Well, this really helps. It is a good case study, for the watt range. And the work is done. You could run 4 of those Flip Chip Opto, 85 mm COBS on a 12 inch cold plate.
http://www.lytron.com/Tools-and-Tec...-a-Heat-Exchanger-for-Cold-Plate-Applications
A customer wants to use a Lytron
Press-Lock CP12, a 12" (30.48 cm) cold plate (plate side), to remove 1200 W of heat from a 12"x5" (30.48 cm x 12.70 cm) electronic device. The coolant is 1 gpm (3.785 lpm) of water and the room temperature is 20°C. He wants the smallest heat exchanger that will remove the 1200 W of heat generated by this device, while maintaining a maximum surface temperature of 80°C.
Step 1: First we determine the system thermal resistance,
SYSTEM:
Step 2: Any combination of cold plates and heat exchangers that provide a thermal resistance less than or equal to the total system requirement will work. In other words:
Table 1 shows that the CP12/6110 combination satisfies the 0.050 °C/W condition at 2 gpm (0.006 +0.042 = 0.048
By looking at the system as a whole, we can start to see trade offs between the components, including how flow rate can impact heat exchanger selection. At low flow rates, the cold plate thermal resistance increases. This requires a larger heat exchanger with more thermal capacity, and therefore lower thermal resistance. At higher flow rates, it is possible to use a smaller heat exchanger.