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DEER 2011
Improving the Efficiency of Light-Duty Vehicle HVAC Systems using
Zonal Thermoelectric Devices and Comfort Modeling Authors: Clay Maranville, Ford Motor Company Mike Munoz, Visteon Corporation Larry Chaney, National Renewable Energy Laboratory Todd Barnhart, BSST Joseph Heremans, The Ohio State University Dmitri Kossakovski, ZT Plus DOE Technology Manager: John Fairbanks NETL Project Manager: Carl Maronde
DEER Conference Detroit, MI
October 5, 2010
DEER 2011
Disclaimer
This report was prepared as an account of work sponsored by the California Energy Commission and pursuant to an agreement with the United States Department of Energy (DOE). Neither the DOE, nor the California Energy Commission, nor any of their employees, contractors, or subcontractors, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the DOE, or the California Energy Commission. The views and opinions of authors expressed herein do not necessarily state or reflect those of the DOE or the California Energy Commission, or any of their employees, or any agency thereof, or the State of California. This report has not been approved or disapproved by the California Energy Commission, nor has the California Energy Commission passed upon the accuracy or adequacy of the information in this report. .
DEER 2011
Project Relevance / Objectives Project Goal: Identify and demonstrate technical and commercial approaches necessary to
. accelerate deployment of zonal TE HVAC systems in light-duty vehicles Program Objectives: • Develop a TE HVAC system to optimize occupant comfort and reduce fuel consumption • Reduce energy required from AC compressor by 1/3 • TE devices achieve COPcooling > 1.3 and COPheating > 2.3 • Demonstrate the technical feasibility of a TE HVAC system for light-duty vehicles • Develop a commercialization pathway for a TE HVAC system • Integrate, test, and deliver a 5-passenger TE HVAC demonstration vehicle
FY2011 Objectives: • Select a TE HVAC architecture to fully evaluate and design • Model system behavior and comfort response of alternative architecture • Estimate energy savings from use of TE HVAC architecture • Design & test HVAC elements and control strategies using vehicle buck • Develop candidate n-type TE material; design proof-of-principle TE HVAC module • Develop detailed systems-level component requirements and specifications
DEER 2011
Team Structure
Ford Vehicle-Level Design & Test,
Systems Integration, CAE Modeling, Hybrid Systems, Materials Analysis Amerigon
TE System Models & Design, Advanced Devices,
CCS, Module Production, TE Electronics
Ohio State Univ. New TE Materials
ZT Plus Advanced Material
Manufacturing
Ford Test Facilities Garages
Wind Tunnels Proving Grounds
NREL Comfort Models & Correlation,
Ancillary Load Reduction
Visteon HVAC systems, CFD, Comfort Models, CAD,
Subassembly Fab. HVAC Electronics, Vehicle Integration & Instrumentation
DEER 2011
Technical Approach
• Develop test protocols and metrics that reflect real-world HVAC system usage
• Use a combination of CAE, thermal comfort models, and subject testing to determine optimal heating and cooling node locations
• Develop advanced thermoelectric materials and device designs that enable high-efficiency systems
• Design, integrate, and validate performance of the concept architecture and device hardware in a demonstration vehicle
DEER 2011
Phase 2 Task Overview System-level HVAC architecture design
– Develop test conditions & occupant comfort metrics – Determine vehicle-level performance acceptance criteria – Assess and enhance thermal comfort tools – Develop and assess HVAC system architectures through detailed CAE analysis – Develop models to assess baseline HVAC and TE HVAC system power budget and
fuel consumption
TE HVAC system and materials research – Initiate pilot-process development for p-type TE materials research – Begin n-type TE materials research – Extend TE systems model & build liquid-to-air prototype TED hardware for validation
studies
Success Criteria – CAE modeling of TE HVAC architecture indicates required comfort levels can be
achieved – System modeling shows the TE HVAC architecture can achieve reductions in energy
usage from baseline vehicle – Research plan for TE materials and devices shows a specific path to deliver a
technically and commercially viable TE system
Task1: CAE & Comfort Analysis
• Computational Fluid Dynamics (CFD) assesses the temperature performance and airflow characteristics of zonal-HVAC equipped vehicles.
• Thermal Comfort/Sensation modeling will predict whole body thermal response for all test cases and vehicle configurations.
• These modeling tools analyze and compare the performance characteristics of zonal-HVAC equipped vehicles to the baseline vehicle to ensure equal or better performance.
