RCREEE Energy Audit in Building RCREEE Energy Audit in Building   Training Course Program         Tunis, 1st – 5th June 20...
Content   - Refrigeration cycle   - AC/Refrigeration Systems and     Components   -Type of refrigeration   - Assessment of...
TypicalRefrigeration    CycleAdel Mourtada   3
Thermodynamic Cycle            Thermodynamic CycleAdel Mourtada                     4
- Refrigeration cycle   - AC/Refrigeration Systems and     Components   -Type of refrigeration   - Assessment of refrigera...
Components• R fi  Refrigerant • Evaporator/C  hiller   hill• Compressor• Condenser• Receiver• Thermostatic      expansion ...
Compressors There is a large variety of  compressors. Some of variations       p are: The compressor manufacturer Piston, ...
Evaporator Types                Evaporator Types Plate evaporators, top, are  a series of stamped  aluminum plates that ar...
Refrigerant• Desirable properties:  Desirable properties:  –   High latent heat of vaporization ‐ max cooling  –   Non tox...
Condenser Types                Condenser Types                           Condensers A and C are                           ...
Expansion Devices         Expansion Devices•  The expansion device separates the high    side from the low side and provid...
AC Systems      AC options / combinations:     • Air Conditioning (for comfort / machine)                      g(         ...
Refrigeration systems        • Small capacity modular units of direct          expansion type (50 Tons of Refrigeration)  ...
Refrigeration at large Commercial      Buildings      • Bank of units off-site with common            • Chilled water pump...
- Refrigeration cycle   - AC/R f i     AC/Refrigeration S t                 ti Systems and                              d ...
Type of refrigeration           Refrigeration systems           R fi     ti      t           • V             Vapour CCompr...
Type of refrigeration           Vapour Compression Refrigeration           Choice f           Ch i of compressor, design o...
What’s Solar Cooling?                                   g    • The core idea is to use the solar energy directly to       ...
System combined to sub floor exchanger           System combined to sub‐floor exchanger                 Sustainable Archit...
Type of refrigeration            Evaporative Cooling        •    Air in contact with water to cool it close to ‘wet       ...
Type of refrigeration      Main Features of Cooling TowersAdel Mourtada                           21
Type of refrigeration           Components of a cooling tower           • Frame and casing: support exterior             e...
Type of refrigeration           Components of a cooling tower           • Drift eliminators: capture droplets in          ...
Type of refrigeration           Mechanical Draft Cooling Towers           • Large fans to force air through             ci...
Type of refrigeration           Forced Draft Cooling Towers           F    d D ft C li T                         •   Air b...
- Refrigeration cycle   - AC/R f i     AC/Refrigeration S t                 ti Systems and                              d ...
Assessment of Refrigeration           • Cooling effect: Tons of Refrigeration                     1 TR = 3024 kCal/hr heat...
Assessment of Refrigeration          Specific Power Consumption (kW/TR)          • Indicator of refrigeration system s    ...
Assessment of Refrigeration           Coefficient f Performance (COPCarnot)           C ffi i t of P f           •   Stand...
Assessment of Air Conditioning                                         g        Measure        •    Airflow Q (m3/s) at Fa...
Assessment of Ai C diti i           A        t f Air Conditioning           Indicative TR load profile           • Small o...
Considerations for Assessment        • Accuracy of measurements              • Inlet/outlet temp of chilled and condenser ...
Assessment of Cooling Towers           Measured Parameters           •    Wet b lb temperature of air                    b...
Central Plant metrics   • Chiller efficiency – kW/ton   • Cooling tower efficiency – kW/ton   • Condenser water pump effic...
- Refrigeration cycle   - AC/Refrigeration Systems and     Components   -Type of refrigeration   - Assessment of refrigera...
Energy Efficiency Measures              gy          y        1. Optimize process heat exchange        2.        2 Maintain...
Energy Efficiency Measures      1. Optimize Process Heat Exchange          p                          g          High comp...
Energy Efficiency Measures      1. Optimize Process Heat Exchange            Evaporator              Refrigeration        ...
Energy Efficiency Measures      1. Optimize Process Heat Exchange          p                          g           Selectio...
Energy Efficiency Measures       2. Maintain Heat Exchanger Surfaces                              g      • Poor maintenanc...
Energy Efficiency Measures        2. Maintain Heat Exchanger Surfaces           Effect of poor maintenance on           co...
Energy Efficiency Measures           3. Multi-Staging Systems                       g g y          •    Suited for        ...
Energy Efficiency Measures           3. Multi-Stage Systems          a. Compound          •    Two low compression ratios ...
Energy Efficiency Measures      4. Matching Capacity to Load System          • Most applications have varying loads       ...
Energy Efficiency Measures        5. Capacity Control of Compressors       • Cylinder unloading, vanes, valves            ...
Energy Efficiency Measures        5. Capacity Control of Compressors         • Temperature monitoring               • Reci...
Energy Efficiency Measures           6. Multi-Level Refrigeration           Bank of compressors at central plant          ...
