Aiming to identify the validity of fabricating microencapsulated phase change material(PCM) with polymethylmethacrylate(PMMA) by ultraviolet curing emulsion polymerization method using iron(III) chloride as photoiniti...Aiming to identify the validity of fabricating microencapsulated phase change material(PCM) with polymethylmethacrylate(PMMA) by ultraviolet curing emulsion polymerization method using iron(III) chloride as photoinitiator,SA/PMMA microcapsules were prepared and various techniques were employed to determine the ignition mechanism,structural characteristics and thermal properties of the composite.The results shown that the microcapsules containing SA with maximum percentage of 52.20 wt% formed by radical mechanism and only physical interactions existed in the components both in the prepared process and subsequent use.The phase change temperatures and latent heats of the microencapsulated SA were measured as 55.3 °C and 102.1 J·g^(-1) for melting,and 48.8 °C and 102.8 J·g^(-1) for freezing,respectively.Thermal gravimetric analysis revealed that SA/PMMA has good thermal durability in working temperature range.The results of accelerated thermal cycling test are all shown that the SA/PMMA have excellent thermal reliability and chemical stability although they were subjected 1000 melting/freezing cycles.In summary,the comparable thermal storage ability and good thermal reliability facilitated SA/PMMA to be considered as a viable candidate for thermal energy storage.The successful fabrication of SA/PMMA capsules indicates that ferric chloride is a prominent candidate for synthesizing PMMA containing PCM composite.展开更多
The chloride salts have great potential used as high-temperature thermal energy storage(TES) medium for the concentrated solar power system.In this study,LiCl,KCl and CaCl_(2) were selected as energy storage materials...The chloride salts have great potential used as high-temperature thermal energy storage(TES) medium for the concentrated solar power system.In this study,LiCl,KCl and CaCl_(2) were selected as energy storage materials in order to further broaden the working temperature of ternary chloride salt and improve its energy storage density.The new high-temperature energy storage ternary chloride composed of LiCl,KCl,and CaCl_(2) was developed based on the phase diagram generated by FactSage.Three components of LiCl-KCl-CaCl_(2) with the mass ratio of 37.85%-53.38%-8.77%,30.90%-13.82%-55.28% and 1.78%-18.61%-79.61% were developed,of which the corresponding melting temperature(T_(m)) 340.93,433.57 and 626.85℃,respectively,was obtained either.Considering that T_(m) of the third group of salts was too high,only the first two groups of salts were tested.DSC test showed that the actual melting point was only 0.46% and 1.64% different from the melting point predicted by Factsage.The thermal properties of the two ternary chloride salts were also compared.The solid and liquid-specific heat of ternary salts was determined by DSC using sapphire as the standard reference.The vapor pressure and decomposition temperature of ternary chloride salts were investigated.The results showed that the vapor pressure of salt 1 was almost constant below 650℃ by FactSage.Meanwhile,the TG results showed that the upper working temperature of salt 1 was 650℃ under the air atmosphere.In addition,the ternary chloride salts after short-term cycling still exhibited excellent thermal properties,which revealed that these good thermal properties make them have broad application prospects in high-temperature thermal energy storage systems.展开更多
Herein,a novel strategy for regulating the phase structure was used to significantly enhance the recoverable energy storage density(Wrec)and the thermal stability via designing the(1-x)[(Bi_(0.5)Na_(0.5))_(0.7)Sr_(0.3...Herein,a novel strategy for regulating the phase structure was used to significantly enhance the recoverable energy storage density(Wrec)and the thermal stability via designing the(1-x)[(Bi_(0.5)Na_(0.5))_(0.7)Sr_(0.3)TiO_(3)]-xBiScO_(3)((1-x)BNST-xBS)relaxor ferroelectric ceramics.The incorporation of BS into BNST ceramics markedly increases the local micro-structure disorder,causing a high polarization and inhibiting polarization hysteresis for 0.95BNST-0.05BS ceramics,leading to a large Wrec of 5.41 J/cm^(3)with an ideal efficiency(h)of 78.5%.Meanwhile,transmission electron microscope(TEM)results further proved that the nano-domain structure and the tetragonal(P4bm)phase superlattice structure of 0.95BNST-0.05BS ceramics possess an excellent thermal stability(20-200℃).An outstanding Wrec value of 3.18×(1.00±0.03)J/cm^(3)and an h value of 74.500±0.025 are achieved under a temperature range from 20℃to 200℃.This work provides a promising method for phase-structure design that can make it possible to apply temperature-insensitive ceramic dielectrics with a high energy storage density in harsh environments.展开更多
