Tracer gas technique is a method to analyze the airflow path, measure the airflow quantity, and detect any recirculation or leakages in underground mine. In addition, it is also possible to evaluate the axial gas diff...Tracer gas technique is a method to analyze the airflow path, measure the airflow quantity, and detect any recirculation or leakages in underground mine. In addition, it is also possible to evaluate the axial gas diffusion of gas in turbulent bulk flow by utilizing the tracer gas data. This paper discussed about the measurement using tracer gas technique in Cibaliung Underground Mine, Indonesia and the evaluation of effective axial diffusion coefficient, E, by numerical simulation. In addition, a scheme to treat network flow in mine ventilation system was also proposed. The effective axial diffusion coefficient for each airway was evaluated based on Taylor's theoretical equation. It is found that the evaluated diffusion coefficient agrees well with Taylor's equation by considering that the wall friction factor, f, is higher than those for smooth pipe flow. It also shows that the value of effective diffusion coefficient can be inherently determined and the value is constant when matching with other measurements. Furthermore, there are possibilities to utilize the tracer gas measurement data to evaluate the airway friction factors.展开更多
The use of sulfur hexafiuoride （SF6） as a tracer gas for analyzing underground mine ventilation systems has been practiced for over 30 years. As a result, the methods used to release, sample, and analyze SF6 are wel...The use of sulfur hexafiuoride （SF6） as a tracer gas for analyzing underground mine ventilation systems has been practiced for over 30 years. As a result, the methods used to release, sample, and analyze SF6 are well accepted. As the complexity and size of underground mine ventilation networks increase, the ability of a SF6 to function as a convenient and rapid means of analysis diminishes. The utilization of multiple tracer gases can mitigate this by removing the need to purge the background presence of a tracer before conducting another release and allowing for a more comprehensive evaluation using multi-zone tech- niques. Recent studies have identified perfluoromethylcyclohexane （PMCH） as a possible supplement for SF6 in underground mine ventilation tracer studies. However, the deployment of PMCH remains a challenge because of this compounds physical properties. This paper evaluates a PMCH permeation plug release vessel （PPRV） under controlled turbulent conditions. The details of the experimental parameters used in the evaluation as well as a discussion regarding the performance of the PPRV are included.展开更多
Objective To investigate the effects of continuous tracheal gas insufflation (CTGI) combined with biphasic intermittent positive airway pressure (BIPAP) ventilation on dogs with spontaneous breathing. Methods Eight ...Objective To investigate the effects of continuous tracheal gas insufflation (CTGI) combined with biphasic intermittent positive airway pressure (BIPAP) ventilation on dogs with spontaneous breathing. Methods Eight canine models with oleic acid induced lung injury and spontaneous breathing were ventilated in a random order by Evita 2 (Drager Inc., Germany) in modes of BIPAP (BIPAP group) and BIPAP with CTGI flow rate of 3, 6 and 9?L/min (T3, T6 and T9 groups), respectively. The setting parameters of BIPAP were fiction of inspired oxygen 60%, inspiratory to expiratory ratio 1∶1, respiratory rate 20 and positive end expiratory pressure 5?cm?H2O. Arterial and mixed venous blood gas, lung mechanics, systemic and pulmonary hemodynamics status were monitored at the same level of PaCO2 obtained by adjusting peak inspiratory pressure of BIPAP. Results Peak inspiratory pressure in the T6 group (14±4?cm?H2O) and in the T9 group (11±3?cm?H2O) were significantly lower than that of BIPAP (20±5?cm?H2O, P<0.01), but there was no significant difference among the T3, T6 and T9 groups or between the T3 and BIPAP groups. PaO2, mean artery blood pressure, mean pulmonary artery pressure, pulmonary artery wedge pressure, cardiac ouput, oxygen delivery and oxygen consumption all remained unchanged in four different conditions.Conclusions Using BIPAP combined with CTGI does not cause asynchrony between ventilator and spontaneous breathing, but significantly decreases airway pressure with no influence on hemodynamics and oxygenation. Therefore, BIPAP with CTGI may be a useful support technique, especially in cases where the airway pressure should be limited.展开更多
