Plate-pin heat sinks are widely used for the electronic cooling system,internal combustion IC engine,cooling of gas turbine blades and other different applications to enhance the thermal performance of heat sinks due ...Plate-pin heat sinks are widely used for the electronic cooling system,internal combustion IC engine,cooling of gas turbine blades and other different applications to enhance the thermal performance of heat sinks due to simplicity,low cost,and a reliable manufacturing process.However,compact heat sinks give higher pressure drop compared with other types of heat sinks.The purpose of this article is to summarise the main advantages and disadvantages of the compact heat sink with some recommendation studies for future works heat sink thermal airflow experiment and simulations.Furthermore,the research attempts to highlight the importance of balance the relationship between the hydraulic performance and the thermal performance of compact heat sinks。展开更多
To study the seepage and deformation characteristics of coal at high temperatures,coal samples from six different regions were selected and subjected to computed tomography(CT)scanning studies.In conjunction with ANSY...To study the seepage and deformation characteristics of coal at high temperatures,coal samples from six different regions were selected and subjected to computed tomography(CT)scanning studies.In conjunction with ANSYS software,3 D reconstruction of CT images was used for the establishment of fluidsolid conjugate heat transfer model and coal thermal deformation model based on the microstructures of coal.In addition,the structure of coal was studied in 2 D and 3 D perspectives,followed by the analysis of seepage and deformation characteristics of coal at high temperatures.The results of this study indicated that porosity positively correlated with the fractal dimension,and the connectivity and seepage performances were roughly identical from 2 D and 3 D perspectives.As the porosity increased,the fractal dimension of coal samples became larger and the pore-fracture structures became more complex.As a result,the permeability of coal samples decreased.In the meantime,fluid was fully heated,generating high-temperature water at outlet.However,when the porosity was low,the outlet temperature was very high.The average deformation of coal skeleton with different pore-fracture structures at high temperatures showed a trend of initial increase and subsequent decrease with the increase of porosity and fractal dimension.The maximum deformation of coal skeleton positively correlated with connectivity but negatively correlated with the fractal dimension.展开更多
To investigate the role of a single shield on steady temperature measurement using therrnocouples in hot air flow, a methodology for solving convection, conduction, and radiation in one single model is provided. In or...To investigate the role of a single shield on steady temperature measurement using therrnocouples in hot air flow, a methodology for solving convection, conduction, and radiation in one single model is provided. In order to compare with the experimental results, a cylindrical computational domain is established, which is the same size with the hot calibration wind-tannel. In the computational domain, two kinds of thermocouples, the bare-bead and the single-shielded thermocouples, are simulated respectively. Surface temperature distribution and the tempera- ture measurement bias of the two typical thermocouples are compared. The simulation results indicate that： 1） The existence of the shield reduces bead surface heat flux and changes the direction of wires inner heat conduction in a colder surrounding; 2） The existence of the shield reduces the temperature measurement bias both by improving bead surface temperature and by reducing surface temperature gradient; 3） The shield effectively reduces the effect of the ambient temperature on the temperature measurement bias; 4） The shield effectively reduces the influence of airflow velocity on the temperature measurement bias.展开更多
文摘Plate-pin heat sinks are widely used for the electronic cooling system,internal combustion IC engine,cooling of gas turbine blades and other different applications to enhance the thermal performance of heat sinks due to simplicity,low cost,and a reliable manufacturing process.However,compact heat sinks give higher pressure drop compared with other types of heat sinks.The purpose of this article is to summarise the main advantages and disadvantages of the compact heat sink with some recommendation studies for future works heat sink thermal airflow experiment and simulations.Furthermore,the research attempts to highlight the importance of balance the relationship between the hydraulic performance and the thermal performance of compact heat sinks。
基金supported by the National Natural Science Foundation of China(Project Nos.51934004,51674158,51574158,and 51474106)the Major Program of Shandong Province Natural Science Foundation(ZR2018ZA0602)+2 种基金the Taishan Scholar Talent Team Support Plan for Advantaged&Unique Discipline Areasthe Science and technology support plan for Youth Innovation of colleges and universities in Shandong Province(2019KJH006)the special funds for Taishan scholar project(TS20190935)。
文摘To study the seepage and deformation characteristics of coal at high temperatures,coal samples from six different regions were selected and subjected to computed tomography(CT)scanning studies.In conjunction with ANSYS software,3 D reconstruction of CT images was used for the establishment of fluidsolid conjugate heat transfer model and coal thermal deformation model based on the microstructures of coal.In addition,the structure of coal was studied in 2 D and 3 D perspectives,followed by the analysis of seepage and deformation characteristics of coal at high temperatures.The results of this study indicated that porosity positively correlated with the fractal dimension,and the connectivity and seepage performances were roughly identical from 2 D and 3 D perspectives.As the porosity increased,the fractal dimension of coal samples became larger and the pore-fracture structures became more complex.As a result,the permeability of coal samples decreased.In the meantime,fluid was fully heated,generating high-temperature water at outlet.However,when the porosity was low,the outlet temperature was very high.The average deformation of coal skeleton with different pore-fracture structures at high temperatures showed a trend of initial increase and subsequent decrease with the increase of porosity and fractal dimension.The maximum deformation of coal skeleton positively correlated with connectivity but negatively correlated with the fractal dimension.
基金supported by the National Natural Science Foundation of China(Grant No.51776011)
文摘To investigate the role of a single shield on steady temperature measurement using therrnocouples in hot air flow, a methodology for solving convection, conduction, and radiation in one single model is provided. In order to compare with the experimental results, a cylindrical computational domain is established, which is the same size with the hot calibration wind-tannel. In the computational domain, two kinds of thermocouples, the bare-bead and the single-shielded thermocouples, are simulated respectively. Surface temperature distribution and the tempera- ture measurement bias of the two typical thermocouples are compared. The simulation results indicate that： 1） The existence of the shield reduces bead surface heat flux and changes the direction of wires inner heat conduction in a colder surrounding; 2） The existence of the shield reduces the temperature measurement bias both by improving bead surface temperature and by reducing surface temperature gradient; 3） The shield effectively reduces the effect of the ambient temperature on the temperature measurement bias; 4） The shield effectively reduces the influence of airflow velocity on the temperature measurement bias.