The influence of thermal treatment on the dielectric properties and energy storage performances of a classical dielectric nanocomposite system(barium titanate/polyvinylidene fluoride PVDF)was discussed systematically....The influence of thermal treatment on the dielectric properties and energy storage performances of a classical dielectric nanocomposite system(barium titanate/polyvinylidene fluoride PVDF)was discussed systematically.The results demonstrated that the permittivity of thermal treated nanocomposites increased and dielectric loss decreased compared with the untreated system.In addition,the energy density was also greatly improved due to the inclined residual polarization.For example,the energy density of the treated nanocomposite with 50 vol.%nanofillers was 3.14 times higher than the untreated nanocomposite at 50 MV/m.Moreover,the charge–discharge efficiency was also promoted from 6.36%to 56.89%.According to the viewpoint of microstructure,the improvement of the dielectric and energy storage properties would be ascribed to the suppression on void defects in the interphase of dielectric nanocomposite by employing the thermal treatment process.Finally,thermal treatment turns out to be a simple and an effective method to improve the dielectric performances and energy storage properties in the dielectric nanocomposites.展开更多
In this work,a series of nanoencapsulated phase change materials(NanoPCMs)with paraffin wax(PW)as core and melamine-formaldehyde(MF)as shell were synthesized by the in-situ polymerization method.The morphol-ogy,chemic...In this work,a series of nanoencapsulated phase change materials(NanoPCMs)with paraffin wax(PW)as core and melamine-formaldehyde(MF)as shell were synthesized by the in-situ polymerization method.The morphol-ogy,chemical structure and thermal properties of prepared NanoPCMs were characterized by scanning electron microscope,Fourier transform infrared,differential scanning calorimetry and thermogravimertic analyzer.The results show that the PW is successfully encapsulated in the MF without chemical interaction,and the NanoPCMs present regular spherical shape with the average diameter of 260-450 nm.The encapsulation efficiency of the NanoPCMs increases with the augment of the supplied amount of core material.The maximum encapsulation efficiency of the NanoPCMs can reach up to approximately 75%.The NanoPCMs can maintain excellent thermal reliability and stability after 2000 thermal cycling.The prepared NanoPCMs can be well applied in the latent heat thermal energy storage and thermal management systems due to their remarkable encapsulation efficiency and thermal properties enable them to.展开更多
A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scan...A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scanning calorimeter(DSC).The results indicate that these ionic liquids exhibit proper melting points,high value of heats of fusion,and satisfying heat capacities which are suitable for thermal energy storage applications.展开更多
In recent years,heat storage system combining sensible and latent heat materials has received more and more attentions.In this paper,we proposed the hybrid configuration with a macro-encapsulation,and analyzed its cha...In recent years,heat storage system combining sensible and latent heat materials has received more and more attentions.In this paper,we proposed the hybrid configuration with a macro-encapsulation,and analyzed its charging performance with different influencing factors by CFD simulation.In the case,the sensible heat storage materials are magnesia brick or HT concrete and the phase change materials(PCMs)are mixed molten salts.Firstly,we analyzed the heat transfer characteristics of the hybrid configuration in charging process.Then,we analyzed the effect of heating power on charging performance.The maximum temperature of the heating surface shall not exceed 500℃as the constraint condition,the heat storage capacity increases at first and then decreases with the heating power.Then,we compared the charging performance of different solid structure and the hybrid configurations.Whether magnesia brick or HT concrete,the charging performance of the solid structure is better than that of the hybrid configuration,because the thermal conductivity of the molten salt is significantly lower than that of the two sensible heat storage materials.Then,we compared the charging performance of different molten salts.The hybrid configuration with lower melting point molten salt has better performance because of more intensity natural convection.Finally,we analyzed the charging performance of the hybrid configuration used the composite phase change material(CPCM)with high thermal conductivity and specific heat.From the result,the charging performance increases by 22.5%compared with the solid structure.These results indicate that the hybrid configuration with the macro-encapsulation method is a potential form of thermal energy storage,but it needs to be further optimized.展开更多
