Volume 03 Issue 10-2023
9
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
10
Pages:
9-14
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
ABSTRACT
The climatic conditions of Uzbekistan are characterized by relatively long summers with air temperature of 40-45 0C
and higher, which is the reason of significant heating of air suctioned by compressor. Increase in temperature and
corresponding decrease in air density contributes to 8-10% decrease in compressor unit productivity, leading to
significant economic losses in the process of compressed air production.
By means of artificial cooling of suction air at the inlet to the compressor unit it is possible to increase the energy
efficiency of operation of the mine reciprocating compressor unit.
The effectiveness of artificial air temperature reduction depends on the amount of temperature reduction and the
type of plant drive, as well as on the purpose - to reduce the specific electric energy consumption for compression or
to increase the capacity of the reciprocating compressor.
KEYWORDS
Compressor, air temperature, energy efficiency, air suction, air heating, capacity, compression, air pressure, artificial
cooling.
Research Article
TEMPERATURE OF THE COMPRESSOR SUCTION AIR AND ITS INFLUENCE
ON THE EFFICIENT OPERATION OF THE COMPRESSOR UNIT
Submission Date:
October 01, 2023,
Accepted Date:
October 06, 2023,
Published Date:
October 11, 2023
Crossref doi:
https://doi.org/10.37547/ajast/Volume03Issue10-03
D.N. Khatamova
Associate Professor, Mining Engineering Department, Navoi State Mining and Technology University,
Uzbekistan
E.U.Yuldashev
Assistant Professor Of "Mining Electromechanics" Department, Almalyk Branch of Tashkent State Technical
University Named After Islam Karimov, Uzbekistan
Journal
Website:
https://theusajournals.
com/index.php/ajast
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Volume 03 Issue 10-2023
10
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
10
Pages:
9-14
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
INTRODUCTION
The performance of a real compressor differs from an
ideal compressor due to the presence of harmful
volume, hydraulic resistances at the suction, leakages
in the working cavity, relative humidity of the suction
air and suction air heating [1].
One of the main factors affecting the efficient
operation of mine compressors is air heating during
suction, resulting from the resistance of the suction
path and heat exchange with heated components of
the unit. Under normal atmospheric conditions, the
decrease in mass capacity and volumetric delivery of
the equipment is due to a decrease in the density of
heated air [2].
The delivery coefficient, which takes into account the
influence of all factors on the performance of the
actual compressor, is determined by the following
formula [3]:
λ
=
λ
vc
λ
thc
λ
hc
λ
dc
λ
mc
,
(1)
where: λ
vc
is the volumetric coefficient;
λ
th
c - throttling coefficient;
λ
hc
- heating coefficient;
λ
dc
- density coefficient;
λ
вл
- moisture coefficient.
There are several reasons for the warming of the air
observed during suction. The air entering the
compressor unit is heated by contact with the cavity
walls during the suction process. The energy expended
in pushing the suction air through hydraulic
resistances, which is converted into heat, results in a
temperature increase. In addition, the change in air
temperature is caused by the mixing of the air newly
entering the cylinder with the air remaining in the
harmful space.
Taking into account the above, it is revealed that the
decrease in the compressor unit performance is
affected by the suction gas heating due to heat
exchange with the surfaces of hot cylinder parts ΔT1,
and the increase in the suction gas temperature due to
the gas remaining in the dead space ΔT2.
Thus, at the end of the suction process, the conditional
value of the air temperature in the working cavity is
determined by the formula [4]:
𝑇
1
′
= 𝑇
1
+ ∆
Т
1
+ ∆
Т
2
,
(2)
where T_1 is the atmospheric air temperature, °C.
The influence of intake air heating on the plant
performance is estimated by its temperature
coefficient determined by the formula [4]:
𝜆
т
≅
𝑇
1
𝑇
1
′
(3)
As can be observed from the formulas, an increase in
the atmospheric air temperature T1 lead to an increase
in the temperature T1', which reduces the performance
of the piston compressor.
