Water Cooled Chiller Plant Efficiency and Singapore Green Mark Program

- Writing In Progress -

• စကာၤပူ ႏိုင္ငံ လို ပူေႏြးစြတ္စိုတဲ့ ရာသီဥတု ရွိတဲ့ ေဒသမွာ တစ္ႏွစ္ပတ္လံုး Air Conditioning Systems ေတြ လိုအပ္တာမို႔ Chiller Plant ေတြ ကို အေဆာက္အအံု ေတာ္ေတာ္မ်ားမ်ား မွာ ေတြ႕ႏိုင္ပါတယ္။
• Chiller Plant ေတြက Energy အသံုးမ်ားတာမို႔ လည္ပတ္စရိတ္ သက္သာေစဘို႔ (တစ္နည္းအားျဖင့္ စြမ္းအင္ေခြ်တာျခင္းျဖင့္ ပတ္ဝန္းက်င္ ကို ထိန္းသိမ္း ႏိုင္ဘို႔ အတြက္) Energy Efficiency က အေရးပါပါတယ္။
• စကာၤပူ ႏိုင္ငံ မွာ ရွိတဲ့ အေဆာက္အအံု သစ္တိုင္း Energy Efficient ျဖစ္ေစဘို႔ အတြက္ Green Mark Program ကို လိုက္နာဘို႔ လိုအပ္ ပါတယ္။ အနည္းဆံုး အဆင့္က GM Certified ျဖစ္ၿပီး ပိုင္ရွင္စိတ္တိုင္းက် ပိုၿပီး Energy Efficient & Environmental Friendly ျဖစ္ေအာင္ လုပ္လို က လုပ္ႏိုင္ပါတယ္။
  
• ဒီ Green Mark Certification Program အရ လိုအပ္ခ်က္ေတြ ျဖစ္တဲ့ Chiller Plant Efficiency ရဘို႔နဲ႔ Energy Saving ေတြ ရဘို႔ အတြက္ Chiller Plant Efficiency တြက္နည္းေတြ နဲ႔ Efficiency ပိုေကာင္းေအာင္ လုပ္တဲ့ နည္းလမ္းေတြ သိဘို႔ က အေရးပါလာပါတယ္။



• အခုတစ္ပါတ္ Post မွာ ေတာ့ Green Mark အတြက္သာ မဟုတ္ပဲ Chiller Plant Efficiency ကိုပိုေကာင္းေအာင္ ဘယ္လိုလုပ္သင့္သလဲ ဆိုတာ ကိုပါ လက္လွမ္းမီသေလာက္ တင္ျပေပးထားပါတယ္။


Contents
1. Requirements under Green Mark for New Buildings v.4.0: 2010
2. Minimum Energy Efficiency Requirements for Equipments
3. Basic Calculation Procedure and Understanding Work Example Calculations
4. Ways to Improve to achieve better Operation Efficiencies and Performances
5. References

1. Requirements under Green Mark for New Buildings v.4.0: 2010
• လက္ရွိအေျခအေန BCA Certification Standard for New Building (GM version 4.0: 2000) အရ Water-Cooled Chilled-Water Plant အတြက္ လိုအပ္ခ်က္ေတြ ကေတာ့

  Green Mark Rating	Peak Building Cooling Load (RT)
  	< 500	≥ 500
  	Efficiency ( kW/RT)
  Certified	0.80	0.70
  Gold	0.80	0.70
  GoldPlus	0.70	0.65
  Platinum	0.70	0.65

• အကယ္လို႔ GoldPlus (သို႔) Platinum လိုခ်င္တယ္ ဆိုရင္ အနည္းဆံုး ရရွိရမဲ့ Energy Saving နဲ႔ပတ္သက္တဲ့ လိုအပ္ခ်က္ကေတာ့
  Green Mark GoldPlus - At Least 25% energy saving
  Green Mark Platinum - At Least 30% energy saving
  REF: http://www.bca.gov.sg/EnvSusLegislation/others/GM_Certification_Std2010.pdf
• Chiller Plant Efficiency ကို အေျခခံ အားျဖင့္ kW/RT နဲ႔ တိုင္းတာပါတယ္။ Cooling Capacity 1 RT ရဘို႔ အတြက္ သံုးရမဲ့ Electricity kW ဘယ္ေလာက္သံုးရတယ္ ဆိုတဲ့ အခ်က္ပါ။ kW နည္းရင္ သံုးရမဲ့ Electricity နည္းတာမို႔ ပိုေကာင္းတာေပါ့။ ဒါေပမဲ့ ဒီအတြက္ ဘယ္ေလာက္ ပိုၿပီး ေငြအကုန္အက် ခံထားရမလဲ (ပိုရင္းႏွီးထားရမလဲ) ဆိုတဲ့ အခ်က္က လည္း အေရးပါပါတယ္။
• Water-Cooled Chiller Plant တစ္ခု အတြက္ Energy Efficiency တြက္တဲ့ အခါ ပါဝင္တဲ့ စက္ပစၥည္းေတြ ကေတာ့
  1. Chillers
     
