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Exercise Water pipe, Pump and Cooling Tower Selection

Exercise Water pipe, Pump and Cooling Tower Selection. 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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Exercise Water pipe, Pump and Cooling Tower Selection

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  1. Exercise Water pipe, Pump and Cooling Tower Selection

  2. 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 Watercooled VRV Selection: VRV WII - Express

  3. 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 coolers Brand Baltimore: Type VXI Cooling unit Selection

  4. 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:

  5. Selection Evaporator Determine the performance factor using the diagrams provided by Baltimore: Input: Range = 4.4 Approach = 8°C WBT = 22°C Output: Pf = 5

  6. Evaporative cooler selection

  7. 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:

  8. 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 * * C A E D B B C A Water piping: water flow rates

  9. Piping diameters B D C A E

  10. Using Friction loss graph: * * C A E D -0.21 B B +3 +0.15 C A 3m C+B+C+horizontal: 3m A+B+C+horizontal Linear Head Loss Opposite effect of joints Comparable results! Reference Path: Take worse case:

  11. 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 * * C A E D B B C A Water Pipe Design: Local Head losses

  12. T joints “Straight Trough” E to C C to B B to A . * * C A E D B B C A Local Head loss: Blue path vs Red path • T joint “Trough Branch” • A to E • B to A • A to C • E to C • C to B • C to E -1 -0. 11 +0.02 + 1.7 +1 4.2 + 5.7 +0.29 Total: +0.20

  13. Piping design – pump selection properties H = Ha + Hf + Ht + Hk Ht = Linear Head loss = 1.55 mH2O Ha = Actual head (m H2O) = 0 Ht = Partial friction loss = 2,23 m H2O Hk = Internal friction loss = 2,7 mH2O 1 x 1 VRV 10 HP unit, at 96 l/min Hk2 = Given, 5 mH2O Total head loss= 11,48 mH2O at a flow rate of 768 l/min 46 m3/hr +0.14 mH2O

  14. Water piping design: Pump Pre-selection LRC 406

  15. Pump Selection: Pump 406-22/3 or above

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