The immobilization of catalysts on supporting substrates for the removal of organic pollutants is a crucial strategy for mitigating catalyst loss during wastewater treatment.This study presented a rapid and cost-effec...The immobilization of catalysts on supporting substrates for the removal of organic pollutants is a crucial strategy for mitigating catalyst loss during wastewater treatment.This study presented a rapid and cost-effective direct heating method for synthesizing MnO2 nanoflowers on coil substrates for the removal of organic pollutants.Traditional methods often require high power,expensive equipment,and long synthesis times.In contrast,the direct heating approach successfully synthesized MnO2 nanoflowers in just 10 min with a heating power of approximately 40 W·h after the heating power and duration were optimized.These nanoflowers effectively degraded 99%Rhodamine B in 60 min with consistent repeatability.The catalytic mechanisms are attributed to crystal defects in MnO2,which generate electrons to produce H2O2.Mn2+ions in the acidic solution further dissociate H2O2 molecules into hydroxyl radicals(·OH).The high efficiency of this synthesis method and the excellent reusability of MnO2 nanoflowers highlight their potential as a promising solution for the development of supporting MnO2 catalysts for organic dye removal applications.展开更多
1.Introduction B_(4)C ceramics have high potential for use in aerospace,military,nuclear energy,and other fields owing to their excellent properties such as low density,high melting point,high hardness,high chem-ical ...1.Introduction B_(4)C ceramics have high potential for use in aerospace,military,nuclear energy,and other fields owing to their excellent properties such as low density,high melting point,high hardness,high chem-ical stability,excellent wear resistance,and good neutron absorp-tion ability[1-3].However,the fracture toughness(1.9 MPa·m^(1/2))of B_(4)C is poor[2].Furthermore,the low diffusion coefficient asso-ciated with the strong covalent bond of B_(4)C makes it very difficult to achieve densification through traditional pressureless sintering.For example,after the pressureless sintering of B_(4)C at 2375℃ for 1 h,Roy et al.[4]achieved a relative density of only 87%.展开更多
Recovering waste heat is essential for primary energy savings and carbon emission reduction.To provide direct and reliable suggestions for factories to recover waste heat,energetic,economic and exergoeconomic comparis...Recovering waste heat is essential for primary energy savings and carbon emission reduction.To provide direct and reliable suggestions for factories to recover waste heat,energetic,economic and exergoeconomic comparison between direct heat exchange(DHE)and open-cycle mechanical heat pump(MHP)under various operating conditions is carried out in this work.The price ratios R_(ES)(electricity to steam)and R_(HS)(hot water to steam)are introduced to quantify regional impacts and conduct quantitative analysis.A semi-empirical formula is obtained to explore the exergoeconomic performance of the two systems.For waste heat within 373.15-423.15 K,the exergy efficiency of the DHE with a temperature difference of 10-90 K is always lower than that of the MHP with a temperature lift of 10-50 K.The economic performance of the two systems has a break-even point,depending on the operating parameters and relative prices of electricity,steam,and hot water.Under the average R_(ES)(3.8)in China,if R_(HS)is higher than 0.748,the annual revenue of the DHE is always higher,whereas the MHP is more economical when R_(HS)is lower than 0.110.In regions where R_(ES)is higher than 4.353,the annual revenue of the MHP will be negative in some cases.展开更多
Microwave ablation(MWA)is a cancer treatment method.The tumor tissue absorbs electromagnetic energy,which heats and kills it.A microwave ablation antenna plays a critical role in this process.Its radiation field must ...Microwave ablation(MWA)is a cancer treatment method.The tumor tissue absorbs electromagnetic energy,which heats and kills it.A microwave ablation antenna plays a critical role in this process.Its radiation field must completely cover the tumor but not the healthy tissue.At present,the radiation pattern of most invasive ablation antennas is spherical.However,in the clinic,the shape of some tumors may be asymmetrical or the antenna cannot be inserted into the center of the tumor for some other reason.In order to solve these problems,a directional heating antenna for microwave ablation is proposed in this paper.The proposed antenna,operating at 2.45 GHz,consists of a monopole and a reflector.The feed is given by a substrate integrated coaxial line(SICL)and coplanar waveguide(CPW).The omnidirectional radiation field of the monopole is reflected by a reflector that is extended from the outer conductors of the SICL to form a directional radiation field.The impedance matching network is designed on SICL to match the antenna to 50Ω.The antenna is fabricated using a mature printed circuit board(PCB).The reflection coefficient of the antenna in porcine liver tissue measured by a vector network analyzer shows good agreement with the simulations.Then,an ablation experiment in porcine liver is conducted with power of 10 W for 10 min,and the experimental results confirm the validity of the design.展开更多
