,.-' I--
r-1-
!~ ~ t/
~
r--.. 1\./r-2 ~ ~
0.1 !~
I
\
~
0.2
0
~
_\
0.6
0.3
~
\
08
Q5
~
---
\
\
1.0
--
4.60
/
5,75
6,90
BJJ5
~
9.20
10.2
L[m)
Fig. 5. Diagrams of 6p ., r/1/ for different distances of chamber
damper from compressor at 500 [rev/min]: 1 - outlet
pipeline without chamber damper, 2 - chamber damper
at 0,3 [ml , 3 - chamber damper at 1,875 [m] , 4- c~
ber damper at 5,325 [m].
1125
l!Jb [bar]
16
1lbar)::: 14,503 [psi)
t _ _l_U__ j____
I
1,4
!
900 [reV/min] i
13
12
11
10 1\
Q9
QB
\
)
1\
\
~
07
Q6
0/.
Q3
Q2
0;I
/
\
f-
~
//
v
1\
v
·--- t---
j
-
I
--
1\\~
\
-~
r---.
f---- - --
1--
1\
vd
b- )...-a"'
0
1.15
,_!_
~
~
+-----
-·- .
-
~
-.
\
\-\
'
-gr--.._,
·"' · -- ·
----
..
,.
/
v v
!?"
v ....
~
~
'"-<l
___.,
----
v
r-,
-- f..--
r-v
-"'
_.Do ~
I
2))
.
4.60
5,75
/.'
r-1-
.-"' ~
1--o ~
JJ~ I-'
6,90
8.05
9,20
10,2
l [m]
Fig. 6. Diagrams of lip =f/1/ fo:r:- different distances of ehamb6r
damper from eompnssor at 900 I rev/min) r 1 - outlet
pipeline without or~ber damper, 2 - chamber damper
at 0,3 lml , 3 - chamber dampor at 1,875 Iml , 4 - chamber damper at 5,325 [m].
1126
1lkWI = 1,304 l hpJ
Nel
(Wi)
14
12
I
-G
~
~
~
m
-
e
10
8
.....
.....
N
-1
6
900
&
single cbllaber
re~.nanc•
[rev /mi nj
1
l:JO
1 (kW]
~~
1,3
-§ I
14
12
I
-
I
v
~
)v
I
I
8
/
I
7
v
J
/_
10
6
=1304 [hpJ
I
I
v
7
v
v
[7
4
3
2
t-..,
--.v
l..----""
/
.......____
0
500
Fig.
900
s.
mo sao
Diagrams of fol'llllllae N =
91
r/:V
/
v--'
..... . /
900
[rev/min] 1300
and Kt'"' r/~ for
a resonanc e chamber damper and a chamber resonance
damper.
1128