Experimentation of a banded tandem ventilation [631717]

Experimentation of a banded tandem ventilation
system with balanced structure
Doru Cioclea*, Ion Gherghe , Florin Rădoi, Adrian Matei, and Răzvan Drăgoescu
National Institute for Research and Development in Mine Safety and Protection to Explosion –
INSEMEX , 32-34, G -ral Vasile Milea Street, Petroșani, Romania
Abstract. The problem of industrial ventilation has arisen as a result of
the serious pollution problems of both the industrial areas and the
industrial premises. The polluted atmosphere, outside the industrial
premises, can penetrate inside them naturally or through ventilation
systems. The commissioning of a ventilation system occurs whenever a
workplace generates more pollutants than those normally accepted by
hygiene of work conditions, safety, he alth, etc. In order to be able to
choose the correct ventilation system, a complete analysis of the workplace
to be ventilated must be carried out so that the solution chosen to solve the
problem of the exhaust, but also be well received by the user, respe cting
the thermal comfort of it. The paper presents the results of experimenting
with a balanced tandem ventilation system with stable and unstable
operation.
1 Experimentation premises
Experimenting the balanced ventilation system with stable and unstabl e operation has been
carried out in the body for industrial ventilation stands on the ta ndem fan experimentation
stand [1-4].
The testing special tandem fan stand is made up from three fan battery, parallel
mounted, for fresh air, which operated in blowin g mode, and a three fan battery for
evacuation of vicious air, mounted in parallel with operating on an suction mode and which
are located on the wall opposite to the one on which the blower fans are mounted [5-7].
The suction and blowing fans are conne cted to 315 mm circular tubing. The V1, V2 and
V3 suction fans as well as the blowing fans are VAS 315 type. Standard industrial axial
fans VAS designed for the transport of air or gases without corrosive, abrasive or toxic
agents, metal dust or suspension s with agglomeration or sticking tendencies. The power
supply of the experiment stand is provided by the automation panel fig. 1.
The fans experimental stand [8-10], which are mounted in tandem, consists in two
groups of axial fans, namely:
– fresh air ven tilation fan group consisting of two fans of 0.75 kW and a fan of 0.5 kw fig.
2;
– the exhaust fans group consisting of two fans of 0.75 kw and a fan of 0.5 kw fig. 3;

* Corresponding author: [anonimizat]

Fig. 1 . Power supply and automation panel

Fig. 2. The fresh air fan assembly Fig. 3. The exhaust fans assembly

The entire ventilation system is controlled by a SCADA control and control program,
fig. 4. Individual fans are controlled by frequency converters fig. 5.

Fig. 4. SCADA command and control program Fig. 5. Frequency co nverters
2 Measurement results
For the experimentation of the balanced ventilation system with stable and unstable
operation, measurements were made on the experimental stand of fans mounted in tandem
in six variants, namely:

– Experimenting the ventilation system in a stable condition, when the 0.75 kW
blowing fans and the 0.75 kW suction fans are switched on;
– Experimenting the ventilation system in a stable condition where a 0.75 kW
blowing fan and a 0.75 kW suction fan are switched on;
– Experimenting the v entilation system in a stable condition when the 0.5 kW
blowing fan and the 0.5 kW suction fan are switched on;
– Unstable ventilation system experimentation when 0.75 kW blowing fans and
0.75 kW suction fans are switched on;
– Unstable ventilation system expe rimentation when a 0.75 kW blowing fan and a
0.75 kW suction are switched on;
– Unstable ventilation system experimentation when the 0.5 kW blowing fan and
the 0.5 kW suction are switched on.
– Measurements were made at an air temperature of 17.0 ° C and air h umidity of
43%.
2.1 Experimenting the ventilation system in a stable condition, when the 0.75
kW blowing fans and the 0.75 kW suction fans are switched on
For the experimentation, measurements were made at the level of each duct for determining
the air vel ocity and the depression developed by the active fans. The results of the
measurements are shown in table no. 1.

