This work examines the microstructure and corrosion properties of fine-grained Al 7075 across different regions under varying cooling conditions during friction stir welding.The findings demonstrate that forced coolin...This work examines the microstructure and corrosion properties of fine-grained Al 7075 across different regions under varying cooling conditions during friction stir welding.The findings demonstrate that forced cooling significantly improves the corrosion resistance of the welded joints.Specifically,the corrosion resistance was the highest in the stir zone,followed by the thermo-mechanical affected zone,and then the heat affected zone.Forced cooling mitigates grain growth by controlling the welding thermal effects,thereby increasing the proportion ofΣ3 grain boundaries.The modification of these microstructural characteristics promotes the formation of a dense oxide layer,thereby enhancing the corrosion resistance.Furthermore,forced cooling mitigates the precipitation and coarsening of the anodic phase in the stir zone,which in turn reduces the susceptibility of the joint to pitting corrosion.Additionally,the lower recrystallization texture content in the joint,resulting from forced cooling,contributes to a reduction in the number of corrosion-active sites,thereby further improving the corrosion performance of the welded joint.展开更多
Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strate...Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strategy.With the continuous development of radiative cooling technologies,the material selection,preparation process,structural design,and applica-tion fields have also made more diverse progress.Therefore,this review aims to systematically introduce the fundamental concepts and underlying principles of radiative cooling.A summary of the commonly used materials for radiative cooling is provided.In addition,the advanced fabrication processes and structural designs of radiative cooling materials are further explored and discussed.Subsequently,the unique functions of radiative cooling materials are highlighted to enhance their applicability and usefulness across various fields.An overview of combining radiative cooling materials with different fields is also provided.In reality,these applications hold the potential to improve thermal management across a range of fields.Finally,it summarizes the shortcomings and great potential of radiative cooling materials in various fields.It also looks forward to the future,aiming to promote the progress and widespread adoption of radiative cooling technologies.展开更多
The cooling gradient of Mg-3 Zn-1 Ca-0.5 Sr alloy in cast ingots under different cooling methods(air cooling,warm-water cooling and ice-water-mixture cooling) was examined and the effect of cooling rate on the structu...The cooling gradient of Mg-3 Zn-1 Ca-0.5 Sr alloy in cast ingots under different cooling methods(air cooling,warm-water cooling and ice-water-mixture cooling) was examined and the effect of cooling rate on the structure and corrosion properties was studied.The microstructure of the alloy was composed of α-Mg,Ca_(2) Mg_(6) Zn_(3) and Mg_(17)Sr_(2) phases.As the solidification cooling rate increased,the grain was refined,Zn and Sr were less segregated,the distributions of Zn and Sr were more uniform,and corrosion rate was found to first increase and then decrease;this contradicts the findings of recent research.With cooling rate increasing,the number of corroded microcouples comprising second phase and α-Mg increases.More α-Mg participates in corrosion,leading to a layered and deep corrosion pit and an increased corrosion rate.However,as the microstructure became sufficiently dense,the corroded structure protected the deep α-Mg from participating in corrosion,thus reducing the corrosion rate.展开更多
Effects of cooling methods on stability and methane conversion rate using dielectric-barrier discharges （DBD） were systematically investigated in this article. The results showed that the methane conversion rate was...Effects of cooling methods on stability and methane conversion rate using dielectric-barrier discharges （DBD） were systematically investigated in this article. The results showed that the methane conversion rate was as high as 44.43% in a pure methane system at a flow rate of 100 mL·min^-1 and an input power of 234.2 W with air cooling. A dark greenish and soft film-like carbon was deposited on the outer surface of quartz tube when the outer electrode was watercooled, which decreased the methane conversion. With air cooling of inner electrode the selectivity of C2 hydrocarbons was higher than that with other cooling methods, while the C3 hydrocarbons had higher selectivity with flowing water cooling. Cooling the inner electrode could restrain the carbon deposition, but would decrease the methane conversion rate. The stability of both reaction and plasma operation can be improved through cooling the reactor. From thermodynamic analysis, it was found that the effective collisions frequency among the reactant molecules and free electrons （e^-） increased with temperature, which in turn led to a higher methane conversion rate and a change in the distribution of products.展开更多
