In this paper we describe a study on image grid display with automatic vertical scrolling.While scroll operations are normally carried out manually by the user,in the context of RSVP(Rapid Serial Visual Presentation)t...In this paper we describe a study on image grid display with automatic vertical scrolling.While scroll operations are normally carried out manually by the user,in the context of RSVP(Rapid Serial Visual Presentation)techniques this work considers a presentation mode in which the image grid is automati-cally scrolled.Through experiments carried out with 50 testers,we have investigated user performance while looking for specific target subjects within large collections of images.Different numbers of columns and scrolling speeds have been considered.The search task implied both clicking on the identified target pictures and simply vocally stating their visual recognition.To this purpose,and to identify possible specific gaze behaviours,eye tracking technology has been exploited.The obtained results show that number of columns and scroll speed do affect search performance.Moreover,the user’s gaze tends to focus on different screen areas depending on the values of these two parameters.Although it is not possible to definitely find an optimal columns-speed combination that is valid in all cases,the particular context of use can suggest feasible solutions according to one’s needs.To the best of our knowledge,image grid display with automatic scrolling has never been studied to date.展开更多
Deeply-rooted in China’s popular culture,precious scrolls(Baojuan)are the golden material to display popular religious belief of the mass.Based on the rare texts sorted and annotated by Shang Lixin,Dutch Sinologist W...Deeply-rooted in China’s popular culture,precious scrolls(Baojuan)are the golden material to display popular religious belief of the mass.Based on the rare texts sorted and annotated by Shang Lixin,Dutch Sinologist Wilt L.Idema continues his journey of translating precious scrolls.Focused on the theme of devoted women Buddhist followers in Ming dynasty,he explores the ethical choices of married women in facing the betrayal of servants or concubines.His translations not only add important reading material to Western readers in the field of Chinese popular literature,but also set standard for the coming translators in rendering Chinese ballads.展开更多
Although Ti3 C2 MXene sheets have attracted extensive attention in lithium-ion storage techniques,their restacking makes against and even hinders the Li ions diffusion within them,thereby decreasing the capacity as we...Although Ti3 C2 MXene sheets have attracted extensive attention in lithium-ion storage techniques,their restacking makes against and even hinders the Li ions diffusion within them,thereby decreasing the capacity as well as rate performance of conventional MXene anode.Here,for the first time,we roll up the Ti3 C2 Tx sheets into scrolls with unclosed topological structure and the interlayer galleries to alleviate the restacking problem.Thus,Ti3 C2 Tx scrolls as anode materials in lithium-ion batteries(LIBs)have higher capacity and better rate performance than Ti3 C2 Tx sheets.On the bases of these,high-capacity silicon nanoparticles are added during the rolling process to in-situ produce Ti3 C2 Tx/Si composite scrolls.The addition of 10%silicon nanoparticles shows the best overall improvement among capacity,rate capability and cyclic stability for Ti3 C2 Tx scrolls.展开更多
The aluminum alloy scroll is one of the key parts of the scroll compressors widely used in the air-conditioning,refrigeration,and heat pump systems.In this work,the semi-solid squeeze casting(SSSC)process was used to ...The aluminum alloy scroll is one of the key parts of the scroll compressors widely used in the air-conditioning,refrigeration,and heat pump systems.In this work,the semi-solid squeeze casting(SSSC)process was used to fabricate the aluminum alloy scroll.The effects of process parameters including the pouring temperature,mold temperature,and squeezing velocity on the filling and solidification behaviors of the alloys were investigated through simulations based on the power law cut-off(PLCO)material model.Results show that there is a significant increase in the flow velocity of the slurry,and the area of the high-speed region enlarges with the increase of the pouring temperature.The homogeneity of the temperature and velocity fields in the slurry is improved with an increase in mold temperature.Both the filling time and its variation rate decrease with an increase in squeezing velocity.The maximum solidification time exhibits a linear variation with the increase in pouring temperature.The shrinkage area is decreased by increasing the mold temperature.The optimal process parameters of the SSSC process were obtained from simulation analysis,which are the pouring temperature of 595°C,mold temperature of 350°C,and squeezing velocity of 0.3 m·s-1.Moreover,the qualified scroll casting was fabricated using the SSSC process under the optimal process parameters.展开更多