  2. Chilled Water Pumps
     
  3. Condenser Water Pumps
     
  4. Cooling Towers
• ဒီ Equipment ေလးမ်ိဳး အတြက္ တစ္မ်ိဳးစီ ရဲ့ kW/RT ကို တြက္ထုတ္ေပးရမွာ ျဖစ္ပါတယ္။ ဒါေတြကို မတြက္ေသးခင္ ARI 550 မွာသတ္မွတ္ထားတဲ့ Standard Condition မွာ ရွိတဲ့ Water Flowrate ေတြ ကို မိတ္ဆက္ေပးလိုပါတယ္။
  • Condenser Water Flowrate : 3 gpm/RT (0.18925 l/s.RT) at 29.4 °C Entering Temperature
  • Evaporator Water (Chilled Water) Flowrate: 2.4 gpm/RT ( 0.1514 l/s.RT) at ΔT=5.6 °C
  သတိျပဳရမွာ က Water Flowrate ေတြ ဟာ ΔT နဲ႔ ေျပာင္းျပန္ အခ်ိဳးက်တယ္ ဆိုတာပါ။ Ref: http://www.ahrinet.org/App_Content/ahri/files/standards%20pdfs/AHRI%20standards%20pdfs/AHRI%20550-590_2003.pdf
• ဒါဆိုရင္ GM Ver 4.0:2010, pg-101 မွာရွိတဲ့ Method A: Calculation နဲ႔တြဲၿပီး ဆက္လက္ ေလ့လာ နားလည္လို႔ ရပါၿပီ။
  
... Back to Top (Contents)....
2. Minimum Energy Efficiency Requirements for Equipments
• ပထမ သိသင့္တာ ကေတာ့ Singapore Regulation (Codes) အရ အနည္းဆံုး ရရွိရမဲ့ Efficiency ေတြကိုပါ။ ဒီေနရာ မွာ Water-Cooled Chilled-Water Plant at Reference Standard Condition ေပၚမူတည္ၿပီး Code Compliance အတြက္ Minimum Efficiency ကိုတြက္ထုတ္ ထားတာ ျဖစ္ပါတယ္။ ဒီေနရာ မွာ ဒီေနရာမွာ GM Ver 4.0:2010, pg-101 မွာရွိတဲ့ Method A: Calculation က Plant Configuration အတြက္ တြက္ထားတာ ျဖစ္ပါတယ္။
1. Minimum Efficiency required for Chillers
   Ref: SS530:2006. pg 14: for Chiller ≥ 1055kW : COP > 6.1
   3.517 kW/RT ÷ 6.1 kW/kW (COP) = 0.577 kW/RT
   Therefore: Minimum Chiller Efficiency ≤ 0.58 kW/RT
2. Minimum Efficiency required for Chilled Water Pumps
   Ref: SS553: 2009: pg.22: For chilled water system 349 kW/m³/s
   Water Flowrate: 0.1514 l/s.RT (at ARI 550: Standard Condition)
   0.1514 l/s.RT × 349 kW/m³/s × 1 / 1,000 m³/l = 0.053 kW/RT
   Therefore: Minimum Chilled Water Pumps Efficiency < 0.053 kW/RT
3. Minimum Efficiency required for Condenser Water Pumps
   Ref: SS553: 2009: pg.22: For condenser water system 301 kW/m³/s
   Water Flowrate: 0.18925 l/s.RT (at ARI 550: Standard Condition)
   0.18925 l/s.RT × 301 kW/m³/s × 1 / 1,000 m³/l = 0.057 kW/RT
   Therefore: Minimum Condenser Water Pumps Efficiency < 0.057 kW/RT
4. Minimum Efficiency required for Cooling Towers
   Ref: SS530:2006. pg 15: for Propeller or Axial Fan Cooling Tower ≥ 3.23 l/s.kW
   Water Flowrate: 0.18925 l/s.RT (Same as Condenser Water Pumps)
   0.18925 l/s.RT ÷ 3.23 l/s.kW = 0.059 kW/RT
   Therefore: Minimum Cooling Tower Efficiency < 0.059 kW/RT
• အထက္က တြက္ခဲ့တဲ့ Minimum Efficiency ေတြ က Equipment တစ္မ်ိဳးစီ အတြက္သာ ျဖစ္ပါတယ္။ အားလံုး စုတဲ့ အခါမွာ ေတာ့ ဒါေတြ ကိုေပါင္းလို႔ ရတဲ့ 0.75 kW/RT ( 0.58+0.053+0.057+0.059 ) အစား အနည္းဆံုး GM Certified အတြက္ 0.7 kW/RT ရကိုရရမယ္ လို႔ သတ္မွတ္ထားတာပါ။
  
