Typical Cooling Load Profile

Transcription

1 Ice Storage Systems and Impact on Electric Demand Georges Hoeterickx Specialists in Heat Transfer Products and Services 1

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3 Cooling Load Typical Cooling Load Profile Time of Day 3

4 Conventional System Chiller Cooling Load 4

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6 Ice Storage System Ice Storage Tank Chiller Cooling Load 6

7 Cooling Load Ice Storage Cycle Ice Storage Cycle Ice Storage Cycle Time of Day 7

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9 Advantages of Thermal Ice Storage Reduced equipment costs Only 60% - 90% of chillers and heat rejection equipment and is required Associated electrical equipment is reduced Reduced thermal energy storage space Reduced energy and operating costs Reduced GHG emissions Increased flexibility to adapt to changing utility structures and requirements 9

10 % Peak Load Reduced Equipment Size with Ice Storage 100% 80% 60% 40% 20% 0% Time of Day 10

11 % Peak Load Reduced Equipment Size with Ice Storage 100% 80% 60% 40% 20% 0% Time of Day 11

12 Advantages of Thermal Ice Storage Reduced thermal energy storage space Ice storage requires 1/4 to 1/6 of the space of chilled water storage 41.4 kw-hr/m³ (1 Ton-Hr/3 ft³) Ice storage insensitive to system ΔT Lower real estate costs 12

13 310 mw-hours (88,000 Ton-Hours) Chilled Water Storage 55m D x 16m H

14 Advantages of Thermal Ice Storage Reduced equipment costs Reduced energy and operating costs Reduced GHG emissions Increased flexibility to adapt to changing utility structures and requirements 14

15 Thermal Ice Storage Uses Less Energy At night, chillers operate when ambient temperatures are much lower During days, chillers operate at higher CHW supply temperatures and greater efficiency when piped upstream of ice storage Pump energy can be less by taking full advantage of colder CHW supply temperatures 15

16 COP COP of Chillers with Air-Cooled Radiators 5 Ambient Temperature ( C) Final Ice-Build 3 2 Normal Design Point CHW Pre-Cool CHW Supply Temperature ( C) 16

17 17 Chiller Piped in Series with Ice Storage

18 Thermal Ice Storage Uses Less Energy At night, chillers operate when ambient temperatures are much lower During days, chillers operate at higher CHW supply temperatures and greater efficiency when piped upstream of ice storage Pump energy can be less by taking full advantage of colder CHW supply temperatures 18

19 Advantages of Colder Chilled Water Supply Water Temperatures Smaller distribution pumps and piping Reduced pumping power Allows for economical building isolation (indirect interface) with smaller heat exchangers 19

20 Colder Supply Water Temperatures 70 mw (19,900 TR) Peak Load CHW Supply Temp. CHW Flow* Difference 5 C (44.6 F) 8610 m³/h (37900 gpm) Base 4 C (44.6 F) 7530 m³/h (33170 gpm) -13% 3 C (44.6 F) 6700 m³/h (29480 gpm) -22% 2 C (44.6 F) 6030 m³/h (26530 gpm) -30% 1 C (44.6 F) 5480 m³/h (24120 gpm) -36% *12 C (53.6 F) CHW Return Temp. 20

21 Advantages of Thermal Ice Storage Reduced equipment costs Reduced energy and operating costs Reduced GHG emissions Increased flexibility to adapt to changing utility structures and requirements 21

22 Advantages of Thermal Ice Storage Require less kwh than conventional systems Energy line losses at night are 4% to 5% lower than during the daytime Utilize efficiently produced power that produces fewer carbon dioxide emissions Source: Source Energy and Environmental Impacts of Thermal Energy Storage, California Energy Commission - February

23 mw TES Meeting Summer System Load in South Florida, USA Base Nuke Base Coal Combined Cycle TES Adds to CC Steam GT TES Shifts Steam GT lbs. of CO 2 reduced per mwh shifted Hour 23 Source: Thermal Energy Storage Time of Day Impact on Power Plant Emissions, John Nix - June, 2008