For the sake of a more accurate shell boundary and calculation of radiation heat transfer in the Directional Solidification(DS) process, a radiation heat transfer model based on the Finite Element Method(FEM)is develo...For the sake of a more accurate shell boundary and calculation of radiation heat transfer in the Directional Solidification(DS) process, a radiation heat transfer model based on the Finite Element Method(FEM)is developed in this study. Key technologies, such as distinguishing boundaries automatically, local matrix and lumped heat capacity matrix, are also stated. In order to analyze the effect of withdrawing rate on DS process,the solidification processes of a complex superalloy turbine blade in the High Rate Solidification(HRS) process with different withdrawing rates are simulated; and by comparing the simulation results, it is found that the most suitable withdrawing rate is determined to be 5.0 mm·min^(-1). Finally, the accuracy and reliability of the radiation heat transfer model are verified, because of the accordance of simulation results with practical process.展开更多
Zn-5wt% Al eutectic alloy was directionally solidified with different growth rates （5.32-250.0μm/s） at a constant temperature gradient of 8.50 K/mm using a Bridgman-type growth apparatus.The values of eutectic spac...Zn-5wt% Al eutectic alloy was directionally solidified with different growth rates （5.32-250.0μm/s） at a constant temperature gradient of 8.50 K/mm using a Bridgman-type growth apparatus.The values of eutectic spacing were measured from transverse sections of the samples.The dependences of the eutectic spacing and undercooling on growth rate are determined as λ=9.21V-0.53 and ΔT=0.0245V0.53,respectively.The results obtained in this work were compared with the Jackson-Hunt eutectic theory and the similar experimental results in the literature.Microhardness of directionally solidified samples was also measured by using a microhardness test device.The dependency of the microhardness on growth rate is found as Hv=115.64V0.13.Afterwards,the electrical resistivity （r） of the casting alloy changes from 40×10-9 to 108×10-9 Ω·m with the temperature rising in the range of 300-630 K.The enthalpy of fusion （ΔH） and specific heat （Cp） for the Zn-Al eutectic alloy are calculated to be 113.37 J/g and 0.309 J/（g·K）,respectively by means of differential scanning calorimetry （DSC） from heating trace during the transformation from liquid to solid.展开更多
The preparation of dense ZrB_(2)-based ceramics typically requires high temperatures and long sintering time,which often result in significant grain coarsening and thus deterioration of mechanical properties.Ultrafast...The preparation of dense ZrB_(2)-based ceramics typically requires high temperatures and long sintering time,which often result in significant grain coarsening and thus deterioration of mechanical properties.Ultrafast sintering techniques offer a solution to inhibit grain coarsening by reducing the processing time.However,the ultrafast preparation of dense ZrB_(2)-based ceramics remains a challenge.In this work,we successfully fabricated dense ZrB_(2)-based ceramics in just a few minutes using heavy continuous direct current(DC)Joule heating and pressing.Notably,the densification rate peaked at 1218℃,and the densification process was nearly complete at a relatively low temperature of 1500℃.The application of heavy continuous direct current not only promotes the densification of the ceramics but also enhances the texturization of ZrB_(2).This results in optimally aligned ZrB_(2) grains that form a three-dimensional bonded skeletal network.These unique microstructures can effectively induce multi-stage fracture surfaces during failure,which helps synergistic strengthening and toughening of the ceramics.The ceramics exhibit remarkable comprehensive mechanical properties,with flexural strength and fracture toughness values reaching 773±114 MPa and 5.88±0.08 MPa·m^(1/2),respectively,surpassing those of conventional hot pressed samples.This technique is expected to be applied to other ultra-high temperature ceramics,providing a promising approach for the development of thermal protection materials.展开更多
