The behavior of single-phase flow and conjugate heat transfer in micro-channel heat sinks(MCHS)subjected to auniform heat flux is investigated by means of numerical simulations.Various geometrical configurations areex...The behavior of single-phase flow and conjugate heat transfer in micro-channel heat sinks(MCHS)subjected to auniform heat flux is investigated by means of numerical simulations.Various geometrical configurations areexamined,particularly,the combinations of rectangular solid and perforated blocks,used to create a disturbancein the flow.The analysis focuses on several key aspects and related metrics,including the temperature distribution,the mean Fanning friction factor,the pressure drop,the Nusselt number,and the overall heat transfer coefficientacross a range of Reynolds numbers(80–870).It is shown that the introduction of such blocks significantlyenhances the heat transfer performances of the MCHS compared to the straight-through flow channel.Specifically,a case is found where the Nusselt number increases by 2.3 times relative to the reference case.The integrationof perforated blocks facilitates the generation of vorticity within the channel,promoting the mixing of coldand hot fluids.Notably,MCHS incorporating perforated rectangular blocks exhibit more pronounced heat transferbenefits at Reynolds numbers smaller than 400.展开更多
In order to reduce or avoid the fluctuations from interface breakup, a meandering microchannel with curved multi-bends(44 turns) is fabricated, and investigations of scaling bubble/slug length in Taylor flow in a rect...In order to reduce or avoid the fluctuations from interface breakup, a meandering microchannel with curved multi-bends(44 turns) is fabricated, and investigations of scaling bubble/slug length in Taylor flow in a rectangular meandering microchannel are systematically conducted. Based on considerable experimental data,quantitative analyses for the influences of two important characteristic times, liquid phase physical properties and aspect ratio are made on the prediction criteria for the bubble/slug length of Taylor flow in a meandering microchannel. A simple principle is suggested to predict the bubble formation period by using the information of Rayleigh time and capillary time for six gas–liquid systems with average deviation of 10.96%. Considering physical properties of the liquid phase and cross-section configuration of the rectangular mcirochannel,revised scaling laws for bubble length are established by introducing Ca, We, Re and W/h whether for the squeezing-driven or shearing-driven of bubble break. In addition, a simple principle in terms of Garstecki-type model and bubble formation period is set-up to predict slug lengths. A total of 107 sets of experimental data are correlated with the meandering microchannel and operating range: 0.001 b CaTPb 0.05, 0.06 b WeTPb 9.0,18 b ReTPb 460 using the bubble/slug length prediction equation from current work. The average deviation between the correlated data and the experimental data for bubble length and slug length is about 9.42% and9.95%, respectively.展开更多
基金funded by the Project of the Hubei Provincial Department of Science and Technology(Grant No.2022CFB957)the Project of Hubei Engineering University of Teaching Research(Grant No.JY2024032)+1 种基金Ministry of Education University-Industry Cooperation Collaborative Education Project(Grant No.220903584161245)College Students’Innovation and Entrepreneurship Training Program(Grant Nos.DC2024031,DC2024032).
文摘The behavior of single-phase flow and conjugate heat transfer in micro-channel heat sinks(MCHS)subjected to auniform heat flux is investigated by means of numerical simulations.Various geometrical configurations areexamined,particularly,the combinations of rectangular solid and perforated blocks,used to create a disturbancein the flow.The analysis focuses on several key aspects and related metrics,including the temperature distribution,the mean Fanning friction factor,the pressure drop,the Nusselt number,and the overall heat transfer coefficientacross a range of Reynolds numbers(80–870).It is shown that the introduction of such blocks significantlyenhances the heat transfer performances of the MCHS compared to the straight-through flow channel.Specifically,a case is found where the Nusselt number increases by 2.3 times relative to the reference case.The integrationof perforated blocks facilitates the generation of vorticity within the channel,promoting the mixing of coldand hot fluids.Notably,MCHS incorporating perforated rectangular blocks exhibit more pronounced heat transferbenefits at Reynolds numbers smaller than 400.
基金Supported by the National Natural Science Foundation of China(21476037,21606034).
文摘In order to reduce or avoid the fluctuations from interface breakup, a meandering microchannel with curved multi-bends(44 turns) is fabricated, and investigations of scaling bubble/slug length in Taylor flow in a rectangular meandering microchannel are systematically conducted. Based on considerable experimental data,quantitative analyses for the influences of two important characteristic times, liquid phase physical properties and aspect ratio are made on the prediction criteria for the bubble/slug length of Taylor flow in a meandering microchannel. A simple principle is suggested to predict the bubble formation period by using the information of Rayleigh time and capillary time for six gas–liquid systems with average deviation of 10.96%. Considering physical properties of the liquid phase and cross-section configuration of the rectangular mcirochannel,revised scaling laws for bubble length are established by introducing Ca, We, Re and W/h whether for the squeezing-driven or shearing-driven of bubble break. In addition, a simple principle in terms of Garstecki-type model and bubble formation period is set-up to predict slug lengths. A total of 107 sets of experimental data are correlated with the meandering microchannel and operating range: 0.001 b CaTPb 0.05, 0.06 b WeTPb 9.0,18 b ReTPb 460 using the bubble/slug length prediction equation from current work. The average deviation between the correlated data and the experimental data for bubble length and slug length is about 9.42% and9.95%, respectively.
