This paper presents a numerical case study of heat transfer mechanisms during the charging process of a stratified thermal storage tank applied in a specific adsorption heat pump cycle. The effective thermal conductiv...This paper presents a numerical case study of heat transfer mechanisms during the charging process of a stratified thermal storage tank applied in a specific adsorption heat pump cycle. The effective thermal conductivity of the heat transfer fluid during the charging process is analyzed through CFD simulations using Unsteady Reynolds-averaged Navier-Stokes equations (URANS). The aim of the study is to provide an equivalent thermal conductivity for a one-dimensional storage tank model to be used in a system simulation of the complete adsorption heat pump cycle. The influence of the turbulent mixing and also the advection effect due to fluid bulk motion are investigated. The results show that in the case considered here, the turbulence effect on the effective thermal conductivity is more considerable than the advection effect.展开更多
With countries proposing the goal of carbon neutrality,the clean transformation of energy structure has become a hot and trendy issue internationally.Renewable energy generation will account for the main proportion,bu...With countries proposing the goal of carbon neutrality,the clean transformation of energy structure has become a hot and trendy issue internationally.Renewable energy generation will account for the main proportion,but it also leads to the problem of unstable electricity supply.At present,large-scale energy storage technology is not yet mature.Improving the flexibility of coal-fired power plants to suppress the instability of renewable energy generation is a feasible path.Thermal energy storage is a feasible technology to improve the flexibility of coal-fired power plants.This article provides a review of the research on the flexibility transformation of coal-fired power plants based on heat storage technology,mainly including medium to low-temperature heat storage based on hot water tanks and high-temperature heat storage based on molten salt.The current technical difficulties are summarized,and future development prospects are presented.The combination of the thermal energy storage system and coal-fired power generation system is the foundation,and the control of the inclined temperature layer and the selection and development of molten salt are key issues.The authors hope that the research in this article can provide a reference for the flexibility transformation research of coal-fired power plants,and promote the application of heat storage foundation in specific coal-fired power plant transformation projects.展开更多
In this paper,the thermal and mechanical dynamic performances of molten salt packed-bed thermal energy storage(TES)system are investigated by coupling Finite Volume Method(FVM)and Finite Element Method(FEM).Firstly,an...In this paper,the thermal and mechanical dynamic performances of molten salt packed-bed thermal energy storage(TES)system are investigated by coupling Finite Volume Method(FVM)and Finite Element Method(FEM).Firstly,an integration model coupling FVM and FEM in packed-bed tank is developed.Particularly,the pore water static pressure caused by the liquid level of molten salt is applied in the coupled method.Based on this model,the dynamic characteristics of thermal and stress distributions are simulated.Finally,the effects of porosity,inlet temperature and velocity on the thermal and stress performances are analyzed.The results indicate that the temperature and stress of the wall increase during the discharging process,and the peak stress occurs at the tank bottom connecting with the ground foundation.The method of increasing porosity is helpful to improve the discharging power,but the plastic failure on the wall would probably occur due to the higher stress level.Increasing inlet temperature has negative influence on the thermal and safety performances,because lower discharging power and higher stress would be produced adversely.Although the lower stress can be achieved when the higher inlet velocity is adopted,the effective discharge time would be decreased significantly.展开更多
文摘This paper presents a numerical case study of heat transfer mechanisms during the charging process of a stratified thermal storage tank applied in a specific adsorption heat pump cycle. The effective thermal conductivity of the heat transfer fluid during the charging process is analyzed through CFD simulations using Unsteady Reynolds-averaged Navier-Stokes equations (URANS). The aim of the study is to provide an equivalent thermal conductivity for a one-dimensional storage tank model to be used in a system simulation of the complete adsorption heat pump cycle. The influence of the turbulent mixing and also the advection effect due to fluid bulk motion are investigated. The results show that in the case considered here, the turbulence effect on the effective thermal conductivity is more considerable than the advection effect.
基金funded by National Key R&D Program of China,grant number 2019YFB1505400 and 2022YFB2405205.
文摘With countries proposing the goal of carbon neutrality,the clean transformation of energy structure has become a hot and trendy issue internationally.Renewable energy generation will account for the main proportion,but it also leads to the problem of unstable electricity supply.At present,large-scale energy storage technology is not yet mature.Improving the flexibility of coal-fired power plants to suppress the instability of renewable energy generation is a feasible path.Thermal energy storage is a feasible technology to improve the flexibility of coal-fired power plants.This article provides a review of the research on the flexibility transformation of coal-fired power plants based on heat storage technology,mainly including medium to low-temperature heat storage based on hot water tanks and high-temperature heat storage based on molten salt.The current technical difficulties are summarized,and future development prospects are presented.The combination of the thermal energy storage system and coal-fired power generation system is the foundation,and the control of the inclined temperature layer and the selection and development of molten salt are key issues.The authors hope that the research in this article can provide a reference for the flexibility transformation research of coal-fired power plants,and promote the application of heat storage foundation in specific coal-fired power plant transformation projects.
基金supported by the National Natural Science Foundation of China(No.51906172)the Applied Basic Research Programs of Shanxi Province(Grant No.201901D111058)。
文摘In this paper,the thermal and mechanical dynamic performances of molten salt packed-bed thermal energy storage(TES)system are investigated by coupling Finite Volume Method(FVM)and Finite Element Method(FEM).Firstly,an integration model coupling FVM and FEM in packed-bed tank is developed.Particularly,the pore water static pressure caused by the liquid level of molten salt is applied in the coupled method.Based on this model,the dynamic characteristics of thermal and stress distributions are simulated.Finally,the effects of porosity,inlet temperature and velocity on the thermal and stress performances are analyzed.The results indicate that the temperature and stress of the wall increase during the discharging process,and the peak stress occurs at the tank bottom connecting with the ground foundation.The method of increasing porosity is helpful to improve the discharging power,but the plastic failure on the wall would probably occur due to the higher stress level.Increasing inlet temperature has negative influence on the thermal and safety performances,because lower discharging power and higher stress would be produced adversely.Although the lower stress can be achieved when the higher inlet velocity is adopted,the effective discharge time would be decreased significantly.
