Interfacial solar evaporation holds immense potential for brine desalination with low carbon footprints and high energy utilization.Hydrogels,as a tunable material platform from the molecular level to the macroscopic ...Interfacial solar evaporation holds immense potential for brine desalination with low carbon footprints and high energy utilization.Hydrogels,as a tunable material platform from the molecular level to the macroscopic scale,have been considered the most promising candidate for solar evaporation.However,the simultaneous achievement of high evaporation efficiency and satisfactory tolerance to salt ions in brine remains a challenging scientific bottleneck,restricting the widespread application.Herein,we report ionization engineering,which endows polymer chains of hydrogels with electronegativity for impeding salt ions and activating water molecules,fundamentally overcoming the hydrogel salt-impeded challenge and dramatically expediting water evaporating in brine.The sodium dodecyl benzene sulfonate-modified carbon black is chosen as the solar absorbers.The hydrogel reaches a ground-breaking evaporation rate of 2.9 kg m−2 h−1 in 20 wt%brine with 95.6%efficiency under one sun irradiation,surpassing most of the reported literature.More notably,such a hydrogel-based evaporator enables extracting clean water from oversaturated salt solutions and maintains durability under different high-strength deformation or a 15-day continuous operation.Meantime,on the basis of the cation selectivity induced by the electronegativity,we first propose an all-day system that evaporates during the day and generates salinity-gradient electricity using waste-evaporated brine at night,anticipating pioneer a new opportunity for all-day resource-generating systems in fields of freshwater and electricity.展开更多
Physics-informed neural networks(PINNs)are proved methods that are effective in solving some strongly nonlinear partial differential equations(PDEs),e.g.,Navier-Stokes equations,with a small amount of boundary or inte...Physics-informed neural networks(PINNs)are proved methods that are effective in solving some strongly nonlinear partial differential equations(PDEs),e.g.,Navier-Stokes equations,with a small amount of boundary or interior data.However,the feasibility of applying PINNs to the flow at moderate or high Reynolds numbers has rarely been reported.The present paper proposes an artificial viscosity(AV)-based PINN for solving the forward and inverse flow problems.Specifically,the AV used in PINNs is inspired by the entropy viscosity method developed in conventional computational fluid dynamics(CFD)to stabilize the simulation of flow at high Reynolds numbers.The newly developed PINN is used to solve the forward problem of the two-dimensional steady cavity flow at Re=1000 and the inverse problem derived from two-dimensional film boiling.The results show that the AV augmented PINN can solve both problems with good accuracy and substantially reduce the inference errors in the forward problem.展开更多
Two-dimensional(2D)thermoelectric(TE)materials have been widely developed;however,some 2D materials exhibit isotropic phonon,electron transport properties,and poor TE performance,which limit their application scope.Th...Two-dimensional(2D)thermoelectric(TE)materials have been widely developed;however,some 2D materials exhibit isotropic phonon,electron transport properties,and poor TE performance,which limit their application scope.Thus,exploring excellent anisotropic and ultrahigh-performance TE materials are very warranted.Herein,we first investigate the phonon thermal and TE properties of a novel 2D-connectivity ternary compound named Ga2I2S2.This paper comprehensively studies the phonon dispersion,phonon anharmonicity,lattice thermal conductivity,electronic structure,carrier mobility,Seebeck coefficient,electrical conductivity,and the dimensionless figure of merit(ZT)versus carrier concentration for 2D Ga_(2)I_(2)S_(2).We conclude that the in-plane lattice thermal conductivities of Ga_(2)I_(2)S_(2) at room temperature(300 K)are found to be 1.55 W mK^(−1) in the X-axis direction(xx-direction)and 3.82 W mK^(−1)in the Y-axis direction(yy-direction),which means its anisotropy ratio reaches 1.46.Simultaneously,the TE performance of p-type and n-type doping 2D Ga2I2S2 also shows significant anisotropy,giving rise to the ZT peak values of p-type doping in xx-and yy-directions being 0.81 and 1.99,respectively,and those of n-type doping reach ultrahigh values of 7.12 and 2.89 at 300 K,which are obviously higher than the reported values for p-type and n-type doping ternary compound Sn2BiX(ZT∼1.70 and∼2.45 at 300 K)(2020 Nano Energy 67104283).This work demonstrates that 2D Ga_(2)I_(2)S_(2) has high anisotropic TE conversion efficiency and can also be used as a new potential room-temperature TE material.