In this paper, the ring-type ingot of hypereutectic high Cr cast iron was obtained by slope cooling bodycentrifugal casting method （SC-CCM）, and its microstructure and impact toughness were investigated, respectivel...In this paper, the ring-type ingot of hypereutectic high Cr cast iron was obtained by slope cooling bodycentrifugal casting method （SC-CCM）, and its microstructure and impact toughness were investigated, respectively. The results indicated that, first, the primary carbides in the microstructure are prominently finer than those in the hypereutectic high Cr cast iron prepared by conventional casting method. Second, in the ring-type ingot, the primary carbides near radial outer field are finer than those near radial inner field; furthermore, there is dividing field in the microstructure. Finally, the impact toughness values of the specimens impacted on the radial outer face and on the radial inner face are improved respectively about 36% and 138% more than that of the hypereutectic high Cr one prepared by conventional casting method.展开更多
In semi-solid forming process, preparing the slurry with rosette or globular microstructure is very important. A new approach named the damper cooling tube method （DCT）, to produce the semi-solid metal slurry, has b...In semi-solid forming process, preparing the slurry with rosette or globular microstructure is very important. A new approach named the damper cooling tube method （DCT）, to produce the semi-solid metal slurry, has been introduced. To optimize the technical parameters in designing the apparatus, the finite volume method was adopted to simulate the flow process. The temperature effects on the rheological properties of the slurries were also considered. The effects of the technical parameters on the slurry properties were studied in detail.展开更多
Soft magnetic properties of Fe82Mo7B10Cu1 nanocrystalline alloy were studied as a function of cooling condition. The results show that higher permeability and relaxation frequency can be obtained by the two-step cooli...Soft magnetic properties of Fe82Mo7B10Cu1 nanocrystalline alloy were studied as a function of cooling condition. The results show that higher permeability and relaxation frequency can be obtained by the two-step cooling method, and the pinning field of the sample obtained by this method is smaller than that of the furnace-cooled and water-quenched samples. This phenomenon was interpreted in terms of internal stress and the magnetic ordering of the residual amorphous phase. The two-step cooling treatment is an effective way to improve the soft magnetic properties of Fe82Mo7B10Cu1 nanocrystalline alloy.展开更多
Static uniaxial compression tests were conducted on 16 granite specimens after thermal treatment using a heating device and an electro-hydraulic servo pressure-testing machine. The effects of air cooling and water coo...Static uniaxial compression tests were conducted on 16 granite specimens after thermal treatment using a heating device and an electro-hydraulic servo pressure-testing machine. The effects of air cooling and water cooling on the physical and mechanical properties of the high-temperature granite specimens were studied. Test results showed that the longitudinal wave velocities of the high-temperature specimens gradually decreased after they were cooled by water and air. The peak stress and elastic modulus of the samples decreased gradually with an increase in temperature, whereas their peak strain increased gradually. The effects of peak stress and peak strain were considerably more evident when cooling by water than by air. This result demonstrated that the thermal cracking of the granite specimens, and consequently, their internal micro-fractures, further developed when the specimens were cooled by water.展开更多
It was tried to prepare the thermosensitive microcapsules containing the water soluble solid powder by the melting dispersion cooling method and to establish the optimum preparation conditions. As a model water solubl...It was tried to prepare the thermosensitive microcapsules containing the water soluble solid powder by the melting dispersion cooling method and to establish the optimum preparation conditions. As a model water soluble solid powder, sodium hydrogen carbonate was adopted in order to generate carbon dioxide gas and as a thermosensitive shell material, olefin resin with the melting point of ca. 40°C was used. In the experiment, the concentration of olefin resin in the shell material solution was mainly changed together with the concentrations of the oil soluble surfactant species and the α-tocopherol as a modifier of shell. Addition of α-tocopherol into the shell material solution could prevent the core from breaking away during the microencapsulation process and result in the higher microencapsulation efficiency, because the dispersion stability of solid powder in the shell material solution could be increased due to the increase in affinity between the shell material solution and solid powder. Also, the microencapsulation efficiency increased with the concentration of olefin resin, became maximum at 50 wt% and then, decreased. The microcapsules were found to begin melting at 36°C and to generate carbon dioxide gas.展开更多
