Feasibility of Energy Recovery in Conjunction With The Application of A Redesigned Central Cooling And Heating Plant

1. Feasibility of Energy Recovery in Conjunction With The Application of A Redesigned Central Cooling And Heating Plant

2. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

3. Project Team • Owner: QIAGENSciences, Inc. • Architect: Capital Design Assocs., Inc. • CM: Whiting-Turner • GC: CDI Engineering Group • Mech. Contractor: Pierce Associates • MEP Engineer: Herzog-Hart Corp. • Structural: Cagley and Associates

4. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

5. Existing Overall Conditions • Location: 118 Germantown Road, Germantown, Maryland • Size: 213,000 Ft2 • Cost: $52.5 Million • Use : Research and production of biotechnological products such as RNA and DNA, state of the art research facilities and laboratory spaces, chemical and biotech storage, and administrative offices

6. Building 1 Building 2

7. Existing Mechanical Conditions • 16 Air-handling units; 4,770 to 46,105 CFM • 5 – 100% Outdoor air units; 4,770 to 18,105 CFM • 2 – 900 ton electric driven centrifugal chillers • Constant speed primary, variable speed secondary chilled water distribution system • 2 – 2,700 GPM induced draft cooling towers • 2 – 400 boiler horsepower fire-tube steam boilers • 2 – 400 GPM shell and tube steam-to-water heat exchangers • Variable speed primary hot water distribution system

8. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

9. Problem Statement • Large energy consumption from the 100% outdoor air air-handling units • Energy recovery measures are currently not in place to take advantage of the conditioned air being removed from the spaces Existing 100% Outdoor Air Air-Handling Unit

10. Problem Statement • Peak summer energy costs coincide with peak central cooling plant loads • Currently no approach to reducing peak demand and energy costs Existing Chiller Plant

11. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

12. Energy Recovery System (ERS) • 4 existing 100% outdoor air air-handling units modified with total energy recovery wheels • SEMCO TE3 EXCLU-SIEVE® Total Energy Wheels selected to recover both sensible and latent energy • Preheat coil located before enthalpy wheel for fail safe frost protection of the wheel substrate

13. ERS Wheel Selection • SEMCO provided performance charts used to select proper wheel size • Selection based on supply and return air quantities • Return air from general room exhaust, not fume hoods • Optimum face velocity of 800 FPM across wheel

14. ERS Performance • Controlling cross-contamination is critical for laboratory spaces • 3Å Molecular Sieve Desiccant • Adjustable Purge Air Section • Independent Testing Results Microscopic view of 3Å molecular sieve Purge Air Schematic Testing Results

15. ERS Energy Analysis • Carrier’s Hourly Analysis Program (HAP) V4.10 used to model base building and ERS design loads • The peak cooling load is reduced from 1,045 tons of cooling to 885 tons, a reduction of 160 tons • The peak preheating load is reduced from 7,015 MBH to 4,650 MBH, a 2,365 MBH reduction • Energy analysis for the mechanical system utilizing the ERS is done in conjunction with the central plant redesign

16. ERS First Cost • Cost information was obtained from Spencer Goland at Rotor Source, Inc. • First cost information is used in the life-cycle cost analysis later on in the presentation

17. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

18. Central Plant Redesign • The central plant redesigns take into account the load reductions from the ERS design • 3 alternatives are analyzed, along with the existing plant Case A Case B Case C • 2 – 700 nominal ton electric driven centrifugal chillers • Associated primary and secondary chilled water pumps • 2 – 2100 GPM cooling towers • Associated condenser water pumps • 1 – 400 and 1 – 300 boiler horsepower fire-tube steam boilers • Associated hot water pumps • 2 – 675 nominal ton gas-fired double-effect absorption chiller-heaters • 1 – 200 nominal ton electric driven centrifugal chiller • Associated primary and secondary chilled water pumps • 2 – 2700 GPM cooling towers • 1 – 600 GPM cooling tower • Associated condenser water pumps • 1 – 100 boiler horsepower fire-tube steam boiler • Associated hot water pumps • 1 – 675 nominal ton gas-fired double-effect absorption chiller-heater • 1 – 700 nominal ton electric driven centrifugal chiller • Associated primary and secondary chilled water pumps • 1 – 2700 GPM cooling towers • 1 – 2100 GPM cooling tower • Associated condenser water pumps • 1 – 400 boiler horsepower fire-tube steam boiler • Associated hot water pumps

