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The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
July 2017
Advances in Caloric Cooling Technologies
Yunho Hwang, Suxin Qian
Center for Environmental Energy EngineeringDepartment of Mechanical Engineering
University of MarylandCollege Park, MD 20742-3035
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Introduction• To minimize environmental effects of HVAC systems,
their direct and indirect GHG emissions should be reduced.
• Use working fluids with ultra-low GWPs• Improve the efficiency of vapor compression cycles• Develop a new cooling technology, which uses
working fluids with ultra-low GWPs and is more efficient.
• This work presents the overview of caloric cooling technologies.
4
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Introduction
3
Not-in-kind Cooling Technologies
Solid-State
Magnetocaloric
Electrocaloric
Elastocaloric
Thermoelectric
Thermoionic
Heat activated
Absorption
Adsorption
Ejector
Vuilleumier heat pump
Gaseous
Thermoacoustic
Brayton heat pump
Stirling heat pump
Vortex-tube
Pulse-tube
Liquid-vapor
Membrane heat pump
Metal hydride
Electro-chemical
compression
Others
Malone cycle
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Caloric Cooling Process
4
Kitanovski et al., IJR, 57 (2015)
Brayton Cycle
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Active Caloric Regeneration Process
5
Kitanovski et al., IJR, 57 (2015)
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Magnetocaloric (MC)
6
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
MC Working Principle
7
Refrigerant is solid, and the system requires a heat transfer fluid to exchange
heat with the conditioned space.
Refrigerant is fluid and moves through the conditioned space to
exchange heat.
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
List of Magnetocaloric Cooling Projects
8
Kitanovski et al., IJR, 57 (2015)
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Magnetic Material: La(Fe-Mn-Si)13
9
L. Huang, D. Y. Cong, L. Ma, Z. H. Nie et al., Large reversible magnetocaloric effect in a Ni-Co-Mn-Inmagnetic shape memory alloy, Appl. Physics Letters, 108 032405 (2016).
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Magnetic Material: La(Fe-Mn-Si)13
10
M. Krautz, K. Skokov, T. Gottschall, C.S. Teixeira, A. Waske, J. Liu, L. Schultz, O. Gutfleisch,Systematic investigation of Mn substituted La(Fe,Si)13 alloys and their hydrides for room-temperature magnetocaloric application, AIP. 118, 053907 (2015).
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ELICit: EU’s Research Project
11
• European Union (EU) started the three year researchproject, ELICiT “Environmentally Low Impact CoolingTechnology” in 2014 to enhance the commercialization ofmagnetic cooling.
• The ELICiT Project focused on applying magnetic coolingto domestic refrigeration.
• Objectives are:• Life Cycle Optimization• System Optimization• Benchmarked Validation• Regulations and Standards
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ELICit: Camfridge
12
• Magnetic cooling can double COP than R600a freezer• Pump efficiency doubled.• Optimized HXs• Volume of three magnetic cooling systems:
• Camfridge: 5,292 cm3• Astronautics: 86,400 cm3• CoolTech: 784,000 cm3
• Used shaped magnetic material/HXs (others use sphere orpowder) to make a compact system
Source: ICR 2015, Yokohama, Japan
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ELICit: CoolTech
13
• 2 heat exchangers and 2 small pumps to circulate HTF• For 380 liter volume cabinet, achieved 3.5-4.2°C Tcabin at 21.5°C
Tamb, Power 38 W with direct HX loop• Designed for wine cooler: capacity 200 W, COP 4.54, Achieved
-4°C Tlow and 40°C Thigh at 20°C Tini
http://www.cooltech-applications.com/magnetic-refrigeration-system.html
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
MC Challenges
14
• Magnetocaloric effect decreases as temperature moves away from Curie temperature, thus efficiency of all cycles degrades with increasing temperature lift.
• Need multi-stage cycles using different Curie temperatures as each stage can make only 1-2 K.
• Pumping power is a larger contributor to loss than in vapor compression; systems require 25~60X more pumping power.
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Electrocaloric (ETC)
15
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
List of Electrocaloric and ElastocaloricCooling Projects
16
Kitanovski et al., IJR, 57 (2015)
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Electrocaloric: Polymer
17
Zhang et al, 2015. Adv. Materials.
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Electrocaloric: Ceramic
18
Zhao et al, 2015. J. Alloys & Compounds. 653 (2015).
• Developed PLZST 2/57/38/5 anti-ferroelectrics (AFE) thick films with ZrO2 buffer layer on LNO bottom electrodes
• Achieved an enhanced relative dielectric constant and a reduced leakage current. Improved ECE by about 10 K from 27.3°C to 37.1°C at room temperature 21°C.
• The corresponding entropy changes are 31 and 42 J/kg-K.
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Electrocaloric: Ceramic
19
S. Hirasawa, T. Kawanami, K. Shirai,, American J. of Physics and Applications, 4 (2016) 134-139.
Predicted average heat flux performancewas 70 kW/m2 with 1,000 Hz frequencyand the 20 µm thicknesses of theelectrocaloric material and 20 µm heatstorage material.
