The heat transfer characteristics of supercritical carbon dioxide(SCO_(2)) based on natural circulation loop(NCL) are investigated experimentally.A comprehensive analysis is conducted on the impact of single-factor va...The heat transfer characteristics of supercritical carbon dioxide(SCO_(2)) based on natural circulation loop(NCL) are investigated experimentally.A comprehensive analysis is conducted on the impact of single-factor variations in inlet temperature,heat flux,operating pressure,and mass flux on the heat transfer characteristics of SCO_(2).The results indicate that heat transfer deterioration(HTD) more easily occurs when the inlet temperature exceeds the pseudo-critical temperature.Moreover,the peak of deterioration shifts upstream in the heated section with the increase of heat flux.The inner wall temperature rises with an increase in operating pressure,while it falls with the increase of mass flux.Through an exhaustive analysis of the buoyancy parameter Bo^(*),it is deduced that buoyancy effect exerts a pivotal influence on the heat transfer process.An improved buoyancy parameter Bo_(adv)^(*) is proposed,enabling precise anticipation of variations in heat transfer coefficients under both normal and deteriorated heat transfer scenarios.Based on experimental data,a novel heat transfer correlation suitable for SCO_(2) heat transfer in natural circulation is proposed.This new correlation exhibits a more satisfactory predictive accuracy compared to previous correlations;98.31% and 76.58% of the new correlation predictions under normal heat transfer(NHT) and HTD are within ±20% error range.The research results have significant guiding implications for theoretical research and prediction correlation of HTD phenomenon.This establishes the theoretical groundwork for the implementation of SCO_(2) natural circulation in Fourth Generation Nuclear Reactors.展开更多
Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve a...Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve adaptive cooling.To enhance the universality of this internal cooling pipe design and facilitate its application,numerical studies are conducted on this systemwith four commonly used cooling mediums as coolant.Firstly,the accuracy of the numerical method is verified through an established experimental platform.Then,transient numerical simulations are performed on the flow states of different cooling mediums in the new self-circulation system.Based on the numerical result,the flow,phase change,and heat transfer characteristics of different cooling mediums are analyzed.Differences in fluid velocity and latent heat of phase change result in significant variation in heat exchange capacity among different coolingmediums,with the maximumdifference reaching up to 3 times.Besides,faster circulation speed leads to greater heat transfer capacity,with a maximum of 7600 W/m^(2).Consequently,the operating mechanism and cooling laws of the natural circulation system is further investigated,providing a reference for the practical application of this system.展开更多
The global concern over the greenhouse gas emissions and its effect on global warming and climate change has focused attention on the necessity of carbon dioxide capture and sequestration. There are many processes pro...The global concern over the greenhouse gas emissions and its effect on global warming and climate change has focused attention on the necessity of carbon dioxide capture and sequestration. There are many processes proposed to capture carbon either before or after combustion and these processes invariably involve investigation and application of traditional particuology. The solids employed are of different sizes, densities, morphologies, and strengths. Their handling, transportation, recirculation, and reactor applications are the essence of ＇particuology＇. Particuology can play an important and vital role in achieving cost-effective removal of carbon and minimize emissions of greenhouse gases. In this paper, the existing and developing carbon capture processes are briefly reviewed and the opportunities for application of particuology are identified. The review was not intended to be exhaustive. It is only in sufficient detail to make connection between particuology and climate change. For immediate and future challenges of reducing global warming and carbon capture and sequestration, innovative reactor design and application of parricuology is imperative. Expertise and innovation in particuology can greatly enhance the speed of development of those technologies and help to achieve cost-effective implementation. Particuology is indeed intimately related to the climate change and global warming.展开更多
文摘The heat transfer characteristics of supercritical carbon dioxide(SCO_(2)) based on natural circulation loop(NCL) are investigated experimentally.A comprehensive analysis is conducted on the impact of single-factor variations in inlet temperature,heat flux,operating pressure,and mass flux on the heat transfer characteristics of SCO_(2).The results indicate that heat transfer deterioration(HTD) more easily occurs when the inlet temperature exceeds the pseudo-critical temperature.Moreover,the peak of deterioration shifts upstream in the heated section with the increase of heat flux.The inner wall temperature rises with an increase in operating pressure,while it falls with the increase of mass flux.Through an exhaustive analysis of the buoyancy parameter Bo^(*),it is deduced that buoyancy effect exerts a pivotal influence on the heat transfer process.An improved buoyancy parameter Bo_(adv)^(*) is proposed,enabling precise anticipation of variations in heat transfer coefficients under both normal and deteriorated heat transfer scenarios.Based on experimental data,a novel heat transfer correlation suitable for SCO_(2) heat transfer in natural circulation is proposed.This new correlation exhibits a more satisfactory predictive accuracy compared to previous correlations;98.31% and 76.58% of the new correlation predictions under normal heat transfer(NHT) and HTD are within ±20% error range.The research results have significant guiding implications for theoretical research and prediction correlation of HTD phenomenon.This establishes the theoretical groundwork for the implementation of SCO_(2) natural circulation in Fourth Generation Nuclear Reactors.
基金funded by Fei He,National Natural Science Foundation of China(contract no.52376154)Anhui Provincial Natural Science Foundation(contract no.2308085J21).
文摘Aiming at the global design issue of transpiration cooling thermal protection system,a self-driven circulation loop is proposed as the internal coolant flow passage for the transpiration cooling structure to achieve adaptive cooling.To enhance the universality of this internal cooling pipe design and facilitate its application,numerical studies are conducted on this systemwith four commonly used cooling mediums as coolant.Firstly,the accuracy of the numerical method is verified through an established experimental platform.Then,transient numerical simulations are performed on the flow states of different cooling mediums in the new self-circulation system.Based on the numerical result,the flow,phase change,and heat transfer characteristics of different cooling mediums are analyzed.Differences in fluid velocity and latent heat of phase change result in significant variation in heat exchange capacity among different coolingmediums,with the maximumdifference reaching up to 3 times.Besides,faster circulation speed leads to greater heat transfer capacity,with a maximum of 7600 W/m^(2).Consequently,the operating mechanism and cooling laws of the natural circulation system is further investigated,providing a reference for the practical application of this system.
文摘The global concern over the greenhouse gas emissions and its effect on global warming and climate change has focused attention on the necessity of carbon dioxide capture and sequestration. There are many processes proposed to capture carbon either before or after combustion and these processes invariably involve investigation and application of traditional particuology. The solids employed are of different sizes, densities, morphologies, and strengths. Their handling, transportation, recirculation, and reactor applications are the essence of ＇particuology＇. Particuology can play an important and vital role in achieving cost-effective removal of carbon and minimize emissions of greenhouse gases. In this paper, the existing and developing carbon capture processes are briefly reviewed and the opportunities for application of particuology are identified. The review was not intended to be exhaustive. It is only in sufficient detail to make connection between particuology and climate change. For immediate and future challenges of reducing global warming and carbon capture and sequestration, innovative reactor design and application of parricuology is imperative. Expertise and innovation in particuology can greatly enhance the speed of development of those technologies and help to achieve cost-effective implementation. Particuology is indeed intimately related to the climate change and global warming.
