In product design, thermal solutions typically have a designated volume, called a working envelope.
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In the "Project Conditions" page of Boyd Genie, there is a box that asks you the "Working Envelope." This term refers to the heat sink design volume.
Think of this as the volume you have available for your heat sink in your application. Genie defines your working envelope in terms of where your air flow comes from.
The width of the working envelope refers to the dimension perpendicular to your air flow.
The envelope height is the distance above your heat sources that is available for your heat sink design. Typically the height refers to the thickness of the base plus the height of your fins and any additional flow bypass you might include above the fin tips.
Length is considered as the flow length, the length that air will flow along the heat sink. Length also refers to how long the fins are on the heat sink.
Defining Heat Sink Design Volume
In retrofit applications, these dimensions may be somewhat concrete, as you may be trying to fit a new heat sink into an existing duct or enclosure. Those would be the dimensions you use for your Working Envelope.
New applications have more flexibility in your available heat sink volume. For cases like these, use the volume that is your preferred volume. You can return and increase and decrease your volume size after checking what options the "Technology Selection" page calculates before you simulate your heat sink design.
Allow the Heat Sink to be Smaller
You have the option to ask Genie to recommend heat sinks that are smaller than your defined working envelope. Genie will first meet your thermal design constraints that you defined in the Project Conditions page. Then it will reduce the size of the heat sink until it cannot meet the thermal and flow parameters you set. You'll see a red box in the Technology Matrix if Genie can't meet your requirements. If the Genie can't make a heat sink within the technology manufacturing limits, the box will be greyed out
So, go ahead and try a few custom heat sink design volumes and see what works best for you!