A modification of central profile with trigonometric curve is proposed based on the theory of engagement of scroll compressor. General modification equations for central profile of a pair of scrolls are given and vari...A modification of central profile with trigonometric curve is proposed based on the theory of engagement of scroll compressor. General modification equations for central profile of a pair of scrolls are given and various modification patterns are discussed. The equidistant method is employed to calculate the volume of a sealed chamber and a set of general equations is represented. Modification parameters affecting geometric and dynamic property of a scroll compressor are analyzed systematically, and the relations between them are accurately determined. The condition for transforming a trigonometric curve modification into an arc-curve modification is explained. The conclusions can also be applied to other scroll fluid machines.展开更多
In this paper a new simple multi-scroll chaotic generator is studied. The characteristic of this new multi-scroll chaotic generator is that it is easy to generate different number of scroll chaotic attractors through ...In this paper a new simple multi-scroll chaotic generator is studied. The characteristic of this new multi-scroll chaotic generator is that it is easy to generate different number of scroll chaotic attractors through modifying the nature number n after fixing the suitable system parameters and it does not need complex mathematical derivation. Various number of scroll chaotic attractors are illustrated not only by computer simulation but also by the realization of an electronic circuit experiment on Electronic Workbench (EWB).展开更多
The motion of organization center of three_dimensional untwisted scroll waves in excitable media with single diffusion is studied by singular perturbation method in this paper. The relation of curvature and the linear...The motion of organization center of three_dimensional untwisted scroll waves in excitable media with single diffusion is studied by singular perturbation method in this paper. The relation of curvature and the linear law are derived for untwisted organization center. These results have explicit physical meaning and are in good agreement with experiments.展开更多
This paper proposes a new simple autonomous chaotic system which can generate multi-scroll chaotic attractors. The characteristic of this new multi-scroll chaotic system is that the 4n + 2rn + 4-scroll chaotic attra...This paper proposes a new simple autonomous chaotic system which can generate multi-scroll chaotic attractors. The characteristic of this new multi-scroll chaotic system is that the 4n + 2rn + 4-scroll chaotic attractors are generated easily with n and m vaxying under n ≤ m. Various number of scroll chaotic attractors are illustrated not only by computer simulation but also by the realization of an electronic circuit experiment on EWB (Electronics Workbench).展开更多
Instead of manual polishing work for aluminum wheel hub (hub) surface, a new planetary scroll surface polishing method based on the rotation and revolution of hub in abrasives is presented in this paper. Since conve...Instead of manual polishing work for aluminum wheel hub (hub) surface, a new planetary scroll surface polishing method based on the rotation and revolution of hub in abrasives is presented in this paper. Since conventional barrel rotation polishing mode is unsatisfactory, shorter polishing period and lower energy consumption are expected. The surface polishing mechanism of the proposed method is ghen introduced. The influence of cutting velocity, cutting angle, abrasive on surface polishing quality and efficiency, as well as the correlation of the revolution velocity and the rotation velocity of hub are discussed. Experimental results show that high surface polishing quality and efficiency can be achieved with the new polishing method implying that a dustless clean working environment is realized.展开更多
BACKGROUND Retrocorneal hyaline scrolls are a rare phenomenon.We report a case of bilateral retrocorneal hyaline scrolls that were likely induced by asymptomatic congenital syphilis.CASE SUMMARY A 71-year-old woman pr...BACKGROUND Retrocorneal hyaline scrolls are a rare phenomenon.We report a case of bilateral retrocorneal hyaline scrolls that were likely induced by asymptomatic congenital syphilis.CASE SUMMARY A 71-year-old woman presented with blurred vision due to cataracts.Slit-lamp microscopy revealed bilateral hyaline scrolls with a dichotomous branching pattern extending to the anterior chamber or rods attaching to the rough posterior surface of the cornea.The patient was positive for syphilis-specific antibodies,with no ocular or systemic evidence of congenital or acquired syphilis.Binocular cataract,retrocorneal scroll,and corneal endothelial gutta were considered.The scroll of the right eye was removed during cataract surgery and further observed using hematoxylin–eosin staining and scanning electron microscopy.The cornea of the right eye remained transparent,and the residual scroll seemed stable,however,the corneal endothelial density declined at 13 mo after surgery.In vivo confocal microscopy revealed coalescence of corneal guttae at the level of the corneal endothelium or adhesion to the posterior surface of the endothelium,with enlarged endothelial cells in both eyes.Activated keratocytes in the stroma and a highly reflective acellular structure at the level of the Descemet’s membrane were observed.The removed scroll had a cartilage-like hardness and a circularly arranged fiber-like acellular structure.CONCLUSION Occult congenital syphilis could induce corneal endothelial gutta and theformation of retrocorneal scrolls without other signs of ocular syphilis.展开更多
