Chilled water Meyrin consolidation Study1st Part

Many thanks for their contribution to:Pasquale Alemanno, Fortunato Candito, Alexander Putzu

Outline

• Loads• Proposed layouts• System design Parameters “variations”• Savings strategies• Summary / Conclusions

Plan Reference Numéro Niv sol BâtimentPuissance Nominale

Débit Technologie CP Régime d'eauCondensation par

Pompe Fixe ou Variable

Eau PerduPuissance Nominale

DébitHMT de Travail

700 Kw 100 M3/H Vis 11/5°C Eau Fixe

1400 Kw 200 M3/H Centrifuge 11/5°C Eau Fixe

Fixe 1250 Kw 180 M3/H

Fixe 385 Kw 55 M3/H

700 Kw 100 M3/H Vis 11/5° C Eau Fixe1400 Kw 200 M3/H Centrifuge 11/5° C Eau Fixe1400 Kw 200 M3/H Centrifuge 11/5° C Eau Fixe

485 Kw 70 M3/H Vis 12/6 °C Eau Fixe

485 Kw 70 M3/H Vis 12/6 °C Eau Fixe

Fixe9.62Kw x 2 2 M3/h 13/17.5°C Fixe

Fixe50 Kw x 4 7.7 M3/h 13/19°C Fixe

FixeFixe

65.6 Kw x 2 9.4 M3/h 13/19 °C Fixe121 Kw 17.3 M3/h

Prod./Distribution

435

Production

Production

361 Booster Distribution

Puiss. Totale Production

100

50

Puiss. Totale Distribution

700

1400

700

378

300

420

40

97

20

A

B

C

D

E

F

9

8

6

11

1

10

POPS Production

12/6 °C

Scroll

193 Hall AD

193 Salle de contrôle AD

50

12/6 °C51 M3/H355 Kw

2 Pompes Back up

POPS Distribution

18/12°C Air227 Kw 32 M3/H

55 M3/H Uniquement pour la ventilation.

Eau perdu voir Alex pour data sheet

Ventilation PSVariable

Voir client si besoin froid

Batterie en eau glacée à rajouter ? Si oui prévoir piquage , si besoin eau glacée.

CW2 430 Batterie en eau perdu.Local C.A.O Puiss. 97 Kw.

CV3 74 Batterie en eau perdu .

2 pompes de 400 M3/H (vitesse variable réglé à ?)

Air

Air

959.6 Kw en régime

6/12°C+et 1314.56 Kw

autre régime

Nouveau groupe froid CARRIER UHF1 191 installé par Alex.

8 centrales de traitement d'air à eau perdu.4 en RUN et 4 en Back-up.Il y a deux centrales TRANE en détente direct qui pourraient être raccordé 10 Kw

chacunes.

Hall AD

8 x 100 Kw + 2 Centrales

TRANE de 10 Kw chacunes.

50 Kw Scroll

355 PS Distribution

193 AD Target

AD Target

195

2011

Back-up

3

4

5

40Kw eau à 13°C

197 Isolde Distribution Bât. 197

355 PS ProductionBack-up

7.2 M3/H.

2 pompes de 180 M3/H

2 pompes de 55 M3/H ( Puissance été)

361 Booster

15 M3/H par batterie

7001400

197 Isolde Production

383 Kw

378 Kw 54 M3/H

370

17000 f/h soit environ 20 Kw.

269

366

2300

121131

300

100

210

19

200

1400

485

485

Fixe

Fixe

Eau perdu

Eau perdu

Eau perdu

Eau perdu

Eau perdu

Eau perdu

2011

Bât .2010

Bât .2002

Bât .2008

Bât .2006Bât .2007

Bât .2003

Bât .2001 Pompe distribution 130 M3/H fixe.

ProductionBack-up

Distribution vers Bâtiment Commentaires

12/6 °C

361 (Ventilation Booster) ventilation

359 (Centre anneau) + 6 armoires de ventilation bât.

359 Hall

2

Vieux groupe froid.Possibilité de réalimenter ce chiller mais peu de places dans les galeries

Vis

Voir détail puissance Foglio 3.

Fixe

Fixe

Variable

Loads summary table

Courtesy of F. Candito and A. Putzu

Present layout of Installed Cooling Power

378 kW

700+1400 kW

227 kW

485+485 kW

700 + 1400 + 1400 kW

50 kW

Eau Perdu

Total installed Cooling Power4640 kW

Courtesy of P. Alemanno

Actual cooling power used (Summer)

300 kW43 m³/h

630 kW90 m³/h

700 kW100 m³/h

100 kW14 m³/h

300 kW43 m³/h

2195 kW (960 kW buildings + 1235 kW PS) 315 m³/h

Besides POPS (12/18° C), production is 6/12° C.Distribution flows calculated assuming 6 ° C ΔT.Total cooling power: 4225 kW.