Table 1.
No. Fan
Technical
data V1i
V2i
V3i
V1e
V2e
V3e
Recircu –
lation
0 1 2 3 4 5 6 7 8
1 ø (mm) 315 315 315 315 315 315
2 S (m2) 0.0779 0.0779 0.0779 0.0779 0.0779 0.0779
3 V (m/s) 12.4 15.7 0 13.5 17.5 – 0.42
4 Q (m3/s) 0.96 1.22 0 1.05 1.36 -0.03 0.26
5 Q (m3/min) 57.96 73.38 0 63.09 81.79 -1.96 15.7
6 Δ H (daPa) 0.4 0.4 0 -15 -20 0.4
7 Pn (kw) 0.75 0.75 0.5 0.75 0.75 0.5
8 Pa (kw) 0.79 0.78 0 0.78 0.81 0
9 U (V) 373 377 0 374 374 0
10 I (A) 1.53 1.51 0 1.52 1,58 0
11 f (Hz) 50 50 0 50 50 0
2.2 Experimenting the ventilation system in a stable condition where a 0.75
kW blowing fan and a 0.75 kW suction fan are switched on
For the experimentation, measurements were made at the level of each duct for determining
the air velocity and the depression developed by the active fans. The results o f the
measurements are shown in table no. 2.
Table 2.
No. Fan
Technical
data V1i
V2i
V3i
V1e
V2e
V3e
Recircu –
lation
0 1 2 3 4 5 6 7 8

1 ø (mm) 315 315 315 315 315 315
2 S (m2) 0.0779 0.0779 0.0779 0.0779 0.0779 0.0779
3 V (m/s) 0.28 14.11 0 0.70 17.47 0
4 Q (m3/s) 0.02 1.09 0 0.05 1.36 0 0.33
5 Q (m3/min) 1.31 65.95 0 3.27 81.65 0 20.28
6 Δ H (daPa) 0.5 10.6 0 0.6 -12.6 0
7 Pn (kw) 0.75 0.75 0.5 0.75 0.75 0.5
8 Pa (kw) 0 0.79 0 0 0.82 0
9 U (V) 0 374 0 0 372 0
10 I (A) 0 1.54 0 0 1.61 0
11 f (Hz) 0 50 0 0 50 0
2.3 Experimenting the ventilation system in a stable condition when the 0.5
kW blowing fan and the 0.5 kW suction fan are switched on
For the experimentation, measurements were made at the level of each duct for d etermining
the air velocity and the depression developed by the active fans. The results of the
measurements are shown in table no. 3.

Table 3.
No. Fan
Technical
data V1i
V2i
V3i
V1e
V2e
V3e
Recircu –
lation
0 1 2 3 4 5 6 7 8
1 ø (mm) 315 315 315 315 315 315
2 S (m2) 0.0779 0.0779 0.0779 0.0779 0.0779 0.0779
3 V (m/s) 0.36 0 13.5 0.79 0.26 16.3
4 Q (m3/s) 0.03 0 1.05 0.06 0.02 1.26 0.32
5 Q (m3/min) 1.68 0 63.09 3.69 1.21 76.18 19.67
6 Δ H (daPa) -0.4 0 10.3 0.5 0.4 -21.5
7 Pn (kw) 0.75 0.75 0.5 0.75 0.75 0.5
8 Pa (kw) 0 0 0.65 0 0 0.68
9 U (V) 0 0 374 0 0 372
10 I (A) 0 0 1.01 0 0 1.06
11 f (Hz) 0 0 50 0 0 50
2.4 Unstable ventilation system experimentation when 0.75 kW blowing fans
and 0.75 kW suction fans are switched on
For the experimentation, measurements were made at the level of each duct for
determining the air velocity and the depression developed by the active fans. The results of
the measurements are shown in table no. 4.

Table 4.
No. Fan
Technical
data V1i
V2i
V3i
V1e
V2e
V3e
Recircu –
lation
0 1 2 3 4 5 6 7 8
1 ø (mm) 315 315 315 315 315 315
2 S (m2) 0.0779 0.0779 0.0779 0.0779 0.0779 0.0779
3 V (m/s) 12.0 14.45 0.22 13.7 17.25 0.51

4 Q (m3/s) 0.93 1.12 0.02 1.07 1.34 0.04 0.4
5 Q (m3/min) 56.08 67.53 1.03 64.03 80.62 2.38 24.45
6 Δ H (daPa) 0.6 1.1 -0.5 -25.7 -29.4 0.4
7 Pn (kw) 0.75 0.75 0.5 0.73 0.76 0.5
8 Pa (kw) 0.72 0.76 0 0.78 0.81 0
9 U (V) 372 376 0 372 373 0
10 I (A) 1.41 1.46 0 1.42 1.48 0
11 f (Hz) 50 50 0 50 50 0
2.5 Unstable ventilation system experim entation when a 0.75 kW blowing fan
and a 0.75 kW suction are switched on
For the experimentation, measurements were made at the level of each duct for determining
the air velocity and the depression developed by the active fans. The results of the
measure ments are shown in table no. 5.

