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
Permafrost along the Qinghai-Tibet railway is featured by abundant ground ice and high ground temperature. Under the influence of climate warming and engineering activities, the permafrost is under degradation process...Permafrost along the Qinghai-Tibet railway is featured by abundant ground ice and high ground temperature. Under the influence of climate warming and engineering activities, the permafrost is under degradation process. The main difficulty in railway roadbed construction is how to prevent thawing settlement caused by degradation of permafrost. Therefore the proactively cooling methods based on controlling solar radiation, heat conductivity and heat convection were adopted instead of the traditional passive methods, which is simply increasing thermal resistance. The cooling methods used in the Qinghai-Tibet railway construction include sunshine-shielding roadbeds, crushed rock based roadbeds, roadbeds with rock revetments, duct-ventilated roadbeds, thermosyphon installed roadbeds and land bridges. The field monitored data show that the cooling methods are effective in protecting the underlying permafrost, the permafrost table was uplifted under the embankments and therefore the roadbed stability was guaranteed.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
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
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
We report a highly efficient three-dimensional degenerated Raman sideband cooling(3D dRSC)that enhances the loading of a magnetically levitated optical dipole trap,and observe the strong atom loss due to the three-bod...We report a highly efficient three-dimensional degenerated Raman sideband cooling(3D dRSC)that enhances the loading of a magnetically levitated optical dipole trap,and observe the strong atom loss due to the three-body recombination.The 3D dRSC is implemented to obtain 5×10^(7)Cs atoms with the temperature of~480 nK.The cold temperature enables 1.8×10^(7)atoms loaded into a crossed dipole trap with an optimized excessive levitation magnetic gradient.Compared to the loading of atoms from a bare magneto-optical trap or the gray-molasses cooling,there is a significant increase in the number of atoms loaded into the optical dipole trap.We derive for the three-body recombination coefficient of L_(3)=7.73×10^(-25)cm^(6)/s by analyzing the strong atom loss at a large scattering length of 1418 Bohr radius,and discover the transition from the strong three-body loss to the dominant one-body loss.Our result indicates that the lifetime of atoms in the optical dipole trap is finally decided by the one-body loss after the initial strong three-body loss.展开更多
The thermal evolution of steel coil during cooling was simulated and investigated by the use of in-house Q-CSP software. The dependence of the thermal evolution of steel coil on cooling methods, temperature distributi...The thermal evolution of steel coil during cooling was simulated and investigated by the use of in-house Q-CSP software. The dependence of the thermal evolution of steel coil on cooling methods, temperature distribution of the strip before coiling, coil size and steel grades was also discussed. The study plays a significant role in helping steel makers to better understand and control the cooling process.展开更多
1 Introduction The homogenization temperature of fluid inclusions reflects the temperatures of the brines from which halite crystals grew.Therefore,it is a powerful mean to reveal the paleoclimate.Northern Shaanxi Sal...1 Introduction The homogenization temperature of fluid inclusions reflects the temperatures of the brines from which halite crystals grew.Therefore,it is a powerful mean to reveal the paleoclimate.Northern Shaanxi Salt Basin is located in the central and eastern of Ordos Basin.We have detail petrographical research and the homogenization展开更多
We report the production of^(39) K and^(87) Rb Bose–Einstein condensates(BECs) in the lowest hyperfine states |F =1, m_(F) = 1 simultaneously. We collect atoms in bright/dark magneto-optical traps(MOTs) of^(39) K/^(8...We report the production of^(39) K and^(87) Rb Bose–Einstein condensates(BECs) in the lowest hyperfine states |F =1, m_(F) = 1 simultaneously. We collect atoms in bright/dark magneto-optical traps(MOTs) of^(39) K/^(87) Rb to overcome the light-assisted losses of^(39) K atoms. Gray molasses cooling on the D1 line of the^(39) K is used to effectively increase the phase density, which improves the loading efficiency of^(39) K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for^(87) Rb. After the microwave evaporation cooling on^(87) Rb in the optically plugged magnetic trap,the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of^(39) K and^(87) Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a_(KRb)= 34 a_(0)(a_(0) is the Bohr radius) and the intraspecies scattering length a_K= 20.05 a_(0).展开更多
