taming of the screw part 1 - soundproof material, sound ... · sponsored by tc 2.6 ... Łpiping...
TRANSCRIPT
The Taming of the Screw:Screw Chiller Noise Sources and Their Mitigation
ASHRAE Seminar 07Sponsored by TC 2.6
Patrick Marks
Staff EngineerCarrier Corporation, Syracuse, NY
28 January 2001
A United Technologies Company
Carrier
Return to www.enoisecontrol.com
Seminar 07, 28 January 2001
Screw Chiller Noise Sources and Their Mitigation
q Review of Screw Compression Technologyq Types of Screw Chillersq Screw Compressor Noise Generation Mechanismsq Chiller Noise Sourcesq Component Level Mitigationq System Level Mitigation
ASHRAE TC 2.6
Seminar 07, 28 January 2001
Screw Compression Technology
q Advantages of Screw Compression:è Positive Displacementè Few Moving Partsè Efficient
q Disadvantages of Screw Compression:è Complex Machining Requirements (Tight Tolerances)è Oil Sealsè Noise - Pure Tones at Relatively High Frequencies
(Sound Quality)
ASHRAE TC 2.6
Seminar 07, 28 January 2001
è Compressor(s)è Evaporatorè Pipingè Oil Separator(s)è Fans
Screw Chiller Types & Noise Sourcesq Water-Cooled
è Compressor(s)è Heat Exchangersè Pipingè Oil Separator(s)
q Air-Cooled
Compressor Oil Separator
Lw
Evaporator Piping
Lw
Vibration
Pulsation
Vibration
Vibr
atio
n
Puls
atio
n
Vibration
Pulsation
Lw Lw
LwVi
brat
ion
Puls
atio
n
Lw
Fan
Compressor Oil Sep.
Lw
Evaporator Piping
Lw
Condenser
Vibration
Pulsation
Vibration
Vibr
atio
n
Puls
atio
n
Vibration Vibration
Pulsation Pulsation
Lw Lw
LwLw
Vibr
atio
n
Puls
atio
n
ASHRAE TC 2.6
Seminar 07, 28 January 2001
Screw Compression Noiseq Pressure Pulsations (Unsteady Mass Flow)q Unsteady Forcesq Tonal - Lobe Passage Frequency (LPF)q Two Paths:
è Gas-Bornem Compressor Shellm Pipingm Heat Exchangers
è Structure-Bornem Heat Exchangers / Piping
q At Typical Screw Compressor LPF’s, Shell andTube Heat Exchangers are Very Responsive.
ASHRAE TC 2.6
Seminar 07, 28 January 2001
Gas-Borne Excitationq Pressure Pulsations in Refrigerant
è Discharge Side Symptoms:m Oil Separator(s)m Compressor Discharge Plenumm Discharge Pipingm Condenser
è Suction Side Symptoms:m Evaporatorm Suction Piping
è “Taming” Procedure:m Muffling (Usually difficult for an installed problem, more of
a design fix)m Lagging - Mass and Decoupling Layer
ASHRAE TC 2.6
Seminar 07, 28 January 2001
Structure-Borne Excitationq Compressor Vibration Transmitted to Other
Componentsè Symptoms:
m Components Directly Connected to the Compressorm Heat Exchangersm Stiff Piping
è “Taming” Procedure:m Component Structural Modification (OEM fix only -
must be qualified)m Lagging - Mass and Decoupling Layer (Radiating
Component)
ASHRAE TC 2.6
Seminar 07, 28 January 2001
Taming of the Screw - Lagging
q Limp Mass with Absorptionq f > 250 Hzq Mass > 1.0 lb./ft2 (4 kg/m2)q 0.5 < ρ < 2.0 lb./ft3 (8 to 32 kg/m3)
Impervious Outer Layer
Adhere this side to chiller
Absorptive Material
0
2
4
6
8
10
100 200 400 800 1600 3150 6300
One-Third Octave Band Center Frequency (Hz)
Typi
cal I
L (d
B)
A
ASHRAE TC 2.6
Seminar 07, 28 January 2001
Water Cooled - System Level Noise Controlq Enclosures
è Rigidm Panelsm Absorption
è “Flexible”m Quilted Barrierm Absorption and
TL Combined
0
2
4
6
8
10
12
14
16
18
20
125 250 500 1000 2000 4000 8000 A
Octave Band Center Frequency (Hz)
Typi
cal I
nser
tion
Loss
(dB
)
ASHRAE TC 2.6
Seminar 07, 28 January 2001
Water Cooled - System Level Noise Controlq Sealing of Leaks is Critical
05
1015202530354045
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75Shield Sound I.L. with No Openings, dB
Shie
ld S
ound
I.L.
with
Ope
ning
s, d
B
.01 %
50 %
10 %
5.0 %
1.0 %
.50 %
.05 %
.10 %% open-
area
ASHRAE TC 2.6
Seminar 07, 28 January 2001
Air Cooled Chiller Noise Mitigationq Fan Noise Control
è Reduce Fan Speedè Reduce System
Lossesè Swept Bladesè Reduce Inflow
Distortion
0
2
4
6
8
10
12
14
16
18
20
125 250 500 1000 2000 4000 8000 A
Octave Band Center Frequency (Hz)
Typi
cal I
nser
tion
Loss
(dB
)
q Partial Enclosure (Fans andRefrigerant System Noise)è Louversè Sound Traps above Fan Deckè Barriers
ASHRAE TC 2.6
Seminar 07, 28 January 2001
The Taming of the Screw - Summary
q Screw Chillers Produce Predominantly TonalNoise
q Two Paths:è Structure-borneè Gas-borne
q Taming:è Components - Laggingè Water-Cooled System - Enclosureè Air-Cooled System - Partial Enclosure
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eASHRAE TC 2.6