Energy Efficiency Measures           6. Multi Level Refrigeration              Multi-Level           Packaged units (inste...
Energy Efficiency Measures           7. Chilled Water Storage           • Chilled water storage facility with             ...
Energy Efficiency Measures           8. System Design Features           •   FRP impellers film fills PVC drift eliminator...
Energy Efficiency Measures          9. System Design Features              y         g           - Selecting a cooling tow...
Energy Efficiency Measures           Selecting           S l ti a cooling tower                       li t           Capac...
Energy Efficiency Measures           Selecting a cooling tower         Range               •     Range determined by proce...
Energy Efficiency Measures           Selecting a cooling tower           Heat Load           • Determined by process      ...
Energy Efficiency Measures           Selecting a cooling tower          Wet bulb temperature – considerations:          • ...
Energy Efficiency Measures           Selecting a cooling tower           Relationship range, flow and heat load           ...
Energy Efficiency Measures          Selecting a cooling tower          Relationship Approach and Wet bulb           temper...
Energy Efficiency Measures           Fill media                  di           • Hot water distributed over fill media     ...
Energy Efficiency Measures           Pumps and water distribution              p           • Pumps: see pumps session     ...
Energy Efficiency Measures           Cooling Tower Fans           • Fans must overcome system             resistance, pres...
Benefits of Variable Flow •   Lowest Energy consumption •   Low Differential Pressure •   Easier Operation •   Reduced & T...
Why Variable Flow?            Why Variable Flow?• Power varies with Cube of New Flow  Ratio.  - New Energy = New Flow / Ol...
Energy Efficiency Measures           Fill media           Comparing 3 fill media: film fill more           efficient      ...
VPF system configurations            Manifolded            M if ld d pumps                          –   Redundancy        ...
Keep it Simple    • Well designed control system is      Well designed control system is          mandatory.    • Mi i i  ...
- Refrigeration cycle   - AC/R f i     AC/Refrigeration S t                 ti Systems and                              d ...
Typical Cooling Load Profile    yp           g                                                   Load in TR               ...
Energy Saving Possibilities       Energy Saving Possibilities                                Reduce cooling Load          ...
Interior Window Films          Interior Window Films                       • If acceptable by                          bui...
Programmable Thermostats or BMS    Programmable Thermostats or BMS                    • They work when                    ...
VAV Fans Control• Static Pressure Reset on VAV Systems.   – P id     Provides significant fan energy savings              ...
Heat recovery from Chiller                               y                                                                ...
Partial Heat               Partial Heat Recovery                                                                         R...
Hot Water EconomicsESTIMATES OF ANNUAL SAVINGS:        Hot water capacity : 10000 Lts/day        Diesel cost :  0.70$ per ...
Thermal Energy Storage System Thermal Energy Storage System                     CRISTOPIA STL phase change thermal energy ...
Some Possibilities with STL                                                                                               ...
ALMEE                        77        Adel Mourtada    77
ALMEE        Adel Mourtada   78
Thank you for your attentionAdel Mourtada                           79
Annex   - Instruments Required   - Cost Effectives MeasuresAdel Mourtada                   80
Instruments Required    Instruments Required• Power Analyzer: Used for measuring electrical  parameters of motors such as ...
Measurements & Observation Energy consumption pattern of pumps and cooling tower fans Motor electrical parameters (kW, kVA...
Exploration of Energy Conservation Possibilities    Water pumping and cooling tower•   Improvement of systems and drives• ...
Exploration of Energy Conservation Possibilities  p                gy•   Measuring water use and energy consumption is    ...
Exploration of Energy Conservation Possibilities  p                gy     System Effect Factors •   Equipment cannot perfo...
Exploration of Energy Conservation Possibilities  p                gy•   Internal Running Clearances: The internal running...
Sources: - “Energy Equipments” UNEP/SIDA/Gerlap, - “HVAC System Design”, Mark Hydeman, P.E., FASHRAE Taylor Engineering, L...