Zongza Lhagyicannot forgetDecember 3,1999,When hereceived the entry certifi-cate from me London-based Guinness Book ofWorld Records while hewas in Shanghai.It reads:China Tibetan Cultural ArtColor Painting, the longes...Zongza Lhagyicannot forgetDecember 3,1999,When hereceived the entry certifi-cate from me London-based Guinness Book ofWorld Records while hewas in Shanghai.It reads:China Tibetan Cultural ArtColor Painting, the longest.measures 618 meters longand 2.3 meters wide.展开更多
Superlubricity is an ideal lubrication state where friction nearly vanishes between contact interfaces. It has become one of the most important research topics and approaches owing to its significance in reducing ener...Superlubricity is an ideal lubrication state where friction nearly vanishes between contact interfaces. It has become one of the most important research topics and approaches owing to its significance in reducing energy consumption and preventing device failures. As an efficient and universal lubricating principle capable of achieving superlubricity, rolling lubrication has attracted widespread attention in recent years. In this review, the theoretical concept of rolling lubrication and the experimental research progress of spherical/scroll structures are summarized. The review focuses on the possibility of achieving rolling lubrication using spherical/scroll structures(such as spherical fullerenes, carbon nanotubes, and formed and constructed spherical/scroll structures). The challenges in achieving rolling lubrication are summarized, and the possibility of molecular rolling lubrication,as well as its potential applications in superlubrication, are discussed.展开更多
In the design theory of scroll profiles for refrigeration scroll compressor,a mechanism principle of scroll profiles based on the center of natural temporal involutes and meshing region is presented,by which the perfo...In the design theory of scroll profiles for refrigeration scroll compressor,a mechanism principle of scroll profiles based on the center of natural temporal involutes and meshing region is presented,by which the performance characteristics of the various involutes are studied. Profiles type selection is very important for scroll compressor. Through analyzing the characteristic geometry,natural meshing mechanism is discovered in the study of scrolls. And a novel method for scroll profiles based on natural meshing mechanism is proposed. The result shows that the meshing region angle of odd regular polygon involutes is half of the characteristic-geometry exterior angle,and that of even regular polygon involutes is equal to the exterior angle to the moment. The corresponding meshing region angle is reduced increasingly with the increase of the edge number of characteristic geometry. The performance characteristics of scroll compressor tend towards the best correspondingly. Aiming at the existing problems of profile design for scrolls,we developed a novel methodology to study scroll profile. Originality research was done for the further study of scroll profile. It is the fundamentality factor representing essence character of scroll profiles function itself.展开更多
The development of engine waste heat recov- ery technologies attracts ever increasing interests due to the rising strict policy requirements and environmental con- cerns. This paper presented the study of engine coola...The development of engine waste heat recov- ery technologies attracts ever increasing interests due to the rising strict policy requirements and environmental con- cerns. This paper presented the study of engine coolant and exhaust heat recovery using organic Rankine cycle (ORC). Eight working fluids were selected to evaluate and compare the performance of the integrated waste heat recovery system. Rather than the conventional engine ORC system mainly focusing on the utilization of exhaust energy, this work proposed to fully use the engine coolant energy by changing the designed parameters of the ORC system. The case study selected a small engine as the heat source to drive the ORC system using a scroll expander for power production. The evaluation results suggest that under the engine rated condition, the solution to fully recover the engine coolant energy can achieve a higher power generation performance than that of the conven- tional engine ORC system. The results suggest that adding a recuperator to the ORC system can potentially improve the system performance when the working fluids are dry and the overall dumped heat demand of the system can be reduced by 12% under optimal conditions. When the ORC evaporating and condensing temperature are respectivelyset at 85℃ and 30℃, the integrated engine waste heat recovery system can improve the overall system efficiency by 9.3% with R600, R600a or n-Pentane as the working fluid.展开更多
