hvac talk - · pdf filesuper-e electric motor 5. ... improperly mounted ultrasonic flow meter...

Date

By Lee Eng Lock

HVAC Talk

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• Chong Qing, • Hang Zhou, • Shen Zhen

in China

Psychometric Chart for Weather Data from:

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Location Map of the 3 cities

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Chong Qing Weather Data

2004 - 2006

2004 2006

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Hang Zhou Weather Data

2004 - 2006

2004 2006

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Shen Zhen Weather Data

2004 - 2006

2004 2006

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AHU ENERGY RETROFIT

New AHU Design Criteria

1. Low air velocity across filter and cooling coil2. Air pre-cool by 15 degC chilled water3. High efficiency Airfoil direct driven fan4. Super-E electric motor5. Variable speed drive6. Digital temperature Control7. Non flammable AHU panel8. High resistance of coil to corrosion (powder coating)

CASE STUDY 1. ST Microelectronics CASE STUDY 1. ST Microelectronics PtePte LtdLtd

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AHU ENERGY RETROFIT

New AHU Plan View

CASE STUDY 1. ST Microelectronics CASE STUDY 1. ST Microelectronics PtePte LtdLtd

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AHU ENERGY RETROFIT

New AHU Section

CASE STUDY 1. ST Microelectronics CASE STUDY 1. ST Microelectronics PtePte LtdLtd

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AHU ENERGY RETROFIT

CASE STUDY 1. ST Microelectronics CASE STUDY 1. ST Microelectronics PtePte LtdLtd

Executive SummaryOLD and NEW AHU PERFORMANCE

# AHU Parameter (100% fresh air): Unit OLD AHU NEW AHU

1 Total cooling capacity Ton refrigerant 340 354

2 Chilled water supply temperature Degree C 6

15-pre-cool,

6-final cooling

3 Chilled water temperature rise Degree C 5.5 11

4 Fan power consumption KW 35 7

5 Chiller power consumption KW 212 170

6 AHU efficiency KW/Ton 0.1 0.02

SAVINGS

# Savings (for 2 units): kW % $Sin/Year

1 Fan power consumption 56 80 72,800

2 Chiller power consumption 84 20 109,200

3 Total 140 182,000

Payback period of investments 1.9 years

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Existing Ultrasonic Flow Meter

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Newly Installed Ultrasonic Flow Meter

Header MF?

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Magnetic flow meter on condenser flow

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Magnetic flow meter on chilled water flow

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New USFOld USF on the vertical pipe

Three MFs on chilled side

Three MFs on condenser side

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UF installation

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MF installation

From OMEGA Engineering

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Flow measure comparison

Flow measurement comparison (GPM) 18Nov08

1000.00

1100.00

1200.00

1300.00

1400.00

1500.00

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1700.00

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1900.00

2000.00

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time

gpm USFnew(header)

USFold(header)

MF existing(header)

1) Correctly mounted ultrasonic flow meter reading matches the existing magnetic flow reading

2) Improperly mounted ultrasonic flow meter reading is 15% lower than correctly mounted ultrasonic flow meter and the existing magnetic flow meter

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Cooling load comparison

Cooling load comparison (tons) 18Nov08

400

500

600

700

800

900

1000

1100

7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00

Cooling load (USF new)

Cooling load (USF old)

Cooling load (MF existing)

1) Equipment switched on at 7.30am, switched off at 6:pm

2) There is a cooling load spike in the early morning due to the heat accumulation during the night.

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Efficiency comparison (kw/ton) (18Nov08)

0.60

0.70

0.80

0.90

1.00

1.10

1.20

7:00

7:30

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8:30

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:30

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Efficiency (USF new)

Efficiency (USF old)

Efficiency (MF existing)

Efficiency comparison

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Efficiency comparison

Efficiency comparison (kw/ton) (18Nov08)

0.00

0.20

0.40

0.60

0.80

1.00

1.20

7:00

7:30

8:00

8:30

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:30

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Efficiency (USF new)

Efficiency (USF old)

Efficiency (MF existing)

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Spot measurement

Chill plant power: 421.8 kw

Chiller plant flow rate: 2441gpm

Chiller Chw temp in: 52.34F (11.3 C)

Chiller Chw temp out: 46.22F(7.9C)

The resultant plant efficiency: 0.6776 kw/ton

The measurement time is around 9:30am to 10:30amComparing with the logging graph, the spot measured efficiency is lower than logging data which is 0.71-0.88kw/ton based on UF new and MF existing flow measurement, but acceptable

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• The sampling rate is 1 minute

• The readings from correctly mounted ultrasonic flow meter matches well those from magnetic flow meter mounted on the header

• Due to the improper mounting of the old ultrasonic ( air accumulation), the readings from old UF is 15% lower than new correctly mounted UF, which causes the higher efficiency deviation