Metallographic microscopy,scanning electron microscopy and TiN growth thermodynamic and kinetic equations were used to investigate the morphology,quantity,and size of TiN in the center of high-titanium high-strength s...Metallographic microscopy,scanning electron microscopy and TiN growth thermodynamic and kinetic equations were used to investigate the morphology,quantity,and size of TiN in the center of high-titanium high-strength steels under different solidification cooling rates.The results showed that TiN in the center of the experimental steels mainly existed in three forms:single,composite(Al2O3-TiN),and multi-particle aggregation.TiN began precipitating at around 1497℃(solidification fraction of 0.74).From the end of melting to solidification for 180 s,the cooling rates in the center of the experimental steels for furnace cooling,air cooling,refractory mold cooling,and cast iron mold cooling tended to stabilize at 0.17,0.93,1.65,and 2.15℃/s,respectively.The size of TiN in the center of the experimental steel cooled using furnace cooling was mainly concentrated in the 5-15 pm range.In contrast,the size of TiN in the center of the experimental steels cooled using air cooling,refractory mold cooling,and cast iron mold cooling were mainly concentrated in the 1-5 pm range.In addition,their density of TiN in the center of the experimental steels is signif-icantly higher than that of the furnace-cooled experimental steel.Thermodynamic and kinetic precipitation models of TiN established predicted the growth size of TiN in a high-titanium high-strength steel when the solidification cooling rates are not below 0.93℃/s.展开更多
The healthy and rapid development of the controlled cooling technology was hampered by the uneven cooling phenomenon. During the process of hot plate production,the homogeneous cooling along the length direction of pl...The healthy and rapid development of the controlled cooling technology was hampered by the uneven cooling phenomenon. During the process of hot plate production,the homogeneous cooling along the length direction of plate was constrained by lots of factors. And because the speed was a flexible control parameter,the calculation method of optimal speed profile was developed based on the measured start cooling temperature and its matrix equation was solved by the Cholesky decomposition method. The optimal speed profile was used in online control system. As a result,the temperature distribution along the plate length direction was relatively uniform,and 95% of measured final cooling temperature difference from the target temperature 700 ℃ was controlled within ±20 ℃.展开更多
The embedded water pipe system is often used as a standard cooling technique during the construction of large-scale mass concrete hydrostructures. The prediction of the temperature distribution considering the cooling...The embedded water pipe system is often used as a standard cooling technique during the construction of large-scale mass concrete hydrostructures. The prediction of the temperature distribution considering the cooling effects of embedded pipes plays an essential role in the design of the structure and its cooling system. In this study, the singular boundary method, a semi-analytical meshless technique, was employed to analyze the temperature distribution. A numerical algorithm solved the transient temperature field with consideration of the effects of cooling pipe specification, isolation of heat of hydration, and ambient temperature. Numerical results are verified through comparison with those of the finite element method, demonstrating that the proposed approach is accurate in the simulation of the thermal field in concrete structures with a water cooling pipe.展开更多
Microcapsules containing the aqueous solution of Azur B of a water soluble dye were prepared with the melting dispersion cooling method and applied to the amplification detector of plant DNA. Paraffin wax with melting...Microcapsules containing the aqueous solution of Azur B of a water soluble dye were prepared with the melting dispersion cooling method and applied to the amplification detector of plant DNA. Paraffin wax with melting temperature of 75°C was used as the shell material. In the experiment, the aqueous solution (W) of Azur B as the core material was dispersed in the melted paraffin wax (O) to form the (W/O) emulsion and then, the (W/O) emulsion was dispersed in the silicon oil (O’) as the continuous phase to form the (W/O)/O’ emulsion at 85°C. After formation of the (W/O)/O’ emulsion, the microcapsules were prepared by cooling the (W/O)/O’ emulsion to 50°C. The microcapsules were prepared by changing the concentration of oil soluble surfactant in the (W/O) emulsion and the volume of the (W/O) emulsion in the (W/O)/O’ emulsion. The microencapsulation efficiency increased with the concentration of oil soluble surfactant and finally became 100% under the optimum conditions. Furthermore, the microcapsules were melted down at temperature of 85°C to reveal the sharp thermal responsibility and to release the aqueous solution of Azur B. As a result, it was found that the microcapsules were able to be applied to the amplification detector of plant DNA by utilizing the reaction between DNA and Azur B.展开更多