24 Ice Storage System Design Considerations Full Storage vs. Partial Storage Specialists in Heat Transfer Products and Services 24

25 Cooling Load (Tons) Batch Cooling or Process Load Profile Time of Day 25

26 Cooling Load (Tons) Full Ice Storage System Example Batch Cooling or Process Application Ice Charge Ice Discharge Time of Day 26

27 Cooling Load (Tons) Air Conditioning Load Profile Time of Day 27

28 Cooling Load (Tons) Full Ice Storage System Example Air Conditioning Application Ice Charge Ice Discharge Time of Day 28

29 Ice Storage System Design Full Ice Storage Advantages Best suited for short, peak demand periods and/or high, peak loads Shifts largest electrical demand that provides the lowest operating cost Provides system standby capability and operating flexibility Disadvantages Largest storage volume required Larger chiller required Most expensive thermal storage design 29

30 Cooling Load (Tons) Partial Ice Storage System Example Air Conditioning Application Ice Discharge Ice Charge Chiller Time of Day 30

31 Cooling Load (Tons) Partial Ice Storage System Example Air Conditioning Application Ice Discharge Ice Charge Chiller Time of Day 31

32 Cooling Load (Tons) Partial Ice Storage System Example Air Conditioning Application Ice Discharge Ice Charge Chiller Time of Day 32

33 Cooling Load (Tons) Partial Ice Storage System Example Air Conditioning Application Ice Discharge Ice Charge Chiller Base Chiller Time of Day 33

34 Ice Storage System Design Partial Ice Storage Advantages Best suited for long cooling periods Lower first cost due to reduced storage volume and smaller chiller Provides system operating flexibility Disadvantages Less standby capability Less electrical demand shifted to off-peak 34

35 Ice Storage System Design Considerations Internal Melt vs. External Melt Specialists in Heat Transfer Products and Services 35

36 Ice Storage System Types Direct Contact Cooling Indirect Contact Cooling External Melt Internal Melt 36

37 Ice Storage System Design Ice on Coil - Internal Melt Indirect COLD GLYCOL OUT WARM GLYCOL IN ICE ON COIL MELTING OCCURS FROM INSIDE ICE Cold glycol solution is circulated through the coil to the chilled water (glycol) system Warm glycol solution, circulating through the coil, is cooled indirectly by the melting ice WARM GLYCOL 37

38 Ice Storage System Design Internal Melt (Indirect Contact) 38

39 Ice Water Supply Temp. ( C) Internal Melt Ice Coils Discharge Temperature Profile % Ice Depleted 39 Note: 10 Hour constant discharge; 28 mm nominal ice thickness

40 Ice Water Supply Temp. ( C) Internal Melt Ice Coils Discharge Temperature Profile Without Air Agitation % Ice Depleted 40 Note: 6 Hour constant discharge; 25 mm nominal ice thickness

41 Ice Water Supply Temp. ( C) Internal Melt Ice Coils Discharge Temperature Profile % Ice Depleted With Air Agitation 41 Note: 6 Hour constant discharge; 25 mm nominal ice thickness

42 Ice Water Supply Temp. ( C) Internal Melt Ice Coils Discharge Temperature Profile Without Air Agitation % Ice Depleted With Air Agitation 42 Note: 6 Hour constant discharge; 25 mm nominal ice thickness

43 43 Internal Melt System Schematic

44 44 Internal Melt System Schematic

45 Ice Storage System Design Internal Melt Advantages Simple to design and operate simple controls for various operating modes closed, pressurized loop Stable, cold discharge temperatures 36 F to 38 F typical 45

46 Ice Storage System Design Internal Melt Disadvantages Heat exchanger required to eliminate glycol from chilled water loop Not able to discharge as quickly as direct contact cooling ( ice melt limited by heat transfer through coil ) 46

47 Ice Storage System Design Ice on Coil - External Melt Direct AIR AIR WATER OUT WATER IN ICE ON COIL MELTING OCCURS FROM OUTSIDE ICE Ice water is circulated through the ice storage tank to the chilled water system Warm return water, circulating through the tank, is cooled via direct contact with the ice REFRIGERANT OR GLYCOL WARM WATER 47