Computational fluid dynamics( CFD) techniques are used to investigate effects of both wind direction and wind speed on net solar heat gain of south wall with internal insulation in winter.Results show that wind effect...Computational fluid dynamics( CFD) techniques are used to investigate effects of both wind direction and wind speed on net solar heat gain of south wall with internal insulation in winter.Results show that wind effect has a significant influence on the net solar heat gain,where the impact of wind direction is stronger than that of wind speed. For regions in lower reaches of the Yangtze River,difference of their average net solar heat gains( NSHGS) is about 20% due to various wind speeds and wind directions.Buildings in districts with a dominant wind direction of north achieve the highest solar energy utilization.展开更多
Solid-state thermoelectric coolers,which enable direct heat pumping by utilizing electricity,play an essential role in electronic refrigeration.Given that these devices usually cool down to the sub-ambient temperature...Solid-state thermoelectric coolers,which enable direct heat pumping by utilizing electricity,play an essential role in electronic refrigeration.Given that these devices usually cool down to the sub-ambient temperature range,their performance is critically dependent on the material properties at temperatures below 300 K.Consequently,enhancing the thermoelectric properties of materials at sub-ambient temperature is of paramount importance for advancing cooling technology.Herein,a single-crystalline Mg_(3)Bi_(2)-based material has been prepared and exhibits high electron mobility.As a result,thermoelectric figure-of-merit values of~1.05 at 300 K and~0.87 at 250 K(along the ab plane)have been achieved,which are superior to commercial n-type Bi_(2)(Te,Se)_(3).Thermoelectric coolers(single-and double-stage devices)based on the n-type single-crystalline Mg_(3)Bi_(1.497)Sb_(0.5)Te_(0.003)and p-type(Bi,Sb)_(2)Te_(3)have been fabricated.The double-stage cooler demonstrates a remarkable maximum cooling temperature difference of~106.8 K at the hot-side temperature of 350 K,surpassing the performance of commercial Bi_(2)Te_(3)-based devices.Notably,the Mg_(3)Bi_(2)-based doublestage device exhibits exceptional cyclic stability,maintaining its cooling performance without any observable degradation after approximately 2,000 cycles between the input currents of 1 and 3 A.These findings show that single-crystalline Mg_(3)Bi_(2)alloys hold great promise for thermoelectric cooling applications.展开更多
Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand...Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ~ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.展开更多
The interaction of evaporating droplets and hot catalyst particles plays a major role in heterogeneously catalysed reactions. The liquid feed is injected into a gas-solid flow and is mixed with the catalyst. The inter...The interaction of evaporating droplets and hot catalyst particles plays a major role in heterogeneously catalysed reactions. The liquid feed is injected into a gas-solid flow and is mixed with the catalyst. The interaction phenomena determine the evaporation time which should be minimised to keep the reactor vessel small. First measurements with a bed of fixed hot FCC-particles （fluid catalytic cracking） and two model fluids have been conducted. The interactions of ethanol and water droplets with the hot bed surface were captured via a high-speed camera. While the ethanol droplet developed a stable steam cushion due to Leidenfrost phenomena, water showed intense interaction and steam explosions which induced repulsion and atomisation of the droplet.展开更多
基金supported by Ministry of Higher Education,Malaysia,through the Fundamental Research Grant Scheme(FRGS)(Grant No.FRGS/1/2020/TK0/USM/02/27)。
文摘The immobilization of catalysts on supporting substrates for the removal of organic pollutants is a crucial strategy for mitigating catalyst loss during wastewater treatment.This study presented a rapid and cost-effective direct heating method for synthesizing MnO2 nanoflowers on coil substrates for the removal of organic pollutants.Traditional methods often require high power,expensive equipment,and long synthesis times.In contrast,the direct heating approach successfully synthesized MnO2 nanoflowers in just 10 min with a heating power of approximately 40 W·h after the heating power and duration were optimized.These nanoflowers effectively degraded 99%Rhodamine B in 60 min with consistent repeatability.The catalytic mechanisms are attributed to crystal defects in MnO2,which generate electrons to produce H2O2.Mn2+ions in the acidic solution further dissociate H2O2 molecules into hydroxyl radicals(·OH).The high efficiency of this synthesis method and the excellent reusability of MnO2 nanoflowers highlight their potential as a promising solution for the development of supporting MnO2 catalysts for organic dye removal applications.