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Day 2: Energy Audit of Air Conditioning And Cooling Systems

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Energy Audit in Building A Regional Training Workshop
1 - 5 June, 2010

Day 2: Energy Audit of Air Conditioning And Cooling Systems

  1. 1. RCREEE Energy Audit in Building RCREEE Energy Audit in Building Training Course Program  Tunis, 1st – 5th June 2010 Energy audit of air‐conditioning and  cooling systems by Adel Mourtada
  2. 2. Content - Refrigeration cycle - AC/Refrigeration Systems and Components -Type of refrigeration - Assessment of refrigeration and AC -Energy Efficiency Measures Energy -Energy Audit of HVAC System in Commercial Building UtilitiesAdel Mourtada 2
  3. 3. TypicalRefrigeration CycleAdel Mourtada 3
  4. 4. Thermodynamic Cycle Thermodynamic CycleAdel Mourtada 4
  5. 5. - Refrigeration cycle - AC/Refrigeration Systems and Components -Type of refrigeration - Assessment of refrigeration and AC - Energy Efficiency Measures - Energy Audit of HVAC System in Commercial Building UtilitiesAdel Mourtada 5
  6. 6. Components• R fi Refrigerant • Evaporator/C hiller  hill• Compressor• Condenser• Receiver• Thermostatic     expansion  valve (TXV) Adel Mourtada 6
  7. 7. Compressors There is a large variety of  compressors. Some of variations  p are: The compressor manufacturer Piston, vane, or scroll type The piston and cylinder  arrangement How the compressor is mounted Style and position of ports Type and number of drive belts Compressor displacement Fixed or variable displacementAdel Mourtada 7
  8. 8. Evaporator Types Evaporator Types Plate evaporators, top, are  a series of stamped  aluminum plates that are  aluminum plates that are joined together. Tube and  fin evaporators, bottom,  fin evaporators, bottom, have tubes for the  refrigerant that are joined  to the fins.Adel Mourtada 8
  9. 9. Refrigerant• Desirable properties: Desirable properties: – High latent heat of vaporization ‐ max cooling – Non toxicity (no health hazard) Non‐toxicity (no health hazard) – Desirable saturation temp (for operating pressure) – Chemical stability (non flammable/non explosive) Chemical stability (non‐flammable/non‐explosive) – Ease of leak detection – Low cost – Readily available• Commonly named “FREON” (R 114, etc.) Commonly named  FREON (R‐114, etc.) Adel Mourtada 9
  10. 10. Condenser Types Condenser Types Condensers A and C are  round tube, serpentine  condensers. Condenser B is an  C d Bi oval/flat tube, serpentine  condenser. Condenser D is an  oval/flat tube, parallel  flow  condenser. Flat tube condensers are  more efficient. ffi i tAdel Mourtada 10
  11. 11. Expansion Devices Expansion Devices• The expansion device separates the high  side from the low side and provides a  id f h l id d id restriction for the compressor to pump  against.• There are two styles of expansion  y p devices: ‐ The TXV can open or close to change  flow. It is controlled by the superheat  spring, thermal bulb that senses  spring, thermal bulb that senses evaporator outlet temperature, and  evaporator pressure ‐ The OT is a tubular, plastic device with a  small metal tube inside. The color of the  small metal tube inside The color of the OT is used to determine the diameter of  the tube. Most OT have a fixed diameter  orifice.Adel Mourtada 11
  12. 12. AC Systems AC options / combinations: • Air Conditioning (for comfort / machine) g( ) • Split air conditioners • Fan coil units in a larger system • Air handling units in a larger systemAdel Mourtada 12
  13. 13. Refrigeration systems • Small capacity modular units of direct expansion type (50 Tons of Refrigeration) • Centralized chilled water plants with chilled water as a secondary coolant (>50 TR)13 Adel Mourtada 13
  14. 14. Refrigeration at large Commercial Buildings • Bank of units off-site with common • Chilled water pumps p p • Condenser water pumps • Cooling towers • More levels of refrigeration/AC, e.g. • Comfort air conditioning (20-25 oC) • Chilled water system (5 – 10 oC)Adel Mourtada 14
  15. 15. - Refrigeration cycle - AC/R f i AC/Refrigeration S t ti Systems and d Components -Type of refrigeration - Assessment of refrigeration and AC g -Energy Efficiency Measures -Energy Audit of HVAC System in Commercial Building UtilitiesAdel Mourtada 15
  16. 16. Type of refrigeration Refrigeration systems R fi ti t • V Vapour CCompression i Refrigeration (VCR): uses mechanical energy • Vapour Absorption Refrigeration (VAR): (VAR) uses thermal energy th l16 Adel Mourtada 16
  17. 17. Type of refrigeration Vapour Compression Refrigeration Choice f Ch i of compressor, design of d i f condenser and evaporator determined by: • Refrigerant • Required cooling • Load • E Ease of maintenance f i t • Physical space requirements • A il bilit of utilities (water, power) Availability f tiliti ( t )17 Adel Mourtada 17
