The importance of energy efficiency in RAC


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The importance of energy efficiency in RAC and documentation of performance in the field (Klas Berglof, Consultant).

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The importance of energy efficiency in RAC

  1. 1. Performance Inspections for Optimisation DIN-mounted fixed installation With Ethernet or GSM/GPRS Field inspection unit connection ClimaCheck Sweden AB Klas Berglöf
  2. 2. Background • Method developed and patented in 1986 – Development triggered by booming heat pump market, to document performance when contractor and consumer had disputes • First generation on the market 1987-1995 • Second generation redeveloped 2003 – 2004 • Web site for on-line monitoring opened 2007 • Refrigeration product of the Year in UK 2009 • Increasing interest for actual performance in the field – Increasing energy prices – Green buildings – Low Carbon foot print becomes strategic importance 2
  3. 3. Refrigeration is everywhere! use 15-20% of all electricity 3
  4. 4. Master Thesis analyse 164 inspections • Royal Institute of Technology is the leading technical university in this field in Sweden • Savings from 164 ”Performance Inspections” • Annual savings of 10 % from direct low cost measures • Further identification of need for optimisation of systems and controls • Individual cases with 40% savings and identification of critical problems • All on systems ”ready” for inspections 4
  5. 5. Swedish Survey of 164 installations • 87 % of inspected systems not optimised • 10% energy savings from “simple” optimisation • Systems were said to be ready for inspections Source: Master Thesis by John Arul Mike Prakash, KTH Stockholm 2006 5
  6. 6. 13% of 164 systems were OK! Source: Master Thesis by John Arul Mike Prakash, , KTH Stockholm 2006 Inspections were planned and contractor informed Huge difference between theory and practice! 6
  7. 7. Huge variation in COP Source: Master Thesis by John Arul Mike Prakash, , KTH Stockholm 2006 7
  8. 8. Significant potential to save Energy Energy Performance in Buildings Directive (EPBD) require Performance Analyses of all AC systems above 12 kW Cooling capacity 10% Energy Savings in AC and Refrigeration in Europe ≈ Electricity Generation of Denmark or Portugal or the total Wind Power Generation for EU25. That this is possible is supported by Data from Master Thesis at the Royal Institute of technology in Stockholm Energy Optimisation Potential through Improved Onsite Analysing Methods in Refrigeration Master Thesis by John Arul Mike Prakash, 8
  9. 9. Directives and standards in Europe 9
  10. 10. Energy Performance in Building Directive (EPBD) All AC-system with more than 12 kW capacity The inspection is to include “an assessment of the air conditioning efficiency and the sizing compared to the cooling requirements of the building”. Advice is also to be provided to the users on “possible improvement or replacement of the air- conditioning system and on alternative solutions”. 10
  11. 11. Energy Performance in Building Directive (2002/91/EC) Requires Inspections of AC- systems • Focus is on performance, cooling demand, installed capacity and kWh consumption • Standards for performance Inspections (EN15240) – It will be difficult to get a good information on “degradation” of performance based on kWh due to all factors (change of use/climate) – Advice to check maintenance records but no “standard” for these • EN378-4 address field inspections for maintenance but are not specific to give relevant information to EPBD inspections No method on how to generate maintenance log! or How to measure and stability 11
  12. 12. Internal Method for Performance Inspections 12
  13. 13. Easy to apply – to standard service “points” in 20 minutes Electrical input volt/current 7 surface temperatures 2 pressures from service ports 13 13
  14. 14. Application of sensors to standard system (typically done in 20-30 minutes) • 2 pressures • 7 temperatures • 1 power input 14
  15. 15. Simple Refrigeration Cycle P condensation m m Expansion compression m m m Vaporization h 15
  16. 16. Analyses on ”standard” process Ideal compression Pressure 1. Low pressure and Heat cap. suction gas temp. P HP 3 2 2. High pressure and discharge gas temp. P LP 1 Cool cap. 3. High pressure and Power in liquid temp. Enthalpy Mass flow = power in – heat losses /enthalpy difference over compressor COP = Cooling capacity / Power Input Bring theory to practical use in the industry 16
  17. 17. Theory Performance analysing using ”Black Box” perspective on compressor Enthalpy increase refrigerant Heat losses (relatively small and predictable) Electric energy input (e.g. Electric input = enthalpy increase + heat losses from shell) 17