• အရင္ တုန္းက CP13 နဲ႔ SS530 လိုအပ္ခ်က္ေတြ အရ ဆိုရင္ေတာ့
  - xxxx -
  
  
... Back to Top (Contents)....
3. Basic Calculation Procedure and Understanding Work Example Calculations
1. Chillers Efficiency
   ကိုယ္ေရြးခ်ယ္တဲ့ Chiller ရဲ့ Full Load Efficiency ကို Manufacturer's Catalogue / Technical Data ကေန ဖတ္ယူရပါမယ္။ ARI 550 Standard Condition ျဖစ္ဘို႔ သတိထားပါ။
2. Chilled Water Pumps Efficiency
   
   • Primary Chilled Water Pumps ေတြ ကိုပဲ စဥ္းစားဘို႔ လိုအပ္ပါတယ္။
   • Water Flowrate : အေပၚမွာ တြက္ျပထားတဲ့ Flowrate ကိုပဲ အေျခခံပါတယ္။
   • Pump Head Chiller Plant ရဲ့ Piping Configuration ေပၚမူတည္ၿပီး တြက္ယူရပါမယ္။ စဥ္းစားဘို႔ လိုအပ္တာကေတာ့ Pressure Loss at Chiller + Pipe Friction Loss + Pipe Fitting Loss
   • Pump Efficiency : ကိုယ္ေရြးမဲ့ Pump အတြက္ Manufacturer's Catalogue ကေန ဖတ္ယူရပါမယ္။ Duty Point က Pump Curve ေအာက္ သိပ္မေရာက္လြန္းေစဘို႔ သတိျပဳပါ။
   • Motor Efficiency ကိုယ္ေရြးမဲ့ Motor အတြက္ Manufacturer's Catalogue ကေန ဖတ္ယူရပါမယ္။
   • ၿပီးရင္ ေအာက္က Pump Power Formula ကို သံုးၿပီး Pump Power Usage ကို တြက္ယူႏိုင္ပါတယ္။
     
     Where;
     Q = Water Flowrate (l/s )
     h = Pump Head (m )
     η_p = Pump Efficiency
     η_m = Motor Efficiency
     သူ႔ရဲ့ မူရင္း က ေတာ့
   • ဒီေနရာမွာ VSD ရဲ့ Efficiency ကို ထည့္မတြက္ေသးတာ ေတြ႕ရပါတယ္။
   
   
3. Condenser Water Pumps Efficiency
   
   • Water Flowrate : အေပၚမွာ တြက္ျပထားတဲ့ Condenser Water Flowrate ကိုပဲ အေျခခံပါတယ္။
   • Pump Head Chiller Plant ရဲ့ Piping Configuration ေပၚမူတည္ၿပီး တြက္ယူရပါမယ္။ စဥ္းစားဘို႔ လိုအပ္တာကေတာ့ Pressure Loss at Chiller + Pipe Friction Loss + Pipe Fitting Loss + Height Difference between Cooling Tower Return Inlet and Basin
   • Pump Efficiency နဲ႔ : ကိုယ္ေရြးမဲ့ Pump အတြက္ Manufacturer's Catalogue ကေန ဖတ္ယူရပါမယ္။ Duty Point က Pump Curve ေအာက္ သိပ္မေရာက္လြန္းေစဘို႔ သတိျပဳပါ။
   • Motor Efficiency ကိုယ္ေရြးမဲ့ Motor အတြက္ Manufacturer's Catalogue ကေန ဖတ္ယူရပါမယ္။
   • တြက္နည္းကေတာ့ Chilled Water Pumps တြက္တုန္းက သံုးတဲ့ Formula ကို ပဲ ျပန္သံုးရပါတယ္။
   