基金supported by the National Natural Science Foun-dation of China(No.52372061)the Project of the Education Department of Jilin Province(No.JJKH20231163KJ).
文摘1.Introduction B_(4)C ceramics have high potential for use in aerospace,military,nuclear energy,and other fields owing to their excellent properties such as low density,high melting point,high hardness,high chem-ical stability,excellent wear resistance,and good neutron absorp-tion ability[1-3].However,the fracture toughness(1.9 MPa·m^(1/2))of B_(4)C is poor[2].Furthermore,the low diffusion coefficient asso-ciated with the strong covalent bond of B_(4)C makes it very difficult to achieve densification through traditional pressureless sintering.For example,after the pressureless sintering of B_(4)C at 2375℃ for 1 h,Roy et al.[4]achieved a relative density of only 87%.
基金Financial support from the National Natural Science Foundation of China(21736008)。
文摘Recovering waste heat is essential for primary energy savings and carbon emission reduction.To provide direct and reliable suggestions for factories to recover waste heat,energetic,economic and exergoeconomic comparison between direct heat exchange(DHE)and open-cycle mechanical heat pump(MHP)under various operating conditions is carried out in this work.The price ratios R_(ES)(electricity to steam)and R_(HS)(hot water to steam)are introduced to quantify regional impacts and conduct quantitative analysis.A semi-empirical formula is obtained to explore the exergoeconomic performance of the two systems.For waste heat within 373.15-423.15 K,the exergy efficiency of the DHE with a temperature difference of 10-90 K is always lower than that of the MHP with a temperature lift of 10-50 K.The economic performance of the two systems has a break-even point,depending on the operating parameters and relative prices of electricity,steam,and hot water.Under the average R_(ES)(3.8)in China,if R_(HS)is higher than 0.748,the annual revenue of the DHE is always higher,whereas the MHP is more economical when R_(HS)is lower than 0.110.In regions where R_(ES)is higher than 4.353,the annual revenue of the MHP will be negative in some cases.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1966201)the Fundamental Research Funds for the Central Universities,China(Grant No.A03019023801224)。
文摘Microwave ablation(MWA)is a cancer treatment method.The tumor tissue absorbs electromagnetic energy,which heats and kills it.A microwave ablation antenna plays a critical role in this process.Its radiation field must completely cover the tumor but not the healthy tissue.At present,the radiation pattern of most invasive ablation antennas is spherical.However,in the clinic,the shape of some tumors may be asymmetrical or the antenna cannot be inserted into the center of the tumor for some other reason.In order to solve these problems,a directional heating antenna for microwave ablation is proposed in this paper.The proposed antenna,operating at 2.45 GHz,consists of a monopole and a reflector.The feed is given by a substrate integrated coaxial line(SICL)and coplanar waveguide(CPW).The omnidirectional radiation field of the monopole is reflected by a reflector that is extended from the outer conductors of the SICL to form a directional radiation field.The impedance matching network is designed on SICL to match the antenna to 50Ω.The antenna is fabricated using a mature printed circuit board(PCB).The reflection coefficient of the antenna in porcine liver tissue measured by a vector network analyzer shows good agreement with the simulations.Then,an ablation experiment in porcine liver is conducted with power of 10 W for 10 min,and the experimental results confirm the validity of the design.
基金financially supported by the Program for New Century Excellent Talents in University(No.NCET-13-0229,NCET-09-0396)the National Science & Technology Key Projects of Numerical Control(No.2012ZX04010-031,2012ZX0412-011)the National High Technology Research and Development Program("863"Program)of China(No.2013031003)
文摘For the sake of a more accurate shell boundary and calculation of radiation heat transfer in the Directional Solidification(DS) process, a radiation heat transfer model based on the Finite Element Method(FEM)is developed in this study. Key technologies, such as distinguishing boundaries automatically, local matrix and lumped heat capacity matrix, are also stated. In order to analyze the effect of withdrawing rate on DS process,the solidification processes of a complex superalloy turbine blade in the High Rate Solidification(HRS) process with different withdrawing rates are simulated; and by comparing the simulation results, it is found that the most suitable withdrawing rate is determined to be 5.0 mm·min^(-1). Finally, the accuracy and reliability of the radiation heat transfer model are verified, because of the accordance of simulation results with practical process.
