| With the development of microelectronics technology, computer technology, aerospace technology, communication technology, network technology and electric equipment industry are promoted rapidly. This makes the power density of electronic components increase sharply, and whether it can be effectively cooled has become a key problem to be solved. Take computer chips for example, the traditional heat sink-fan cooler increasingly reveals its weaknesses and limitations, so we must put forward new solutions to deliver this high heat transfer flux. And in such challenges and opportunities, liquid cooling technology appeared. From the aspect of heat dissipation, the liquid directly applied in cooling the electronic devices in the form of jet impingement has its unique advantages. Jet impingement is known as the highest single-phase heat transfer coefficient of convective heat transfer mode, especially in the smaller heat transfer temperature difference, the heat dissipation performance is becomes more obvious.In this paper, the thermal performance and flow characteristic of pin-fin heat sinks with confined and submerged liquid water jet array impingement are investigated. The results indicate that:compared with free-surface, Nusselt number of enhanced-surface will increase 50% in average. The performance of heat sinks is closely related to the height of the pin-fin, but not the higher the better; Nusselt number is pyramidal distribution in 0.625≤W/G≤1.0; For the confined and submerged jet arrays are strongly depend on both jet-to-target and jet-to-jet spacing was observed, Nusselt number falls continuously between 2.5≤H/d≤10; An increment in jet-to-jet spacing between 3~4.5 was found to decrease Nusselt number when Re<4000; A reduction in jet-to-jet spacing between 4.5~7 is found to decrease Nusselt number rapidly, especially for high Reynolds number. The thermal resistance of heat sinks will decline with the increase of pump power, and then slowly. In addition, the results indicate that the pressure drop mainly occurred in orifices, inlet and outlet, and they take up nearly 80%. In short, the effect of jet arrays and pin-fin surfaces on heat transfer is extremely complicated, and it requires more in-depth exploration.One of the standards to measure the strengths and weaknesses of a cooler performance is the distribution of temperature, especially the temperature magnitude and uniformity of the cooled surface. In this paper, based on the numerical simulation on confined and submerged liquid water jet array impingement, the distributions of temperature, velocity and pressure field are discussed. The results indicate that: The turbulence model RNG k-εis usually applied in confined and submerged liquid water jet array impingement. Generally, the heat transfer is poor among orifices and near the boundary. Moreover, the velocities from every orifice were not the same, and there was a phenomenon of main flow deviation. This result indicates that there is some error when treat the impinging velocity as homogeneous value.Finally, based on the above study, we designed a complete set of liquid cooling system of computer CPU chip, and then tested it on the running computer. The results are shown as following: this liquid cooling system can effectively lower the temperature of the CPU, so compared with the traditional air-cooled and ordinary water cooler, this system has more superior heat dissipation performance. This system is not only applied to CPU chip but also other electronic chips. So it has a wider application prospects, and can be popularized easily. |
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