  18. 18. What’s Solar Cooling? g • The core idea is to use the solar energy directly to  gy y produce chilled water. • The high temperature required by absorption  chillers is provided by solar troughs. p y g • The system doesn’t require “High Technology”  materials (like in PV systems) and has peak  p production in the moment of peak demand. p Chilled water Heat  Transfer Fluid Transfer Fluid Sustainable Architecture Applied to Replicable  Public Access Buildings www.sara‐project.netAdel Mourtada 18
  19. 19. System combined to sub floor exchanger System combined to sub‐floor exchanger Sustainable Architecture Applied to Replicable  Public Access Buildings www.sara‐project.netAdel Mourtada 19
  20. 20. Type of refrigeration Evaporative Cooling • Air in contact with water to cool it close to ‘wet bulb temperature’ • Advantage: efficient cooling at low cost • Disadvantage: air is rich in moisture Sprinkling Water Hot Air Cold Air20 Adel Mourtada 20
  21. 21. Type of refrigeration Main Features of Cooling TowersAdel Mourtada 21
  22. 22. Type of refrigeration Components of a cooling tower • Frame and casing: support exterior enclosures • Fill: facilitate heat transfer by maximizing water / air contact i i i t i t t • Splash fill • Film fill • Cold water basin: receives water at bottom of tower22 Adel Mourtada 22
  23. 23. Type of refrigeration Components of a cooling tower • Drift eliminators: capture droplets in air stream • Air inlet: entry point of air • Louvers: equalize air flow into the fill and retain water within tower • N Nozzles: spray water t wet th fill l t to t the • Fans: deliver air flow in the tower23 Adel Mourtada 23
  24. 24. Type of refrigeration Mechanical Draft Cooling Towers • Large fans to force air through circulated water • Water falls over fill surfaces: maximum heat transfer • Cooling rates depend on many parameters • Large range of capacities • C b grouped, e.g. 8-cell tower Can be d 8 ll t24 Adel Mourtada 24
  25. 25. Type of refrigeration Forced Draft Cooling Towers F d D ft C li T • Air blown through tower g by centrifugal fan at air inlet • Advantages: suited for high air resistance & fans are relatively quiet • Disadvantages: recirculation due to high air entry air-entry and low air exit air-exit velocities25 Adel Mourtada 25
  26. 26. - Refrigeration cycle - AC/R f i AC/Refrigeration S t ti Systems and d Components -Type of refrigeration - Assessment of refrigeration and AC g -Energy Efficiency Measures - Energy Audit of HVAC System in Commercial Building UtilitiesAdel Mourtada 26
  27. 27. Assessment of Refrigeration • Cooling effect: Tons of Refrigeration 1 TR = 3024 kCal/hr heat rejected • TR is assessed as: TR = Q x⋅Cp x⋅ (Ti – To) / 3024 p ( ) Q= mass flow rate of coolant in kg/hr Cp = is coolant specific heat in kCal /kg deg C Ti = inlet, temperature of coolant to evaporator (chiller) in 0C To T = outlet t tl t temperature of coolant from evaporator (chiller) i 0C t f l tf t ( hill ) in27 Adel Mourtada 27
  28. 28. Assessment of Refrigeration Specific Power Consumption (kW/TR) • Indicator of refrigeration system s system’s performance • kW/TR of centralized chilled water system is sum of • Compressor kW/TR • Chilled water pump kW/TR • Condenser water pump kW/TR p p • Cooling tower fan kW/TR28 Adel Mourtada 28
  29. 29. Assessment of Refrigeration Coefficient f Performance (COPCarnot) C ffi i t of P f • Standard measure of refrigeration efficiency • Depends on evaporator temperature Te and condensing temperature Tc: COPCarnot = Te / (Tc - Te) • COP calculated for type of compressor: Cooling effect (kW) COP = Power input to compressor (kW)29 Adel Mourtada 29
  30. 30. Assessment of Air Conditioning g Measure • Airflow Q (m3/s) at Fan Coil Units ( ( ) (FCU) or Air ) Handling Units (AHU): anemometer • Air density ρ (kg/m3) • Dry bulb and wet bulb temperature: psychrometer • Enthalpy (kCal/kg) of inlet air (hin) and outlet air (Hout) psychrometric charts ): h ti h t Calculate TR Q × ρ × (h in − h out ) TR = 302430 Adel Mourtada 30
  31. 31. Assessment of Ai C diti i A t f Air Conditioning Indicative TR load profile • Small office cabins: 0.1 TR/m2 • Medium size office (10 – 30 people occupancy) with central A/C: 0.06 TR/m2 • Large multistoried office complexes with central A/C: 0 04 TR/m2 0.0431 Adel Mourtada 31
  32. 32. Considerations for Assessment • Accuracy of measurements • Inlet/outlet temp of chilled and condenser water • Flow of chilled and condenser water • Integrated Part Load Value (IPLV) • kW/TR for 100% load but most equipment operate between 50-75% of full load • IPLV calculates kW/TR with partial loads • Four points in cycle: 100%, 75%, 50%, 25%32 Adel Mourtada 32
  33. 33. Assessment of Cooling Towers Measured Parameters • Wet b lb temperature of air bulb temperat re • Dry bulb temperature of air • Cooling tower inlet water temperature C li t i l t t t t • Cooling tower outlet water temperature • Exhaust air temperature E h i • Electrical readings of pump and fan motors • Water flow rate • Air flow rate33 Adel Mourtada 33
  34. 34. Central Plant metrics • Chiller efficiency – kW/ton • Cooling tower efficiency – kW/ton • Condenser water pump efficiency – kW/ton • Chilled water pump efficiency – kW/tonAdel Mourtada 34