Until now, the value of
𝜆
т
could not be determined
precisely because of the difficulty in determining the
instantaneous temperatures at the beginning of
suction [5].
The compressor capacity Q_pr taking into account the
effect of temperature can be determined by the
following expression [5]:
𝑄
пр
= 𝑉
р
′
∙
𝑃
1
′
𝑃
1
∙
𝑇
1
𝑇
1
′
,
м
3
h
⁄
(4)
Volume 03 Issue 10-2023
11
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
10
Pages:
9-14
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
where
𝑉
р
′
' is the volume of atmospheric air intake,
m3/h;
𝑇
1
and
𝑃
1
−
temperature and pressure of air at the
suction, respectively;
𝑇
1
′
and
𝑃
1
′
- respectively temperature and pressure
of air in the cylinder during suction.
The effect of suction temperature
𝑇
1
on the amount
of work expended by the compressor to compress air
can be determined from equation (5).
Total energy consumption for compression of 1 kg of
air [6]:
𝑙
п
.
э
=
𝑘
𝑘−1
∙ 𝑅 ∙ 𝑇
1
∙ [(
𝑃
н
𝑃
1
)
𝑘−1
𝑘
− 1] ,
(5)
Where k-is the adiabatic index of air;
R-
is the gas constant, j/(kg∙ deg);
𝑃
1
- pressure of inlet air, MPa;
𝑃
н
- pressure of injected air, MPa.
As can be seen from equation (5), in the compressor at
constant relative pressure rise
rise
𝜀 =
𝑃
н
𝑃
1
,,
,, the
compressor work for compressing and moving 1 kg of
air increases with increasing temperature T1. Work
spent on compression of 1 kg of air, for each 10C
increase in temperature at suction T1, increases by
0.16% [7].
The
climatic
conditions
of
Uzbekistan
are
characterized by relatively long summers with air
temperatures of 40-45 0C and higher, which is the
reason for significant heating of air suctioned by the
compressor. The increase in temperature and the
corresponding decrease in air density contributes to an
8-10% decrease in compressor unit productivity,
resulting in significant economic losses in the
compressed air production process.
By artificially cooling the intake air at the inlet to the
compressor unit, the energy efficiency of a mine
reciprocating compressor unit can be increased.
The effectiveness of artificial air temperature
reduction depends on the magnitude of the
temperature reduction and the type of drive of the
unit, as well as on the goal of reducing the specific
electrical energy consumption for compression or
increasing the capacity of the reciprocating
compressor.
Undoubtedly, reducing the temperature of the
compressor suction air leads to an increase in its
weight capacity and increases the power of the drive.
In this regard, by artificially cooling the suction air, it is
possible to increase the annual compressor capacity in
summer, which is especially important in the
conditions of plant operation in areas with hot climate,
to eliminate the need to install additional compressors
or avoid replacing existing units with more powerful
ones, which will give a significant economic effect [8].
Reduction of reciprocating compressor performance in
summer period is primarily due to the increase in
ambient temperature. As a consequence, the
temperature of the air sucked in by the compressor
increases, and the air density changes accordingly. Air
density is commonly understood as the amount of air
contained in 1 m3, its value can be determined by the
following expression:
𝛾
воз
=
𝑀
𝑉
,
к
𝑔𝑠
м
3
⁄
,
(6)
where M-weight of air, kgs;
V - volume of air, m3.
Volume 03 Issue 10-2023
12
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
10
Pages:
9-14
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
At normal atmospheric pressure (
P
nor
=760 mm.Hg
)
and temperature
t
nor
=15-25 °C 1 m3 air density
determined by formula (6) is
γ
a
=1,225 kgs⁄(m3)
It has been established that in winter period at twin=0
°C the air density is
γ
a
is=1,29 kgs⁄m3 , while in summer
period
Ts=40°C, γ_(air.l.)=1.13 kgs⁄m3. Hence, the air density in
summer period is less than that in winter period. Thus,
to ensure greater performance of reciprocating
compressor units there is a need for artificial cooling of
the air entering the compressor.