展开更多
High-pressure has been widely utilized to improve material performances such as thermal conductiv-ityκand interfacial thermal conductance G.Gallium arsenide(GaAs)as a functional semiconductor has attracted extensive ...High-pressure has been widely utilized to improve material performances such as thermal conductiv-ityκand interfacial thermal conductance G.Gallium arsenide(GaAs)as a functional semiconductor has attracted extensive attention in high-pressure studies for its technological importance and complex structure transitions.Thermal properties of GaAs under high pressure are urgent needs in physics but remain elusive.Herein,we systematically investigateκGaAs and G Al/GaAs of multi-structure up to -23 GPa.We conclude that:(1)in pressurization,phonon group velocity,lattice defects,and electrons play a central role inκGaAs in elastic,plastic,and metallization regions,respectively.The increased phonon density of states(PDOS)overlap,group velocity,and interfacial bonding enhances G Al/GaAs.(2)In depressurization,electrons remain the dominant factor on κ GaAs from 23 to 13.5 GPa.G Al/GaAs increases dramatically at -12 GPa due to the larger PDOS overlap.With decompressing to ambient,lattice defects including grain size reduction,arsenic vacancies,and partial amorphization reduce κ GaAs to a glass-like value.Remarkably,the released G Al/GaAs is 2.6 times higher than that of the initial.Thus our findings open a new dimension in synergistically realizing glass-like κ and enhancing G,which can facilitate thermoelectric performance and its potential engineering applications.展开更多
In order to study the theoretical cycle characteristic of [mmim]DMP(1-methyl-3-methylimidazolium dimethylphosphate)/methanol absorption refrigeration,the modified UNIFAC group contribution model and the Wilson model a...In order to study the theoretical cycle characteristic of [mmim]DMP(1-methyl-3-methylimidazolium dimethylphosphate)/methanol absorption refrigeration,the modified UNIFAC group contribution model and the Wilson model are established through correlating the experimental vapor pressure data of [mmim]DMP/methanol at T=280～370K and methanol mole fraction x=0.529～0.965.Thermodynamic performances of absorption refrigeration utilizing [mmim]DMP/methanol,LiBr/H2O and H2O/NH3 are investigated and compared with each other under the same operating conditions.From the results,some conclusions are obtained as follows:1)the circulation ratio of the [mmim]DMP /methanol absorption refrigeration is higher than that of the LiBr/H2O absorption refrigeration,but still can be acceptable and tolerable.2)The COP of the [mmim]DMP/methanol absorption refrigeration is smaller than that of the LiBr/H2O absorption refrigeration,while it is higher than that of the H2O/NH3 absorption refrigeration under most operating conditions.3)The[mmim]DMP/methanol absorption refrigeration are still available with high COP when the heat source temperature is too high to drive LiBr/H2O absorption refrigeration.展开更多
The 3ω approach was used to measure the effective thermal conductivity of phase-change material microcapsules (PCMMs) based on urea formaldehyde and sliced paraffin. The effective thermal conductivities of PCMMs with...The 3ω approach was used to measure the effective thermal conductivity of phase-change material microcapsules (PCMMs) based on urea formaldehyde and sliced paraffin. The effective thermal conductivities of PCMMs with different densities were measured within the phase-change temperature range. The relationships between effective thermal conductivity, density and temperature were analysed. The effective thermal conductivity reached peak values within the phase-change temperature range and the temperature peak value was consistent with the peak value of the phase-change temperature. The effective thermal conductivity increased with increasing density due to the decreased porosity of samples and their increased solid-phase conduction.展开更多
