The use of carbon dioxide as a working fluid has been the subject of extensive studies in recent years, particularly in the field of refrigeration where it is at the heart of research to replace CFC and HCFC. Its ther...The use of carbon dioxide as a working fluid has been the subject of extensive studies in recent years, particularly in the field of refrigeration where it is at the heart of research to replace CFC and HCFC. Its thermodynamic properties make it a fluid of choice in the efficient use of energy at low and medium temperatures in engine cycles. However, the performance of transcritical CO2 cycles weakens under high temperature and pressure conditions, especially in refrigeration systems;On the other hand, this disadvantage becomes rather interesting in engine cycles where CO2 can be used as an alternative to the organic working fluid in small and medium-sized electrical systems for low quality or waste heat sources. In order to improve the performance of systems operating with CO2 in the field of refrigeration and electricity production, research has made it possible to develop several concepts, of which this article deals with a review of the state of the art, followed by analyzes in-depth and critical of the various developments to the most recent modifications in these fields. Detailed discussions on the performance and technical characteristics of the different evolutions are also highlighted as well as the factors affecting the overall performance of the systems studied. Finally, perspectives on the future development of the use of CO2 in these different cycles are presented.展开更多
We re-evaluate the Raman spectroscopic quantification of the molar ratio and pressure for CH4–CO2 mixtures.Firstly,the Raman quantification factors of CH4 and CO2 increase with rising pressure at room temperature,ind...We re-evaluate the Raman spectroscopic quantification of the molar ratio and pressure for CH4–CO2 mixtures.Firstly,the Raman quantification factors of CH4 and CO2 increase with rising pressure at room temperature,indicating that Raman quantification of CH4/CO2 molar ratio can be applied to those fluid inclusions(FIs)with high internal pressure(i.e.,>15 MPa).Secondly,the v1(CH4)peak position shifts to lower wavenumber with increasing pressure at constant temperature,confirming that the v1(CH4)peak position can be used to calculate the fluid pressure.However,this method should be carefully calibrated before applying to FI analyses because large discrepancies exist among the reported v1(CH4)-P curves,especially in the highpressure range.These calibrations are applied to CH4-rich FIs in quartz veins of the Silurian Longmaxi black shales in southern Sichuan Basin.The vapor phases of these FIs are mainly composed of CH4 and minor CO2,with CO2 molar fractions from4.4%to 7.4%.The pressure of single-phase gas FI ranges from 103.65 to 128.35 MPa at room temperature,which is higher than previously reported.Thermodynamic calculations supported the presence of extremely high-pressure CH4-saturated fluid(218.03–256.82 MPa at 200°C),which may be responsible for the expulsion of CH4 to adjacent reservoirs.展开更多
We first report discovery of the spinel-garnet-orthopyroxene granulite with pure CO2 fluid inclusions from the Fuyun region of the late Paleozoic Altay orogenic belt in Central Asia, NW China. The rock is characterize...We first report discovery of the spinel-garnet-orthopyroxene granulite with pure CO2 fluid inclusions from the Fuyun region of the late Paleozoic Altay orogenic belt in Central Asia, NW China. The rock is characterized by an assemblage of garnet, orthopyroxene, spinel, cordierite, biotite, plagioclase and quartz. Symplectites of orthopyroxene and spinel, and orthopyroxene and cordierite indicate decompression under UHT conditions. Mineral chemistry shows that the orthopyroxenes have high XMg and Al2O3 contents (up to 9.23 wt%). Biotites are enriched in TiO2 and XMg and are stable under granulite facies conditions. The garnet and quartz from the rock carry monophase fluid inclusions which show peak melting temperatures of around -56.7℃, indicating a pure CO2 species being presented during the ultrahigh-T metamorphism in the Altay orogenic belt. The inclusions homogenize into a liquid phase at temperatures around 15.3-23.8℃ translating into CO2 densities of the order of 0.86-0.88g/cm^3. Based on preliminary mineral paragenesis, reaction textures and petrogenetic grid considerations, we infer that the rock was subjected to UHT conditions. The CO2-rich fluids were trapped during exhumation along a clockwise P-T path following isothermal decompression under UHT conditions.展开更多
文摘The use of carbon dioxide as a working fluid has been the subject of extensive studies in recent years, particularly in the field of refrigeration where it is at the heart of research to replace CFC and HCFC. Its thermodynamic properties make it a fluid of choice in the efficient use of energy at low and medium temperatures in engine cycles. However, the performance of transcritical CO2 cycles weakens under high temperature and pressure conditions, especially in refrigeration systems;On the other hand, this disadvantage becomes rather interesting in engine cycles where CO2 can be used as an alternative to the organic working fluid in small and medium-sized electrical systems for low quality or waste heat sources. In order to improve the performance of systems operating with CO2 in the field of refrigeration and electricity production, research has made it possible to develop several concepts, of which this article deals with a review of the state of the art, followed by analyzes in-depth and critical of the various developments to the most recent modifications in these fields. Detailed discussions on the performance and technical characteristics of the different evolutions are also highlighted as well as the factors affecting the overall performance of the systems studied. Finally, perspectives on the future development of the use of CO2 in these different cycles are presented.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41922023 and 41830425)the Fundamental Research Funds for the Central Universities(Grant Nos.020614380056 and 020614380078).
