Chilled Water Loop Optimization...Chilled Water Loop Optimization • Kazimir Gasljevic • Richard Dewey • Sandro Sanchez . ... cooling tower fan, condenser pump. Use performance

Chilled Water Loop

Optimization

• Kazimir Gasljevic

• Richard Dewey

• Sandro Sanchez

WHAT WE STARTED WITH:

LOOP OUTLINE:


LOOP OUTLINE:

- Justification for the loop


LOOP OUTLINE:

- Justification for the loop

Value of the loop piping, $10 Million Vs. Value of the

chillers on the loop, $5 Million


LOOP OUTLINE:

- The game changed after the introduction of

variable speed chillers


LOOP OUTLINE:



•There will probably be no further expansion of the

loop.


LOOP OUTLINE:



•There will probably be no further expansion of the

loop.

•Modular variable speed chillers are the better way to go

in our climate.


ORIGINAL CONTROLS CONCEPT:


ORIGINAL CONTROLS CONCEPT:

• Focused mostly on functionality with not much concern

given to efficiency issues.


OVERALL LOOP ENERGY EFFICIENCY:


OVERALL LOOP ENERGY EFFICIENCY:

• 0.85 kW/ton, 0.8 kW/ton after installation of the variable

speed chiller.

SCOPE OF THE MBCx

PROJECT:

SCOPE OF THE MBCx

PROJECT:

An MBCx project focused on improving existing

hardware with better usage and controls (no

capital costs).

SCOPE OF THE MBCx

PROJECT:

FUNCTIONALITY:

SCOPE OF THE MBCx

PROJECT:

FUNCTIONALITY:

• To automatically maintain a constant Differential

Pressure, as well as staging the chillers off and on

smoothly.

SCOPE OF THE MBCx

PROJECT:

ENERGY EFFICIENCY:

SCOPE OF THE MBCx

PROJECT:

ENERGY EFFICIENCY:

• Improve the efficiency of all chiller plants.

SCOPE OF THE MBCx

PROJECT:

EXTRAS:

SCOPE OF THE MBCx

PROJECT:

EXTRAS:

• Critical cooling

• Use loop thermal capacity for load shedding

• Leak detection and leak location.

STRATEGY:

STRATEGY:

Hiring Consultants

vs.

Doing the work in House:

STRATEGY:

Hiring Consultants

vs.

Doing the work in House:

• "Fits all" algorithm vs. "algorithm for a given situation“

• Intimate Knowledge of the plant

STRATEGY:

OTIMIZATION METHODOLOGY:

STRATEGY:

OTIMIZATION METHODOLOGY:

• Sacrifice slightly on the ideal mathematical optimum for

a robust sustainable system.

• Take in to account temporal changes in the performance

of the system components.

OPTIMIZATION

ALGORITHM :

OPTIMIZATION

ALGORITHM :

Optimization of the Loop

OPTIMIZATION

ALGORITHM :

• Decide which chillers to run based on the capacity and

efficiency of individual chillers.


OPTIMIZATION

ALGORITHM :



• Decide the Condenser Water temperature set point.


OPTIMIZATION

ALGORITHM :




• Decide the Differential Pressure set point (constant for

now).


OPTIMIZATION

ALGORITHM :




• Decide the Differential Pressure set point (constant for

now).

• Consider a needed cooling capacity of the loop in the

immediate future (few hours), based on the time of day

and the weather forecast.


0

0.2

0.4

0.6

0.8

1

1.2

0 200 400 600 800 1000 1200

Eff

icie

ncy

[k

W/t

on

]

Load [tons]

Chiller Efficiencies at 74 F Condenser Temp and 42 F Supply Temp

ESB

CNSI

Bren

Library

Chemistry, Broida

ENG 1

BIO 2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 200 400 600 800 1000 1200

Eff

icie

ncy

[k

W/t

on

]

Load [tons}

Plant efficiencies at WB 60 F

ESB

CNSI

Bren

Library

Chemistry

ENG 1

BIO 2

Broida

OPTIMIZATION

ALGORITHM :

Optimization of individual chillers

OPTIMIZATION

ALGORITHM :

● Balancing power for compressor, cooling tower fan,

condenser pump. Use performance curves updated for the

momentary changes (maintenance issues etc.)