19. Central Plant Redesign Modeling • The Engineering Equation Solver (EES) is used to model the equipment for each plant case • Electric driven chiller modeling • DOE2 model for evaluating chiller performance • Cooling tower modeling • Curve fitting of manufacturer performance curves • Pump modeling • Curve fitting of manufacturer curves as well as application of pump affinity laws for variable speed application • Fire-tube steam boiler modeling • Constant efficiency model

20. Central Plant Redesign Modeling • Gas-fired absorption chiller-heater modeling • Unique aspect of central plant modeling • Chiller-heaters can provide simultaneous heating and cooling • York YPC double-effect absorption chiller-heater model • Curve fit part load performance charts provided by York for individual and simultaneous operation Individual Performance (York) Individual Performance (EES) Simultaneous Performance (York) Simultaneous Performance (EES)

21. Central Plant Redesign Modeling • Procedures written in EES for base building and 3 redesign case operating sequences • Base building and Case A use conventional system • Electric driven centrifugal chillers • Gas-fired fire-tube steam boilers • Case B uses chiller-heaters as main plant • Case C utilizes gas-electric hybrid plant • Absorption chiller-heater used as primary chiller

22. Central Plant Redesign Energy Analysis • EES produces hourly energy consumption for central plant components • Microsoft Excel is used to calculate energy costs • Utility rates are taken from service providers

23. Central Plant Redesign Energy Analysis • Peak demand kW reductions • Central plant gas usage • kW Demand charge reductions • Total Annual Energy Costs

24. Central Plant Redesign First Cost Analysis • Plant first cost used in life-cycle cost analysis • First cost information for chillers from Jim Thompson at York International • R.S. Means • First cost for central plant redesign cases • Includes main plant equipment • Chillers • Boilers • Heat Exchangers • Cooling Towers • Pumps • Chilled Water • Condenser Water • Hot Water

25. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

26. Electrical Analysis • The effect of the central plant redesigns on the existing electrical system is analyzed • 2 direct points of connection on main switchgear #2 for existing electric driven chillers • Existing electrical loads on switchgear #2 • Power Panel PP4 • Chillers #1 and #2 • Emergency Distribution Panel EDP #3 • Serves 4 Emergency Motor Control Centers (EMCC) • Spare connection

27. Electrical Analysis • kVA demand is calculated for load on switchgear • NEC Table 430-150 used to determine the full load current for the motors connected to EMCC’s • Feeder sizing done for each case • NEC Table 310-16 used for wire ampacity • Branch Conductor • NEC 430-22 D at 125% of the full load current • Overload Protection • NEC 430-31 and NEC Table 430-152 ; time delay fuses @ 175% FLC • Disconnect • NEC 430-110 at 115% of full load current • Air-conditioning and refrigeration equipment analyzed per NEC 440 • Grounding sized according to NEC Table 250-94 • Conduit sized according to NEC Chapter 9

28. Electrical Analysis • Case A shows no reduction in electrical service • Case C reduces load by 558 kVA • 2500 kVA transformer downsized to 2000 kVA • $6,015 savings • Wire size reduced • $8,960 savings

29. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

30. Structural Analysis • Analyze the impact of the central plant redesigns on structural system • Equipment foundations for centrifugal chillers and gas-fired absorption chiller-heaters • Centrifugal chiller foundation design • 4 times the equipment weight in concrete for vibration • Reinforcing for temperature and shrinkage • Absorption chiller-heater foundation design • Few moving parts, vibration not critical • Foundation needs to support equipment operating weight