A small amount of mineralizer MgO was added into Al2TiO5 synthesized from the sludge of aluminum factory to form Al(2-x)Mg(x+y)Ti(1-y)O(5-0.5x-y) solid solution and inhibit the decomposition of Al2TiO5 solid ...A small amount of mineralizer MgO was added into Al2TiO5 synthesized from the sludge of aluminum factory to form Al(2-x)Mg(x+y)Ti(1-y)O(5-0.5x-y) solid solution and inhibit the decomposition of Al2TiO5 solid solution. It increased the content of Al2TiO5 solid solution and improved the thermal stability of materials. In this work,XRD and SEM methods were adopted to characterize the crystalline structure and microstructure of each kind of sample. Rietveld Quantification method was used to determine the content of crystalline phases in each sample. Results show as follows: the optimal addition concentration of MgO was 2.0%,and the corresponding content of Al2TiO5 solid solution which displayed irregular bulk shape was 100%; the addition of mineralizer MgO could enhance the flexural strength and thermal stability of Al2TiO5 solid solution materials. The optimal addition concentration of MgO determined by performance analysis was 2.0%,and its corresponding retention rate of thermal-shock flexural strength was 86.4%. Structure analysis and performance analysis resulted in good accordance.展开更多
In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling spe...In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated.The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°C.The mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling rate.Acoustic emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage mechanism.It is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by water.Furthermore,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode.In addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical properties.The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.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
The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the chan...The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the change of macroscopic characteristics and evolution of micro-structure would be induced,ultimately resulting in different degrees of thermal damage in rocks.To better understand the thermal damage mechanism of different rocks and its effect on the rock performance,this study reviews a large number of test results of rock specimens experiencing heating and cooling treatment in the laboratory.Firstly,the variations of macroscopic behaviors,including physical parameters,mechanical parameters,thermal conductivity and permeability,are examined.The variations of mechanical parameters with thermal treatment variables(i.e.temperature or the number of thermal cycles)are divided into four types.Secondly,several measuring methods for microstructure,such as polarizing microscopy,fluorescent method,scanning electron microscopy(SEM),X-ray computerized tomography(CT),acoustic emission(AE)and ultrasonic technique,are introduced.Furthermore,the effect of thermal damage on the mechanical parameters of rocks in response to different thermal treatments,involving temperature magnitude,cooling method and thermal cycle,are discussed.Finally,the limitations and prospects for the research of rock thermal damage are proposed.展开更多
Actively cooled thermal protection system has great influence on the engine of a hypersonic vehicle, and it is significant to obtain the thermal and stress distribution in the system. So an analytic estimation and num...Actively cooled thermal protection system has great influence on the engine of a hypersonic vehicle, and it is significant to obtain the thermal and stress distribution in the system. So an analytic estimation and numerical modeling are performed in this paper to investigate the behavior of an actively cooled thermal protection system. The analytic estimation is based on the electric analogy method and finite element analysis(FEA) is applied to the numerical simulation. Temperature and stress distributions are obtained for the actively cooled channel walls with three kinds of nickel alloys with or with no thermal barrier coating(TBC). The temperature of the channel wall with coating has no obvious difference from the one with no coating, but the stress with coating on the channel wall is much smaller than that with no coating. Inconel X-750 has the best characteristics among the three Ni-based materials due to its higher thermal conductivity, lower elasticity module and greater allowable stress. Analytic estimation and numerical modeling results are compared with each other and a reasonable agreement is obtained.展开更多
We present the application of the recent physics-conforming COOL method[2,4]to the eigenvalue problem of a cylindrical waveguide filled with unmagnetized plasma.Using the Fourier transform only along the waveguide and...We present the application of the recent physics-conforming COOL method[2,4]to the eigenvalue problem of a cylindrical waveguide filled with unmagnetized plasma.Using the Fourier transform only along the waveguide and not in poloidal direction,this is a relevant test case for a numerical discretization method in two dimensions(radial and poloidal).Analytically,the frequency spectrum consists of discrete electromagnetic parts and,depending on the electron density profile of the plasma,of infinitely degenerate and/or continuous,essentially electrostatic parts.If the plasma is absent,the latter reduces to the infinitely degenerate zero eigenvalue of electrostatics.A good discretization method for the Maxwell equations must reproduce these properties.It is shown here that the COOL method meets this demand properly and to very high precision.展开更多