11% of Irish electricity was consumed by data centres in 2020. The Irish data centre industry and the cooling methods utilised require reformative actions in the coming years to meet EU Energy policies. The resell of ...11% of Irish electricity was consumed by data centres in 2020. The Irish data centre industry and the cooling methods utilised require reformative actions in the coming years to meet EU Energy policies. The resell of heat, alternative cooling methods or carbon reduction methods are all possibilities to conform to these policies. This study aims to determine the viability of the resell of waste heat from data centres both technically and economically. This was determined using a novel application of thermodynamics to determine waste heat recovery potential in Irish data centres, and the current methods of heat generation for economical comparison. This paper also explores policy surrounding waste heat recovery within the industry. The Recoverable Carnot Equivalent Power (RCEP) is theoretically calculated for the three potential cooling methods for Irish data centres. These are air, hybrid, and immersion cooling techniques. This is the maximum useable heat that can be recovered from a data centre rack. This study is established under current operating conditions which are optimised for cooling performance, that air cooling has the highest potential RCEP of 0.39 kW/rack. This is approximately 8% of the input electrical power that can be captured as useable heat. Indicating that Irish data centres have the energy potential to be heat providers in the Irish economy. This study highlighted the technical and economic aspects of prevalent cooling techniques and determined air cooling heat recovery cost can be reduced to 0.01 €/kWhth using offsetting. This is financially competitive with current heating solutions in Ireland.展开更多
This paper implemented cooling configuration design on certain gas turbine HP rotor using parameterized method.It is convenient for complicated gas turbine blade modeling using parameters and also benefit for the geom...This paper implemented cooling configuration design on certain gas turbine HP rotor using parameterized method.It is convenient for complicated gas turbine blade modeling using parameters and also benefit for the geometry modify in later period.Parameterized modeling is the foundation of air cooling turbine blade design method engineering application.Mesh quality can be awarded when generated complicated cooling configuration blade grids,and also the increase of calculation error can arise by many mesh blocks.Film cooling and serpentine passage can effectively enhance the cooling effectiveness and protect blade.展开更多
1 Today,many people face the challenge of extreme summer heat,often relying on air conditioning to stay cool.However,air conditioning consumes significant energy and contributes to climate change.To address this issue...1 Today,many people face the challenge of extreme summer heat,often relying on air conditioning to stay cool.However,air conditioning consumes significant energy and contributes to climate change.To address this issue,researchers are exploring innovative cooling methods inspired by both ancient techniques and modern technology.展开更多
The aluminum(Al)/steel transition joints used in ships are processed from composite plates,and their mechanical properties have a significant impact on the safety of ships.In this paper,the Al/steel composite plate wa...The aluminum(Al)/steel transition joints used in ships are processed from composite plates,and their mechanical properties have a significant impact on the safety of ships.In this paper,the Al/steel composite plate was prepared using rolling,with 5083 aluminum plate as the cladding plate,Q235 steel plate as the substrate,and TA1 titanium(Ti)plate and DT4 pure iron(Fe)plate as the intermediate layers.The heterothermic billet was prepared through induction heating by the magnetic effects of the steel plate and the pure Fe plate,and then the Al/steel composite plate was obtained by rolling.The impacts of post-rolling cooling process on the microstructure and properties of the Al/Ti/pure Fe/steel composite plate were studied.The results manifested that the pure Fe/steel interface had a good composite effect.With the increase in the cooling rate,the bonding strength of the Al/Ti interface was raised,and that of the Ti/Fe interface was increased first and then decreased.When the oil cooling process was adopted,the Al/Ti/pure Fe/steel composite plate exhibited the highest comprehensive performance.The shear strength of the Al/Ti interface and the Ti/Fe interface was 102 MPa and 186 MPa,respectively.The plastic fracture was determined as the mode of interface fracture.展开更多
As a potential candidate for generation IV reactors, lead-alloy cooled reactor has attracted much attentions in recent years. The China LEAd-based research Reactor(CLEAR) is proposed as the primary choice for the acce...As a potential candidate for generation IV reactors, lead-alloy cooled reactor has attracted much attentions in recent years. The China LEAd-based research Reactor(CLEAR) is proposed as the primary choice for the accelerator driven subcritical system project launched by Chinese Academy of Sciences. Lead-bismuth eutectic(LBE) is selected as the coolant of CLEAR owing to its efficient heat conductivity properties and high production rate of neutrons. In order to compensate the buoyancy due to the high density of lead-alloy, fixation methods of fuel assembly(FA) have become a research hotspot worldwide. In this paper, we report an integrated system of ballast and fuel element for CLEAR FA. It guarantees the correct positioning of each FA in normal and refueling operations. Force calculation and temperature analysis prove that the FA will be stable and safe under CLEAR operation conditions.展开更多