Ejector can utilize high pressure energy from liquid mechanism,it can be used in heat pump system coupled with economized vapor injection(EVI)scroll compressor.When running under low temperature conditions,the perform...Ejector can utilize high pressure energy from liquid mechanism,it can be used in heat pump system coupled with economized vapor injection(EVI)scroll compressor.When running under low temperature conditions,the performance of the EVI system with ejector can be improved further.In this paper,the design method of the heat pump system with ejector is presented,and the process for designing the heat pump with ejector(EVIe)was summarized.One prototype heat pump was designed under the condition of the evaporation temperature of -20oC,and an experimental setup was established to test the prototype.The measured results demonstrated that the heating EER(energy efficiency ratio)of the EVIe could reach about 4%higher than that of the system without the ejector when the heating capacity remained nearly constant.The design method is helpful to development of a heat pump system coupled with scroll compressor and ejector.展开更多
Tangential leakage loss reduction has great significance on improving the performance of scroll compressors.In this study,the flow field of a scroll compressor working with CO_(2) was numerically investigated.The deve...Tangential leakage loss reduction has great significance on improving the performance of scroll compressors.In this study,the flow field of a scroll compressor working with CO_(2) was numerically investigated.The development characteristics of the tangential leakage flow in different working chambers were carried out,which was obtained by analyzing the field quantities distributions.The impacts of the radial clearances and sidewall roughness on the tangential leakage were also taken into consideration,in order to explore the feasible method of the flow control for the tangential leakage in scroll compressors.Results showed that the tangential leakage flow had various characteristics in the suction and compression chambers due to the different interactions between the tangential leakage flow and mainstream.Owing to little reverse pressure gradient,the tangential leakage flow maintained the typical jet form in the suction chambers.By contrast,the mixing of the tangential leakage flow and mainstream induced the passage vortex and secondary flows in the compression chamber.The secondary flow was the primary factor that results in the occurrence of localized high temperature region rather than the tangential leakage.With the increase of the radial clearance,the volumetric efficiency declined and the discharge temperature increased rapidly.In terms of flow control of the tangential leakage,the increase of sidewall roughness by 2μm could achieve the same effect as the decrease of the radial clearance by 4μm,while the volumetric efficiency increased by almost 5%and average discharge temperature decreased by 5K.展开更多
文摘In this paper we describe a study on image grid display with automatic vertical scrolling.While scroll operations are normally carried out manually by the user,in the context of RSVP(Rapid Serial Visual Presentation)techniques this work considers a presentation mode in which the image grid is automati-cally scrolled.Through experiments carried out with 50 testers,we have investigated user performance while looking for specific target subjects within large collections of images.Different numbers of columns and scrolling speeds have been considered.The search task implied both clicking on the identified target pictures and simply vocally stating their visual recognition.To this purpose,and to identify possible specific gaze behaviours,eye tracking technology has been exploited.The obtained results show that number of columns and scroll speed do affect search performance.Moreover,the user’s gaze tends to focus on different screen areas depending on the values of these two parameters.Although it is not possible to definitely find an optimal columns-speed combination that is valid in all cases,the particular context of use can suggest feasible solutions according to one’s needs.To the best of our knowledge,image grid display with automatic scrolling has never been studied to date.
基金Under a doctoral project endowed by Gansu Provincial Department of Education,China,in 2022(2022QB-164)an innovation project endowed by Gansu Provincial Department of Education,China,in 2023(2023B-208)+1 种基金a humanities and social sciences project endowed by Gansu Federation of Social Science,China,in 2022(22ZC53)a doctoral project endowed by Longdong University,China,in 2022(XYBYSK2201).
