为研究自然工质CO2在风冷热泵复合冷凝系统中的热力学特性,引入有限时间热力学与■分析方法,采用MATLAB/SIMULINK进行仿真,建立了自然工质CO2在风冷热泵复合冷凝系统的时间序列模型,模拟和测试了自然工质CO2在风冷热泵复合冷凝系统中的...为研究自然工质CO2在风冷热泵复合冷凝系统中的热力学特性,引入有限时间热力学与■分析方法,采用MATLAB/SIMULINK进行仿真,建立了自然工质CO2在风冷热泵复合冷凝系统的时间序列模型,模拟和测试了自然工质CO2在风冷热泵复合冷凝系统中的热力学特性,并与自然工质CO2单制冷系统及原风冷热泵复合冷凝系统的性能做了对比。结果表明:制热水模式下,两个风冷热泵复合冷凝系统的■效率都随用户要求的卫生热水水温温度升高而降低;达到用户需要水温53℃时,自然工质CO2风冷热泵复合冷凝系统卫生热水机组运行约需18 min,而R22风冷热泵复合冷凝系统约为30 min。复合冷凝模式下自然工质CO2风冷热泵系统的COP(coefficient of performance)为4.7左右,比R22风冷热泵系统略高。展开更多
Low critical temperature limits the application of CO_2 trans-critical power cycle.The binary mixture of R290/CO_2has higher critical temperature.Using mixture fluid may solve the problem that subcritical CO_2 is hard...Low critical temperature limits the application of CO_2 trans-critical power cycle.The binary mixture of R290/CO_2has higher critical temperature.Using mixture fluid may solve the problem that subcritical CO_2 is hardly condensed by conventional cooling water.In this article,theoretical analysis is executed to study the performance of the zeotropic mixture for trans-critical power cycle using low-grade liquid heat source with temperature of200℃.The results indicated that the problem that CO_2 can't be condensed in power cycle by conventional cooling water can be solved by mixing R290 to CO_2.Variation trend of outlet temperature of thermal oil in supercritical heater with heating pressure is determined by the composition of the mixture fluid.Gliding temperature causes the maximum outlet temperature of cooling water with the increase of mass fraction of R290.There are the maximum values for cycle thermal efficiency and net power output with the increase of supercritical heating pressure.展开更多
Carbon dioxide （CO2） capture and geological storage （CCS） is one of promising technologies for greenhouse gas effect mitigation. Many geotechnical challenges remain during carbon dioxide storage field practices, a...Carbon dioxide （CO2） capture and geological storage （CCS） is one of promising technologies for greenhouse gas effect mitigation. Many geotechnical challenges remain during carbon dioxide storage field practices, among which effectively detecting CO2 from deep underground is one of engineering problems. This paper reviews monitoring techniques currently used during CO2 injection and storage. A method developed based on measuring seismic microtremors is of main interest. This method was first successfully used to characterize a site in this paper. To explore its feasibility in C02 storage monitoring, numerical simulations were conducted to investigate detectable changes in elastic wave signatures due to injection and geological storage of CO2. It is found that, although it is effective for shallow earth profile estimation, the surface wave velocity is not sensitive to the CO2 layer physical parameter variations,especially for a thin CO2 geological storage layer in a deep underground reservoir.展开更多
文摘为研究自然工质CO2在风冷热泵复合冷凝系统中的热力学特性,引入有限时间热力学与■分析方法,采用MATLAB/SIMULINK进行仿真,建立了自然工质CO2在风冷热泵复合冷凝系统的时间序列模型,模拟和测试了自然工质CO2在风冷热泵复合冷凝系统中的热力学特性,并与自然工质CO2单制冷系统及原风冷热泵复合冷凝系统的性能做了对比。结果表明:制热水模式下,两个风冷热泵复合冷凝系统的■效率都随用户要求的卫生热水水温温度升高而降低;达到用户需要水温53℃时,自然工质CO2风冷热泵复合冷凝系统卫生热水机组运行约需18 min,而R22风冷热泵复合冷凝系统约为30 min。复合冷凝模式下自然工质CO2风冷热泵系统的COP(coefficient of performance)为4.7左右,比R22风冷热泵系统略高。
基金Project 51306198 supported by the National Natural Science Foundation of China
文摘Low critical temperature limits the application of CO_2 trans-critical power cycle.The binary mixture of R290/CO_2has higher critical temperature.Using mixture fluid may solve the problem that subcritical CO_2 is hardly condensed by conventional cooling water.In this article,theoretical analysis is executed to study the performance of the zeotropic mixture for trans-critical power cycle using low-grade liquid heat source with temperature of200℃.The results indicated that the problem that CO_2 can't be condensed in power cycle by conventional cooling water can be solved by mixing R290 to CO_2.Variation trend of outlet temperature of thermal oil in supercritical heater with heating pressure is determined by the composition of the mixture fluid.Gliding temperature causes the maximum outlet temperature of cooling water with the increase of mass fraction of R290.There are the maximum values for cycle thermal efficiency and net power output with the increase of supercritical heating pressure.
基金the financial supports from the State Key Laboratory for Geomechanics & Deep Underground Engineering, China University of Mining and Technology (No. SKLGDUEK1002)the Fundamental Research Funds for the Central Government Supported Universities of Tongji University, China (No. 0270219037)
文摘Carbon dioxide （CO2） capture and geological storage （CCS） is one of promising technologies for greenhouse gas effect mitigation. Many geotechnical challenges remain during carbon dioxide storage field practices, among which effectively detecting CO2 from deep underground is one of engineering problems. This paper reviews monitoring techniques currently used during CO2 injection and storage. A method developed based on measuring seismic microtremors is of main interest. This method was first successfully used to characterize a site in this paper. To explore its feasibility in C02 storage monitoring, numerical simulations were conducted to investigate detectable changes in elastic wave signatures due to injection and geological storage of CO2. It is found that, although it is effective for shallow earth profile estimation, the surface wave velocity is not sensitive to the CO2 layer physical parameter variations,especially for a thin CO2 geological storage layer in a deep underground reservoir.