48 Ice Storage System Design External Melt (Direct Contact) 48

49 Ice Water Supply Temp. ( C) External Melt Ice Coils Discharge Temperature Profile Hour 2 Hour 1 Hour % Ice Depleted 49

50 50 External Melt System Schematic

51 51 External Melt System Schematic

52 Ice Storage System Design External Melt Advantages Lowest chilled water supply temperatures Quickest discharge capability Eliminates glycol from chilled water loop 52

53 Ice Storage System Design External Melt Disadvantages Chiller with lower temperature capability generally used Glycol control valves required on multi-coil systems Heat exchanger may be required to manage static head of open system 53

54 Ice Storage System Design External Melt vs. Internal Melt External Melt Project requires a constant, cold supply water temperature of 1 C or quick discharge periods Trained operating staff available Large savings in distribution piping system Highest energy efficiency Internal Melt Project does not require coldest possible supply temperature Simpler design and operation Individual buildings Energy efficiency is less critical (extra heat transfer step required) 54

55 Ice Storage System Design External Melt vs. Internal Melt Most air conditioning applications use internal melt Most process and district cooling systems use external melt 55

56 Ice Storage System Coil Design Specialists in Heat Transfer Products and Services 56

57 Ice Storage Coil Design Countercurrent flow in adjacent circuits Less wasted space Better ice packing factor (IPF) 57

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59 Ice Storage Coil Design Counterflow Headers and Circuits 59

60 Ice Storage Coil Design Others 3.85 Evapco

61 Extra-Pak Ice Coils Elliptical Tubes Less Wasted Space Evapco Others 61

62 Ice Storage Coil Design Discharge method (internal or external) Ice thickness Ice build performance Ice melt performance Quantity of circuits and rows (passes) Length of coil/circuit Circuit and row spacing 62

63 63 Ice Storage Coil Design

64 Ice Storage Coil Design Internal Melt External Melt 64

65 Glycol Supply Temperature ( F) Custom Ice Coil Configurations Glycol Temperature vs. Build Time Thin Design for Centrifugal Chillers Thick Design for Screw Chillers Time (Hours) 65

66 Ice Storage Products and Installations Specialists in Heat Transfer Products and Services 66

67 Ice Storage Product Offering Ice coils internal or external melt Ice inventory controls Ice thickness controls Air blowers 67

68 Ice Storage Applications Commercial A/C and industrial District cooling Colleges and universities Corporate campuses Hospitals Convention centers Sports arenas Utilities 68

69 Key Evapco Ice Coil Installations Project Location Ton-Hours King Abdul Aziz University, Phase 1&2 Jeddah, Saudi Arabia 84,600 Entergy New Orleans District Cooling New Orleans, Lousiana, USA 52,800 Entergy Houston District Cooling, Phase 2 Houston, Texas, USA 44,000 NATO Command and Control Center Naples, Italy 34,120 Solaris Dutamas, Phases 1 & 2 Kuala Lumpur, Malaysia 34,000 New Pearl River District Cooling, Phase 1 Guangzhou, China 28,728 Hainan Sanya Ice District Cooling Hainan, China 25,536 Moab Khotsong Gold Mine Vaal Reefs, South Africa 24,136 Mponeng Gold Mine Carletonville, South Africa 19,800 Singapore Disrict Cooling DCP1, Phase 2 Singapore 18,326 Leipzig Exhibition Centre Leipzig, Germany 15,350 69

70 Entergy Solutions Houston, Texas Plant constructed in 1998 Expanded in ,000 kwr peak capacity 310,000 kwr-hr ice storage Four (4) tanks 1.1 C chilled water supply Specialists in Heat Transfer Products and Services 70

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72 72 Entergy Houston 2008 Capacity Upgrade

73 73 Entergy Houston 2008 Capacity Upgrade

74 Entergy Houston 2008 Capacity Upgrade 74

75 75 Entergy Houston 2008 Capacity Upgrade

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80 80 Entergy Houston 2008 Capacity Upgrade

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84 Thank You! Specialists in Heat Transfer Products and Services 84