基金supported by Erciyes University Scientific Research Project Unit (No.FBA-10-3376)
文摘Zn-5wt% Al eutectic alloy was directionally solidified with different growth rates （5.32-250.0μm/s） at a constant temperature gradient of 8.50 K/mm using a Bridgman-type growth apparatus.The values of eutectic spacing were measured from transverse sections of the samples.The dependences of the eutectic spacing and undercooling on growth rate are determined as λ=9.21V-0.53 and ΔT=0.0245V0.53,respectively.The results obtained in this work were compared with the Jackson-Hunt eutectic theory and the similar experimental results in the literature.Microhardness of directionally solidified samples was also measured by using a microhardness test device.The dependency of the microhardness on growth rate is found as Hv=115.64V0.13.Afterwards,the electrical resistivity （r） of the casting alloy changes from 40×10-9 to 108×10-9 Ω·m with the temperature rising in the range of 300-630 K.The enthalpy of fusion （ΔH） and specific heat （Cp） for the Zn-Al eutectic alloy are calculated to be 113.37 J/g and 0.309 J/（g·K）,respectively by means of differential scanning calorimetry （DSC） from heating trace during the transformation from liquid to solid.
基金supported by the Natural Science Basic Research Program of Shaanxi(Nos.2024JC-YBQN-0580 and 2020JM-599)Shaanxi Province’s Key Research and Development Project(No.2023-YBGY-172)+1 种基金the Scientific Research Program Funded by Education Department of Shaanxi Provincial Government(No.24JK0360)the Graduate Scientific Research Foundation of Shaanxi Univerisity of Technology(No.SLGYCX2401).
文摘The preparation of dense ZrB_(2)-based ceramics typically requires high temperatures and long sintering time,which often result in significant grain coarsening and thus deterioration of mechanical properties.Ultrafast sintering techniques offer a solution to inhibit grain coarsening by reducing the processing time.However,the ultrafast preparation of dense ZrB_(2)-based ceramics remains a challenge.In this work,we successfully fabricated dense ZrB_(2)-based ceramics in just a few minutes using heavy continuous direct current(DC)Joule heating and pressing.Notably,the densification rate peaked at 1218℃,and the densification process was nearly complete at a relatively low temperature of 1500℃.The application of heavy continuous direct current not only promotes the densification of the ceramics but also enhances the texturization of ZrB_(2).This results in optimally aligned ZrB_(2) grains that form a three-dimensional bonded skeletal network.These unique microstructures can effectively induce multi-stage fracture surfaces during failure,which helps synergistic strengthening and toughening of the ceramics.The ceramics exhibit remarkable comprehensive mechanical properties,with flexural strength and fracture toughness values reaching 773±114 MPa and 5.88±0.08 MPa·m^(1/2),respectively,surpassing those of conventional hot pressed samples.This technique is expected to be applied to other ultra-high temperature ceramics,providing a promising approach for the development of thermal protection materials.
基金National Natural Science Foundation of China(No.51478098)Innovation Foundation of Shanghai Education Commission,China(No.13ZZ054)
文摘Computational fluid dynamics( CFD) techniques are used to investigate effects of both wind direction and wind speed on net solar heat gain of south wall with internal insulation in winter.Results show that wind effect has a significant influence on the net solar heat gain,where the impact of wind direction is stronger than that of wind speed. For regions in lower reaches of the Yangtze River,difference of their average net solar heat gains( NSHGS) is about 20% due to various wind speeds and wind directions.Buildings in districts with a dominant wind direction of north achieve the highest solar energy utilization.
