Below are the questions asked during the event, along with their respective answers.
Q: Is it possible to add Monitor points in specific zones of the Heat Sink?
A: Currently Aavid Genie does not offer this capability. The Genie is meant for rapid modeling for either less complex solutions or to help guide users to a better starting point in their full CFD environment.
Q: Can this tool be used if the condenser region and fins are remote to the evaporator region?
A: Aavid Genie only handles embedded heat pipes at this time. The full Aavid CFD software will have the ability to analyze remote condenser relative to the evaporator. This software is currently in Beta and does not yet have a set release date, but is slated to come out in 2018.
Q: What is Aavid Genie doing different as compared to other tools in the market to reduce simulation time?
A: Aavid Genie is not a full CFD software, but an online tool meant to speed up the design process of heat sinks. It utilizes a combination of back end CFD and correlations based on empirical data to reduce the number of cells in the fluid mesh without impacting the accuracy of the simulated results.
Q: Do you have an option in Genie that allows for a customized placement of the heat pipe?
A: At this juncture, the only placement options are the number and diameter of the pipes and the axis direction. This is to enable the rapid modeling and simplified heat sink design that Aavid Genie is designed to do. For more informantion on exactly how Aavid Genie places heat pipes, please check the Genie blog post at aavidgenie.com/heat-pipe-placement. More complicated designs and placements would need to be designed in the full Aavid CFD.
Q: Does Genie model heat pipes as two phase systems or just as solid materials with very high thermal conductivity?
A: Aavid Genie models the heat pipes as two phase cooling and takes into account the rapid phase change and heat transfer associated with phase change cooling. However, the Genie will not alert you if you are approaching dry out.
Q: On what basis of calculation the Genie shows choices of heat sink based on user input?
A: Aavid Genie designs heat sinks within the manufacturing constraints of each heat sink technology while reducing the mass to the least material possible while still trying to reach user inputs. Keeping material at a mininimum will also keep costs down.
Q: Any experimental comparison with un-ducted flow condition?
A: We have conducted experimental comparisons with un-ducted flow as part of the development of the tool. In all of the validated cases, the results were verified within the 3-7% error range. Examples are not yet published.
Q: How is grid independence checked for multiple configurations?
A: This goes into proprietary development details. Although if you have specific concerns or design requirements, Aavid design engineers can help once you’ve accomplished your initial rapid modeling.
Q: Does Aavid offer heat pipes for -35degC to 130C?
A: Aavid does offer heat pipes to cover this range. Please contact our Two Phase Cooling Specialists in either Lancaster, PA USA or Ashington UK and we will help. The website is www.thermacore.com.
Q: Are there .pdml files available? With cold start capabilities?
A: Aavid Genie generates .pdf files for drawings and thermal reports, .stl files for 3D models and Aavid CFD files. To keep Aavid Genie a rapid design analysis tool, it only simulates steady state conditions.
Q: What is the working fluid modeled for the heat pipes?
A: At this point in time, Aavid Genie only utilizes water as the heat pipe working fluid.
Q: Can you change the shape and size of the heat pipes within Aavid Genie?
A: Currently, Aavid Genie only allows the heat pipe diameters available in the drop down. To do more with shape and placement of the heat pipes you would need to go into the full Aavid CFD Software.
Q: What wick structure is used in the heat pipe two-phase model in Genie?
A: Aavid Genie models heat pipes with a copper sintered wick structure.
Q: How does the heatpipe diameter affect the heat conduction?
A: The amount of heat that is transferred is correlated to the diameter of the heat pipe. Larger diameters can transfer more heat. If you have more specific questions, please feel free to ask in this forum or contact us directly.
Q: How do you predict the effective resistance of the heat pipe?
A: This goes into proprietary development details. However, if you have specific concerns or design requirements, Aavid design engineers are available to help, you would simply share your design within the application and request assistance.
Q: What is more efficient: to have more pipes of smaller diameter or less pipes of bigger diameter on the same surface size?
A: This is very application specific. Larger heat pipes transfer more heat than smaller diameter heat pipes, however heat source placement, gravity, cost, and many other variables should be considered when choosing heat pipe size and layout. The presentor prefers fewer larger diameter heat pipes if they can be fit into the application.
Q: Can the fin thickness and number be optimized for heat flow?
A: Yes, Aavid Genie allows you to adjust the fin thickness, number, and height and will give real time estimations for temperature rise, pressure drop, and fin efficiency to guide you in your choices prior to simulation. In order to properly optimize fin density, iterative simulations may be necessary.
Q: How do vapor chambers compare with individual embedded heat pipes in the example illustrated?
A: The vapor chamber would offer better performance than heat pipes in the presented application by approximately 4°C, however vapor chambers are not always the best solution given certain parameters. The Aavid Genie blog post regarding the difference between heat pipes and vapor chambers in applications provides more detail: aavidgenie.com/heat-pipes-versus-vapor-chambers.
Q: How can we compare efficiency of heat pipes and microchannels as both are used for same purpose?
A: These types or comparisons will be available in the upcoming Aavid CFD software.
Q: What is the cost of this Software?
A: Aavid Genie is an online design application and does not require any subscriptions or downloads. It is free to register and use Aavid Genie until the point of running a thermal simulation. Simulations and Drawings can be purchased using Aavid Genie Credits which can be purchased within the application or offline. A single Credit begins at $15 and the Credit Pricing Structure can be found at aavidgenie.com/get-aavid-genie-credits.