PowerTHERM: A Complete Thermal Management Solution

Thermal management is a critical aspect of every vehicle design, with ever-tighter packaging, increasing use of plastics for lighter weight, and an explosion in use of sensitive electronics. Components can become so hot that they potentially fail, or degrade nearby components leading to serious safety, durability, and warranty issues. Many vehicle systems, such as the engine, transmission, HVAC, or power steering, have significant energy requirements and their thermal efficiency has a direct impact on the fuel economy, performance, and passenger comfort. Globalization is making the challenges worse with vehicle platforms that must operate in extremely wide temperature ranges. Careful analysis of cooling airflow, component placement and thermal shielding is required to avoid costly late-stage design fixes or, worse, failures when in production.

Above: Coupled PowerFLOW (right) and PowerTHERM (left) automatically map surface distributions.

 

Thermal design traditionally depends heavily on prototype testing in thermal wind tunnels or on-road testing with hundreds of thermocouples. The testing process is very expensive, time consuming, and inflexible. Testing with thermocouple instrumentation requires test engineers to a-priori estimate where thermal problems may occur - but the highly turbulent nature of engine compartment and underbody flows makes this very difficult or impossible to predict. Relying on redesign and retesting is an expensive hit and miss process that often ultimately fails to identify the highest temperature locations. The inherently transient nature of turbulent flow is almost impossible to visualize in a wind-tunnel, yet these complex structures must be understood in order to optimally locate and protect components. In addition, temperature is a function of the complex interaction between conduction, radiation, and convection in the surrounding fluid, especially for very hot components. Accurately predicting this is extremely challenging.

 

EXA’S SOLUTION

PowerTHERM® coupled with PowerFLOW provides a complete, extensively validated, digital thermal management solution. PowerFLOW's unique, inherently transient Lattice Boltzmann-based physics allows simulations to be performed that accurately predict real-world transient air-flow conditions on the most complex geometry. PowerTHERM is a fully-coupled, highly accurate, conduction and radiation solver. The combination of PowerFLOW and PowerTHERM enables engineers to accurately predict temperatures and visualize the flow and temperature fields for the entire vehicle. This enables the engineer to identify problem areas and provide recommendations to improve the design to eliminate problems. Rapid turnaround time for simulation and model setup allows the engineer to quickly make design changes to the baseline and evaluate the improvements in thermal performance.

 

PowerTHERM has been validated to help solve many thermal management problems, including:

Underbody and engine compartment thermal protection

Brake cooling

Key-off /soak

Electronics and battery cooling

HVAC system performance

Cabin comfort

Defrost and demist

 

 

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PwerFLOW results (bottom right) and PowerTHERM results (upper left) combine to provide engineers the opportunity to simulate and analyze accurate aero/thermal results on even the most complex geometry.

 

BENEFITS OF POWERTHERM FOR THERMAL MANAGEMENT:

• Reduced product development time through early-stage analysis and design improvement

• Reduction of development costs by reducing or eliminating prototype testing

• Improvement in component lifetime and reliability

• Reduction of warranty risks and costs

• Improvement in vehicle efficiency by maintaining optimal thermal operating conditions

• Increased customer satisfaction through analysis of cabin airflow and occupant comfort

 

CAPABILITIES

PowerTHERM predicts surface temperatures and heat fluxes generated by heat radiation, conduction and convection. Convection is calculated by PowerFLOW and coupled to PowerTHERM via an integrated coupling interface enabling two-way data exchange. The coupled simulation is easily set up as part of a regular PowerFLOW simulation. The result is a complete flow and heat transfer simulation allowing the user to efficiently and accurately predict thermal results.

 

Advanced solver for radiation, conduction and convection

• Multi-bounce radiation

• Shell and solid conduction models

• Convection via coupling with PowerFLOW

• 1-D advection and fluid stream models for modeling coupled internal flows, for example, within an exhaust system

• Temperature dependent properties including, conduction, specific heat, and emissivity

• Handles multi layer parts: solid, air, vacuum or mixed

• Efficient and robust numerical scheme with adaptive solution algorithms

 

Accurate and efficient over many time scales

• Steady-state or transient

• From a few seconds to hours

 

High performance and easy-to-use

• Rapid, easy-to-use, thermal model creation and case setup

• Seamless, integrated coupling with PowerFLOW fluid simulation

• Results analyzed in PowerVIZ, Exa’s powerful simulation results visualization & analysis environment - a single environment for analyzing the flow results.

• Optional parallel processing for reduced simulation time

 

Battery cell model

• Optional module for coupled thermal-electrical analysis of a battery cell or pack

• Supports both charging and discharging states

• Captures realistic time-varying loads and charges

 

Natural environment models for accurate climate control analysis

• Solar loading–Direct, Diffuse, and Reflected

• Wind loading

 

Human comfort model

• Optional module for advanced human thermal comfort within complex environments

• Place virtual test dummies with layers of clothes into virtual operating environment and compute comfort indexes

• Full radiant, convective and conductive heat transfer is accounted for

• Computes localized thermoregulatory response such as perspiration, respiration, and blood flow changes

• Steady state or transient localized thermal sensation and comfort analysis

 

 

References

PowerTHERM

Product Brief

 

The Physics behind PowerFLOW

 

Technical Publications highlighting the Exa PowerFLOW Suite

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