The temperature of a friction pair exerts considerable influence on the tribological behavior of a system.In two cases,one with and the other without Cu(copper)nanoparticles,the temperature increase in friction pairs ...The temperature of a friction pair exerts considerable influence on the tribological behavior of a system.In two cases,one with and the other without Cu(copper)nanoparticles,the temperature increase in friction pairs caused by frictional heating and its tribological properties at various temperatures are studied by using the molecular dynamics approach.The results show that temperature distribution and surface abrasion are significantly improved by the presence of Cu nanoparticles.This is one of the reasons for the improvements in tribological properties achieved in the presence of nanoparticles.The temperature and range of influence of frictional heating for the model without nanoparticles are significantly increased with the increase in the sliding velocity;however,in the model with nanoparticles,the temperature gradient is confined to the area near the Cu film.With an increase in the temperature of the friction pair,the improvement in anti-wear properties associated with the presence of Cu nanoparticles becomes more significant.展开更多
A simulation for piston effect in supercritical carbon dioxide by employing a simple model is conducted.In the first place,the thermal properties of carbon dioxide near its liquid-vapor critical point are discussed.It...A simulation for piston effect in supercritical carbon dioxide by employing a simple model is conducted.In the first place,the thermal properties of carbon dioxide near its liquid-vapor critical point are discussed.It is calculated that the heat capacity ratio and isobaric expansion coefficient of supercritical fluids are extremely high.Furthermore,the simulation for piston effect in supercritical carbon dioxide between two infinite vertical walls is presented.The numerical results prove that piston effect has a much faster speed of heat transfer than thermal conduction under microgravity conditions.Moreover,the piston effect turns out to be stronger when closer to the critical point.展开更多
基金the National Natural Science Foundation of China(Grant No.52076028).
文摘Interfacial solar evaporation holds immense potential for brine desalination with low carbon footprints and high energy utilization.Hydrogels,as a tunable material platform from the molecular level to the macroscopic scale,have been considered the most promising candidate for solar evaporation.However,the simultaneous achievement of high evaporation efficiency and satisfactory tolerance to salt ions in brine remains a challenging scientific bottleneck,restricting the widespread application.Herein,we report ionization engineering,which endows polymer chains of hydrogels with electronegativity for impeding salt ions and activating water molecules,fundamentally overcoming the hydrogel salt-impeded challenge and dramatically expediting water evaporating in brine.The sodium dodecyl benzene sulfonate-modified carbon black is chosen as the solar absorbers.The hydrogel reaches a ground-breaking evaporation rate of 2.9 kg m−2 h−1 in 20 wt%brine with 95.6%efficiency under one sun irradiation,surpassing most of the reported literature.More notably,such a hydrogel-based evaporator enables extracting clean water from oversaturated salt solutions and maintains durability under different high-strength deformation or a 15-day continuous operation.Meantime,on the basis of the cation selectivity induced by the electronegativity,we first propose an all-day system that evaporates during the day and generates salinity-gradient electricity using waste-evaporated brine at night,anticipating pioneer a new opportunity for all-day resource-generating systems in fields of freshwater and electricity.