Optimization of individual chillers

0

10

20

30

40

50

60

70

80

90

100

0 20 40 60 80 100 120 140

Tem

per

atu

re [

F]

Time [Minutes]

ESB Chiller Temperatures

Condenser Refrigerant

Condenser Water Supply

Air Wet Bulb

Condenser Water Return

Evaporator Water

Return

Evaporator Water

Supply

Evaporator Refrigerant

Condenser

Evaporator

Condenser Pump

Cooling Tower

Del

iver

ed

Ch

ille

r L

oa

din

g

0

1

2

3

4

5

6

7

0 100 200 300 400 500 600 700 800 900

Ap

pro

ach

= T

sat

-T c

hw

[F

]

Tons

ESB Condenser Problem, 8/26/2014

Before Cleaning

Ideal

After First Cleaning

After Second Cleaning

0

5

10

15

20

25

30

35

0 5 10 15 20 25 30 35 40 45

Ap

pro

ach

Tem

p [

F]

Fan power (both) [HP]

Broida Cooling Tower Performance (BAC model)

100% speed 90% speed 80% speed 60% speed

55 F WB, 100% load

55 F WB, 50% Load

70 F WB, 100% Load

70 F WB, 50% Load

100% Load = 8.2 kW/F

50% Load = 4.2 kW / F

55 WB, 75% Load

70F WB, 75% Load

1.2 F

1.8 F

2.5 F

2.4 F

3.6 F

4.8 F

3.33 F

5 F

6.66 F

4.3 F

6.45 F

8.6 F

1.8 F

2.7 F

3.6 F

0.6 F

0.9 F

1.2 F

3 F

4.5 F

6 F

100%

75%

50%

How many F App T can be increased at any fan power saving before compressor power increase becomes larger than fan power reduction.

1 HP = 0.84 kW (0.9 motor efficiency)

70% speed

50, 19

75, 18

100, 17

50, 14.5

75, 13.75

100, 13

y = -0.04x + 21

y = -0.03x + 16

10

11

12

13

14

15

16

17

18

19

20

0 20 40 60 80 100 120

Ap

pro

ach

Tem

[F

]

Chiller Load %

Broida; Cooling Tower Approach Set Point

WB 55 F

WB 70 F

Linear (WB 55 F)

Linear (WB 70 F)

For a given % load: AT = (AT55WB - AT70WB) * (70 - WB) / 15

Add few F for a degraded cooling tower performance (determine experimentally)

MEASUREMENTS:

MEASUREMENTS:

● Typically electrical power OK, tons not OK.

MEASUREMENTS:


● Uncertainty in a typical Btu measurement is in the

range of improvements one is trying to achieve.

MEASUREMENTS:




● Temperature measurements

MEASUREMENTS:





● Flow rate measurements.

MEASUREMENTS:





● Flow rate measurements.

● Improving measurements may amount to a third of the

total effort.

CONCLUSIONS:

CONCLUSIONS: ● 0.63 kW/ton a yearly average compared with 0.8

kW/ton baseline.


kW/ton baseline.

● With 11 bill tons annual cooling load, we used 8.8 mil

kWh before and 6.93 kWh after.


kW/ton baseline.



● Annual savings 1.87 mill kWh = $225,000


kW/ton baseline.



● Annual savings 1.87 mill kWh = $225,000

● Additional energy savings thanks to the improved

functionality (maintaining a desired chilled water

temperature and pressure differential).

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400 500 600 700 800

Eff

icie

ncy

[k

W/t

on

]

Time [h]

Loop Efficiency September 2014

Measured: Average 0.64 kW/ton

Baseline: 0.8 kW/ton

Linear (Measured: Average 0.64 kW/ton)

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 100 200 300 400 500 600 700

Eff

icie

ncy

[k

W/t

on

]

Time [h]

Loop Efficiency June 2015

Measured: Average 0.625 kW/ton

Baseline: 0.8 kW/ton

Linear (Measured: Average 0.625

kW/ton)

CONCLUSIONS:

CONCLUSIONS:

REMAINS TO BE DONE:

CONCLUSIONS:

● What we have achieved is a near optimum and further

improvements are to be done in both areas of control

(optimize the loop and optimize individual chillers).

REMAINS TO BE DONE:

CONCLUSIONS:

● What we have achieved is a near optimum and further

improvements are to be done in both areas of control

(optimize the loop and optimize individual chillers).

● About 70% of the expected total improvement in

efficiency achieved , 30% remains to be done.

REMAINS TO BE DONE:

THANK YOU!

Documents

Chilled Water Loop Optimization...Chilled Water Loop Optimization • Kazimir Gasljevic • Richard Dewey • Sandro Sanchez . ... cooling tower fan, condenser pump. Use performance