The temperature of the compressor suction air can be
reduced by simple and cheap heat exchangers using
cold water from the cooling tower, in this case it is
recommended to install the cooler of the suction air
between the filter and the first stage of the
compressor. The proposed design of the cooler is
shown in Fig. 1.
a) b) c)
1 - cooling water inlet side; 2 - housing; 3 - tubes; 4 - cooling water outlet side;
a)
front view; b) general view; c) top view
b)
Fig.1. Compressor suction air cooler
Volume 03 Issue 10-2023
13
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
10
Pages:
9-14
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
Installation of coolers at the suction before the
compressor creates additional hydraulic resistance to
the movement of suction air, which in turn leads to
an increase in energy costs of the drive unit.
In our proposed cooler design, the distance between
the tubes through which the cooling water circulates
is chosen in such a way that the created hydraulic
resistance will not be significant.
Fig. 2 shows a schematic of an open-circuit cooling
system for a two-stage reciprocating compressor
using a heat exchanger to cool the suction air.
1 - air intake; 2 - filter; 3 - air cooler before the compressor; 4 - first compressor stage; 5 - intermediate
cooler; 6 - second compressor stage; 7 - end cooler; 8 - cooling tower; 9 - water atomizer; 10 and 11 - fans; 12
- pump; 13 - cooled water pipeline; 14 - heated water pipeline.
Fig.2. Scheme of open-circuit cooling system of two-stage reciprocating compressor with heat exchanger for
artificial cooling of suction air
Pre-cooling of the compressor intake air, shown in Fig.
2, is carried out as follows: air cooler 3 is installed
between the filter 2 and the first stage of the
compressor 4. Pump 12 supplies cold cooling water
from the cooling tower 8 to the compressor to cool its
parts, to the intermediate 5 and end coolers 7 to cool
the compressed air. At the same time, the water is
supplied to the air cooler 3. The water heated as a
result of air cooling is fed to the cooling tower for
cooling and then back to the air cooler upstream of the
compressor unit.
REFERENCES
Volume 03 Issue 10-2023
14
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
10
Pages:
9-14
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
1.
Khatamova D.N., UrunovaKh.Sh. Improvement of
the cooling system of compressor units //
Universum: technical sciences. - Moscow, 2021. -
№
5 (86). - p. 68-71.
2.
Dzhuraev R.U., Karamatova Z.H. Improvement of
the efficiency of the cooling systems of
compressor units // Prospects of innovative
development of mining and metallurgical complex.
International scientific and technical conference
dedicated to the 60th anniversary of NGMK.-
Navoi, 2018. - p. 264.
3.
Dzhuraev R.U., Shomurodov B.H., Khatamova D.N.
Modernization of the cooling system of piston
compressor units// Proceedings of IXInternational
Scientific and Technical Conference on the theme:
"Achievements, problems and modern trends in
the development of mining and metallurgical
complex". - Navoi, 2017. - p. 176.
4.
Khatamova D.N., Dzhuraev R.U. Investigation of
the influence of the suction air temperature on the
efficiency of the reciprocating compressor //
Universum: Technical Sciences. - Moscow, 2021. -
№6 (87).
- p. 44-47.
5.
Plastinin P. I. Piston compressors. Т. 2.
Fundamentals of design. Constructions. 3rd
edition. - M.: Kolos, 2008. - 711 p.
6.
Abduazizov N.A., Khatamova D.N., Dzhurayev R.U.
Analysis of the cooling systems of mine piston
compressor units // Mining Bulletin of Uzbekistan. -
Navoi, 2021. -
№1.
- p.104-107.
7.
Plastinin P. I. Piston compressors. Volume 1. Theory
and calculation. - Moscow: Kolos, 2000. - 456 p.