Laser cooling of Li-like C^3+and O^4+relativistic heavy ion beams is planned at the experimental Cooler Storage Ring(CSRe). Recently, a preparatory experiment to test important prerequisites for laser cooling of r...Laser cooling of Li-like C^3+and O^4+relativistic heavy ion beams is planned at the experimental Cooler Storage Ring(CSRe). Recently, a preparatory experiment to test important prerequisites for laser cooling of relativistic^12C^3+ion beams using a pulsed laser system has been performed at the CSRe. Unfortunately, the interaction between the ions and the pulsed laser cannot be detected. In order to study the laser cooling process and find the optimized parameters for future laser cooling experiments, a multi-particle tracking method has been developed to simulate the detailed longitudinal dynamics of laser-cooled ion beams at the CSRe. Simulations of laser cooling of the^12C^3+ion beams by scanning the frequency of the RF-buncher or continuous wave(CW) laser wavelength have been performed. The simulation results indicate that ion beams with a large momentum spread could be laser-cooled by the combination of only one CW laser and the RF-buncher, and show the requirements of a successful laser cooling experiment. The optimized parameters for scanning the RF-buncher frequency or laser frequency have been obtained.Furthermore, the heating effects have been estimated for laser cooling at the CSRe. The Schottky noise spectra of longitudinally modulated and laser-cooled ion beams have been simulated to fully explain and anticipate the experimental results. The combination of Schottky spectra from the highly sensitive resonant Schottky pick-up and the simulation methods developed in this paper will be helpful to investigate the longitudinal dynamics of RF-bunched and ultra-cold ion beams in the upcoming laser cooling experiments at the CSRe.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
Thermal management is considered a critical issue in proton exchange membrane fuel cells(PEMFCs),since it not only influences the cell performance but also impacts PEMFC’s reliability and durability.With the ever-inc...Thermal management is considered a critical issue in proton exchange membrane fuel cells(PEMFCs),since it not only influences the cell performance but also impacts PEMFC’s reliability and durability.With the ever-increasing power density of PEMFC,traditional cooling approaches including air cooling and water cooling become difficult to meet the demand for highpower heat dissipation.Therefore,phase-change cooling is proposed for fuel cell application in this work,and the potential advantages are discussed and demonstrated via a mathematical model incorporating phase-change heat transfer.The thermal management performance is evaluated by temperature uniformity,maximum temperature difference,and the cooling capacity to compare the difference between phase-change cooling and traditional methods,which demonstrates that phase-change cooling owns a greatly improved thermal management performance.In addition,a simple method to broaden the operating temperature of phase-change cooling based on one certain coolant is offered,which is pressurizing in the coolant channel to regulate the boiling temperature that could further improve the application feasibility of phase-change cooling strategy in fuel cells.展开更多
We report the growth of high quality Fe excess and Co doped,FeTxSe single crystals in nominal ratio via slow cooling method of high temperature solution growth technique and,their structural and physical properties th...We report the growth of high quality Fe excess and Co doped,FeTxSe single crystals in nominal ratio via slow cooling method of high temperature solution growth technique and,their structural and physical properties through the X‐ray diffraction,Raman spectroscopy,magnetic and transports measurements.Selective area electron diffraction(SAED)patterns and X‐ray diffraction of cleavage piece confirm the growth of single crystals in(h0l)orientations.Observations of phonon vibration modes(A_(1g) and B_(1g))in Raman spectroscopy measurements mark the qualitative analysis of these single crystals.Low temperature magnetic and electrical transport studies manifest the superconducting nature of both single crystals.展开更多
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the Chinese Natural Science Fund(No.40471023);the Outstanding Youth Foundation Project,Natural Science Foundation of China(No.40625004);the Knowledge Innovation Program of the CAS(No.KZCX1-SW-04,KZCX-XB-10);the National Science Supporting Project of the Ministry of Science and Technology of China(2006BAC07B02).
