Experimental study on single-phase convective heat transfer of interlocking double-layer counterflow mini-channel heat sink

This study proposes an interlocking double-layer mini-channel heat sink that can realize counterflow in which the flow direction is opposite in the adjacent channel. The heat sink consists of two-channel layers and a header/ plenum structure serving as a pre-flow path for counterflow into the channels. The novelty and significance of the current study are that the counterflow multi-channel heat sink was first experimentally implemented through the design of a new internal flow distribution structure. The test data are obtained from the experimental evaluation of the single-phase flow cooling performance of the heat sink. The heat transfer characteristics of the heat sink are analyzed by separating the change in the single channel heat transfer coefficient increased by the counterflow channel effect. The thermal resistance representing the overall cooling performance of the proposed heat sink shows a significantly small value of 10-4 K-m2/W order, which indicates the heat transfer performance advantage of the new heat sink. The beneficial effect of counterflow is verified by comparing the heat transfer coefficient obtained from the proposed heat sink and the prediction using the previous correlation for unidirectional single-phase flow heat transfer coefficient. The measured heat transfer coefficients are much larger than the predicted values by all kinds of past correlations. The difference between the measured value and the predicted value is much greater at low flow conditions where the temperature gradient increases more significantly with the flow direction. It can be concluded that this indirectly implies the fact that temperature gradient mitigation by counterflow results in an additional heat transfer improvement that is unpredictable in the previous unidirectional flow correlations. A new correlation is proposed to predict the heat transfer coefficient affected by the counterflow. This study is the first to experimentally implement a counterflow heat sink, confirming the distinct advantage of improved cooling performance over conventional heatsinks. In addition, this study is meaningful in that it presents a performance prediction model that can be used in design for the practical application of counterflow heat sinks.