  35. 35. - Refrigeration cycle - AC/Refrigeration Systems and Components -Type of refrigeration - Assessment of refrigeration and AC -Energy Efficiency Measures - Energy Audit of HVAC System in Commercial Building UtilitiesAdel Mourtada 35
  36. 36. Energy Efficiency Measures gy y 1. Optimize process heat exchange 2. 2 Maintain heat exchanger surfaces 3. Multi-staging systems 4. Matching capacity to system load 5. Capacity control of compressors 6. Multi-level refrigeration for plant needs 7. Chilled 7 Chill d water storage t t 8. System design features 9. Optimize cooling tower36 Adel Mourtada 36
  37. 37. Energy Efficiency Measures 1. Optimize Process Heat Exchange p g High compressor safety margins: energy loss gy 1. Proper sizing heat transfer areas of heat exchangers and evaporators g p • Heat transfer coefficient on refrigerant side: 1400 – 2800 Watt/m2K • Heat transfer area refrigerant side: >0.5 m2/TR 2. Optimum driving force (difference Te and p g ( Tc): 1oC raise in Te = 3% power savings37 Adel Mourtada 37
  38. 38. Energy Efficiency Measures 1. Optimize Process Heat Exchange Evaporator Refrigeration Specific Power Increase Temperature (0C) Capacity*(tons) Consumption (kW/TR) kW/TR (%) 5.0 67.58 0.81 - 0.0 56.07 0.94 16.0 -5.0 45.98 1.08 33.0 -10.0 37.20 1.25 54.0 -20.0 23.12 1.67 106.0 Condenser temperature 40◦C Condensing Refrigeration Specific Power Increase Temperature (0C) p ) Capacity (tons) p y( ) Consumption (kW /TR) p ( ) kW/TR (%) ( ) 26.7 31.5 1.17 - 35.0 21.4 1.27 8.5 40.0 20.0 1.41 20.5 *Reciprocating compressor using R-22 refrigerant. Evaporator temperature.-10◦ C38 Adel Mourtada 38
  39. 39. Energy Efficiency Measures 1. Optimize Process Heat Exchange p g Selection of condensers • O ti Options: • Air cooled condensers • Air-cooled with water spray condensers • Shell & tube condensers with water-cooling • Water-cooled shell & tube condenser • Lower discharge pressure • Higher TR g • Lower power consumption39 Adel Mourtada 39
  40. 40. Energy Efficiency Measures 2. Maintain Heat Exchanger Surfaces g • Poor maintenance = increased power consumption • Maintain condensers and evaporators • S Separation of lubricating oil and refrigerant ti f l b i ti il d f i t • Timely defrosting of coils • Increased velocity of secondary coolant • Maintain cooling towers • 0 55◦C reduction in returning water from cooling 0.55 tower = 3.0 % reduced power40 Adel Mourtada 40
  41. 41. Energy Efficiency Measures 2. Maintain Heat Exchanger Surfaces Effect of poor maintenance on compressor power consumption Specific Increase Te Tc Refrigeration Power kW/TR Condition (0C) (0C) Capacity* (TR) Consumption (%) (kW/TR) Normal 7.2 40.5 17.0 0.69 - Dirty condenser y 7.2 46.1 15.6 0.84 20.4 Dirty evaporator 1.7 40.5 13.8 0.82 18.3 Dirty condenser 1.7 46.1 12.7 0.96 38.7 and evaporator41 Adel Mourtada 41
  42. 42. Energy Efficiency Measures 3. Multi-Staging Systems g g y • Suited for • Low temp applications with high compression • Wide temperature range • Two types for all compressor types • Compound • Cascade42 Adel Mourtada 42
  43. 43. Energy Efficiency Measures 3. Multi-Stage Systems a. Compound • Two low compression ratios = 1 high • First stage compressor meets cooling load • Second stage compressor meets load evaporator and flash gas • Single refrigerant b. b Cascade • Preferred for -46 oC to -101oC • Two systems with different refrigerants43 Adel Mourtada 43
  44. 44. Energy Efficiency Measures 4. Matching Capacity to Load System • Most applications have varying loads • Consequence of part-load operation q p p • COP increases • but lower efficiency • Match refrigeration capacity to load requires knowledge of • Compressor performance • Variations in ambient conditions • Cooling load44 Adel Mourtada 44
  45. 45. Energy Efficiency Measures 5. Capacity Control of Compressors • Cylinder unloading, vanes, valves • Reciprocating compressors: step-by-step through cylinder unloading: • Centrifugal compressors: continuous modulation through vane control • Screw compressors: sliding valves • Speed control p • Reciprocating compressors: ensure lubrication system is not affected • Centrifugal compressors: >50% of capacity45 Adel Mourtada 45
  46. 46. Energy Efficiency Measures 5. Capacity Control of Compressors • Temperature monitoring • Reciprocating compressors: return water (if varying loads) water leaving chiller loads), (constant loads) • Centrifugal compressors: outgoing water temperature • Screw compressors: outgoing water temperature • Part load applications: screw compressors more efficient46 Adel Mourtada 46
  47. 47. Energy Efficiency Measures 6. Multi-Level Refrigeration Bank of compressors at central plant • Monitor cooling and chiller load: 1 chiller full load l d more efficient than 2 chillers at part-load ffi i t th hill t tl d • Distribution system: individual chillers feed all branch lines; Isolation valves; Valves to isolate sections • Load individual compressors to full capacity before operating second compressor • Provide smaller capacity chiller to meet peak demands47 Adel Mourtada 47