Central Plant production/distribution

Central Plant: ΔT 6 °C4225 kW @ 607 m³/h

249 m³/hDN 200

135 m³/hDN 150

90 m³/hDN 125

45 m³/hDN 100

358 m³/hDN 250

177 m³/hDN 200

45 m³/hDN 100

14 m³/hDN 65

• 5 MW cooling tower, axial fans.• Centrifugal Chillers with VFD compressors.• Chiller staging control.• Primary/Secondary (VFD).• No buffer tank.• Two sets of chilled water pumps.

Two Main Plants production/distribution

Summer

Plant “PSB area”: ΔT 6 °C1730 kW @ 249 m³/h

249 m³/hDN 200

135 m³/hDN 150

90 m³/hDN 125

45 m³/hDN 100

45 m³/hDN 100

14 m³/hDN 65

Plant “PS area”: ΔT 6 °C2495 kW @ 358 m³/h

Two Main Plants production/distribution

Winter (based on 50% load)

Plant “PSB area”: Shut down

124 m³/hDN 150- DN 200

67 m³/hDN 150

45 m³/hDN 125

21.5 m³/hDN 100

21.5m³/hDN 100

7 m³/hDN 65

Plant “PS area”: ΔT 6 °C2113 kW @ 303 m³/h193 m³/h

DN 200

Standard flow vs Low flow

4225 kW coolingCOP 6 -> 5 MW towerCondenser water inlet 25 ° C ( 21 ° C w.b.)

Standard flow Low flow

Chilled water Supply T (°C) 6 6

Chilled water ΔT (°K) 6 8

Condenser water ΔT (°K) 5 10

Chilled water flow (m³/h) 607 455

Condenser water flow (m³/h) 861 430

Standard (kW) Low flow (kW) Standard -> Low flow

Chiller 705 753 Higher lift due to higher condenser temperature,

Chilled water pump 175 74 Same pipes and accessories sizeΔP=K*Flow 1.85

Cooling tower fans 90 60 Tower 30% smaller

Condenser water pump 70 35 Smaller pipes, ΔP about the same, half flow

TOTAL 1040 922

Power Comparison

Central Plant production/distribution

Central Plant: ΔT 8 °C4225 kW @ 455 m³/h

187 m³/hDN 200

100 m³/hDN 150->125

67 m³/hDN 125

34 m³/hDN 100->80

268 m³/hDN 250->200

133 m³/hDN 200->150

34 m³/hDN 100->80

10 m³/hDN 65->50

Further analysis:Impact on AHUs (fan power with bigger batteries and/or different control valves).

General considerationsLow flow about 10% less power “hungry”.

• Assuming VFDs for cooling tower fans and chilled water pumps and constant condenser water flow, even at part load the chilled water system benefits from “Low flow”.• Anyway, part load analysis needed with actual manufacturer data for cooling towers and chillers. • Low flow can be used with standard flow (bigger) tower size, therefore approach can be reduced: colder condenser water.• Higher lift will be offset by colder condenser water inlet.

Keeping same piping size and tower as in standard flow conditions, would allow for future system expansion with a careful choice of new chiller parameters.

Further savings strategies

• Increase Chilled water supply temperature 6 °C -> 8 °C.• This would represent a saving of about 7% on chiller power.• Chilled water temperature reset at part load: about 0.5%- 1% /°C chiller power reduction.• Reset condenser water temperature as w.b. falls: about 1% /°C chiller power reduction.

Is there a real need for 6°C chilled water setpoint?

• Put in place all the means to monitor chilled water ΔT and energy consumption.• Keep the ΔT as close as possible to design value:• system balancing• use of two way control valves,• avoid unnecessary water bypasses, • no three way valves (just for minimum flow and remote locations),• shut off clients not using water,• verify that the instrumentation is placed and calibrated well in order to avoid excessive valve opening, • verify batteries cleanliness.

Foreseen budget for a central plant(VERY preliminary)

Main components Euros

Hydraulics and accessories for main plant (3 condenser pumps, 3 evaporator pumps, 4 distribution pumps, 2 cooling towers, piping and accessories)

1,200,000

3 Chillers 600,000

Electricity 400,000

Main distribution piping 600,000

Terminal loads modifications (AHU batteries, heat exchangers,…)

500,000

Civil Engineering ?

Total 3,300,000 + ?

Conclusions/Future study development• Low flow system seems a better choice.• Review the need of 6 °C chilled water supply temperature.• Monitor the loads during the next summer and winter.• Try to get an idea of future system expansion needs if any.• Meet Chiller manufacturer (end of this month) for better understanding:• equipment size,• load split (1/3 + 2/3, 50%/50%, else….), • VFD compressors,• Cooling power redundancy (1 air cooled chiller as a backup during cooling tower maintenance or main chillers failure?),• the phase out of HFC refrigerants in favour of more “green” refrigerants like HFO.

• Collect info from Cooling tower manufacturer (variation of size, fan power, approach…).• Identify Life cycle costs (purchase price, installation, operation, maintenance,..)• CE study for central plant vs two main plants.• Heat exchanger economizer, heat recovery?