TASK 1 – IDENTIFY/DESCRIBE
COOLING/REFRIGERATION FOCUS AREAS
FOR ANNEX TECHNICAL CONTRIBUTIONSOak Ridge National Laboratory
Van Baxter, Brian Fricke, Ayyoub Momen

ORNL is managed by UT-Battelle, LLC for the US Department of Energy

Proposed Focus Areas• An Alternative Cooling Technology Using Magnetocaloric

Materials• Expansion Loss Reduction Using a Pressure Exchanger2

Alternative Cooling Technology Using Magnetocaloric
Materials• Oak Ridge National Laboratory• Ayyoub M. Momen, R&D Staff• momena@ornl.gov
3

Magnetocaloric Refrigeration: SignificanceTechnology Potential:• There are >200M refrigerators units in U.S.A.
–Refrigerator is the second largest user of electricity (13.7%) right after air conditioning (14.1%).

• Magnetocaloric refrigeration has the potential to be 20% more efficient thanthe conventional vapor compression systems.

• According to the recent DOE study on 17 non-vapor compression HVAC technologies,

Magnetocaloric refrigeration technology ranked as “very promising” alternatives because they
exhibit moderate-to-high energy savings potential, offer significant non-energy benefits, and/orfit well with the BTO mission.

Note:
Early stage R&D is needed to fully utilize the recent and future emerging MCMs. Developing a highperformance magnetocaloric refrigeration system is a very challenging task from systemdevelopment perspective.

4

Tech. Background: How to make large ΔT?
Effective
operatingrange,
material 2

Effective
operatingrange,
material 1

Effective
operatingrange,
material 1

ΔTadb

ΔTadb

The temperature swing of each MCM is only few degree C.

Layered bed
Tc1

Tc2 Tc1

Temperature

Temperature

0°F

5100°FChallenges
Magnetocaloric Refrigeration Challenges
New Material
discovery
Not addressed
under this project

Source: J. Liu et al. Nat. Mater. 2012

6Processing the material

System integration

Reducing cost

High performance MCM
are difficult to form
because they are:
• Heat sensitive• Very reactive• Brittle

At the system level,pressure drop across
MCM heatexchanger is themain challenge:• Excessive
pressure drop
hurts theperformance• Limits theoperatingfrequency• Limits thecooling/heating
capacity

Cost
reduction isinversely
proportional
to system
cooling
power
densityApproach
MCM Microchannel development
R&D
Advanced
Manufacturing
3D Printing

Magnetic stabilization(random shapemicrochannels)

Fully solid state systems

Sintering

Machine Design
GEA 5 generation ofcooling machines

ORNL flexible
evaluation platform

Model development
Identifying loss
mechanisms
7

Model Validation

Improving machine design

Approach
Pressure drop of MCM particulate regenerator is one of the primary loss
sources of the MCM system.
𝑄𝑐𝑜𝑜𝑙
𝐶𝑂𝑃 =
𝑤𝑖𝑛

Pressure drop
hurts twice

𝑄𝑐𝑜𝑜𝑙 − 𝑃𝑢𝑚𝑝 𝑝𝑜𝑤𝑒𝑟 ℎ𝑒𝑎𝑡
𝐶𝑂𝑃 =𝑤𝑖𝑛 + 𝑃𝑢𝑚𝑝 𝑝𝑜𝑤𝑒𝑟 ℎ𝑒𝑎𝑡

Target(Microchannels)

To depart from the state of the art, we need tofind develop manufacturing processes to makeMicrochannels from MCM.
High performance MCM are difficult to be formed
or manufactured in shapes (i.e. Microchannel),because they are:
- Heat sensitive- Very reactive- Brittle
8

State of the art(Packed bed)

Source: J. Tian, T. Kim, T.J. Lu, H.P. Hadson,
D. T. Qucheillilt, D.J. Sypeck, H.N.H. Hadky.

Advanced Manufacturing• 3D printing of the heat exchangers is a new field and very

challenging.

• Additional, complexity is added when we want to do this on

the new material (MCM) that does not like to cooperate(reactive, heat sensitive and fragile)!!

• After 18 months of early stage R&D, we fabricated MCM

microchannels of 150 µm at 100% MCM full density.

• Variable Parameters Investigated:

9–

Particle diameter–

Binder saturation–

Print orientation–

Type of binder–

Cleanability–

Curing temperature–

Pixilation issues.

Magnetic Stabilization• No heating is involved• Scalable process (compared to additive manufacturing)• Simple and low cost solution• Significantly reduces the pressure drop
• Provides very high interstitial heat transfer rates• Random microchannels as small as 20–100 µm• Enhance magnetization of particles by 10%• MCE properties intact

2015
Idea developed

102016
Process developed(binder, fluidization, magnetization,curing, pressure drop)2017
3 Stage AMR
developed, evaluated2019
10 Stage AMR
Evaluation and finetuning the process

Fully Solid-State System (no HT fluid)• Investigate magnetocaloric material (MCM)
manufacturing methods• Analytically model the concept to characterize it• Build and test
• Identify market barriers and entry points

Theoretically11

Prototyping: GEA’s Prototype Development ProgressPrototype 1—early 2014

Prototype 3- 2015
12Prototype 2- 2014

Prototype 4- 2016

Multistage Regenerator Model Development
Model development: A paper was published in a
Nature family journal on 16-layer regenerator.