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ETC Challenges
20
• The limitation in the shape of the materials. Only thin films can be applied since a high electric field is needed (hundreds of MV/m).
• Lacking of ETC multilayer modules with high reliability (> 100 cycles) and high ETC performance (DT > 5 K),
• There is no ETC device demonstration reported showing large temp. span (> 10 K) with any cooling power.
Source: Q. M. Zhang, Penn State, 2016
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Elastocaloric (ESC)
21
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Elastocaloric Effect
22
LiquidPsat < Psys
VaporPsat < Psys
Martensiteσsat < σsys
Austeniteσsat < σsys
Apply stress (compression) /pressure to the system
°C °C
Pressure induced
condensation
°C °C
Austeniteσsat > σsys
Martensiteσsat > σsys
Remove stress/pressure to the system
LiquidPsat > Psys
VaporPsat > Psys
°C °C
Pressure induced boiling
°C°C
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Elastocaloric Cooling
23
https://www.nature.com/articles/nenergy2016159/figures/1
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Comparison of Elastocaloric Materials
24
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
(isothermal)
Can we increase latent heat, reduce heat capacity, lower operational stress, and increase work recovery?
Comparison of Elastocaloric Materials
25
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Elastocaloric Effect in Ni-Ti Wire
26
• 3 mm Nitinol (Ni-Ti alloy)• 3 mm NiTi wire• ∆Tad ~ 17K Martensite –
Austenite phase change (solid)
• Direction for material developments
• High latent heat (Ni-Ti 12 J/g)• Low transitional stress (Ni-Ti
700 MPa)• Long fatigue life (Ni-Ti >
360,000 cycles)• Low hysteresis to reduce
loss (Ni-Ti 1 J/g)
Cui et al., 2012, App. Phy. Lett., 101, 073904
∆Τad = 24K
∆∆Τad = -17K
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Elastocaloric Effect in Ni-Ti Ribbon
27
Ni-Ti (50.8/49.2)DTad ~ 9.5 K
M. Schmidt, A. Schutze, S. Seelecke, Int. J. Refrig. 54 (2015) 88-97.
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Elastocaloric Effect in NiTiFe Film
28
Ossmer et al., Smart Mater. Struct. 25 (2016) 085037.
• NiTiFe (49.1/50.5/0.4)• 3 micron foil• DTad ~ 9.4 K
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ESC Prototype: NiTi Tube
29
Nitinol tube holder
Water in Water out
Compressible solid:• Deformation: 0.5’’ (12.7 mm), which is 5% of 10’’ (254
mm) tube• Force: each tube requires 1,350 lbf (6 kN)
Nitinol tubes
Linear bearing
Hexagon arranged NiTi (SMA) tubes in
each bed
OD = 4.72 mmID = 3.76 mm
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ESC Prototype: Ni-Ti Tube
30
• Work recovery: two beds were 50-50 percent pre-compressed
• Linear actuator attached to the “moving box”
Ni-Ti bed
Loading Head & Water Distributor
Linear actuator
Top view
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ESC From Material to System
31
Entropy
T
1
3
4
100%M
0%MMartensite
2
Austenite56
Th
Tc
Entropy
1
3
4
100%M
0%M
2
Austenite56
T
MartensiteTh
Tc
Entropy
1
3
4
100%M0%M
2
Austenite56
T
MartensiteTh
Tc
Loading/unloading Heat transfer Heat recovery
Same initial temperature
T4 < T1!
