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

Project Timeline

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

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Baseline Vehicle Configuration

Zonal Vehicle Configuration

28C Test Case: Comparison of Driver Whole Body Thermal Sensation

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Time (Minutes)Th

erm

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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

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PredictedComfort

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Subject 1 - Comfort - 8/10

Subject 2 - Sensation - 8/10

Subject 2 - Comfort - 8/10

Very Hot

Hot

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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

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S ( µ

V K

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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

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DEER 2011

Baseline Vehicle Testing: HVAC Performance & Thermal Comfort

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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

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)

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-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

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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.