Based on the concept of a diffusion absorption system,a hot-cold conversion pipe utilizing 1,1,1,2-tetrafluoroethane(R134 a)-dimethylformamide(DMF)-helium(He)as the working pair is presented with the aim of cooling ou...Based on the concept of a diffusion absorption system,a hot-cold conversion pipe utilizing 1,1,1,2-tetrafluoroethane(R134 a)-dimethylformamide(DMF)-helium(He)as the working pair is presented with the aim of cooling output by recovering the low-grade waste heat.The model of the hot-cold conversion pipe is established,in which a heat pipe is used to transfer the waste heat as the heat input.The equations of the thermodynamic properties of the working pair are established by equation of state method(EOS).The model of the hot-cold conversion pipe is built based on the mass,species and energy balance equations of each component.The direct conversion of heat to cold is achieved by the desorption,absorption,condensation and diffusion evaporation processes of R134 a.The hot-cold conversion pipe is cooled by natural convection,which can be enhanced by chimney effect.The thermodynamic analysis is carried out to analyze the effect of the boundary conditions,i.e.the heat source temperature,the refrigeration temperature,and the environmental temperature,on the system performance.This paper provides a theoretical basis for actual application of the hot-cold conversion pipe in waste heat recovery field.展开更多
为揭示变化环境下长江和黄河流域不同区域枯水遭遇对国家水网工程的规划、设计与运行的影响,采用Copula函数、空间插值、冷热点分析、SWAT模型等方法,分析了两流域枯水遭遇概率的时空演变特征并预测其未来趋势。结果表明:上游大金-兰州...为揭示变化环境下长江和黄河流域不同区域枯水遭遇对国家水网工程的规划、设计与运行的影响,采用Copula函数、空间插值、冷热点分析、SWAT模型等方法,分析了两流域枯水遭遇概率的时空演变特征并预测其未来趋势。结果表明:上游大金-兰州组合、雅江-兰州组合枯水遭遇概率以每10 a 1.46%~1.57%的速率显著上升,而大通-花园口组合以每10 a 1.04%的速率显著下降;大金站与雅江站的热点区域主要位于长江中上游与长三角地区,冷点区域位于黄河“几字弯”及长江两湖地区;兰州站与花园口站的热点区域位于黄河中游黄土高原以南,冷点区域集中于长江中下游;未来各站点组合枯水遭遇概率的多模式平均值均超过20%,其中大金-兰州组合与大通-花园口组合呈先减小后增大的趋势,雅江-兰州组合呈线性增大趋势,黄家港-花园口组合呈先减小后缓升趋势。展开更多
基金supported by the National Natural Science Foundation of China under contract No.51706133Sponsored by Shanghai Rising-Star Program under contract No.17QB1404800。
文摘Based on the concept of a diffusion absorption system,a hot-cold conversion pipe utilizing 1,1,1,2-tetrafluoroethane(R134 a)-dimethylformamide(DMF)-helium(He)as the working pair is presented with the aim of cooling output by recovering the low-grade waste heat.The model of the hot-cold conversion pipe is established,in which a heat pipe is used to transfer the waste heat as the heat input.The equations of the thermodynamic properties of the working pair are established by equation of state method(EOS).The model of the hot-cold conversion pipe is built based on the mass,species and energy balance equations of each component.The direct conversion of heat to cold is achieved by the desorption,absorption,condensation and diffusion evaporation processes of R134 a.The hot-cold conversion pipe is cooled by natural convection,which can be enhanced by chimney effect.The thermodynamic analysis is carried out to analyze the effect of the boundary conditions,i.e.the heat source temperature,the refrigeration temperature,and the environmental temperature,on the system performance.This paper provides a theoretical basis for actual application of the hot-cold conversion pipe in waste heat recovery field.
文摘为揭示变化环境下长江和黄河流域不同区域枯水遭遇对国家水网工程的规划、设计与运行的影响,采用Copula函数、空间插值、冷热点分析、SWAT模型等方法,分析了两流域枯水遭遇概率的时空演变特征并预测其未来趋势。结果表明:上游大金-兰州组合、雅江-兰州组合枯水遭遇概率以每10 a 1.46%~1.57%的速率显著上升,而大通-花园口组合以每10 a 1.04%的速率显著下降;大金站与雅江站的热点区域主要位于长江中上游与长三角地区,冷点区域位于黄河“几字弯”及长江两湖地区;兰州站与花园口站的热点区域位于黄河中游黄土高原以南,冷点区域集中于长江中下游;未来各站点组合枯水遭遇概率的多模式平均值均超过20%,其中大金-兰州组合与大通-花园口组合呈先减小后增大的趋势,雅江-兰州组合呈线性增大趋势,黄家港-花园口组合呈先减小后缓升趋势。