文摘Permafrost along the Qinghai-Tibet railway is featured by abundant ground ice and high ground temperature. Under the influence of climate warming and engineering activities, the permafrost is under degradation process. The main difficulty in railway roadbed construction is how to prevent thawing settlement caused by degradation of permafrost. Therefore the proactively cooling methods based on controlling solar radiation, heat conductivity and heat convection were adopted instead of the traditional passive methods, which is simply increasing thermal resistance. The cooling methods used in the Qinghai-Tibet railway construction include sunshine-shielding roadbeds, crushed rock based roadbeds, roadbeds with rock revetments, duct-ventilated roadbeds, thermosyphon installed roadbeds and land bridges. The field monitored data show that the cooling methods are effective in protecting the underlying permafrost, the permafrost table was uplifted under the embankments and therefore the roadbed stability was guaranteed.
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.
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.
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Project funded by the National Key Research and Development Program of China(Grant No.2022YFA1404201)the National Natural Science Foundation of China(Grant Nos.62020106014,92165106,62175140,12074234,and 11974331)the Applied Basic Research Project of Shanxi Province,China(Grant No.202203021224001)。
文摘We report a highly efficient three-dimensional degenerated Raman sideband cooling(3D dRSC)that enhances the loading of a magnetically levitated optical dipole trap,and observe the strong atom loss due to the three-body recombination.The 3D dRSC is implemented to obtain 5×10^(7)Cs atoms with the temperature of~480 nK.The cold temperature enables 1.8×10^(7)atoms loaded into a crossed dipole trap with an optimized excessive levitation magnetic gradient.Compared to the loading of atoms from a bare magneto-optical trap or the gray-molasses cooling,there is a significant increase in the number of atoms loaded into the optical dipole trap.We derive for the three-body recombination coefficient of L_(3)=7.73×10^(-25)cm^(6)/s by analyzing the strong atom loss at a large scattering length of 1418 Bohr radius,and discover the transition from the strong three-body loss to the dominant one-body loss.Our result indicates that the lifetime of atoms in the optical dipole trap is finally decided by the one-body loss after the initial strong three-body loss.
基金This work was financially supported by the National High-Tech Research and Development Program of China (No.2001AA339030),the National Natural Science Foundation of China (No.50334010) and the Ministry of Sciences and Technology of China.
文摘The thermal evolution of steel coil during cooling was simulated and investigated by the use of in-house Q-CSP software. The dependence of the thermal evolution of steel coil on cooling methods, temperature distribution of the strip before coiling, coil size and steel grades was also discussed. The study plays a significant role in helping steel makers to better understand and control the cooling process.
文摘1 Introduction The homogenization temperature of fluid inclusions reflects the temperatures of the brines from which halite crystals grew.Therefore,it is a powerful mean to reveal the paleoclimate.Northern Shaanxi Salt Basin is located in the central and eastern of Ordos Basin.We have detail petrographical research and the homogenization
基金supported by the National Key R&D Program of China (Grants Nos. 2016YFA0301602 and 2018YFA0307601)the National Natural Science Foundation of China (Grant Nos. 11974224, 11704234, 11804203, 12034011, 12022406, 12004229, and 92065108)+1 种基金the Fund for Shanxi “1331 Project” Key Subjects Constructionthe Program of Youth Sanjin Scholar。
文摘We report the production of^(39) K and^(87) Rb Bose–Einstein condensates(BECs) in the lowest hyperfine states |F =1, m_(F) = 1 simultaneously. We collect atoms in bright/dark magneto-optical traps(MOTs) of^(39) K/^(87) Rb to overcome the light-assisted losses of^(39) K atoms. Gray molasses cooling on the D1 line of the^(39) K is used to effectively increase the phase density, which improves the loading efficiency of^(39) K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for^(87) Rb. After the microwave evaporation cooling on^(87) Rb in the optically plugged magnetic trap,the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of^(39) K and^(87) Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a_(KRb)= 34 a_(0)(a_(0) is the Bohr radius) and the intraspecies scattering length a_K= 20.05 a_(0).