基金Project supported by the Fundamental Research Funds for the Central Universities of China(No.DUT21RC(3)063)the National Natural Science Foundation of China(No.51720105007)the Baidu Foundation(No.ghfund202202014542)。
文摘Physics-informed neural networks(PINNs)are proved methods that are effective in solving some strongly nonlinear partial differential equations(PDEs),e.g.,Navier-Stokes equations,with a small amount of boundary or interior data.However,the feasibility of applying PINNs to the flow at moderate or high Reynolds numbers has rarely been reported.The present paper proposes an artificial viscosity(AV)-based PINN for solving the forward and inverse flow problems.Specifically,the AV used in PINNs is inspired by the entropy viscosity method developed in conventional computational fluid dynamics(CFD)to stabilize the simulation of flow at high Reynolds numbers.The newly developed PINN is used to solve the forward problem of the two-dimensional steady cavity flow at Re=1000 and the inverse problem derived from two-dimensional film boiling.The results show that the AV augmented PINN can solve both problems with good accuracy and substantially reduce the inference errors in the forward problem.
基金support from the National Natural Science Foundation of China[51720105007,52076031,11602149,51806031,52176166]the Fundamental Research Funds for the Central Universities[DUT19RC(3)006]the computing resources from the Supercomputer Center of Dalian University of Technology and RWTH Aachen University under project 3357.
文摘Two-dimensional(2D)thermoelectric(TE)materials have been widely developed;however,some 2D materials exhibit isotropic phonon,electron transport properties,and poor TE performance,which limit their application scope.Thus,exploring excellent anisotropic and ultrahigh-performance TE materials are very warranted.Herein,we first investigate the phonon thermal and TE properties of a novel 2D-connectivity ternary compound named Ga2I2S2.This paper comprehensively studies the phonon dispersion,phonon anharmonicity,lattice thermal conductivity,electronic structure,carrier mobility,Seebeck coefficient,electrical conductivity,and the dimensionless figure of merit(ZT)versus carrier concentration for 2D Ga_(2)I_(2)S_(2).We conclude that the in-plane lattice thermal conductivities of Ga_(2)I_(2)S_(2) at room temperature(300 K)are found to be 1.55 W mK^(−1) in the X-axis direction(xx-direction)and 3.82 W mK^(−1)in the Y-axis direction(yy-direction),which means its anisotropy ratio reaches 1.46.Simultaneously,the TE performance of p-type and n-type doping 2D Ga2I2S2 also shows significant anisotropy,giving rise to the ZT peak values of p-type doping in xx-and yy-directions being 0.81 and 1.99,respectively,and those of n-type doping reach ultrahigh values of 7.12 and 2.89 at 300 K,which are obviously higher than the reported values for p-type and n-type doping ternary compound Sn2BiX(ZT∼1.70 and∼2.45 at 300 K)(2020 Nano Energy 67104283).This work demonstrates that 2D Ga_(2)I_(2)S_(2) has high anisotropic TE conversion efficiency and can also be used as a new potential room-temperature TE material.
基金financially supported by the National Natural Science Foundation of China(Nos.51720105007,51976025,and 52206219)the Fundamental Research Funds for the Central Universities(No.DUT22ZD216).
文摘High-pressure has been widely utilized to improve material performances such as thermal conductiv-ityκand interfacial thermal conductance G.Gallium arsenide(GaAs)as a functional semiconductor has attracted extensive attention in high-pressure studies for its technological importance and complex structure transitions.Thermal properties of GaAs under high pressure are urgent needs in physics but remain elusive.Herein,we systematically investigateκGaAs and G Al/GaAs of multi-structure up to -23 GPa.We conclude that:(1)in pressurization,phonon group velocity,lattice defects,and electrons play a central role inκGaAs in elastic,plastic,and metallization regions,respectively.The increased phonon density of states(PDOS)overlap,group velocity,and interfacial bonding enhances G Al/GaAs.(2)In depressurization,electrons remain the dominant factor on κ GaAs from 23 to 13.5 GPa.G Al/GaAs increases dramatically at -12 GPa due to the larger PDOS overlap.With decompressing to ambient,lattice defects including grain size reduction,arsenic vacancies,and partial amorphization reduce κ GaAs to a glass-like value.Remarkably,the released G Al/GaAs is 2.6 times higher than that of the initial.Thus our findings open a new dimension in synergistically realizing glass-like κ and enhancing G,which can facilitate thermoelectric performance and its potential engineering applications.