基金supported by the Key-Area Research and Development of Guangdong Province(2024B0101040002)the Shenzhen Science and Technology Program(KQTD20200820113045081)+11 种基金the GuangDong Basic and Applied Basic Research Foundation(2024B1515040022)support fromthe NationalNatural Science Foundation of China(52473298)the Shenzhen Science and Technology Program(RCJC20221008092725020)the Fundamental Research Funds for the Central Universities(2024FRFK03013)the StateKey Laboratory of Precision Welding&Joining of Materials and Structures(no.24-Z-14)the Shenzhen Stable Support Plan for Higher Education Institutions(GXWD20220818151757003)support from the National Natural Science Foundation of China for Distinguished Young Scholars(52425108)the National Natural Science Foundation of China(52172194)the Shenzhen Science and Technology Program(RCJC20210609103733073)support fromtheNationalNatural Science Foundation ofChina(52472196)support from the China Postdoctoral Science Foundation(2023M730841)the National Natural Science Foundation of China(12404046).
文摘Solid-state thermoelectric coolers,which enable direct heat pumping by utilizing electricity,play an essential role in electronic refrigeration.Given that these devices usually cool down to the sub-ambient temperature range,their performance is critically dependent on the material properties at temperatures below 300 K.Consequently,enhancing the thermoelectric properties of materials at sub-ambient temperature is of paramount importance for advancing cooling technology.Herein,a single-crystalline Mg_(3)Bi_(2)-based material has been prepared and exhibits high electron mobility.As a result,thermoelectric figure-of-merit values of~1.05 at 300 K and~0.87 at 250 K(along the ab plane)have been achieved,which are superior to commercial n-type Bi_(2)(Te,Se)_(3).Thermoelectric coolers(single-and double-stage devices)based on the n-type single-crystalline Mg_(3)Bi_(1.497)Sb_(0.5)Te_(0.003)and p-type(Bi,Sb)_(2)Te_(3)have been fabricated.The double-stage cooler demonstrates a remarkable maximum cooling temperature difference of~106.8 K at the hot-side temperature of 350 K,surpassing the performance of commercial Bi_(2)Te_(3)-based devices.Notably,the Mg_(3)Bi_(2)-based doublestage device exhibits exceptional cyclic stability,maintaining its cooling performance without any observable degradation after approximately 2,000 cycles between the input currents of 1 and 3 A.These findings show that single-crystalline Mg_(3)Bi_(2)alloys hold great promise for thermoelectric cooling applications.
文摘Recently, much attention has been paid to investigate the latent heat storage system. Using of ice heat storage system brings an equalization of electric power demand, because it will solved the electric -power-demand-concentration on day-time of summer by the air conditioning. The flowable latent heat storage material, Oil/Water type emulsion, microencapsulated latent heat material-water mixture or ice slurry, etc., is enable to transport the latent heat in a pipe. The flowable latent heat storage material can realize the pipe size reduction and system efficiency improvement. Supercooling phenomenon of the dispersed latent heat storage material in continuous phase brings the obstruction of latent heat storage. The latent heat storage rates of dispersed water drops in W/O (Water/Oil) emulsion are investigated experimentally in this study. The water drops in emulsion has the diameter within 3 ~ 25μm, the averaged water drop diameter is 7.3μm and the standard deviation is 2.9μm. The direct contact heat exchange method is chosen as the phase change rate evaluation of water drops in W/O emulsion. The supercooled temperature and the cooling rate are set as parameters of this study. The evaluation is performed by comparison between the results of this study and the past research. The obtained experimental result is shown that the 35K or more degree from melting point brings 100% latent heat storage rate of W/O emulsion. It was clarified that the supercooling rate of dispersed water particles in emulsion shows the larger value than that of the bulk water.
基金supported by the Deutsche Forschungsgemeinschaft(WI 972/20-1)
文摘The interaction of evaporating droplets and hot catalyst particles plays a major role in heterogeneously catalysed reactions. The liquid feed is injected into a gas-solid flow and is mixed with the catalyst. The interaction phenomena determine the evaporation time which should be minimised to keep the reactor vessel small. First measurements with a bed of fixed hot FCC-particles （fluid catalytic cracking） and two model fluids have been conducted. The interactions of ethanol and water droplets with the hot bed surface were captured via a high-speed camera. While the ethanol droplet developed a stable steam cushion due to Leidenfrost phenomena, water showed intense interaction and steam explosions which induced repulsion and atomisation of the droplet.
