Clay has a significant influence on the relationship between resistivity index I and water saturation Sw （i.e, I-Sw relationship） of reservoir rocks because it complicates the current paths of these rocks. It is dif...Clay has a significant influence on the relationship between resistivity index I and water saturation Sw （i.e, I-Sw relationship） of reservoir rocks because it complicates the current paths of these rocks. It is difficult to reveal the physical mechanisms of these clay effects on the conductivities of various rocks by physical laboratory measurements because the pore structure, micro distribution and content of clay inside a rock can not be observed and controlled during the experiments. We present a digital rock approach to study these clay effects on the electrical transport properties of reservoir rocks at pore scale using lattice gas automation （LGA） method. The digital rock samples are constructed with the information of grain size distribution from SEM images of reservoir rocks. The LGA is then applied on these digital rocks fully saturated with fluids to simulate the electrical transport properties for revealing the effects of volume and distribution patterns of clay on the non-Archie behaviors of the I-Sw relationship. The very good agreement between the simulated results and the laboratory measurements clearly demonstrates the validity of the LGA in numerical research of rock physics. Based on these studies, a new model has been developed for quantitatively describing the relationship between the saturation exponent and the volume of clay （Vsh）. This development may improve the evaluation for the fluid saturations in reservoir rocks.展开更多
This research presents the results of system validation tests for an SOFC power system. In the study, the system was heated up without electric device, i.e., the fuel providing the required thermal energy through an i...This research presents the results of system validation tests for an SOFC power system. In the study, the system was heated up without electric device, i.e., the fuel providing the required thermal energy through an integrated BOP （balance of plant）. The ex-situ experiments, without an SOFC stack installed in the system, were fast conducted to investigate the operability of a BOP apparatus. It was found that the BOP possessed high conversion rates for both steam reforming and water gas shift reactions. The total fuel concentration of hydrogen and carbon monoxide from the reformer was around 91.2%. The system validation tests showed that, with the natural gas as fuel, the output power from the stack reached to 1,060 W, while the fuel utilization efficiency and electrical efficiency were 67.16% and 45.0%, respectively. A steady 600-hour system operation test was carried out at an average system temperature of 694℃. Of which, a 36-cell stack was employed for the test. Meanwhile, the current, voltage and output power were 26 A, 32.3 V and 840 W, respectively, and its electrical efficiency was around 33.4%.展开更多
The paper investigated the performance of a solar chimney, by measuring the chimney air temperature and velocity. A short solar chimney prototype was designed and constructed at Botswana Technology Center. A wind turb...The paper investigated the performance of a solar chimney, by measuring the chimney air temperature and velocity. A short solar chimney prototype was designed and constructed at Botswana Technology Center. A wind turbine was installed to rotate a small DC generator. Temperatures and velocities were measured at different times of the day with thermocouples and hotwire anemometer, respectively. Irradiance was measured with pyranometer. A Delta-T data logger was used to store data at intervals of 30 s. Various graphs depicting the influence of irradiance on temperature, velocity and power have been plotted. Irradiance was found to affect the chimney temperature and subsequently affects chimney air velocity and power produced. Ambient air （wind） velocity was found to have influence on the performance of the solar chimney by increasing chimney air velocity.展开更多
基金sponsored by the National Natural Science Foundation of China（Grant No.41074103） the National Key Fundamental R＆D Project（Grant No.2007CB209601） the China National Petroleum Cooperation Fundamental Research Program（Grant No.06A30102）
文摘Clay has a significant influence on the relationship between resistivity index I and water saturation Sw （i.e, I-Sw relationship） of reservoir rocks because it complicates the current paths of these rocks. It is difficult to reveal the physical mechanisms of these clay effects on the conductivities of various rocks by physical laboratory measurements because the pore structure, micro distribution and content of clay inside a rock can not be observed and controlled during the experiments. We present a digital rock approach to study these clay effects on the electrical transport properties of reservoir rocks at pore scale using lattice gas automation （LGA） method. The digital rock samples are constructed with the information of grain size distribution from SEM images of reservoir rocks. The LGA is then applied on these digital rocks fully saturated with fluids to simulate the electrical transport properties for revealing the effects of volume and distribution patterns of clay on the non-Archie behaviors of the I-Sw relationship. The very good agreement between the simulated results and the laboratory measurements clearly demonstrates the validity of the LGA in numerical research of rock physics. Based on these studies, a new model has been developed for quantitatively describing the relationship between the saturation exponent and the volume of clay （Vsh）. This development may improve the evaluation for the fluid saturations in reservoir rocks.
文摘This research presents the results of system validation tests for an SOFC power system. In the study, the system was heated up without electric device, i.e., the fuel providing the required thermal energy through an integrated BOP （balance of plant）. The ex-situ experiments, without an SOFC stack installed in the system, were fast conducted to investigate the operability of a BOP apparatus. It was found that the BOP possessed high conversion rates for both steam reforming and water gas shift reactions. The total fuel concentration of hydrogen and carbon monoxide from the reformer was around 91.2%. The system validation tests showed that, with the natural gas as fuel, the output power from the stack reached to 1,060 W, while the fuel utilization efficiency and electrical efficiency were 67.16% and 45.0%, respectively. A steady 600-hour system operation test was carried out at an average system temperature of 694℃. Of which, a 36-cell stack was employed for the test. Meanwhile, the current, voltage and output power were 26 A, 32.3 V and 840 W, respectively, and its electrical efficiency was around 33.4%.
文摘The paper investigated the performance of a solar chimney, by measuring the chimney air temperature and velocity. A short solar chimney prototype was designed and constructed at Botswana Technology Center. A wind turbine was installed to rotate a small DC generator. Temperatures and velocities were measured at different times of the day with thermocouples and hotwire anemometer, respectively. Irradiance was measured with pyranometer. A Delta-T data logger was used to store data at intervals of 30 s. Various graphs depicting the influence of irradiance on temperature, velocity and power have been plotted. Irradiance was found to affect the chimney temperature and subsequently affects chimney air velocity and power produced. Ambient air （wind） velocity was found to have influence on the performance of the solar chimney by increasing chimney air velocity.