  48. 48. Energy Efficiency Measures 6. Multi Level Refrigeration Multi-Level Packaged units (instead of central plant) • Diverse applications with wide temp range and long distance • Benefits: economical flexible and reliable economical, • Disadvantage: central plants use less power Flow control • Reduced flow • Operation at normal flow with shut-off periods48 Adel Mourtada 48
  49. 49. Energy Efficiency Measures 7. Chilled Water Storage • Chilled water storage facility with insulation • Suited only if temp variations are acceptable • Economical because • Chillers operate during low peak demand hours: reduced peak demand charges • Chillers operate at nighttime: reduced tariffs and improved COP49 Adel Mourtada 49
  50. 50. Energy Efficiency Measures 8. System Design Features • FRP impellers film fills PVC drift eliminators impellers, fills, • Softened water for condensers • Economic insulation thickness • Roof coatings and false ceilings • Energy efficient heat recovery devices • Variable air volume systems • Sun film application for heat reflection • Optimizing lighting loads50 Adel Mourtada 50
  51. 51. Energy Efficiency Measures 9. System Design Features y g - Selecting a cooling tower - Fills - Pumps and water distribution - Fans and motors51 Adel Mourtada 51
  52. 52. Energy Efficiency Measures Selecting S l ti a cooling tower li t Capacity • Heat dissipation (kCal/hour) • Circulated flow rate (m3/hr) • Other factors52 Adel Mourtada 52
  53. 53. Energy Efficiency Measures Selecting a cooling tower Range • Range determined by process, not by system Approach • Closer to the wet bulb temperature • Bigger size cooling tower • More expensive53 Adel Mourtada 53
  54. 54. Energy Efficiency Measures Selecting a cooling tower Heat Load • Determined by process • Required cooling is controlled by the desired operating temperature • High heat load = large size and cost of cooling tower54 Adel Mourtada 54
  55. 55. Energy Efficiency Measures Selecting a cooling tower Wet bulb temperature – considerations: • Water i W t is cooled to temp hi h th wet bulb l dt t higher than t b lb temp • Conditions at tower site • Not to exceed 5% of design wet bulb temp • Is wet bulb temp specified as ambient (preferred) or inlet • Can tower deal with increased wet bulb temp • Cold water to exchange heat55 Adel Mourtada 55
  56. 56. Energy Efficiency Measures Selecting a cooling tower Relationship range, flow and heat load • Range increases with increased • Amount circulated water (flow) • Heat load • Causes of range increase • Inlet water temperature increases p • Exit water temperature decreases • Consequence = larger tower q g56 Adel Mourtada 56
  57. 57. Energy Efficiency Measures Selecting a cooling tower Relationship Approach and Wet bulb temperature • If approach stays the same (e.g. 4.45 oC) • Higher wet bulb temperature (26.67 oC) = more heat picked up (15.5 kCal/kg air) = smaller tower needed • Lower wet bulb temperature (21.11 oC) = less heat picked up (12.1 kCal/kg air) = larger tower needed57 Adel Mourtada 57
  58. 58. Energy Efficiency Measures Fill media di • Hot water distributed over fill media and cools down through evaporation • Fill media impacts electricity use • Efficiently designed fill media reduces pumping costs • Fill media influences heat exchange: surface area, duration of contact, turbulence58 Adel Mourtada 58
  59. 59. Energy Efficiency Measures Pumps and water distribution p • Pumps: see pumps session • O ti i cooling water treatment Optimize li t t t t • Increase cycles of concentration (COC) by cooling water treatment helps reduce make up water • Indirect electricity savings y g • Install drift eliminators • Reduce drift loss from 0 02% to only 0 003 – 0.02% 0.003 0.001%59 Adel Mourtada 59
  60. 60. Energy Efficiency Measures Cooling Tower Fans • Fans must overcome system resistance, pressure loss: impacts electricity use • Fan efficiency depends on blade profile fil • Replace metallic fans with FBR blades (20- 30% savings) • Use blades with aerodynamic profile (85-92% fan efficiency) y)60 Adel Mourtada 60
  61. 61. Benefits of Variable Flow • Lowest Energy consumption • Low Differential Pressure • Easier Operation • Reduced & Timely Maintenance • Greatest Diversity • Fewer or smaller chillers possibleAdel Mourtada 61
  62. 62. Why Variable Flow? Why Variable Flow?• Power varies with Cube of New Flow Ratio. - New Energy = New Flow / Old Flow (½), Cubed (½) = 1/8 - Most reliable operation. Therefore, Energy Savings = 7/8 of the original energy (less any losses from new equipment)! Adel Mourtada 62
  63. 63. Energy Efficiency Measures Fill media Comparing 3 fill media: film fill more efficient Splash Fill Film Fill Low Clog Film Fill Possible L/G Ratio 1.1 – 1.5 1.5 – 2.0 1.4 – 1.8 Effective Heat Exchange 30 – 45 150 m2/m3 85 - 100 m2/m3 Area m2/m3 Fill Height Required 5 – 10 m 1.2 – 1.5 m 1.5 – 1.8 m Pumping Head 9 – 12 m 5–8m 6–9m Requirement Quantity of Air Required Q tit f Ai R i d High Hi h Much L M h Low Low L63 Adel Mourtada 63
  64. 64. VPF system configurations Manifolded M if ld d pumps – Redundancy – Reduced energy – VFD on all pumps VFD ll – Allows “overpumping”  for “Low ΔT for  Low ΔT  Syndrome”Adel Mourtada 64