Table 5.
No. Fan
Technical
data V1i
V2i
V3i
V1e
V2e
V3e
Recircu –
lation
0 1 2 3 4 5 6 7 8
1 ø (mm) 315 315 315 315 315 315
2 S (m2) 0.0779 0.0779 0.0779 0.0779 0.0779 0.0779
3 V (m/s) 0.21 11.07 0 0.30 17.21 0
4 Q (m3/s) 0.01 0.86 0 0.02 1.34 0 0.51
5 Q (m3/min) 0.98 51.74 0 1.40 80.43 0 31.07
6 Δ H (daPa) -0.5 7.4 0 0.6 -33.2 0
7 Pn (kw) 0.75 0.75 0.55 0.75 0.75 0.55
8 Pa (kw) 0 0.72 0 0 0.83 0
9 U (V) 0 375 0 0 373 0
10 I (A) 0 1.40 0 0 1.61 0
11 f (Hz) 0 50 0 0 50 0
2.6 Unstable ventilation system experimentation when the 0.5 kW blowing fan
and the 0.5 kW suction are switched on
For the experimentation, measurements were made at the level of each duct for determining
the air velocity and the depression developed by the active fans. The results of the
measurements are shown in table no. 6.

Table 6 .
No. Fan
Technical
data V1i
V2i
V3i
V1e
V2e
V3e
Recircu –
lation
0 1 2 3 4 5 6 7 8
1 ø (mm) 315 315 315 315 315 315
2 S (m2) 0.0779 0.0779 0.0779 0.0779 0.0779 0.0779
3 V (m/s) 0.46 0 12.2 0.67 0.41 16.75
4 Q (m3/s) 0.03 0 0.95 0.05 0.03 1.30 0.55
5 Q (m3/min) 2.15 0 57.02 3.13 1.91 78.28 28.45
6 Δ H (daPa) -0.6 0 8.3 0.5 0.4 -25.5

7 Pn (kw) 0.75 0.75 0.55 0.75 0.75 0.55
8 Pa (kw) 0 0 0.47 0 0 0.55
9 U (V) 0 0 377 0 0 378
10 I (A) 0 0 0.91 0 0 1.06
11 f (Hz) 0 0 50 0 0 50
3 Results interpretation
After the experiments we can draw the following conclusions, namely:
– In the case of stable ventilation systems experimentations:
 speeds have been determined at the level of air ducts for active fans between 12.4 –
17.5 m/s;
 air flows ranged from 57.96 to 81.79 m3 / min;
 recirculation air flows rates ranged between 15.7 – 20.28 m3 / min;
 the developed pressures were b etween 0.4 – 21.5 daPa;
– In the unstable experimentation of ventilation systems at the level of the ducts for active
fans:
 the speeds were between 11.07 – 17.25 m / s;
 the air flow rates varied from 51.74 to 80.62 m3 / min;
 recirculation air flow rates ra nged from 24.45 to 31.07 m3 / min;
 the developed pressures were between 0.4 – 33.2 daPa;
Generally, the variation of the recirculation air flows determined du ring the
experimentation of the ventilation systems in the stable mode is proportional to the
variation of the recirculation air flows determined during the experimentation of the
ventilation systems in the unstable mode, fig. 6.

Fig. 6. Variation of the recirculation air flows
4 Conclusions
– Experimentation of the balanced ventilation system with stable and unstable operation
was carried out in the body for the industrial ventilation stands on the experimental stand of
fans mounted in tandem;
– For the experimentation of the balanced ventilation system with stable and unstable
operation, measurements were carried out which included combinations of fans in six
functional variants;

– In the stable and unstable experiments of the ventilation systems the speeds at the level of
the active fan ducts, the air flow rates, the recirculation , the pressures developed, the
current and the supply voltage as well as the absorbed power were determined;
– The variation of the recirculation air flows determined during the experimentation of the
ventilation systems in the stable mode is proportional to the variation of the recirculation air
flows determined during the experimentation of the ventilation systems in the unstable
mode.

This paper was developed within the Nucleu – Programme, car ried out with the support of ANCSI,
project no. PN -19-21-02-04
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