V1 V2
V3 V4
V5 V6
V7 V8
HRV
Pump 1 Pump 2
Pump 3
Bed #1
Bed #2
TcTh
V1 V2
V3 V4
V5 V6
V7 V8
HRV
Pump1 Pump2
Pump3
Bed #1
Bed #2
TcTh
V1 V2
V3 V4
V5 V6
V7 V8
HRV
Pump 1Pump 2
Pump 3
Bed #1
Bed #2
TcTh
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ESC-NiTi Tube: Temperature Lift
32
• Without compression: all fluid temperatures are following the same trend
• With compression: temperature lift exists
V1 V2
V3 V4
V5 V6
V7 V8
Pump1
Pump2
Bed #1
Bed #2
Heat rejection loop(To ambient)
Cooling delivery loop(To target space)
Heat recovery loop(Internal)
T6T5
T7T8
Heat sink
Mass flow meter 1
Mass flow meter 2
Electric heater
MFM
MFM
T2
T1 T3
T4
Pump3
HRV2
HRV1
20
20.5
21
21.5
22
22.5
23
1 11 21 31 41 51
Tem
pera
ture
[°C
]
Time [min]
TC5-cooling inlet °CTC6-cooling outlet °CTC7-heating inlet °CTC8-heating outlet °C
Measured fluid temperature variations
T6
T5T7
T8
22
23
24
25
26
27
28
29
30
0 10 20 30 40
Tem
pera
ture
[°C
]
Time [min]
TC5-cooling inlet °CTC6-cooling outlet °CTC7-heating inlet °CTC8-heating outlet °C
Temperature lift72°F
80°F
76°F
84°F
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ESC-NiTi Tube: Performance Progress
33
Adding screw jack + rail “V” layout Vertical alignment
Adding 0.002’’ shims
Horizontal alignment of
linear actuator
Horizontal alignment
2x locking nuts
Screw jacks
Friction problem: 7 tubes up to 3.8% strain
Sep, 2014May, 2014
∆Tlif
t[K
]
Jan, 2015 Jul, 2015
1.3 K
1.8 K
Plastic tubes distributor
Fluid
Fluid
Nitinol tubes
Rubber seal
Plastic tubesLoading head (dry)Holder
Original design (fluid contacts metal loading head directly)Challenge 1: leak through distributor Challenge 2: leak
through rubber
To PEEK tubes on the other side
Challenge 3: PEEK tubes inside loading head
Heat loss from water to the metal loading heads
2.8 K
10 tubes, 3.4% strain
7 tubes, 4% strain 10 tubes,
4% strain
4.2 K
Limitation of two motors
13
42
4.7 K
Dead thermal mass of HTF
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ESC-NiTi Tube: Test Results
34
• Maximum cooling capacity: 65 ± 10 W• Maximum temperature lift: 4.7 ± 0.4 K
4.8 K
• Achieved 4.7 K ∆Tlift when using plastic insertions to block 50% HTF inside tubes
• Measured 9% heat loss from Ni-Ti tubes to the holder
• Adding 12 W parasitic heat generated from pumps + 9% heat loss 6.1 K ∆Tlift6.1 K
“PEEK” means plastic insulation tubes to reduce heat loss to the metal loading heads
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
ESC Challenges
35
• Material development• Large latent heat, low transitional stress, low
hysteresis and long fatigue life• Custom shape/structure manufacturing capability
• Cycle design: high frequency heat transfer feature
• System integration• Compact and light system• High efficient heat transfer• High efficient heat recovery/regeneration• Cost down
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Performance Comparison
36
Technology Φmat @ ∆Tlift = 10 K Φsys @ ∆Tlift = 10 K Φsys,max @ ∆Tlift
Vapor compression 0.88 0.20 0.27 @ 24 K
Magnetocaloric 0.91 0.29 0.30 @ 9 K
Electrocaloric 0.41 n/a n/a
Elastocaloric 0.63 0.14 0.16 @ 17 K
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Summary of Cooling Technologies
37
Technology R&D statusCost/
complexity RefrigerantWork
input form
Possible heat recovery method
Possible work
recovery method
Vapor compression (baseline)
Mature Low R410A ∫pdv Suction-line heat exchanger Expander
Magnetocaloric Advanced R&D High Gd ∫μ0HdmActive
magnetic regenerator
Multi-bed rotary bed
design
ElectrocaloricR&D,
recently started
Moderate P(VDF-TrFE-CFE) ∫EdDPassive external
regeneratorn/a
Elastocaloric R&D,
recently started
Moderate Ni-Ti ∫σdε Thermowaveheat recovery
Multi-bed symmetric
design
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
• Solid-state caloric cooling technologies are advancing among NIKs because of new material development.
• Summarized the working principles and recent advancements of caloric cooling technologies.
• Solid-state caloric technologies are applicable to small temperature lift applications if single stage is used and require more development in both materials and system integration.
Conclusions
38
The 8th International Conference on Compressors and Refrigeration, Xi’an, China, 2017
Thanks for your attention!
Any Questions?
39
有問題嗎?
感謝您的關注
Slide Number 1IntroductionIntroductionCaloric Cooling ProcessActive Caloric Regeneration ProcessMagnetocaloric (MC)MC Working PrincipleList of Magnetocaloric Cooling ProjectsMagnetic Material: La(Fe-Mn-Si)13Magnetic Material: La(Fe-Mn-Si)13ELICit: EU’s Research ProjectELICit: CamfridgeELICit: CoolTechMC ChallengesElectrocaloric (ETC)List of Electrocaloric and Elastocaloric Cooling ProjectsElectrocaloric: PolymerElectrocaloric: CeramicElectrocaloric: CeramicETC ChallengesElastocaloric (ESC)Elastocaloric EffectElastocaloric CoolingComparison of Elastocaloric Materials Comparison of Elastocaloric MaterialsElastocaloric Effect in Ni-Ti WireElastocaloric Effect in Ni-Ti RibbonElastocaloric Effect in NiTiFe FilmESC Prototype: NiTi TubeESC Prototype: Ni-Ti TubeESC From Material to SystemESC-NiTi Tube: Temperature LiftESC-NiTi Tube: Performance ProgressESC-NiTi Tube: Test ResultsESC ChallengesPerformance ComparisonSummary of Cooling TechnologiesConclusionsThanks for your attention!�����Any Questions?