  65. 65. Keep it Simple • Well designed control system is Well designed control system is  mandatory. • Mi i i Minimize manual operation. l i • Develop clearly written operating  procedure and  backup                   failure mode. • Continual training of                                the operators.Adel Mourtada 65
  66. 66. - Refrigeration cycle - AC/R f i AC/Refrigeration S t ti Systems and d Components -Type of refrigeration - Assessment of refrigeration and AC g -Energy Efficiency Measures -Energy Audit of HVAC System in Commercial Building UtilitiesAdel Mourtada 66
  67. 67. Typical Cooling Load Profile yp g Load in TR Load in TR 300 250 200 150 Load in TR Load in TR 100 50 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 67Adel Mourtada 67
  68. 68. Energy Saving Possibilities Energy Saving Possibilities Reduce cooling Load Adequate Regulation Use VAV fans Use VAV fansShift Cooling Demand To  Reduce Required chiller  Off Peak Hours Capacity  for meeting  the peak load Reduce Maximum  Electrical Demand and  Switch off Chillers during  Switch off Chillers during hence corresponding  h d peak tariff period  Electrical Installation Generate Hot Water up to  Generate Pure water  60 ºC through  through waste heat  waste heat recovery  recovery from Chiller from Chiller from Chiller 68Adel Mourtada 68
  69. 69. Interior Window Films  Interior Window Films • If acceptable by  building  g management,  y window films may be  a useful option.   Choose film tailored  for climate. Pay Back Period 2 years 69Adel Mourtada 69
  70. 70. Programmable Thermostats or BMS Programmable Thermostats or BMS • They work when They work when  you use them.Adel Mourtada 70
  71. 71. VAV Fans Control• Static Pressure Reset on VAV Systems. – P id Provides significant fan energy savings  i ifi t f i since system is often at part load – Reduces fan noise “Variable air volume (VAV ) terminal units  shall be programmed to operate at the  minimum airflow when the zone  temperature is within the set  deadband.” Adel Mourtada 71
  72. 72. Heat recovery from Chiller y Air‐ Air Chiller  Mode conditione d Space 700 kW (200  TR) cooling  load 140 kW  140 kW Electrical  Input 840 kW heat  840 kW heatAbout 8‐12% of heat can be recovered in Chiller mode (i.e. 65‐100 kW  Rejected  heat) through desuperheater (Free of Cost ) through ~0.1 Carbon credit per hour  CT/aircooled~ 720 Carbon Credits/ Year (24hrs x 300 Days) 720 Carbon Credits/ Year (24hrs x 300 Days) condenser d 72 Adel Mourtada 72
  73. 73. Partial Heat Partial Heat Recovery Recovery Air cooled or  water cooled  50°C 55°CAdditional condenser Desuperheater prefrigerant fi t fluid tank Liquid  Desuperheated  Gas  Gas Expansion  valve Compressors Evaporator Partial heat recovery  (Desuperheater) does not require  (Desuperheater) does not require 12°C any additional electrical input. It  Chilled water 7°C recovers (8‐12%) of waste heat  73 Adel Mourtada free of cost. 73
  74. 74. Hot Water EconomicsESTIMATES OF ANNUAL SAVINGS: Hot water capacity : 10000 Lts/day Diesel cost :  0.70$ per liter ; Diesel NCV :10100 Kcal/Liter ;  Boiler efficiency : 85% Saving by Heat Recovery system over diesel fired boiler   S i b di l fi d b il 7000 US$/year  74 Adel Mourtada 74
  75. 75. Thermal Energy Storage System Thermal Energy Storage System CRISTOPIA STL phase change thermal energy storage  offers a unique solution to any of the following  energy management problems: • Reduction of installed power • Peak ‘shaving’ or ‘lopping’ of cyclic loads • Optimization of electrical resources.  • Increase cooling output to meet higher demand  Increase cooling output to meet higher demand without increasing existing plant capacity. • Energy management (off‐peak electricity) • Increase system reliability • Back‐up function • Protect ozone area by a limitation of CFC and HCFC 75Adel Mourtada 75
  76. 76. Some Possibilities with STL Discharge kW of refrigeration 1000,0 Direct Production Discharge 800,0 Charge 1200 k W o f re frig e ra tio n Direct Production 600,0 1000 Charge 400,0 800 f g 600 200,0 400 ,0 200 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 0 Hours 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hours Traditional  Peak shaving with  Solution chiller switched  kW of re frigeration 1,200 Daily Consumption 1,000Peak shaving g 800 600 off during high  off during high 400 200 0 tariff period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Discharge 1 000k W o f refr era tio n Hours Direct Production Discharge 800 Charge 1000 Charge ation rig 600 kW of refrigera 800 400 600 200 400 0 200 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 0 Hours 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hours Chiller switched off during high  Pay Back  Total storage during off  tariff period peak hours period 4 years
  77. 77. ALMEE 77 Adel Mourtada 77
  78. 78. ALMEE Adel Mourtada 78
  79. 79. Thank you for your attentionAdel Mourtada 79
  80. 80. Annex - Instruments Required - Cost Effectives MeasuresAdel Mourtada 80