基金Supported by the National Natural Science Foundation of China(51562023)the Natural Science Foundation of Gansu Provence(145RJZA185)the National science and technology support project(2014BAA01B01)
文摘Aiming to identify the validity of fabricating microencapsulated phase change material(PCM) with polymethylmethacrylate(PMMA) by ultraviolet curing emulsion polymerization method using iron(III) chloride as photoinitiator,SA/PMMA microcapsules were prepared and various techniques were employed to determine the ignition mechanism,structural characteristics and thermal properties of the composite.The results shown that the microcapsules containing SA with maximum percentage of 52.20 wt% formed by radical mechanism and only physical interactions existed in the components both in the prepared process and subsequent use.The phase change temperatures and latent heats of the microencapsulated SA were measured as 55.3 °C and 102.1 J·g^(-1) for melting,and 48.8 °C and 102.8 J·g^(-1) for freezing,respectively.Thermal gravimetric analysis revealed that SA/PMMA has good thermal durability in working temperature range.The results of accelerated thermal cycling test are all shown that the SA/PMMA have excellent thermal reliability and chemical stability although they were subjected 1000 melting/freezing cycles.In summary,the comparable thermal storage ability and good thermal reliability facilitated SA/PMMA to be considered as a viable candidate for thermal energy storage.The successful fabrication of SA/PMMA capsules indicates that ferric chloride is a prominent candidate for synthesizing PMMA containing PCM composite.
基金financially supported by the National Natural Science Foundation of China (Grants No.52130607,52090062 and 52211530087)the Double First-Class Key Program of Gansu Provincial Department of Education (Grant No.GCJ2022-38)。
文摘The chloride salts have great potential used as high-temperature thermal energy storage(TES) medium for the concentrated solar power system.In this study,LiCl,KCl and CaCl_(2) were selected as energy storage materials in order to further broaden the working temperature of ternary chloride salt and improve its energy storage density.The new high-temperature energy storage ternary chloride composed of LiCl,KCl,and CaCl_(2) was developed based on the phase diagram generated by FactSage.Three components of LiCl-KCl-CaCl_(2) with the mass ratio of 37.85%-53.38%-8.77%,30.90%-13.82%-55.28% and 1.78%-18.61%-79.61% were developed,of which the corresponding melting temperature(T_(m)) 340.93,433.57 and 626.85℃,respectively,was obtained either.Considering that T_(m) of the third group of salts was too high,only the first two groups of salts were tested.DSC test showed that the actual melting point was only 0.46% and 1.64% different from the melting point predicted by Factsage.The thermal properties of the two ternary chloride salts were also compared.The solid and liquid-specific heat of ternary salts was determined by DSC using sapphire as the standard reference.The vapor pressure and decomposition temperature of ternary chloride salts were investigated.The results showed that the vapor pressure of salt 1 was almost constant below 650℃ by FactSage.Meanwhile,the TG results showed that the upper working temperature of salt 1 was 650℃ under the air atmosphere.In addition,the ternary chloride salts after short-term cycling still exhibited excellent thermal properties,which revealed that these good thermal properties make them have broad application prospects in high-temperature thermal energy storage systems.
基金supported by the National Natural Science Foundation of China(Grant No.51902167,51971005)Natural Science Foundation of Zhejiang Province(Grant No.LY21E020002)Natural Science Foundation of Ningbo City(Grant No.2021J064,2021J097).
文摘Herein,a novel strategy for regulating the phase structure was used to significantly enhance the recoverable energy storage density(Wrec)and the thermal stability via designing the(1-x)[(Bi_(0.5)Na_(0.5))_(0.7)Sr_(0.3)TiO_(3)]-xBiScO_(3)((1-x)BNST-xBS)relaxor ferroelectric ceramics.The incorporation of BS into BNST ceramics markedly increases the local micro-structure disorder,causing a high polarization and inhibiting polarization hysteresis for 0.95BNST-0.05BS ceramics,leading to a large Wrec of 5.41 J/cm^(3)with an ideal efficiency(h)of 78.5%.Meanwhile,transmission electron microscope(TEM)results further proved that the nano-domain structure and the tetragonal(P4bm)phase superlattice structure of 0.95BNST-0.05BS ceramics possess an excellent thermal stability(20-200℃).An outstanding Wrec value of 3.18×(1.00±0.03)J/cm^(3)and an h value of 74.500±0.025 are achieved under a temperature range from 20℃to 200℃.This work provides a promising method for phase-structure design that can make it possible to apply temperature-insensitive ceramic dielectrics with a high energy storage density in harsh environments.