Power Electronic (PE) will play an essential role in future drive concepts. Nowadays, mainly water/glycol-based cooling media are used to cool PE. Due to their high electrical conductivity (EC), water/glycol-based coo...Power Electronic (PE) will play an essential role in future drive concepts. Nowadays, mainly water/glycol-based cooling media are used to cool PE. Due to their high electrical conductivity (EC), water/glycol-based coolants cannot be used for direct cooling of the electrical components. Direct cooling concepts with dedicated transmission fluids show potential usage of fluid in direct contact with electrified parts. This results in special requirements for the fluids and materials. The aimed action as a coolant requires a defined measurement and characterization of fluid properties and heat transfer in order to assess the cooling ability of a fluid. The purpose of the work was to develop a new measurement setup based on the thermal transient method with which the thermal requirements of cooling fluids for a direct cooling concept can be assessed. With this method, relevant transmission fluids have been tested and the thermal performance compared to indirect cooling effect of water/glycol is discussed. The result of the work is that the measurement method is very well suited for the application-related evaluation of the fluids. Direct oil cooling with transmission fluids could increase heat transfer coefficient by a factor of 3 to 8, compared to the indirect cooing with water/glycol as cooling media.展开更多
基金Project(ASM-20240)supported by the Key Laboratory of Advanced Structural Materials(Changchun University of Technology),Ministry of Education,ChinaProject(2022TD-30)supported by the Scientific and Technological Innovation Team Project of Shaanxi Innovation Capability Support Plan,China。
文摘This work examines the microstructure and corrosion properties of fine-grained Al 7075 across different regions under varying cooling conditions during friction stir welding.The findings demonstrate that forced cooling significantly improves the corrosion resistance of the welded joints.Specifically,the corrosion resistance was the highest in the stir zone,followed by the thermo-mechanical affected zone,and then the heat affected zone.Forced cooling mitigates grain growth by controlling the welding thermal effects,thereby increasing the proportion ofΣ3 grain boundaries.The modification of these microstructural characteristics promotes the formation of a dense oxide layer,thereby enhancing the corrosion resistance.Furthermore,forced cooling mitigates the precipitation and coarsening of the anodic phase in the stir zone,which in turn reduces the susceptibility of the joint to pitting corrosion.Additionally,the lower recrystallization texture content in the joint,resulting from forced cooling,contributes to a reduction in the number of corrosion-active sites,thereby further improving the corrosion performance of the welded joint.
基金National Natural Science Foundation of China Excellent Youth Fund(No.52222509)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)+3 种基金National Key Research and Development Program of China(No.2018YFA0703300)National Natural Science Foundation of China(No.52105298)Science and Technology Development Program of Jilin Province(No.SKL202402005)"Fundamental Research Funds for the Central Universities".
文摘Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strategy.With the continuous development of radiative cooling technologies,the material selection,preparation process,structural design,and applica-tion fields have also made more diverse progress.Therefore,this review aims to systematically introduce the fundamental concepts and underlying principles of radiative cooling.A summary of the commonly used materials for radiative cooling is provided.In addition,the advanced fabrication processes and structural designs of radiative cooling materials are further explored and discussed.Subsequently,the unique functions of radiative cooling materials are highlighted to enhance their applicability and usefulness across various fields.An overview of combining radiative cooling materials with different fields is also provided.In reality,these applications hold the potential to improve thermal management across a range of fields.Finally,it summarizes the shortcomings and great potential of radiative cooling materials in various fields.It also looks forward to the future,aiming to promote the progress and widespread adoption of radiative cooling technologies.
基金Jiangsu Province Achievement Transformation Project(BA2017044)。
文摘The cooling gradient of Mg-3 Zn-1 Ca-0.5 Sr alloy in cast ingots under different cooling methods(air cooling,warm-water cooling and ice-water-mixture cooling) was examined and the effect of cooling rate on the structure and corrosion properties was studied.The microstructure of the alloy was composed of α-Mg,Ca_(2) Mg_(6) Zn_(3) and Mg_(17)Sr_(2) phases.As the solidification cooling rate increased,the grain was refined,Zn and Sr were less segregated,the distributions of Zn and Sr were more uniform,and corrosion rate was found to first increase and then decrease;this contradicts the findings of recent research.With cooling rate increasing,the number of corroded microcouples comprising second phase and α-Mg increases.More α-Mg participates in corrosion,leading to a layered and deep corrosion pit and an increased corrosion rate.However,as the microstructure became sufficiently dense,the corroded structure protected the deep α-Mg from participating in corrosion,thus reducing the corrosion rate.