  81. 81. Instruments Required Instruments Required• Power Analyzer: Used for measuring electrical parameters of motors such as kW, kVA, pf, V, A and Hz• Temperature Indicator & Probe• Pressure Gauge: To measure operating pressure and pressure drop in the system• Stroboscope: To measure the speed of the driven equipment and motor• Ultra sonic flow meter or online flow meter• Sling hygrometer or digital hygrometer• A Anemometer t• In addition to the above calibrated online instruments can be used• PH meterAdel Mourtada 81
  82. 82. Measurements & Observation Energy consumption pattern of pumps and cooling tower fans Motor electrical parameters (kW, kVA, Pf, A, V, Hz, THD) for pumps and cooling tower fans Pump operating parameters to be measured/monitored for each pump are: - Discharge, - Head (suction & discharge) - Valve position – Temperature - Load variation, Power variation parameters of pumps - Pumps operating hours and operating schedule Pressure drop in the system (between discharge and user point) Pressure drop and temperatures across the users (heat exchangers, condensers, etc) Cooling water flow rate to users - Pump /Motor g p speedd Actual pressure at the user end User area pressure of operation and requirementAdel Mourtada 82
  83. 83. Exploration of Energy Conservation Possibilities Water pumping and cooling tower• Improvement of systems and drives• Use of energy efficient pumps• Correcting inaccuracies of the Pump sizing / Trimming of impellers• Use of high efficiency motors• Integration of variable speed drives into pumps: The integration of adjustable speed drives (VFD) into compressors could lead to energy efficiency improvements, depending on load characteristics• High Performance Lubricants: The low temperature fluidity and high temperature stability of high performance lubricants can increase energy efficiency by reducing frictional losses• Improvements in condenser performance I t i d f• Improvement in cooling tower performance• Application potential for energy efficient fans for cooling tower fans• Measuring and tracking system performance Adel Mourtada 83
  84. 84. Exploration of Energy Conservation Possibilities p gy• Measuring water use and energy consumption is essential in determining whether changes i i li d i i h h h in maintenance practices or investment in equipment could be cost effective• In this case it is advised to monitor the water flow rate and condenser parameters, cooling tower parameters p p periodically i.e. at least once y in a three months and energy consumption on daily basis. This will help in identifying the - - Deviations in water flow rates - Heat duty of condenser and cooling towers - Measures to up keep the performance Adel Mourtada 84
  85. 85. Exploration of Energy Conservation Possibilities p gy System Effect Factors • Equipment cannot perform at its optimum capacity if fans, pumps, and blowers have poor inlet and outlet conditions • Correction of system effect factors (SEFs) can have a significant effect on performance and energy savings • Elimination f Eli i i of cavitation: Fl i i Flow, pressure, andd efficiency are reduced in pumps operating under cavitation. Performance can be restored to manufacturer s manufacturer’s specifications through modifications. This usually involves inlet alterations and may involve elevation of a supply tank Adel Mourtada 85
  86. 86. Exploration of Energy Conservation Possibilities p gy• Internal Running Clearances: The internal running clearances b t l between rotating and non-rotating t ti d t ti elements strongly influence the turbo machines ability to meet rated performance. Proper set-up reduces the amount of leakage ( g (re-circulation) from ) the discharge to the suction side of the impeller• Reducing work load of pumping: Reducing of obstructions in the suction / delivery pipes thereby ypp y reduction in frictional losses. This includes removal of unnecessary valves of the system due to changes. Even system and layout changes may help in this including increased pipe diameter Replacement of diameter. components deteriorated due to wear and tear during operation, modifications in piping system Adel Mourtada 86
  87. 87. Sources: - “Energy Equipments” UNEP/SIDA/Gerlap, - “HVAC System Design”, Mark Hydeman, P.E., FASHRAE Taylor Engineering, LLC. - “Building Automatic System Bradley Chapman, DWEYER Building System” - “Solar Cooling”, Eco buildings, SARA. - “Ventilation for buildings Energy performance of buildings Guidelines for inspection of air-conditioning systems- EN 15240”, Intelligence Energy. - “Energy Efficiency Guidelines”, Brahm Segal, Power Correction System. - “Results of HVAC system monitoring of tertiary buildings in Italy”, M. Masoero, C. Silvi, J. Toniolo , Politecnico di Torino, HarmonAC - “Saving Energy Municipal Buildings and More”, Ben J Sliwinski Building More” J. Research Council School of Architecture, University of Illinois at Urbana- Champaign. Kreider Curtis Rabl, Mac gGaw Hill. - “Cleanrooms Energy Benchmarking”, Lawrence Berkley laboratory.Adel Mourtada 87

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