Contribution To Thermal Resistance Research Articles

Influence of Thermal Contact Resistance of Aluminum Foams in Forced Convection: Experimental Analysis

In this paper, the heat transfer performances of aluminum metal foams, placed on horizontal plane surface, was evaluated in forced convection conditions. Three different types of contacts between the sample and the heated base plate have been investigated: simple contact, brazed contact and grease paste contact. First, in order to perform the study, an ad hoc experimental set-up was built. Second, the value of thermal contact resistance was estimated. The results show that both the use of a conductive paste and the brazing contact, realized by means of a copper electro-deposition, allows a great reduction of the global thermal resistance, increasing de facto the global heat transfer coefficient of almost 80%, compared to the simple contact case. Finally, it was shown that, while the contribution of thermal resistance is negligible for the cases of brazed and grease paste contact, it is significantly high for the case of simple contact.

Evaluation of Thermal Conductive Resistance at Organic–Inorganic Interface and Effect of Interfaces on Thermal Conductivity of Composite Materials

The effect of organic–inorganic interfaces on the thermal conductivity of composite materials was studied by evaluating thermal conductive resistance at the organic–inorganic interfaces experimentally. Polymer layers were sandwiched between thin ceramic plates to produce multilayer stacked samples. Through the comparison between the thermal conductivities of the multilayer stacked materials and those of single component materials for both polymers and ceramics, the thermal resistance at the interface between a polymer and a ceramic plate was evaluated. The results suggest that the contribution of thermal resistance becomes significant for actual composite materials because of the increase in the number of interfaces. The results also demonstrate that organic modifications of an inorganic surface could effectively reduce interfacial thermal resistance. The control of interfaces seems to be effective for improving the thermal conduction property of composite materials.

Thermal conductivity of YBa2Cu3O7 from 7 K to 260 K

Thermal conductivity of YBa2Cu3O7 has been measured on samples of a few mm thickness. AboveT c thermal conductivity is found to decrease with increase in temperature, pointing towards a contribution to thermal resistivity from three-phonon Umklapp processes. BelowT c thermal conductivity increases rapidly before reaching a maximum at about 50 K and then falls towards zero at lower temperatures. The experimental set up is described and results discussed.