基金supported by the Natural Science Foundation of Fujian Province (No. T08J0129)the Science and Technology Developing Foundation of Fuzhou University (No. 2008-XQ-001)2007-year New Century Talents Supporting Program of Fujian Province (No. XSJRC2007-17)
文摘A small amount of mineralizer MgO was added into Al2TiO5 synthesized from the sludge of aluminum factory to form Al(2-x)Mg(x+y)Ti(1-y)O(5-0.5x-y) solid solution and inhibit the decomposition of Al2TiO5 solid solution. It increased the content of Al2TiO5 solid solution and improved the thermal stability of materials. In this work,XRD and SEM methods were adopted to characterize the crystalline structure and microstructure of each kind of sample. Rietveld Quantification method was used to determine the content of crystalline phases in each sample. Results show as follows: the optimal addition concentration of MgO was 2.0%,and the corresponding content of Al2TiO5 solid solution which displayed irregular bulk shape was 100%; the addition of mineralizer MgO could enhance the flexural strength and thermal stability of Al2TiO5 solid solution materials. The optimal addition concentration of MgO determined by performance analysis was 2.0%,and its corresponding retention rate of thermal-shock flexural strength was 86.4%. Structure analysis and performance analysis resulted in good accordance.
基金The National Natural Science Foundation of China,Grant/Award Number:41702326the Innovative Experts,Long-term Program of Jiangxi Province,Grant/Award Number:jxsq2018106049+1 种基金the Natural Science Foundation of Jiangxi Province,Grant/Award Number:20202ACB214006the Supported by Program of Qingjiang Excellent Young Talents,Jiangxi University of Science and Technology。
文摘In deep-earth engineering,the high earth temperature can significantly affect the rock's mechanical properties,especially when the rock is cooled during the construction process.Accordingly,whether the cooling speed affects the mechanical and physical properties of rocks is worth to be investigated.The present study explored the influence of the cooling rate on the physical and chemical properties of granite heated at 25–800°C.The mechanical and physical properties involved in this study included uniaxial compression strength,peak strain,modulus,P-wave velocity,mass and volume,the change of which could reflect the sensitivity of granite to the cooling rate.Acoustic emission(AE)monitoring,microscopic observation,and X-ray diffraction(XRD)are used to analyze the underlying damage mechanism.It is found that more AE signals and large-scale cracks are accounted for based on the b-value method when the specimens are cooled by water.Furthermore,the microscopic observation by polarized light microscopy indicates that the density,opening degree,and connectivity of the cracks under water cooling mode are higher than that under natural cooling mode.In addition,the XRD illustrates that there is no obvious change in mineral content and diffraction angle at different temperatures,which confirms that the change of mechanical properties is not related to the chemical properties.The present conclusion can provide a perspective to assess the damage caused by different cooling methods to hot rocks.
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supported by the National Key Research and Development Plan(Grant No.2022YFC2905700)Natural Science Foundation of Anhui Province(Grant No.2208085ME120)Key Research and Development Plan of Anhui Province(Grant No.2022m07020001).
文摘The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the change of macroscopic characteristics and evolution of micro-structure would be induced,ultimately resulting in different degrees of thermal damage in rocks.To better understand the thermal damage mechanism of different rocks and its effect on the rock performance,this study reviews a large number of test results of rock specimens experiencing heating and cooling treatment in the laboratory.Firstly,the variations of macroscopic behaviors,including physical parameters,mechanical parameters,thermal conductivity and permeability,are examined.The variations of mechanical parameters with thermal treatment variables(i.e.temperature or the number of thermal cycles)are divided into four types.Secondly,several measuring methods for microstructure,such as polarizing microscopy,fluorescent method,scanning electron microscopy(SEM),X-ray computerized tomography(CT),acoustic emission(AE)and ultrasonic technique,are introduced.Furthermore,the effect of thermal damage on the mechanical parameters of rocks in response to different thermal treatments,involving temperature magnitude,cooling method and thermal cycle,are discussed.Finally,the limitations and prospects for the research of rock thermal damage are proposed.
基金co-supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (No. 51121004)the Fundamental Research Funds for the Central Universities of China (No. HIT.BRETIV.201315)
文摘Actively cooled thermal protection system has great influence on the engine of a hypersonic vehicle, and it is significant to obtain the thermal and stress distribution in the system. So an analytic estimation and numerical modeling are performed in this paper to investigate the behavior of an actively cooled thermal protection system. The analytic estimation is based on the electric analogy method and finite element analysis(FEA) is applied to the numerical simulation. Temperature and stress distributions are obtained for the actively cooled channel walls with three kinds of nickel alloys with or with no thermal barrier coating(TBC). The temperature of the channel wall with coating has no obvious difference from the one with no coating, but the stress with coating on the channel wall is much smaller than that with no coating. Inconel X-750 has the best characteristics among the three Ni-based materials due to its higher thermal conductivity, lower elasticity module and greater allowable stress. Analytic estimation and numerical modeling results are compared with each other and a reasonable agreement is obtained.
