Emerging Refrigeration Technologies

Transcription

1 Emerging Refrigeration Technologies Brandon F Lachner, Jr Research & Technology Forum Madison, WI January 20-21, 2005 University of Wisconsin-Madison 1

2 Today Current Industrial Refrigeration Ammonia in a vapor compression cycle dominates the industrial refrigeration market Beyond Today What about other refrigerants? Other equipment/technologies? 2

3 Ammonia as a Refrigerant The Good Reasonable working pressures High heat of vaporization Inexpensive Good heat transfer characteristics Environmentally-friendly The Bad Toxic Slightly flammable 3

4 Refrigerant Alternatives Halocarbons High cost Environmental impacts Future availability questionable Compatibility w/existing infrastructure Fractionation (mixtures) Secondary refrigerant High cost capital & operating Water temperature-limited High capital cost Large footprint Hydrocarbons Boom! Carbon dioxide High working pressures 4

5 If it isn t broke That s what we ve always used Why fix it? Potential for first cost and energy savings Movement away from global warming and ozone depleting refrigerants Montreal Protocol (1992) Kyoto Protocol (1999) Improved reliability Increased production Inertia 5

6 Vapor Compression Developments Compressor technology Cool Compression (Vilter Mfg) Triple Screw (Carrier Co) Semi-hermetic (Mayekawa Mfg) Other Vilter Cool Compression Membrane technology purger (Enerfex) 6

7 Cool Compression Oil cooling for screw is accomplished using direct contact heat exchange Oil-liquid ammonia interface Liquid ammonia helps de-foam oil Oil separator acts as cooler and coalescer Applicable use is high-stage only Source: Vilter 7

8 Triple Screw Two active compression channels rather than one with single- or twinscrew systems Triple Screw may soon break into the air conditioning market up to 500 TR 8

9 Refrigeration Cycle Alternatives Including (but not limited to): Magnetic Thermoacoustic Absorption CO 2 Transcritical Cascade 9

10 Magnetic Refrigeration Shows promise in performance At 5 T magnetic field, Active Magnetic Regenerator Refrigerator (AMRR) 60% of Carnot (high temp only) No direct environmental impacts Non-toxic Scalability? Current research is on small scale Secure your valuables!!! 10

11 AMRR operation Utilizes materials that have a large magneto-caloric effect (MCE) magnetic field induces temperature swings Using spatially varying alloys of Gd/Si/Ge, a maximum MCE point (Curie Temperature) can be optimized for the regenerator bed 11

12 Magneto-caloric Effect Adiabatic Temperature Change (K) Tesla (Engelbrecht, 2004) Temperature (K) 0-5 Tesla A Numerical Model of an Active Magnetic Regenerator Refrigeration System, Engelbrecht, Kurt Masters Thesis, University of Wisconsin-Madison,

13 Active Magnetic Regenerative Refrigerator Cycle (AMRR) Heat Rejection Hot Reservoir Cold Reservoir Cold-to-Hot Demagnetization Hot-to-Cold Magnetization Flow Refrigeration (Engelbrecht, 2004) 13

14 AMRR layout Development of rotary magnetic regenerator bed is analogous to the advent of centrifugal compressors from recips (Engelbrecht, 2004) 14

15 Thermoacoustic Tuned high volume sound (pressure) waves cool working medium Penn State Team Requires a buffer volume, regenerator Uses benign medium such as helium as refrigerant No direct environmental impacts Non-toxic Ben and Jerry s have installed this system as a small ice-cream freezer 15

16 Thermoacoustic Layout Resembles pulse tubes Buffer volume Regenerator Piston (compressor) Requires large regenerator for high capacity (courtesy of Thermoacoustic Refrigeration Team at Penn State) US Patent #6,725,670 16

17 Thermoacoustic Essentially a reverse-stirling cycle Heat rejection regeneration Load Hot Regenerator Temperature Cold 17

18 Transcritical CO 2 No direct environmental impacts GWP, ODP Extremely high working pressures Low side ~215 [psia] High side ~>1050 [psia] Finding application in near future in auto industry (small scale) No pressure! 18

19 Transcritical CO 2 Cycle Schematic Smaller components Gas cooler instead of condenser Gas Cooler (Condenser) Compressor Evaporator 19

20 Transcritical v. Subcritical Vapor Compression Cycles Transcritical cycle Subcritical cycle 20

21 Cascade System (NH 3 -CO 2 ) No direct environmental impacts GWP, ODP Manageable working pressures Low side 70 [psig] High side 300 [psig] Industrial scale systems currently in operation in both Europe and US Photos: Nestlé 21

22 Cascade System (NH 3 -CO 2 ) to cooling tower from cooling tower NH 3 Condenser/Evaporator CO 2 Refrigeration load 22

23 Absorption Utilizes low quality energy Able to provide refrigeration capacity where electricity is not available Can be useful for recovering waste energy (heat ~140 C) Poor performance Ammonia among typical refrigerants 23

24 Ammonia-Water Absorption Operation Compression process is replaced with generator/ regenerator/ absorber combination Heat is driving energy rather than shaft work Source: Energy Solutions Center 24

25 Absorption Layout Water (absorber) allows ammonia to be pumped rather than compressed less energy consumption 25

26 Any promise? Cost Perform Flexibility Overall Magnetic Low Good Good Good Trans-crit Low Good Good Good Cascade High Fair Good Fair Acoustic High Poor Poor Poor Absorption High Poor Good Poor 26

27 Future of Industrial Refrigeration The end of ammonia in industrial systems is not in sight IRC is developing an industrial refrigeration Technology Map 27

28 Industrial Refrigeration Technology Map New equipment Emerging cycle technologies Evaluation of potential for technology success 28

29 Thank You Questions? University of Wisconsin-Madison 29