Assessment of a Zonal-HVAC Equipped Vehicle 28C Test Case: Comparison of Average Interior
0 5 10 15 20 25 30 35 40
Time (Minutes)
Tem
pera
ture
(C)
Baseline Vehicle Configuration
Zonal Vehicle Configuration
28C Test Case: Comparison of Driver Whole Body Thermal Sensation
-15 -10 -5 0 5 10 15 20 25 30 35 40
Time (Minutes)Th
erm
al S
ensa
tion
Baseline Vehicle Configuration,Not Equipped With Seat Cooling
Zonal Vehicle Configuration, SeatCooling Switched Off
Zonal Vehicle Configuration, SeatCooling Switched On
Preconditioning Pulldown
Air Chamber Evaluation System (ACES) – Half Buck
• Fusion ½ Buck has been installed into the ACES System for the next level of evaluation
• Capability to independently control various distributed HVAC elements has been incorporated
• ACES setup is being used to validate CAE Comfort Model predictions and will include Wind Tunnel Testing conditions as a baseline
• Testing to start end of 3Q2011
ACES Chamber Previous Setup – Man in Box New Setup – ½ Buck
½ Buck in ACES
DEER 2011
Thermal Sensation/Comfort Analysis Options
• Evaluating multiple modeling approaches • AcuSolve CFD / RadTherm / UCB path show good potential for
prediction of thermal sensation and comfort
-4
-3
-2
-1
0
1
2
3
4
-4
-3
-2
-1
0
1
2
3
4
0 5 10 15 20 25 30 35 40Time (minutes)
Predicted Sensation
PredictedComfort
Subject 1 - Sensation - 8/10
Subject 1 - Comfort - 8/10
Subject 2 - Sensation - 8/10
Subject 2 - Comfort - 8/10
Very Hot
Hot
Warm
Slightly Warm
Neutral
Slightly Cool
Cool
Cold
Very Cold
Very Comfortable
Comfortable
JustComfortableJust UnComfortable
Uncomfortable
Very Uncomfotable
AC pull down test
National Renewable Energy Laboratory Innovation for Our Energy Future
Thermoelectric Device Design: Modeling, Design & Testing
TED Calorimeter Apparatus
Liquid HEX CFD
Current Efforts –
Updated Phase 1 CAE model to size and develop Phase 2 designs in support of initial vehicle level requirements.
Model used to understand parasitic loses in potential design architectures and down select design options.
Custom high performance liquid heat exchanger has been designed and is being fabricated for the Phase 2 device. Calorimeter instrumentation upgraded to provide more data on the design and improve accuracy.
Porosity increases zT of p-type Bi0.5Sb1.5Te3
• p-type research efforts focus on reduction in thermal conductivity to increase ZT and optimal doping to improve power factor
• Lab-scale tests reveal peak zT level ~ 1.2 (p-type)
• n-type materials are being evaluated to determine optimal doping and processing strategy
• This effect will be scaled to practical thermoelectric alloys and synthesis routes
0
50
100
150
200
250
300
S ( µ
V K
- 1 )
1 0 0 % d e n s e p = 3 . 7 1 0 1 9 c m - 3
8 0 % d e n s e p = 1 . 8 1 0 1 9 c m - 3
6 6 % d e n s e p = 1 . 4 1 0 1 9 c m - 3
100 200 300 400 T ( K )
0.1
1
0.3
3
ρ ( m
Ω c
m )
0
100
200
κ ( W
c m
- 1 K
- 1 )
250 300 350 400 450 T ( K )
0.5
0.75
1
1.25
z T
DEER 2011
Baseline Vehicle Testing: HVAC Performance & Thermal Comfort
Time (minutes)0 10 20 30 40
Tem
pera
ture
(°C
)
20
25
30
35
40
45
50
55
60
43C32C28C
Thermal Sensation / Comfort 43°C: 6 / –1.5 (16 min) 32°C: 5 / +0.5 (12 min) 28°C: 5 / +1.0 (8 min)
Time (minutes)
-10 0 10 20 30 40
Tem
pera
ture
(°C
)
-20
-10
0
10
20
30
-18C-5C+5C
Thermal Sensation Comfort -18°C: 4 / -1.0 (17 min) - 5°C: 4 / -1.0 (12 min) +5°C: 4 / -1.0 (8 min)
Hot Ambient Testing Cold Ambient Testing
DEER 2011
Modeled Energy Usage
• Cooling energy consumption is initially high due to large demand on blower and A/C compressor
• Heating energy consumption is delayed due to delay in heater core warm-up
A/C Compressor: Weighted Energy Consumption
Heater System: Weighted Energy Consumption
0 to 10 Min 11 to 20 Min 21 to 30 Min 31 to 40 Min
% W
eigh
ted
Ene
rgy
Con
sum
ptio
n
0
5
10
15
20
25
43C32C28C
0 to 10 Min 11 to 20 Min 21 to 30 Min 31 to 40 Min%
Wei
ghte
d E
nerg
y C
onsu
mpt
ion
0
10
20
30
40
-18C-5C+5C
DEER 2011
Summary • HVAC system energy consumption is substantial (but mostly off-cycle)
and must be considered when developing technology for improving overall real-world vehicle efficiency
• A Zonal TE HVAC architecture becomes more viable as vehicles evolve towards higher levels of electrification and engineering attribute criteria accounts for quantitative occupant-based comfort metrics
• Our current project focus is on developing methods to optimize climate system efficiency while maintaining occupant comfort at current levels using new technology, architecture, and controls approaches
• Project is on target to meet Phase 2 milestones and deliverables by the end of 4Q11
• Hardware design-freeze will occur early 1Q12 and subsystem design, build, and test is planned to be completed by this time next year
DEER 2011
Acknowledgements
• We gratefully acknowledge the US Department of Energy and the
California Energy Commission for their funding support of this innovative program
• A special thank you to John Fairbanks (DOE-EERE), Reynaldo Gonzales (CEC), and Carl Maronde (NETL) for their leadership
• Thanks to the teams at Ford, Visteon, NREL, BSST, OSU, Amerigon, and ZT::Plus for their work on the program.
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