文摘Deeply-rooted in China’s popular culture,precious scrolls(Baojuan)are the golden material to display popular religious belief of the mass.Based on the rare texts sorted and annotated by Shang Lixin,Dutch Sinologist Wilt L.Idema continues his journey of translating precious scrolls.Focused on the theme of devoted women Buddhist followers in Ming dynasty,he explores the ethical choices of married women in facing the betrayal of servants or concubines.His translations not only add important reading material to Western readers in the field of Chinese popular literature,but also set standard for the coming translators in rendering Chinese ballads.
基金supported by the National Natural Science Foundation of China(Grant No.21573265,21673263,and 21805291)One-Three-Five Strategic Planning of Chinese Academy of Sciences and the DNL Cooperation Fund,CAS(DNL180307)。
文摘Although Ti3 C2 MXene sheets have attracted extensive attention in lithium-ion storage techniques,their restacking makes against and even hinders the Li ions diffusion within them,thereby decreasing the capacity as well as rate performance of conventional MXene anode.Here,for the first time,we roll up the Ti3 C2 Tx sheets into scrolls with unclosed topological structure and the interlayer galleries to alleviate the restacking problem.Thus,Ti3 C2 Tx scrolls as anode materials in lithium-ion batteries(LIBs)have higher capacity and better rate performance than Ti3 C2 Tx sheets.On the bases of these,high-capacity silicon nanoparticles are added during the rolling process to in-situ produce Ti3 C2 Tx/Si composite scrolls.The addition of 10%silicon nanoparticles shows the best overall improvement among capacity,rate capability and cyclic stability for Ti3 C2 Tx scrolls.
基金the China Postdoctoral Science Foundation(Grant No.2018M 643627)the Open Foundation from the CAS Key Laboratory of Cryogenics,TIPC(Grant No.CRYO201810)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.XZY012019003/XZD012019009)the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(Grant No.GZKF-201912).
文摘The aluminum alloy scroll is one of the key parts of the scroll compressors widely used in the air-conditioning,refrigeration,and heat pump systems.In this work,the semi-solid squeeze casting(SSSC)process was used to fabricate the aluminum alloy scroll.The effects of process parameters including the pouring temperature,mold temperature,and squeezing velocity on the filling and solidification behaviors of the alloys were investigated through simulations based on the power law cut-off(PLCO)material model.Results show that there is a significant increase in the flow velocity of the slurry,and the area of the high-speed region enlarges with the increase of the pouring temperature.The homogeneity of the temperature and velocity fields in the slurry is improved with an increase in mold temperature.Both the filling time and its variation rate decrease with an increase in squeezing velocity.The maximum solidification time exhibits a linear variation with the increase in pouring temperature.The shrinkage area is decreased by increasing the mold temperature.The optimal process parameters of the SSSC process were obtained from simulation analysis,which are the pouring temperature of 595°C,mold temperature of 350°C,and squeezing velocity of 0.3 m·s-1.Moreover,the qualified scroll casting was fabricated using the SSSC process under the optimal process parameters.
基金This project is supported by Provincial Natural Science Foundation of Gansu(No.ZS032-B25-026).
文摘A modification of central profile with trigonometric curve is proposed based on the theory of engagement of scroll compressor. General modification equations for central profile of a pair of scrolls are given and various modification patterns are discussed. The equidistant method is employed to calculate the volume of a sealed chamber and a set of general equations is represented. Modification parameters affecting geometric and dynamic property of a scroll compressor are analyzed systematically, and the relations between them are accurately determined. The condition for transforming a trigonometric curve modification into an arc-curve modification is explained. The conclusions can also be applied to other scroll fluid machines.
文摘In this paper a new simple multi-scroll chaotic generator is studied. The characteristic of this new multi-scroll chaotic generator is that it is easy to generate different number of scroll chaotic attractors through modifying the nature number n after fixing the suitable system parameters and it does not need complex mathematical derivation. Various number of scroll chaotic attractors are illustrated not only by computer simulation but also by the realization of an electronic circuit experiment on Electronic Workbench (EWB).
文摘The motion of organization center of three_dimensional untwisted scroll waves in excitable media with single diffusion is studied by singular perturbation method in this paper. The relation of curvature and the linear law are derived for untwisted organization center. These results have explicit physical meaning and are in good agreement with experiments.