基金National Natural Science Foundation of China(No.20606023)National Key Natural Science Foundation of China(No.20490203)
文摘Effects of cooling methods on stability and methane conversion rate using dielectric-barrier discharges （DBD） were systematically investigated in this article. The results showed that the methane conversion rate was as high as 44.43% in a pure methane system at a flow rate of 100 mL·min^-1 and an input power of 234.2 W with air cooling. A dark greenish and soft film-like carbon was deposited on the outer surface of quartz tube when the outer electrode was watercooled, which decreased the methane conversion. With air cooling of inner electrode the selectivity of C2 hydrocarbons was higher than that with other cooling methods, while the C3 hydrocarbons had higher selectivity with flowing water cooling. Cooling the inner electrode could restrain the carbon deposition, but would decrease the methane conversion rate. The stability of both reaction and plasma operation can be improved through cooling the reactor. From thermodynamic analysis, it was found that the effective collisions frequency among the reactant molecules and free electrons （e^-） increased with temperature, which in turn led to a higher methane conversion rate and a change in the distribution of products.
基金This work was supported by the National Natural Science Foundation of China under grant No.50571079.
文摘In this paper, the ring-type ingot of hypereutectic high Cr cast iron was obtained by slope cooling bodycentrifugal casting method （SC-CCM）, and its microstructure and impact toughness were investigated, respectively. The results indicated that, first, the primary carbides in the microstructure are prominently finer than those in the hypereutectic high Cr cast iron prepared by conventional casting method. Second, in the ring-type ingot, the primary carbides near radial outer field are finer than those near radial inner field; furthermore, there is dividing field in the microstructure. Finally, the impact toughness values of the specimens impacted on the radial outer face and on the radial inner face are improved respectively about 36% and 138% more than that of the hypereutectic high Cr one prepared by conventional casting method.
基金This work was financially supported by the National Natural Science Foundation of China (No.50374014).
文摘In semi-solid forming process, preparing the slurry with rosette or globular microstructure is very important. A new approach named the damper cooling tube method （DCT）, to produce the semi-solid metal slurry, has been introduced. To optimize the technical parameters in designing the apparatus, the finite volume method was adopted to simulate the flow process. The temperature effects on the rheological properties of the slurries were also considered. The effects of the technical parameters on the slurry properties were studied in detail.
基金Project(50501008) supported by the National Natural Science Foundation of China
文摘Soft magnetic properties of Fe82Mo7B10Cu1 nanocrystalline alloy were studied as a function of cooling condition. The results show that higher permeability and relaxation frequency can be obtained by the two-step cooling method, and the pinning field of the sample obtained by this method is smaller than that of the furnace-cooled and water-quenched samples. This phenomenon was interpreted in terms of internal stress and the magnetic ordering of the residual amorphous phase. The two-step cooling treatment is an effective way to improve the soft magnetic properties of Fe82Mo7B10Cu1 nanocrystalline alloy.
基金Supported by"The Training Plan of College Students'Creation"(2017A53449)in Jilin UniversityNew Energy Item of Jilin Province Combining with Universities(SF2017-5-5)
文摘Static uniaxial compression tests were conducted on 16 granite specimens after thermal treatment using a heating device and an electro-hydraulic servo pressure-testing machine. The effects of air cooling and water cooling on the physical and mechanical properties of the high-temperature granite specimens were studied. Test results showed that the longitudinal wave velocities of the high-temperature specimens gradually decreased after they were cooled by water and air. The peak stress and elastic modulus of the samples decreased gradually with an increase in temperature, whereas their peak strain increased gradually. The effects of peak stress and peak strain were considerably more evident when cooling by water than by air. This result demonstrated that the thermal cracking of the granite specimens, and consequently, their internal micro-fractures, further developed when the specimens were cooled by water.
文摘It was tried to prepare the thermosensitive microcapsules containing the water soluble solid powder by the melting dispersion cooling method and to establish the optimum preparation conditions. As a model water soluble solid powder, sodium hydrogen carbonate was adopted in order to generate carbon dioxide gas and as a thermosensitive shell material, olefin resin with the melting point of ca. 40°C was used. In the experiment, the concentration of olefin resin in the shell material solution was mainly changed together with the concentrations of the oil soluble surfactant species and the α-tocopherol as a modifier of shell. Addition of α-tocopherol into the shell material solution could prevent the core from breaking away during the microencapsulation process and result in the higher microencapsulation efficiency, because the dispersion stability of solid powder in the shell material solution could be increased due to the increase in affinity between the shell material solution and solid powder. Also, the microencapsulation efficiency increased with the concentration of olefin resin, became maximum at 50 wt% and then, decreased. The microcapsules were found to begin melting at 36°C and to generate carbon dioxide gas.
基金supported by Baoshan Iron and Steel Co.,Ltd. (Grant No.RH2100003354).
