Learning, our way Exercise Water pipe, Pump and Cooling Tower Selection.

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ExerciseWater pipe, Pump and

Cooling Tower Selection

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Watercooled VRV Selection: VRV WII - Express

• Cooling Load per floor is 40 kW, Heat load 16.5 kW– 10 HP VRV unit gives >130% connection ratio– 20 HP VRV unit gives 80-110% connection ratio,

Depending on piping length– 30 HP VRV unit gives <66% connection ratio

20 Hp unit is selected

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Learning, our wayCooling unit Selection

• Cooling tower, evaporative cooler or dry cooler?Approach: 8°C, mild climate.

Europe, small scale installation(No large water purification installation needed)

Type: Evaporative fluid coolersBrand Baltimore: Type VXI

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Cooling mode: (VRV express)• Total heating capacity available= 49.5W *4 • Total Power Input at 98% connection ratio = 9.0 kW *4• Total rejected heat = 4 *(49.5+9.0)= 234 kW• Total water flow (= max water flow )= 96 * 2* 4

= 768 l/min = 12.8 l/s • Range= EWC – LWC = rejected heat / (4.186 x water flow)

=177.6 / (4,186 x 12,8)= 4,37°C• EWC= cooling tower entering water temperature= 30 + 4,4 = 34,4°C• LWC= cooling tower leaving water temperature = 30 °C

Approach = LWC – WBT = 30°C – 22°C = 8°C

Calculations Evaporative Cooler Selection:

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Selection Evaporator

Determine the performance factor using the diagramsprovided by Baltimore:

Input: Range = 4.4 Approach = 8°C WBT = 22°C

Output: Pf = 5

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Evaporative cooler selection

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Heating mode:

• Total Heat capacity required= 63 kW *4

• Total Power Input = 6 kW *4• Total injected heat = 4 *(63-6)= 228 kW

Calculations Boiler Capacity:

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Water piping: water flow rates

• Each VRV has as design waterflow– 96 l/min per 10 Hp unit.

• Horizontal piping to indoor units:– 2 x 96 l/min = 192 l/min

• Vertical parts: Different sections A, B, C, D– Secton A: Only 1 20 HP unit: 192 l/min (=3,2l/s)– Section B: 2x 20 HP unit : 384 l/min (=6,4l/s)– Section C: 3x 20 HP unit, 576 l/min (=9,6l/s)– Section D: 1x 10 HP Sub-unit, 96l/min (=1,6l/s)– Section E: 4x 20 HP unit: 768 l/min (=12,8l/s)

• Reverse Return Distriubution

* *

A

B

C

DE

A

C

B

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Piping diameters

Reccomendations:

Pipe diameter (mm)

Velocity range (m/s)

125 2.1~2.7

50 ~ 100 1.2~2.1

Around 25 0.6~1.2

A

B

C

D

E

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Reference Path: Take worse case:3m C+B+C+horizontal: 3m A+B+C+horizontal

Linear Head Loss• Using Friction loss graph:

Opposite effect of joints

Comparable results!

Part: Flow rate (l/s)

Diameter (mm)

Water velocity (m/s)

Length (m)

Pressure loss per meter (Pa/m)=10mH2O/m

Total (mH2O)

A 3.2 50 1,5 2x5

+3

70 0,91

B 6.4 65 1.9 3 70 0,21C 9.6 80 1,5 3 50 0,15

D 1.6 40 0,9 2 x 1 50 0,1E 12.8 100 1.6 12 15 0,18

+3 +0.15

-0.21

* *

A

B

C

D

A

C

B

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Water Pipe Design: Local Head losses

• Local friction losses: For 1 water route:– 3 branches “Straight Trough”- 2 x “Trough Branch” connection on main

line (2 for each 10 HP unit, speed )- 2 x “Trough Branch” Joint on indoor piping- 2x 3 elbow joints on indoor piping

• Straight line friction losses: – 4 x 3 m vertical piping, – 2 x 3 m indoor piping

* *

A

B

C

DE

A

C

B

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* *

A

B

C

DE

A

C

B

Local Head loss: Blue path

T joints “Straight Trough”• E to C

• C to B

• B to A

.

Partial head lossHtLocation:

Number ON

1 water path Equivalent piping length (m)

Pressure loss / m (mmH2O/m)

Pressure loss

(mH2O)

Elbows on A 2*2 + 1 5 * 1.6 70 0.56

Elbows on D 2*1 2 * 1.3 70 0.18

Elbows on E 2 2 * 1,3 70 0.18

T-joints Staight-tru (on main line)

3 1,7+1.7+1.4

70 0.34

T-joints Tru Branch (on main line)

1 5.7 70 0.40

T-joints Tru Branch (on horizontal line)

2 2.8+3.5 70 0.44

T joint “Trough Branch”•A to E

-1

+1

-0. 11

+ 5.7

•B to A•A to C

•E to C•C to B•C to E

vs Red path

+0.02

+0.29 4.2

+ 1.7

Total: +0.20

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Learning, our wayPiping design – pump selection properties

H = Ha + Hf + Ht + Hk

Ht = Linear Head loss = 1.55 mH2OHa = Actual head (m H2O) = 0Ht = Partial friction loss = 2,23 m H2OHk = Internal friction loss = 2,7 mH2O

1 x 1 VRV 10 HP unit, at 96 l/minHk2 = Given, 5 mH2O

Total head loss= 11,48 mH2O at a flow rate of 768 l/min46 m3/hr

+0.14 mH2O

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Learning, our wayWater piping design: Pump Pre-selection

LRC 406

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Learning, our wayPump Selection: Pump 406-22/3 or above