Quote:
Originally Posted by foxrena 
I totally understand your concern. Actually I have done some rough simulations to calculate the optimal cold plate thickness. You readings of -10c at end and 20c in the middle is close to my simulation result.
I have a question, What size (thickness) of cold plate did you use in that test?
Here is the simulated temperature distribution across the center line on the top of 10cm by 5cm cold plates (400W cpu power). Note that all temperature is relative, so only take the dT reading.
4mm thickness:
10mm thickness:
Graph for 10mm:
As the cold plate gets thicker, the temperature at the cold side of TEC gets more uniform. But thicker means larger value of C/W value from CPU to TEC, too. The optimal thickness is between between 8-12mm. Certainly this aspect affects the performance of the block. But overall it's not too bad because in the center the hotter area compensates the lost heat transferring across TECs at the two ends, as Qmax is a semi-linear function of temperature.
Yeah, heat pipes will help. I bet you have though about a sandwiched version of direct die block, which the water block is in the middle and on the top and bottom there are two TECs with cold plates linked by heatpipes. I like chillers, with their ever expanding Qmax. Adding more TECs easily fixes the efficiency problem. My only concern is the complexity of two loops and insulation issues.
I totally understand your concern. Actually I have done some rough simulations to calculate the optimal cold plate thickness. You readings of -10c at end and 20c in the middle is close to my simulation result.
I have a question, What size (thickness) of cold plate did you use in that test?
Here is the simulated temperature distribution across the center line on the top of 10cm by 5cm cold plates (400W cpu power). Note that all temperature is relative, so only take the dT reading.
4mm thickness:
10mm thickness:
Graph for 10mm:
As the cold plate gets thicker, the temperature at the cold side of TEC gets more uniform. But thicker means larger value of C/W value from CPU to TEC, too. The optimal thickness is between between 8-12mm. Certainly this aspect affects the performance of the block. But overall it's not too bad because in the center the hotter area compensates the lost heat transferring across TECs at the two ends, as Qmax is a semi-linear function of temperature.
Yeah, heat pipes will help. I bet you have though about a sandwiched version of direct die block, which the water block is in the middle and on the top and bottom there are two TECs with cold plates linked by heatpipes. I like chillers, with their ever expanding Qmax. Adding more TECs easily fixes the efficiency problem. My only concern is the complexity of two loops and insulation issues.
Beautiful similation.. That picture is worth 1000 words and tells the whole story right there!! Yep I've used copper with thickness from 6mm all the way up to 19mm. Bottom line is tecs produce almost no cooling power on the ends. You basically end up with ~ single tec direct die block at double the cost . A test I'd love to see done with that block is one tec in the middle of that block vs both tecs.
Edited by Mindchi|l - 3/17/12 at 10:50am