文摘Metallographic microscopy,scanning electron microscopy and TiN growth thermodynamic and kinetic equations were used to investigate the morphology,quantity,and size of TiN in the center of high-titanium high-strength steels under different solidification cooling rates.The results showed that TiN in the center of the experimental steels mainly existed in three forms:single,composite(Al2O3-TiN),and multi-particle aggregation.TiN began precipitating at around 1497℃(solidification fraction of 0.74).From the end of melting to solidification for 180 s,the cooling rates in the center of the experimental steels for furnace cooling,air cooling,refractory mold cooling,and cast iron mold cooling tended to stabilize at 0.17,0.93,1.65,and 2.15℃/s,respectively.The size of TiN in the center of the experimental steel cooled using furnace cooling was mainly concentrated in the 5-15 pm range.In contrast,the size of TiN in the center of the experimental steels cooled using air cooling,refractory mold cooling,and cast iron mold cooling were mainly concentrated in the 1-5 pm range.In addition,their density of TiN in the center of the experimental steels is signif-icantly higher than that of the furnace-cooled experimental steel.Thermodynamic and kinetic precipitation models of TiN established predicted the growth size of TiN in a high-titanium high-strength steel when the solidification cooling rates are not below 0.93℃/s.
文摘The healthy and rapid development of the controlled cooling technology was hampered by the uneven cooling phenomenon. During the process of hot plate production,the homogeneous cooling along the length direction of plate was constrained by lots of factors. And because the speed was a flexible control parameter,the calculation method of optimal speed profile was developed based on the measured start cooling temperature and its matrix equation was solved by the Cholesky decomposition method. The optimal speed profile was used in online control system. As a result,the temperature distribution along the plate length direction was relatively uniform,and 95% of measured final cooling temperature difference from the target temperature 700 ℃ was controlled within ±20 ℃.
基金supported by the National Natural Science Foundation of China(Grants No.11572111 and 11372097)the 111 Project(Grant No.B12122)
文摘The embedded water pipe system is often used as a standard cooling technique during the construction of large-scale mass concrete hydrostructures. The prediction of the temperature distribution considering the cooling effects of embedded pipes plays an essential role in the design of the structure and its cooling system. In this study, the singular boundary method, a semi-analytical meshless technique, was employed to analyze the temperature distribution. A numerical algorithm solved the transient temperature field with consideration of the effects of cooling pipe specification, isolation of heat of hydration, and ambient temperature. Numerical results are verified through comparison with those of the finite element method, demonstrating that the proposed approach is accurate in the simulation of the thermal field in concrete structures with a water cooling pipe.
文摘Microcapsules containing the aqueous solution of Azur B of a water soluble dye were prepared with the melting dispersion cooling method and applied to the amplification detector of plant DNA. Paraffin wax with melting temperature of 75°C was used as the shell material. In the experiment, the aqueous solution (W) of Azur B as the core material was dispersed in the melted paraffin wax (O) to form the (W/O) emulsion and then, the (W/O) emulsion was dispersed in the silicon oil (O’) as the continuous phase to form the (W/O)/O’ emulsion at 85°C. After formation of the (W/O)/O’ emulsion, the microcapsules were prepared by cooling the (W/O)/O’ emulsion to 50°C. The microcapsules were prepared by changing the concentration of oil soluble surfactant in the (W/O) emulsion and the volume of the (W/O) emulsion in the (W/O)/O’ emulsion. The microencapsulation efficiency increased with the concentration of oil soluble surfactant and finally became 100% under the optimum conditions. Furthermore, the microcapsules were melted down at temperature of 85°C to reveal the sharp thermal responsibility and to release the aqueous solution of Azur B. As a result, it was found that the microcapsules were able to be applied to the amplification detector of plant DNA by utilizing the reaction between DNA and Azur B.
文摘11% of Irish electricity was consumed by data centres in 2020. The Irish data centre industry and the cooling methods utilised require reformative actions in the coming years to meet EU Energy policies. The resell of heat, alternative cooling methods or carbon reduction methods are all possibilities to conform to these policies. This study aims to determine the viability of the resell of waste heat from data centres both technically and economically. This was determined using a novel application of thermodynamics to determine waste heat recovery potential in Irish data centres, and the current methods of heat generation for economical comparison. This paper also explores policy surrounding waste heat recovery within the industry. The Recoverable Carnot Equivalent Power (RCEP) is theoretically calculated for the three potential cooling methods for Irish data centres. These are air, hybrid, and immersion cooling techniques. This is the maximum useable heat that can be recovered from a data centre rack. This study is established under current operating conditions which are optimised for cooling performance, that air cooling has the highest potential RCEP of 0.39 kW/rack. This is approximately 8% of the input electrical power that can be captured as useable heat. Indicating that Irish data centres have the energy potential to be heat providers in the Irish economy. This study highlighted the technical and economic aspects of prevalent cooling techniques and determined air cooling heat recovery cost can be reduced to 0.01 €/kWhth using offsetting. This is financially competitive with current heating solutions in Ireland.
