Performance of water cooled minichannel heat sink with cross flow

Abstract

Minichannels embedded in solid matrix has already been proven as a very efficient way of electronic cooling. Traditional minichannel heat sink consists of a single layer of parallel channels fabricated in silicon or copper substrate. Although the minichannel heat sink can achieve very high heat flux, its pumping requirement for circulating liquid through the channel increases very sharply as the flow velocity increases. Besides, there exists a very sharp temperature rise along the length of the mini channel heat sink. In many cases, the hydrodynamic developing length covers a large portion of the channel and the thermal entrance length is more than the channel length. As the hydrodynamic and thermal boundary layer grows, heat transfer coefficient reduces due to the thickening of the boundary layer. By breaking the boundary layer along the flow length, thermal boundary layer can be redeveloped and thus the benefit of the higher heat transfer coefficient of the entry region can be achieved. Thus, by dividing the flow channel into several zones with the cross channel, heat removal capacity of the heat sink can be increased and at the same time pumping requirements can be reduced. The hydrodynamic and thermal characteristics of the minicahnnel with cross connection has been studied experimentally and numerically. The effect of the cross channel on the thermal performance of the mini channel heat sink has been investigated. A maximum of 18% heat transfer enhancement has been achieved with the cross connection compared with the straight minichannel heat sink. Based on the experimental results, a numerical investigation by using FLUENT has been performed to improve understanding of the fundamental mechanisms involved with the cross channel. Some parametric studies have also been performed with this numerical model to optimize the design parameters of the heat sink with cross connection.