基金supported by National Nature Science Foundation of China(Grant No.51622701)State Grid Corporation Technology Project(5202011600UK)and the Fundamental Research Funds for the Central Universities(No.FRF-TP-16-001C1).
文摘The influence of thermal treatment on the dielectric properties and energy storage performances of a classical dielectric nanocomposite system(barium titanate/polyvinylidene fluoride PVDF)was discussed systematically.The results demonstrated that the permittivity of thermal treated nanocomposites increased and dielectric loss decreased compared with the untreated system.In addition,the energy density was also greatly improved due to the inclined residual polarization.For example,the energy density of the treated nanocomposite with 50 vol.%nanofillers was 3.14 times higher than the untreated nanocomposite at 50 MV/m.Moreover,the charge–discharge efficiency was also promoted from 6.36%to 56.89%.According to the viewpoint of microstructure,the improvement of the dielectric and energy storage properties would be ascribed to the suppression on void defects in the interphase of dielectric nanocomposite by employing the thermal treatment process.Finally,thermal treatment turns out to be a simple and an effective method to improve the dielectric performances and energy storage properties in the dielectric nanocomposites.
基金supported by the National Key Research and Develop-ment Program of China(Grant No.2018YFC0705306)the Chengdu Sci-ence and Technology Project(No:2019-YF05-01332-SN)the Na-tional Natural Science Foundation of China(No:51678488).
文摘In this work,a series of nanoencapsulated phase change materials(NanoPCMs)with paraffin wax(PW)as core and melamine-formaldehyde(MF)as shell were synthesized by the in-situ polymerization method.The morphol-ogy,chemical structure and thermal properties of prepared NanoPCMs were characterized by scanning electron microscope,Fourier transform infrared,differential scanning calorimetry and thermogravimertic analyzer.The results show that the PW is successfully encapsulated in the MF without chemical interaction,and the NanoPCMs present regular spherical shape with the average diameter of 260-450 nm.The encapsulation efficiency of the NanoPCMs increases with the augment of the supplied amount of core material.The maximum encapsulation efficiency of the NanoPCMs can reach up to approximately 75%.The NanoPCMs can maintain excellent thermal reliability and stability after 2000 thermal cycling.The prepared NanoPCMs can be well applied in the latent heat thermal energy storage and thermal management systems due to their remarkable encapsulation efficiency and thermal properties enable them to.
基金Supported by the National Natural Science Foundation of China （21176010, 20706005）.
文摘A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scanning calorimeter(DSC).The results indicate that these ionic liquids exhibit proper melting points,high value of heats of fusion,and satisfying heat capacities which are suitable for thermal energy storage applications.
基金supported by Science and technology plan of Inner Mongolia Autonomous Region of China(Grant numbers 2019ZD014).
文摘In recent years,heat storage system combining sensible and latent heat materials has received more and more attentions.In this paper,we proposed the hybrid configuration with a macro-encapsulation,and analyzed its charging performance with different influencing factors by CFD simulation.In the case,the sensible heat storage materials are magnesia brick or HT concrete and the phase change materials(PCMs)are mixed molten salts.Firstly,we analyzed the heat transfer characteristics of the hybrid configuration in charging process.Then,we analyzed the effect of heating power on charging performance.The maximum temperature of the heating surface shall not exceed 500℃as the constraint condition,the heat storage capacity increases at first and then decreases with the heating power.Then,we compared the charging performance of different solid structure and the hybrid configurations.Whether magnesia brick or HT concrete,the charging performance of the solid structure is better than that of the hybrid configuration,because the thermal conductivity of the molten salt is significantly lower than that of the two sensible heat storage materials.Then,we compared the charging performance of different molten salts.The hybrid configuration with lower melting point molten salt has better performance because of more intensity natural convection.Finally,we analyzed the charging performance of the hybrid configuration used the composite phase change material(CPCM)with high thermal conductivity and specific heat.From the result,the charging performance increases by 22.5%compared with the solid structure.These results indicate that the hybrid configuration with the macro-encapsulation method is a potential form of thermal energy storage,but it needs to be further optimized.