文摘This paper proposes a new simple autonomous chaotic system which can generate multi-scroll chaotic attractors. The characteristic of this new multi-scroll chaotic system is that the 4n + 2rn + 4-scroll chaotic attractors are generated easily with n and m vaxying under n ≤ m. Various number of scroll chaotic attractors are illustrated not only by computer simulation but also by the realization of an electronic circuit experiment on EWB (Electronics Workbench).
基金Project supported by the Science and Technology Department of Zhejiang Province (Grant No.2005D60SA700351)
文摘Instead of manual polishing work for aluminum wheel hub (hub) surface, a new planetary scroll surface polishing method based on the rotation and revolution of hub in abrasives is presented in this paper. Since conventional barrel rotation polishing mode is unsatisfactory, shorter polishing period and lower energy consumption are expected. The surface polishing mechanism of the proposed method is ghen introduced. The influence of cutting velocity, cutting angle, abrasive on surface polishing quality and efficiency, as well as the correlation of the revolution velocity and the rotation velocity of hub are discussed. Experimental results show that high surface polishing quality and efficiency can be achieved with the new polishing method implying that a dustless clean working environment is realized.
基金Zhejiang Provincial Medical and Health Technology Project,No.2020KY215.
文摘BACKGROUND Retrocorneal hyaline scrolls are a rare phenomenon.We report a case of bilateral retrocorneal hyaline scrolls that were likely induced by asymptomatic congenital syphilis.CASE SUMMARY A 71-year-old woman presented with blurred vision due to cataracts.Slit-lamp microscopy revealed bilateral hyaline scrolls with a dichotomous branching pattern extending to the anterior chamber or rods attaching to the rough posterior surface of the cornea.The patient was positive for syphilis-specific antibodies,with no ocular or systemic evidence of congenital or acquired syphilis.Binocular cataract,retrocorneal scroll,and corneal endothelial gutta were considered.The scroll of the right eye was removed during cataract surgery and further observed using hematoxylin–eosin staining and scanning electron microscopy.The cornea of the right eye remained transparent,and the residual scroll seemed stable,however,the corneal endothelial density declined at 13 mo after surgery.In vivo confocal microscopy revealed coalescence of corneal guttae at the level of the corneal endothelium or adhesion to the posterior surface of the endothelium,with enlarged endothelial cells in both eyes.Activated keratocytes in the stroma and a highly reflective acellular structure at the level of the Descemet’s membrane were observed.The removed scroll had a cartilage-like hardness and a circularly arranged fiber-like acellular structure.CONCLUSION Occult congenital syphilis could induce corneal endothelial gutta and theformation of retrocorneal scrolls without other signs of ocular syphilis.
文摘Zongza Lhagyicannot forgetDecember 3,1999,When hereceived the entry certifi-cate from me London-based Guinness Book ofWorld Records while hewas in Shanghai.It reads:China Tibetan Cultural ArtColor Painting, the longest.measures 618 meters longand 2.3 meters wide.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB0470202)the National Natural Science Foundation of China (Grant No. 52275222)+2 种基金the China Postdoctoral Science Foundation (Grant No. 2022M723224)the Postdoctoral Fellowship Program of CPSF (Grant No. GZB20230779)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (Grant No. Y202084)。
文摘Superlubricity is an ideal lubrication state where friction nearly vanishes between contact interfaces. It has become one of the most important research topics and approaches owing to its significance in reducing energy consumption and preventing device failures. As an efficient and universal lubricating principle capable of achieving superlubricity, rolling lubrication has attracted widespread attention in recent years. In this review, the theoretical concept of rolling lubrication and the experimental research progress of spherical/scroll structures are summarized. The review focuses on the possibility of achieving rolling lubrication using spherical/scroll structures(such as spherical fullerenes, carbon nanotubes, and formed and constructed spherical/scroll structures). The challenges in achieving rolling lubrication are summarized, and the possibility of molecular rolling lubrication,as well as its potential applications in superlubrication, are discussed.
基金supported by the National Natural Science Foundation of China(Grant No.50805149)China Postdoctoral Science Foundation(Grant No.20090450166)the Open Foundation of State Key Lab of Mechanical Transmission.