基金the financial support of this work by Japan Ministry of Education, Culture, Sport, Science and Technology and Kyushu University’s Global COE program
文摘Tracer gas technique is a method to analyze the airflow path, measure the airflow quantity, and detect any recirculation or leakages in underground mine. In addition, it is also possible to evaluate the axial gas diffusion of gas in turbulent bulk flow by utilizing the tracer gas data. This paper discussed about the measurement using tracer gas technique in Cibaliung Underground Mine, Indonesia and the evaluation of effective axial diffusion coefficient, E, by numerical simulation. In addition, a scheme to treat network flow in mine ventilation system was also proposed. The effective axial diffusion coefficient for each airway was evaluated based on Taylor's theoretical equation. It is found that the evaluated diffusion coefficient agrees well with Taylor's equation by considering that the wall friction factor, f, is higher than those for smooth pipe flow. It also shows that the value of effective diffusion coefficient can be inherently determined and the value is constant when matching with other measurements. Furthermore, there are possibilities to utilize the tracer gas measurement data to evaluate the airway friction factors.
文摘The use of sulfur hexafiuoride （SF6） as a tracer gas for analyzing underground mine ventilation systems has been practiced for over 30 years. As a result, the methods used to release, sample, and analyze SF6 are well accepted. As the complexity and size of underground mine ventilation networks increase, the ability of a SF6 to function as a convenient and rapid means of analysis diminishes. The utilization of multiple tracer gases can mitigate this by removing the need to purge the background presence of a tracer before conducting another release and allowing for a more comprehensive evaluation using multi-zone tech- niques. Recent studies have identified perfluoromethylcyclohexane （PMCH） as a possible supplement for SF6 in underground mine ventilation tracer studies. However, the deployment of PMCH remains a challenge because of this compounds physical properties. This paper evaluates a PMCH permeation plug release vessel （PPRV） under controlled turbulent conditions. The details of the experimental parameters used in the evaluation as well as a discussion regarding the performance of the PPRV are included.
文摘Objective To investigate the effects of continuous tracheal gas insufflation (CTGI) combined with biphasic intermittent positive airway pressure (BIPAP) ventilation on dogs with spontaneous breathing. Methods Eight canine models with oleic acid induced lung injury and spontaneous breathing were ventilated in a random order by Evita 2 (Drager Inc., Germany) in modes of BIPAP (BIPAP group) and BIPAP with CTGI flow rate of 3, 6 and 9?L/min (T3, T6 and T9 groups), respectively. The setting parameters of BIPAP were fiction of inspired oxygen 60%, inspiratory to expiratory ratio 1∶1, respiratory rate 20 and positive end expiratory pressure 5?cm?H2O. Arterial and mixed venous blood gas, lung mechanics, systemic and pulmonary hemodynamics status were monitored at the same level of PaCO2 obtained by adjusting peak inspiratory pressure of BIPAP. Results Peak inspiratory pressure in the T6 group (14±4?cm?H2O) and in the T9 group (11±3?cm?H2O) were significantly lower than that of BIPAP (20±5?cm?H2O, P<0.01), but there was no significant difference among the T3, T6 and T9 groups or between the T3 and BIPAP groups. PaO2, mean artery blood pressure, mean pulmonary artery pressure, pulmonary artery wedge pressure, cardiac ouput, oxygen delivery and oxygen consumption all remained unchanged in four different conditions.Conclusions Using BIPAP combined with CTGI does not cause asynchrony between ventilator and spontaneous breathing, but significantly decreases airway pressure with no influence on hemodynamics and oxygenation. Therefore, BIPAP with CTGI may be a useful support technique, especially in cases where the airway pressure should be limited.