   
4. Cooling Towers Efficiency
   • ကိုယ္ေရြးခ်ယ္တဲ့ Cooling Tower ကေန လိုအပ္တဲ့ Condenser Water Flowrate ကို မူတည္ၿပီး Manufacturer's Catalogue / Technical Data ကေန ဖတ္ယူရပါမယ္။ ဒီလိုဖတ္တဲ့ အခါ SS530:2006 / CTI ATC-105 အရ လိုအပ္တဲ့ 35°C Entering Water, 29°C Leaving Water And 24°C wb Outdoor Air မွာ ျဖစ္ေနဘို႔ သတိထားပါ။
• အေပၚက အေျခခံ တြက္ခ်က္မႈ ေတြ ကိုနားလည္ၿပီ ဆိုရင္ ေပးထားတဲ့ Work Example ေပၚမွီျငမ္းၿပီး Chilled-Water Plant Efficiency ကို တြက္ခ်က္ ရယူႏိုင္ပါၿပီ။
---- DRAFT ------ ... Back to Top (Contents)....
4. Ways to Improve to achieve better Operation Efficiencies and Performances
1. Sizing the Chiller Plant Right
   • Full Load အတြက္သာ မက Part Load အတြက္ပါ သင့္ေတာ္တဲ့ Chiller Plant အရြယ္ နဲ႔ အေရအတြက္ ကို ေရြးခ်ယ္ရပါမယ္။ လိုအပ္တဲ့ Chillers ေတြ ကိုလည္း ဒီ အေျခအေန ႏွစ္ခု စလံုးအတြက္ သင့္ေတာ္ေအာင္ ေရြးခ်ယ္ရမွာ ျဖစ္ပါတယ္။
2. Selecting High Efficiency Equipments, Know Their Nature and Reserve Space for Them
   1. Chillers
      Select High efficiency Chillers.
      Optimize Size and Quantity Combination. Chillers of different capacities have different efficiencies, optimize them.
      Optimize the refrigerant choice: Choose Higher Efficiency Refrigerant if favorable
      Consider and check for Part Load efficiency
      Watch out for Life Cycle Cost and Initial Investment Cost
      
      Chiller Efficiency Improve with;
      1. Lower Condenser Water Entering Temperature
         
      2. Higher Chilled Water Supply Temperature
         
      3. Higher Chilled Water Return Temperature
         
      4. Higher Chilled-Water ΔT (Temperature Difference)
      Check the efficiency changes for Different Chilled Water Supply/Return Temperature and Entering Condenser Water Temperature Humidity vs High Chilled Water Supply Temperature High dT vs FCU, Air Side
   2. Chilled Water Pumps
      Select the optimum pump size and Use VSD when required to vary the flowrate
      Select high efficiency pumps and motors
      Common Header Pumping (or) One-to-One Pumping
      Primary Only? Or Primary + Secondary
      
      
   3. Condenser Water Pumps
      
   4. Cooling Towers
      Check for Optimum Efficiency
      Get Space for Cooling Tower Performance, prevent hot-moist air short circuit. May utilize VSD however if Chiller Efficiency improve better with Lower Condenser Water Temperature Choose Constant Speed.
      Over-sizing Cooling Tower a little bit will save a lot.
      Bad Cooling Tower Performance : It will drag the whole chiller plant down.
      Don't let Architects give less space than required for cooling tower, don't let them cover or enclose it with decoration. (Major Mistake)
      Cooling Tower ေဘးမွာ ေနရာေတြ အမ်ားႀကီး လြတ္ေနတယ္ လို႔ ထင္တယ္။ Cooling Tower က အရုပ္ဆိုးတယ္ လို႔ထင္တယ္။ Trellis ေတြ၊ Louver ေတြ နဲ႔ ကာတယ္။ အသံလုံေအာင္ ဆိုၿပီး နံရံေတြ နဲ႔ ကပ္ပစ္တယ္။
      
      
   5. VSD: Is it Better (or) Not ?
      
      
      VSD good for Close Loop Pumps with Little or No Static Head
      VSD Good for Fans
      Power Varies proportional to the Cube of Flowrate
      However, Lowering Condenser Water Temperature may offset the fan power
      Condenser Water Temperature and VSD
      Condenser Water Pump and VSD
      
      
   
   
   
3. Arranging the equipments and Piping to improve efficiency
   
   Cooling Tower closer to Chillers (However, Cooling Tower Should not be below the Chiller to prevent System drain to Cooling Tower)
   Provide sufficient space for Cooling Tower. Don't let Architects give less space than required for cooling tower, don't let them cover or enclose it with decoration. (Major Mistake)
   Size the Pipes to Lower Friction Loss (reduce Flow Velocity, Note: It will not Lower equipment Friction Losses)
   Use the fittings with Lower Head Loss
   Use minimum bends (elbows means head loss)
   
   
   
4. Optimizing System Design and Operating Parameters
   Common Header Pumping (or) One-to-One Pumping
   Optimizing chilled water supply temperature and increasing delta T
   Maintain DT
   Improve Condenser Water Temperature
   Use redundant Cooling Tower to Improve Approach (or) Condenser Water Temperature
   Increasing pipe sizes to decrease pump heads (Note: It will not Lower equipment Friction Losses)
   Simulation with weather profile, instead of extreme design condition
   There will be Cost and other system performance impacts associated with any changes in design parameters.
   
   
   




... Back to Top (Contents)....


5. References





... Back to Top (Contents)....