  18. 18. What about error in the heat loss estimate? Conditions +5/50°C R407C T = 85°C T = +15°C 33kW Heat Loss Enthalpy Mass Flow Capacity % Increase Rate kg/s kW 5 48.5 0.653 100 7 48.5 0.641 98.2 40% error in the Heat Loss results in <2% Capacity Error
  19. 19. Key Results • Cooling capacity (± 7% accuracy) • Heating capacity (± 7% accuracy) • COP (± 5% accuracy) • Compressor efficiency • Super heat and sub cooling • Functionality of Control • Evaporation, Condenser pressure and temperature • UA and mean temperature differences in evaporator and condenser • Flow of secondary systems based on Capacity and temp. difference Listed are only key information – standard template consist of > 40 outputs allowing detailed analyses of each component 19
  20. 20. Local or remote – temporary or fixed DIN-mounted fixed installation Flexible PC and or Web based system for: Commissioning – minimize warranty cost Performance inspection – optimisation Preventive maintenance Trouble shooting Descicion support – expansion retrofit 20
  21. 21. Economiser 21
  22. 22. Analyses and presentation of results 22
  23. 23. Presentation of data is key for analyses 23
  24. 24. Comp. eff Start-up Part load Full load
  25. 25. Part load Full load Start-up
  26. 26. COP +10% at full load Temp. diff. Temp. diff. 9.3 K 9.3 K Secondary out – secondary out – 100% evaporation condensing Good ≈ 3-5 K Good ≈ 1-4 K 67% Compressor eff. 48% to 64% When part to full load Super heat. 0.8 K at part load -critical 26 8 compressors no need for part load > saving more than 5000 Euro
  27. 27. Compare current data with earlier recorded or nominal data Give on-line result of measures including estimates of saving and carbon foot print 27
  28. 28. Test rig comparison with manufacturer data (here 94.3 compared to Bitzers 93.8 kW) 28
  29. 29. Where and how can you use ClimaCheck? 29
  30. 30. R-22 Retrofit Procedure Pre-retrofit analyses Post-retrofit analyses Is the system in shape for Optimise system a retrofit? Is replacement the most Document performance environmental solution? What alternative is R22 out suitable? Flush and Recover HFC or recover for drop + in blend New oil?
  31. 31. Experience from 40+ OEMs Dehumidifiers - Telecom - Heat pumps – Chillers - Display cases Development – Production -Aftermarket 31
  32. 32. Field measurements from small to industrial Inspection, trouble shooting, optimisation preventive service 32
  33. 33. Size is not important 2 stage 27 MW * 4 33
  34. 34. Two stage centrifugal Oil clogged demistor 4 K pressure drop 34 34
  35. 35. Integration in existing BMS district heating plant Result from first of four HP + 3 MW after dP in “demistor” detected Annual increased production worth 1 million Euro + lower C02 35
  36. 36. Italian Supermarket Metro Baranzate in Milano saving 16 000 Euro per year in one “pac” Adj. controls Installation Drift som tidigare 27% higher average COP Energy consumption over test periods showed corresponding improvement 36 36
  37. 37. Compressor Pack in Supermarket Comp 2 Low Efficiency 37
  38. 38. Compressor Pack in Supermarket Comp 2 Low Efficiency Full load Full load Full load Comp. Eff. 1, 3 and 4 Average Comp. Efficiency Comp 2 Low Efficiency Stab. Stab. Stab. 38
  39. 39. Design dT water out to evaporation is 4-5 K here 10-11 K 20+% increased energy consumption 39
  40. 40. Undressed Poor distribution in Evaporator Can occur anytime there are multiple circuits (not only plate heat exchangers). Can be on refrigerant or secondary side. Increased risk: A. When freeze depressors are used as the increased viscosity/decrease in heat transfer increase the number of plates/tubes and decrease dP on refrigerant side. B. Exchangers are oversized C. High subcool D. Beware of air stuck in plate heat exchangers as air is pushed into
  41. 41. Method has few limitation (complex systems can be made understandable) Industrial ammonia plant screws + oil cooling 41 41
  42. 42. Start Analysing! • Immediate overview • Full documentation of all parameters • In depths analyses can be done by “remote” experts (in-house, manufacturer or independent) • Before and after measures/optimisation Immediate savings in 87% of analysed systems Average 10% initial saving at minimal cost 42
  43. 43. Validated and well proven method • Experience since 1986 when it was patented • Validated 1989 by SP - Swedish National Testing and Research Institute • Used by 40 manufacturers of heat pumps, dehumidifiers, refrigeration and air conditioning equipment – Development laboratories and production test rigs – Commissioning, trouble shouting, warranty inspections and aftermarket • 400 field measurement systems in use • Leading equipment owners document actual performance – Tesco in UK, Metro in Spain, IKEA/ICA/Axfood/EON in Sweden • Internal method used in education and research – Sweden, Finland, Germany, Spain, Italy, Slovakia and UK • Integration with – OEM control systems and Building Management system (BMS) 43
  44. 44. Thank you! 44