文摘In the design theory of scroll profiles for refrigeration scroll compressor,a mechanism principle of scroll profiles based on the center of natural temporal involutes and meshing region is presented,by which the performance characteristics of the various involutes are studied. Profiles type selection is very important for scroll compressor. Through analyzing the characteristic geometry,natural meshing mechanism is discovered in the study of scrolls. And a novel method for scroll profiles based on natural meshing mechanism is proposed. The result shows that the meshing region angle of odd regular polygon involutes is half of the characteristic-geometry exterior angle,and that of even regular polygon involutes is equal to the exterior angle to the moment. The corresponding meshing region angle is reduced increasingly with the increase of the edge number of characteristic geometry. The performance characteristics of scroll compressor tend towards the best correspondingly. Aiming at the existing problems of profile design for scrolls,we developed a novel methodology to study scroll profile. Originality research was done for the further study of scroll profile. It is the fundamentality factor representing essence character of scroll profiles function itself.
文摘The development of engine waste heat recov- ery technologies attracts ever increasing interests due to the rising strict policy requirements and environmental con- cerns. This paper presented the study of engine coolant and exhaust heat recovery using organic Rankine cycle (ORC). Eight working fluids were selected to evaluate and compare the performance of the integrated waste heat recovery system. Rather than the conventional engine ORC system mainly focusing on the utilization of exhaust energy, this work proposed to fully use the engine coolant energy by changing the designed parameters of the ORC system. The case study selected a small engine as the heat source to drive the ORC system using a scroll expander for power production. The evaluation results suggest that under the engine rated condition, the solution to fully recover the engine coolant energy can achieve a higher power generation performance than that of the conven- tional engine ORC system. The results suggest that adding a recuperator to the ORC system can potentially improve the system performance when the working fluids are dry and the overall dumped heat demand of the system can be reduced by 12% under optimal conditions. When the ORC evaporating and condensing temperature are respectivelyset at 85℃ and 30℃, the integrated engine waste heat recovery system can improve the overall system efficiency by 9.3% with R600, R600a or n-Pentane as the working fluid.
基金supported by the National Natural Science Foundation of China(Grant No.50776001)
文摘Ejector can utilize high pressure energy from liquid mechanism,it can be used in heat pump system coupled with economized vapor injection(EVI)scroll compressor.When running under low temperature conditions,the performance of the EVI system with ejector can be improved further.In this paper,the design method of the heat pump system with ejector is presented,and the process for designing the heat pump with ejector(EVIe)was summarized.One prototype heat pump was designed under the condition of the evaporation temperature of -20oC,and an experimental setup was established to test the prototype.The measured results demonstrated that the heating EER(energy efficiency ratio)of the EVIe could reach about 4%higher than that of the system without the ejector when the heating capacity remained nearly constant.The design method is helpful to development of a heat pump system coupled with scroll compressor and ejector.
基金supported by the National Natural Science Foundation of China(Grant Nos.52006010 and 52006009)。
文摘Tangential leakage loss reduction has great significance on improving the performance of scroll compressors.In this study,the flow field of a scroll compressor working with CO_(2) was numerically investigated.The development characteristics of the tangential leakage flow in different working chambers were carried out,which was obtained by analyzing the field quantities distributions.The impacts of the radial clearances and sidewall roughness on the tangential leakage were also taken into consideration,in order to explore the feasible method of the flow control for the tangential leakage in scroll compressors.Results showed that the tangential leakage flow had various characteristics in the suction and compression chambers due to the different interactions between the tangential leakage flow and mainstream.Owing to little reverse pressure gradient,the tangential leakage flow maintained the typical jet form in the suction chambers.By contrast,the mixing of the tangential leakage flow and mainstream induced the passage vortex and secondary flows in the compression chamber.The secondary flow was the primary factor that results in the occurrence of localized high temperature region rather than the tangential leakage.With the increase of the radial clearance,the volumetric efficiency declined and the discharge temperature increased rapidly.In terms of flow control of the tangential leakage,the increase of sidewall roughness by 2μm could achieve the same effect as the decrease of the radial clearance by 4μm,while the volumetric efficiency increased by almost 5%and average discharge temperature decreased by 5K.