2 Replies Latest reply on Dec 18, 2017 3:42 AM by Mark Keown

    How to simulate LEDs in FloEFD?

    Ewen Rai

      Hi there,

      I have a CAD model of an edge lit display, meaning LEDs are along the bottom and top of the display. I'm going to use the LEDs in the website below.

      http://www.nichia.co.jp/en/product/led_product_data.html?type=%27NJ2W657HR-HG%27

      However, after doing a simulation on this, the temperatures are too high. They were done by assigning a volume heat source.

      The problem I believe is that I assigned the material aluminium to them, meaning the LEDs weren't retaining much of the heat like it would do in real life.

      The website doesn't give the material or their thermal properties, and the internet doesn't provide great answers either.

      How would you simulate this?

       

      Thanks in advance

        • Re: How to simulate LEDs in FloEFD?
          Ryan Dark

          Ewen,

          Do you have a SOLIDWORKS model with your simulation setup already applied to it?  You may want to attach it to your post so we can take a look through it.

          • Re: How to simulate LEDs in FloEFD?
            Mark Keown

            Make the LED with two extrusions 0.3 mm thick - un merge the extrusions (total is 0.6 mm).  The surface between the extrusions is the junction.

            The resistance from junction to the board side surface is 6 °C/W.  Calculate the thermal conductivity of the material in the bottom extrusion so the resistance is 6 °C/W.  Assign this material to the extrusion (the board side).  Possibly make the top of the LED have a thermal conductivity of 10.

            Activate radiation in the general configuration.

            Assign the top of the led an emissitivity of 0.8

            Some of the LED power will leave as light so subtract this from the power assigned to the led (about 6%).

            Assign the LED power to the interface between the extrusions.

            Assign surface goal on the interface between the extrusions (this result shall be less than 125°C).

            ** Ask the LED manufacture for a thermal design guide or if this process is correct.