基金supported by the National Basic Research Program of China (973 Program) under Grant No.2012CB933200the National Natural Science Fundation of China under Grant No.51276180
文摘In order to study the theoretical cycle characteristic of [mmim]DMP(1-methyl-3-methylimidazolium dimethylphosphate)/methanol absorption refrigeration,the modified UNIFAC group contribution model and the Wilson model are established through correlating the experimental vapor pressure data of [mmim]DMP/methanol at T=280～370K and methanol mole fraction x=0.529～0.965.Thermodynamic performances of absorption refrigeration utilizing [mmim]DMP/methanol,LiBr/H2O and H2O/NH3 are investigated and compared with each other under the same operating conditions.From the results,some conclusions are obtained as follows:1)the circulation ratio of the [mmim]DMP /methanol absorption refrigeration is higher than that of the LiBr/H2O absorption refrigeration,but still can be acceptable and tolerable.2)The COP of the [mmim]DMP/methanol absorption refrigeration is smaller than that of the LiBr/H2O absorption refrigeration,while it is higher than that of the H2O/NH3 absorption refrigeration under most operating conditions.3)The[mmim]DMP/methanol absorption refrigeration are still available with high COP when the heat source temperature is too high to drive LiBr/H2O absorption refrigeration.
基金The financial supports provided by National Basic Research Program of China (Grant No.2012CB933200)National Natural Science Foundation of China (Grant No. 51106151) are gratefully acknowledgedprovided by State Key Laboratory of Polymer Physics and Chemistry,Institute of Chemistry, Chinese Academy of Sciences
文摘The 3ω approach was used to measure the effective thermal conductivity of phase-change material microcapsules (PCMMs) based on urea formaldehyde and sliced paraffin. The effective thermal conductivities of PCMMs with different densities were measured within the phase-change temperature range. The relationships between effective thermal conductivity, density and temperature were analysed. The effective thermal conductivity reached peak values within the phase-change temperature range and the temperature peak value was consistent with the peak value of the phase-change temperature. The effective thermal conductivity increased with increasing density due to the decreased porosity of samples and their increased solid-phase conduction.
基金This work is supported by National Natural Science Foundation of China(Grant No.51806028,51876027,51476019,and 51376002)the Fundamental Research Funds for the Central Universities(DUT17RC(3)043 and DUT 17JC23).
文摘The temperature of a friction pair exerts considerable influence on the tribological behavior of a system.In two cases,one with and the other without Cu(copper)nanoparticles,the temperature increase in friction pairs caused by frictional heating and its tribological properties at various temperatures are studied by using the molecular dynamics approach.The results show that temperature distribution and surface abrasion are significantly improved by the presence of Cu nanoparticles.This is one of the reasons for the improvements in tribological properties achieved in the presence of nanoparticles.The temperature and range of influence of frictional heating for the model without nanoparticles are significantly increased with the increase in the sliding velocity;however,in the model with nanoparticles,the temperature gradient is confined to the area near the Cu film.With an increase in the temperature of the friction pair,the improvement in anti-wear properties associated with the presence of Cu nanoparticles becomes more significant.
基金financially supported by the National Basic Research Program of China (973 Program) under Grant No.2012CB933200the National Natural Science Foundation of China under Grant No.51161140332
文摘A simulation for piston effect in supercritical carbon dioxide by employing a simple model is conducted.In the first place,the thermal properties of carbon dioxide near its liquid-vapor critical point are discussed.It is calculated that the heat capacity ratio and isobaric expansion coefficient of supercritical fluids are extremely high.Furthermore,the simulation for piston effect in supercritical carbon dioxide between two infinite vertical walls is presented.The numerical results prove that piston effect has a much faster speed of heat transfer than thermal conduction under microgravity conditions.Moreover,the piston effect turns out to be stronger when closer to the critical point.