• During the equipment switching on and off period, unsteady operating condition affects the flow meter reading greatly

• Chiller plant average efficiency from 8:am to 6pm on Nov.18, 2008 is 0.79kw/ton, which is meet the GreenMark baseline minimum efficiency requirement 0.85kw/ton

• There is big room to improve chiller plant efficiency:

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Figure 3a

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Figure 3b

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Figure 3c

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Figure 5a

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Figure 5b

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Figure 5c

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Figure 5d

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Figure 6a

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Figure 6b

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Figure 6c

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Figure 6d

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Figure 7a

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Figure 7b

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Low Face VelocityAn Energy Conservation Option

forMake-Up Air Units

Presented by:Greg Owen, PE

503-624-3230greg.owen@jacobs.com

October 4, 2000

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Cleanroom facility design decisions must be economically

justified.

FACT:

Low Face Velocity

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• Unit CFM - 43,500 CFM

• Site Elevation - 1500 Ft

• Summer Conditions - 96oF / 65oF

• Winter Conditions - -20oF

• Chilled Water - 39oF / 51oF

• Hot Water - 180oF / 150oF

• Supply Air Conditions - 55oF / 48.6oF

Make-Up Unit Design Conditions

Low Face Velocity

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Elements That Affect Make-up Air Unit Energy Consumption

CoilSize

FilterSize

Fan CFM, Motor Hp

oF &RH%of OA

Under the control ofthe Design Engineer

oF &RH%

Low Face Velocity

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FACE VELOCITIES CONSIDERED

• Unit CFM

Face Area

500FPM

350FPM

425

FPM

300FPM

Low Face Velocity

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Low face velocities reduce air handling unit coil and filter static

pressure and result in lower energy consumption by the unit.

PREMISE #1

Low Face Velocity

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FILTER DIFFERENTIAL PRESSURE

0

0.5

1

1.5

2

2.5

500 425 350 300(FPM)

Pre Filters Carbon Filters 95% Filters HEPA Filters

(INWG)

Low Face Velocity

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COIL DIFFERENTIAL PRESSURE

0

0.2

0.4

0.6

0.8

1

1.2

1.4

(INWG)

500 425 350 300(FPM)

Preheat Cooling Dehum Reheat

Low Face Velocity

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Energy savings from low face velocity systems reduce the operating costs of the units.

PREMISE #2

Low Face Velocity

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Component Cost Impact

Larger Casing Increase Capital Cost

Larger Coils Increase Capital Cost

Increased Filter Count Constant Life Cycle Cost

Smaller Fan Motors Decreased Capital Cost

Reduced Infrastructure Decreased Capital Cost

ECONOMIC IMPACT FOR LOW FACE VELOCITY COMPONENTS

Low Face Velocity

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MAKE-UP AIR UNIT MOTOR SELECTION

Static RPM Brake Hp

• 500 FPM 801 65.0

• 425 FPM 757 55.6

• 350 FPM 709 46.0

• 300 FPM 687 41.8

Low Face Velocity

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Includes

• Fan, Motor & Drives

• Coils

• Filter Racks

• Humidifier

• Housing & Inlet

• EE Infrastructure Impact

MAKE-UP AIR UNIT COST ESTIMATE

Excludes• Filter Media

• Installation Cost

• Building Space

Low Face Velocity

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Make-up Air Unit (MAU) Capital Cost Differential

• 500 FPM

• 425 FPM

• 350 FPM

• 300 FPM

• Base Cost

• +$4,820

• -$1,610

• +$9,450

Low Face Velocity

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Energy Cost

• High Average Industrial / Commercial Rate

– Boston Edison

– $0.097/kWHr

• Low Average Industrial / Commercial Rate

– Portland General Electric

– $0.0382/kWHr

Low Face Velocity

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• 425 FPM Unit $38,187 +37 Weeks (9.5 months)

MAU Electrical Operating Cost (High Rate)

• 500 FPM Unit $44,959 Base Condition

Pay Back PeriodUnit Size Cost/Yr.

• 350 FPM Unit $31,964 Immediate

• 300 FPM Unit $28,764 + 29 Weeks (7.25 months)

Low Face Velocity

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• 425 FPM Unit $15,039 +94 Weeks (23.5 months)

MAU Electrical Operating Cost (Low Rate)

• 500 FPM Unit $17,705 Base Condition

Pay Back PeriodUnit Size Cost/Yr.

• 350 FPM Unit $12,588 Immediate

• 300 FPM Unit $11,328 + 77 Weeks (19.2 months)

Low Face Velocity

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• Low face velocities do save energy & money.

• Return on Investment (ROI) is dependent on local energy rates.

• High tech companies generally require ROI’s of 12 months or less.

CONCLUSION

Low Face Velocity

Questions??

Low Face Velocity

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Questions??

Low Face Velocity

Questions??

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