The model is developed to identify the main loss mechanisms in thesystem and is validated against the magnetically stabilizedstructures.
13Flexible Characterization Platform for Magnetocaloric
Regenerator Performance Evaluation

Future Work
• COP evaluation:– Evaluate the COP of 10 stage magnetic stabilized structure and 10stage 3D printed regenerator.

• Detailed Cost Model Development by Manufacturer:– Develop consumer cost model, Develop manufacturing cost model,market risk and mitigation strategy

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Expansion Loss Reduction Using a Pressure Exchanger

Oak Ridge National Laboratory
Brian A. Fricke (R&D Staff)
865.576.0822, frickeba@ornl.gov

15

Introduction – Motivation• Pressure losses are unavoidable in HVAC&R systems– Pressure drop in piping, heat exchangers, expansion devices, etc.
• Pressure loss in certain components can be recovered, e.g.,

expansion processes– Ejectors– Turbines/expanders• Transcritical CO2 refrigeration systems– Systems operate at high pressures– Expansion processes lead to significant “lost work”– System performance could be enhanced with work recovery

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Introduction – Pressure Exchanger• Design and implement “pressureexchanger” (PX) technology inrefrigeration systems• Challenges for integration– Seals are critical path component forsuccessful implementation– Laboratory data is sparse (performance withtwo-phase flow?)– Information is lacking on component designand implementation
17

Introduction – Potential Implementation• 4-Port PX for CO2 refrigeration– PX is used to replace high-pressure expansion valve and increase pressure of

the medium-temperature suction– Reduces power consumption of medium-temperature compressor– COP increases upwards of 15% if suction flow boosted by PX– Other configurations possible

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Characterization of PX• Analogy to Heat Exchangers
Heat Exchanger

19

Pressure Exchanger

Transfer heat energy

Transfer work energy

Involves heat losses

Involves pressure losses

Fluids can be in liquid/gas or 2phase state

Fluids can be in liquid/gas or 2phase statePhase change process can occur
during the transport process

Phase change process can occur
during the transport process

Geometry establishes theeffectiveness

Geometry establishes theeffectivenessCharacterization of PX• Analogy to Heat Exchangers
Heat Exchanger

Pressure Exchanger

𝑞𝑚𝑎𝑥 = 𝐶𝑚𝑖𝑛 𝑇ℎ,𝑖 − 𝑇𝑐,𝑖𝑊𝑚𝑎𝑥 = 𝑣𝑚𝑖𝑛 𝑃ℎ,𝑖 − 𝑃𝑙,𝑖𝜀=𝜀=𝑞𝑞𝑚𝑎𝑥

𝐶𝑐 𝑇𝑐,𝑜 − 𝑇𝑐,𝑖𝐶𝑚𝑖𝑛 𝑇ℎ,𝑖 − 𝑇𝑐,𝑖𝜀=𝑊
𝑊𝑚𝑎𝑥

𝑣𝑙 𝑃𝑙,𝑜 − 𝑃𝑙,𝑖𝑣𝑚𝑖𝑛 𝑃ℎ,𝑖 − 𝑃𝑙,𝑖𝑞 = 𝜀𝐶𝑚𝑖𝑛 𝑇ℎ,𝑖 − 𝑇𝑐,𝑖

𝑊 = 𝜀𝑣𝑚𝑖𝑛 Pℎ,𝑖 − 𝑃𝑙,𝑖𝐶𝑚𝑖𝑛
𝜀 = 𝑓 𝑁𝑇𝑈,
𝐶𝑚𝑎𝑥𝑣𝑚𝑖𝑛𝑣𝑚𝑎𝑥𝑥𝑁𝑇𝑈 ≡𝑣𝑚𝑖𝑛 ∙ ∆𝑃𝑚𝑖𝑛

𝑁𝑇𝑈 ≡20𝜀=𝑈𝐴𝐶𝑚𝑖𝑛

𝜀 = 𝑓 𝑁𝑇𝑈,

Numerical Analysis• Performance of PX modeled withcomputational fluid dynamics (CFD) software
package• Model assumptions:– Stationary inlet/outlet ports– Rotor (1,000 RPM)
– 12 channels in rotor– Channel length = 0.19 m– Channel diameter = 0.02 m– Rotor outside diameter = 0.18 m– Stationary port depth = 0.05 m
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Numerical Analysis• Comparison of CFD model with

9existing experimental data(desalination data)

travelling distance of any flow inside
the rotor duct
– Mixing is the term that quantifies theamount of mixing that occurs
between the primary and secondaryflow inside the PXExperimental (Xu et al.)
Numerical

76Mixing%– Inflow length is defined as the total

85432
10,35 0,4 0,45 0,5 0,55 0,6 0,65 0,7 0,75 0,8 0,85 0,9 0,95
Inflow Length (L)Enle Xu, Yue Wang, Liming Wu, Shichang Xu, Yuxin Wang, and Shichang Wang,“Computational Fluid Dynamics Simulation of Brine−Seawater Mixing in a Rotary
Energy Recovery Device,” Ind. Eng. Chem. Res., 53, 18304−18310, 2014.

231

Future Work• Develop a pressure exchanger test apparatus and prototype

pressure exchanger for R744 applications– Working with commercial partner to develop prototype PX• Experimental evaluation of pressure exchanger performanceusing R744

• Retrofit pressure exchanger in R744 refrigeration system24

Thank you!
Questions/Comments?

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