文摘We present the application of the recent physics-conforming COOL method[2,4]to the eigenvalue problem of a cylindrical waveguide filled with unmagnetized plasma.Using the Fourier transform only along the waveguide and not in poloidal direction,this is a relevant test case for a numerical discretization method in two dimensions(radial and poloidal).Analytically,the frequency spectrum consists of discrete electromagnetic parts and,depending on the electron density profile of the plasma,of infinitely degenerate and/or continuous,essentially electrostatic parts.If the plasma is absent,the latter reduces to the infinitely degenerate zero eigenvalue of electrostatics.A good discretization method for the Maxwell equations must reproduce these properties.It is shown here that the COOL method meets this demand properly and to very high precision.
基金Supported by National Natural Science Foundation of China(11405237,11504388)
文摘Laser cooling of Li-like C^3+and O^4+relativistic heavy ion beams is planned at the experimental Cooler Storage Ring(CSRe). Recently, a preparatory experiment to test important prerequisites for laser cooling of relativistic^12C^3+ion beams using a pulsed laser system has been performed at the CSRe. Unfortunately, the interaction between the ions and the pulsed laser cannot be detected. In order to study the laser cooling process and find the optimized parameters for future laser cooling experiments, a multi-particle tracking method has been developed to simulate the detailed longitudinal dynamics of laser-cooled ion beams at the CSRe. Simulations of laser cooling of the^12C^3+ion beams by scanning the frequency of the RF-buncher or continuous wave(CW) laser wavelength have been performed. The simulation results indicate that ion beams with a large momentum spread could be laser-cooled by the combination of only one CW laser and the RF-buncher, and show the requirements of a successful laser cooling experiment. The optimized parameters for scanning the RF-buncher frequency or laser frequency have been obtained.Furthermore, the heating effects have been estimated for laser cooling at the CSRe. The Schottky noise spectra of longitudinally modulated and laser-cooled ion beams have been simulated to fully explain and anticipate the experimental results. The combination of Schottky spectra from the highly sensitive resonant Schottky pick-up and the simulation methods developed in this paper will be helpful to investigate the longitudinal dynamics of RF-bunched and ultra-cold ion beams in the upcoming laser cooling experiments at the CSRe.
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.
基金the National Key Research and Development Program of China(Grant No.2016YFB0101312)the National Natural Science Foundation of China(Grant No.21706158)。
文摘Thermal management is considered a critical issue in proton exchange membrane fuel cells(PEMFCs),since it not only influences the cell performance but also impacts PEMFC’s reliability and durability.With the ever-increasing power density of PEMFC,traditional cooling approaches including air cooling and water cooling become difficult to meet the demand for highpower heat dissipation.Therefore,phase-change cooling is proposed for fuel cell application in this work,and the potential advantages are discussed and demonstrated via a mathematical model incorporating phase-change heat transfer.The thermal management performance is evaluated by temperature uniformity,maximum temperature difference,and the cooling capacity to compare the difference between phase-change cooling and traditional methods,which demonstrates that phase-change cooling owns a greatly improved thermal management performance.In addition,a simple method to broaden the operating temperature of phase-change cooling based on one certain coolant is offered,which is pressurizing in the coolant channel to regulate the boiling temperature that could further improve the application feasibility of phase-change cooling strategy in fuel cells.
基金support through the project No.F.30‐303/2016(BSR).
文摘We report the growth of high quality Fe excess and Co doped,FeTxSe single crystals in nominal ratio via slow cooling method of high temperature solution growth technique and,their structural and physical properties through the X‐ray diffraction,Raman spectroscopy,magnetic and transports measurements.Selective area electron diffraction(SAED)patterns and X‐ray diffraction of cleavage piece confirm the growth of single crystals in(h0l)orientations.Observations of phonon vibration modes(A_(1g) and B_(1g))in Raman spectroscopy measurements mark the qualitative analysis of these single crystals.Low temperature magnetic and electrical transport studies manifest the superconducting nature of both single crystals.