A liquid cooler module (LCM) employing a high thermal-conductivity, pitch-based carbon foam is studied. The newly developed carbon foam has an effective conductivity up to 150 W/m-K and porosity up to 90%. It is believed that this highrconductivity carbon foam could significantly enhance the heat transfer due to the thermal dispersion effect. To prove the concept of the carbon foam liquid cooler, a three-dimensional numerical study of the carbon foam cooler was undertaken. The numerical results indicated that the LCM incorporating the carbon foam worked very well. Even with a heat flux as high as 100 W/cm2, the average temperature drop between the substrate and the liquid coolant is less than 20°C. A liquid cooler with such an enhanced heat transfer characteristic could be a candidate for cooling power electronic devices onboard aircraft when the heat dissipation requirement for the electronic device is further increased. Experimental study was also undertaken for the carbon foam LCM. A test sample was prepared by bonding a block of the carbon foam to the substrate using the silver-filled epoxy. The sample was tested on a previously established experimental setup with a modified intermediate-substrate assembly. The modified assembly achieved accurate temperature reading on the bottom surface of the substrate without the need to solder the intermediate plate onto the substrate. As a result, substrates with a variety of materials having different thermal expansion coefficients can be tested on the experimental setup. Experimental data Were collected under different working conditions of the cooler. The experimental results indicated that' the temperature drop between the substrate and the coolant was substantially higher than the corresponding numerical result. It is believed that this high temperature difference was due to the poor thermal conductivity of the epoxy between the substrate and the carbon foam which was used to bond the carbon foam onto the substrate. Further experimental studies are proposed to use carbon-foam liquid coolers that are prepared with a better bonding technique or by directly processing the carbon foam onto a solid metal surface.