31. Structural Analysis • Design Parameters • ACI 318-02 • Shrinkage and Temperature Reinforcing • Wide Beam Shear • Flexure • Punching Shear • Existing centrifugal chiller foundation • 36” depth • 2 chillers weighing 27,000 lbs each • Case A centrifugal chiller foundation • Use 36” depth as in existing building • 2 chillers weighing 23,400 lbs each • Case C absorption chiller-heater foundation • Use 12” depth • 1 chiller-heater weighing 65,500 lbs • Chiller-heater foundation depth reduced 24” from centrifugal chiller foundation despite weight increase of over 42,000 lbs • Reduced depth saves $1,840 compared to base building and Case A foundations • Concrete costs • Reinforcing steel costs

32. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

33. Life-Cycle Cost Analysis • Used to determine most attractive redesign option • First cost information combined with annual energy costs calculated in central plant redesigns • First costs for ERS design, central plant equipment, structural and electrical redesigns • Analysis Method • 20 year life cycle • ERS replacement at 10 years • NIST Energy Price Indices • 3.9% discount rate

34. Life-Cycle Cost Analysis • Case C hybrid plant has lowest LCC • Result of reduced annual energy costs • $864,475 savings over base building • $230,756 savings over Case A redesign • Case A redesign has instant payback • Case C payback; 9 months • Case C net savings over Case A; $133,132 • Difference in LCC savings and first cost savings of 2 cases

35. Outline • Introduction/Background • Existing Conditions • Problem Statement • Energy Recovery System (ERS) Design • Central Plant Redesign • Electrical Analysis • Structural Analysis • Life-Cycle Cost Analysis • Conclusions and Recommendations

36. Conclusions and Recommendations • Energy Recovery System Design • Effective response to high energy consumption of 100% outdoor air units • Decreases size of central cooling and heating plant • Central Plant Redesign • Case B central plant first cost and required area too high; not a feasible option • Cases A and C both provide significant life-cycle cost savings • Case C hybrid plant shows best annual energy costs

37. Conclusions and Recommendations • Final Recommendation • Implement Case C gas-electric hybrid central plant redesign • Short payback period attractive to owner • Highest net savings of all options evaluated • Flexibility of using either gas-fired chiller-heater or electric driven centrifugal as primary chiller • Future electric utility rates may be more or less favorable

38. Acknowledgements AE Faculty William P. Bahnfleth, Ph.D., P.E. Stanley A. Mumma, Ph.D., P.E. James D. Freihaut, Ph.D., P.E. Walt Schneider, P.E. Industry Professionals Dave Johnson, P.E. – QIAGEN Sciences, Inc. John Saber, P.E, – Encon Group, Inc. Jim Thompson – York International Corporation Spencer Goland – Rotor Source, Inc. 5th Year AE Students Andy Tech – Mechanical Jim Meacham – Mechanical/CM 242 South Atherton St. – Multi-disciplinary Family, Friends, and People I Forgot

39. Questions?

40. Thank You ForAttending!

41. Energy Recovery System

43. Central Plant Redesign • DOE 2 electric chiller modeling • Correction factors based on chilled water and condenser water temperatures • Regression coefficients • Capacity correction • Efficiency correction

44. Central Plant Redesign Marley Cooling Tower Curves • Cooling Tower Modeling • Curve fitting using manufacturer plots • Linear regressions for each constant range on plot • Condenser water temperature is a function of range and wet bulb temperature • Curves for full and half speed

45. Central Plant Redesign Bell & Gossett Pump Curve • Pump Modeling • Curve fit existing plot • Head and efficiency as a function of flow • Affinity laws for variable speed pumping • Head is function of flow rate and motor speed

46. Electrical Analysis • kVA demand calculations • Incorporate demand factor and voltage

47. Structural Analysis • Reinforcing design • Chapter 7 specifies minimum area of steel for shrinkage and temperature

48. Structural Analysis • Wide beam shear check • Chapter 11.3 – Shear strength for non-prestressed members • Chapter 11.12 – Special provisions for slabs and footings • Chapter 15.4 – Shear in footings

49. Structural Analysis • Flexure check • Chapter 15.4 – Moments in footings • Chapter 12 – Development and splices of reinforcement

50. Structural Analysis • Punching shear check • Assumes 8”x8” vibration isolation pads at 4 corners • Chapter 15.5 – Shear in footings • Chapter 11.12 – Special provisions for slabs and footings