A New Assessment Modus for Heat Transfer Characteristics of Supercritical Co2 in Horizontal Heated Micro-Channel

An in-depth comprehension of special heat transfer(HT) properties of supercritical CO 2 in microchannels is a key point to achieve compactness and miniaturization of microchannel heat sinks for small electronic devices. Based on theoretical analysis and simulation verification, this paper proposes a new assessment method for evaluating local HT characteristics by combining Richardson number Ri and effective thermal conductivity(ETC). The effects of inlet temperature, inlet pressure, heat and mass flux on the local HT performance in microchannel are analyzed by utilizing the proposed new assessment method. The results show that smaller inlet temperature, ratio of heat flux to mass flux( q/G ) and inlet pressure can bring about the outstanding HT behavior in micro-channel. The deteriorated heat transfer may take place more easily under high ratio of q/G . The local HT characteristics are strongly related to the ETC in buffer layer. The HT increase created via buoyancy force can also ascribe to ameliorated ETC in boundary layer. The HT mechanism of supercritical CO 2 at the heating process is elucidated based on the dual-effect of Ri and ETC. This study may be able to offer a direction for the optimization of the micro-channel heat sinks