文摘We re-evaluate the Raman spectroscopic quantification of the molar ratio and pressure for CH4–CO2 mixtures.Firstly,the Raman quantification factors of CH4 and CO2 increase with rising pressure at room temperature,indicating that Raman quantification of CH4/CO2 molar ratio can be applied to those fluid inclusions(FIs)with high internal pressure(i.e.,>15 MPa).Secondly,the v1(CH4)peak position shifts to lower wavenumber with increasing pressure at constant temperature,confirming that the v1(CH4)peak position can be used to calculate the fluid pressure.However,this method should be carefully calibrated before applying to FI analyses because large discrepancies exist among the reported v1(CH4)-P curves,especially in the highpressure range.These calibrations are applied to CH4-rich FIs in quartz veins of the Silurian Longmaxi black shales in southern Sichuan Basin.The vapor phases of these FIs are mainly composed of CH4 and minor CO2,with CO2 molar fractions from4.4%to 7.4%.The pressure of single-phase gas FI ranges from 103.65 to 128.35 MPa at room temperature,which is higher than previously reported.Thermodynamic calculations supported the presence of extremely high-pressure CH4-saturated fluid(218.03–256.82 MPa at 200°C),which may be responsible for the expulsion of CH4 to adjacent reservoirs.
文摘We first report discovery of the spinel-garnet-orthopyroxene granulite with pure CO2 fluid inclusions from the Fuyun region of the late Paleozoic Altay orogenic belt in Central Asia, NW China. The rock is characterized by an assemblage of garnet, orthopyroxene, spinel, cordierite, biotite, plagioclase and quartz. Symplectites of orthopyroxene and spinel, and orthopyroxene and cordierite indicate decompression under UHT conditions. Mineral chemistry shows that the orthopyroxenes have high XMg and Al2O3 contents (up to 9.23 wt%). Biotites are enriched in TiO2 and XMg and are stable under granulite facies conditions. The garnet and quartz from the rock carry monophase fluid inclusions which show peak melting temperatures of around -56.7℃, indicating a pure CO2 species being presented during the ultrahigh-T metamorphism in the Altay orogenic belt. The inclusions homogenize into a liquid phase at temperatures around 15.3-23.8℃ translating into CO2 densities of the order of 0.86-0.88g/cm^3. Based on preliminary mineral paragenesis, reaction textures and petrogenetic grid considerations, we infer that the rock was subjected to UHT conditions. The CO2-rich fluids were trapped during exhumation along a clockwise P-T path following isothermal decompression under UHT conditions.
基金The authors gratefully acknowledge the financial support of the National Natural Science Foundation of China （Grant Nos. 51374213 and 51674251）, the State Key Research Development Program of China （Grant No. 2016YFC0600705）, the National Natural Science Fund for Distinguished Young Scholars of China （Grant No. 51125017）, the Fund for Innovative Research and Development Group Program of Jiangsu Province （Grant No. 2014- 27）, the Science Fund for Creative Research Groups of the National Natural Science Foundation of China （Grant No. 51421003）, and the Priority Academic Program Development of the Jiangsu Higher Education Institutions （PAPD 2014）.