基金Sponsored by the National Natural Science Foundation of China(Grant No. 50476028)
文摘This paper implemented cooling configuration design on certain gas turbine HP rotor using parameterized method.It is convenient for complicated gas turbine blade modeling using parameters and also benefit for the geometry modify in later period.Parameterized modeling is the foundation of air cooling turbine blade design method engineering application.Mesh quality can be awarded when generated complicated cooling configuration blade grids,and also the increase of calculation error can arise by many mesh blocks.Film cooling and serpentine passage can effectively enhance the cooling effectiveness and protect blade.
文摘1 Today,many people face the challenge of extreme summer heat,often relying on air conditioning to stay cool.However,air conditioning consumes significant energy and contributes to climate change.To address this issue,researchers are exploring innovative cooling methods inspired by both ancient techniques and modern technology.
基金Supported by Science Research Project of Hebei Education Department(Grant No.BJK2024138)Hebei Provincial Natural Science Foundation(Grant No.E2023203129)National Natural Science Foundation of China(Grant Nos.52004242,52075472).
文摘The aluminum(Al)/steel transition joints used in ships are processed from composite plates,and their mechanical properties have a significant impact on the safety of ships.In this paper,the Al/steel composite plate was prepared using rolling,with 5083 aluminum plate as the cladding plate,Q235 steel plate as the substrate,and TA1 titanium(Ti)plate and DT4 pure iron(Fe)plate as the intermediate layers.The heterothermic billet was prepared through induction heating by the magnetic effects of the steel plate and the pure Fe plate,and then the Al/steel composite plate was obtained by rolling.The impacts of post-rolling cooling process on the microstructure and properties of the Al/Ti/pure Fe/steel composite plate were studied.The results manifested that the pure Fe/steel interface had a good composite effect.With the increase in the cooling rate,the bonding strength of the Al/Ti interface was raised,and that of the Ti/Fe interface was increased first and then decreased.When the oil cooling process was adopted,the Al/Ti/pure Fe/steel composite plate exhibited the highest comprehensive performance.The shear strength of the Al/Ti interface and the Ti/Fe interface was 102 MPa and 186 MPa,respectively.The plastic fracture was determined as the mode of interface fracture.
基金Supported by the Strategic Priority Science&Technology Program of the Chinese Academy of Sciences(No.XDA03040000)
文摘As a potential candidate for generation IV reactors, lead-alloy cooled reactor has attracted much attentions in recent years. The China LEAd-based research Reactor(CLEAR) is proposed as the primary choice for the accelerator driven subcritical system project launched by Chinese Academy of Sciences. Lead-bismuth eutectic(LBE) is selected as the coolant of CLEAR owing to its efficient heat conductivity properties and high production rate of neutrons. In order to compensate the buoyancy due to the high density of lead-alloy, fixation methods of fuel assembly(FA) have become a research hotspot worldwide. In this paper, we report an integrated system of ballast and fuel element for CLEAR FA. It guarantees the correct positioning of each FA in normal and refueling operations. Force calculation and temperature analysis prove that the FA will be stable and safe under CLEAR operation conditions.
文摘Power Electronic (PE) will play an essential role in future drive concepts. Nowadays, mainly water/glycol-based cooling media are used to cool PE. Due to their high electrical conductivity (EC), water/glycol-based coolants cannot be used for direct cooling of the electrical components. Direct cooling concepts with dedicated transmission fluids show potential usage of fluid in direct contact with electrified parts. This results in special requirements for the fluids and materials. The aimed action as a coolant requires a defined measurement and characterization of fluid properties and heat transfer in order to assess the cooling ability of a fluid. The purpose of the work was to develop a new measurement setup based on the thermal transient method with which the thermal requirements of cooling fluids for a direct cooling concept can be assessed. With this method, relevant transmission fluids have been tested and the thermal performance compared to indirect cooling effect of water/glycol is discussed. The result of the work is that the measurement method is very well suited for the application-related evaluation of the fluids. Direct oil cooling with transmission fluids could increase heat transfer coefficient by a factor of 3 to 8, compared to the indirect cooing with water/glycol as cooling media.
