Coalbed gas non-Darcy flow has been observed in high permeable fracture systems,and some mathematical and numerical models have been proposed to study the effects of non-Darcy flow using Forchheimer non-Darcy model.Ho...Coalbed gas non-Darcy flow has been observed in high permeable fracture systems,and some mathematical and numerical models have been proposed to study the effects of non-Darcy flow using Forchheimer non-Darcy model.However,experimental results show that the assumption of a constant Forchheimer factor may cause some limitations in using Forchheimer model to describe non-Darcy flow in porous media.In order to investigate the effects of non-Darcy flow on coalbed methane production,this work presents a more general coalbed gas non-Darcy flow model according to Barree-Conway equation,which could describe the entire range of relationships between flow velocity and pressure gradient from low to high flow velocity.An expanded mixed finite element method is introduced to solve the coalbed gas non-Darcy flow model,in which the gas pressure and velocity can be approximated simultaneously.Error estimate results indicate that pressure and velocity could achieve first-order convergence rate.Non-Darcy simulation results indicate that the non-Darcy effect is significant in the zone near the wellbore,and with the distance from the wellbore increasing,the non-Darcy effect becomes weak gradually.From simulation results,we have also found that the non-Darcy effect is more significant at a lower bottom-hole pressure,and the gas production from non-Darcy flow is lower than the production from Darcy flow under the same permeable condition.展开更多
The easy acidification and high hydrogen sulfide （H2S） production during anaerobic digestion of macroalgae limited its application in biomethane production. In order to investigate the effects of ceramsite on methan...The easy acidification and high hydrogen sulfide （H2S） production during anaerobic digestion of macroalgae limited its application in biomethane production. In order to investigate the effects of ceramsite on methane and HzS productions during anaerobic digestion of macroalgae, batch experiments ofMacrocystis pyrifera were carried out. Four groups named C0, C1, C2 and C3 added with 0, 1.5, 3.0 and 4.5 g/g substrate of ceramsite, respectively, were studied and compared. The highest cumulative methane yield of 286.3 mL/g substrate is obtained in C2, which is 40.11% higher than that of CO. The cumulative HzS yields of C1, C2 and C3 are 32.67%, 44.66% and 53.21% lower than that of CO, respectively. Results indicate that ceramsite addition permits higher methane yields, shorter lag-phase time and lower HzS yields during anaerobic digestion of Macrocystispyrifera.展开更多
Two parts were involved in this experiment. In experiment 1, 32 Chinese Holstein cows with relatively similar body condition, lactation number and days in milk were selected. The cows were assigned in a randomized com...Two parts were involved in this experiment. In experiment 1, 32 Chinese Holstein cows with relatively similar body condition, lactation number and days in milk were selected. The cows were assigned in a randomized complete block design trial to determine the effect of supplemental Bacillus cultures to diet on production performance in dairy cattle. Four treatments, i.e., Bacillus licheniformis （strain number 1.813） group, Bacillus subtilis （strain number 1.1086） group, Bacillus cereus var. mycoides （strain number 1.260） group and control group. Each treatment had eight replicates, each replicate had one cow, 50 g per head per day. Results showed that Bacillus licheniformis group increased the milk yield （P〈0.05）. The other two groups didn＇t have significant effect on milk yield than the control group （P〉0.05）. In experiment 2, 3 Chinese Holstein cows with permanent fistulas were used. 3×3 Latin squares were assigned to three diets： Bacillus lincheniformis culture, Bacillus subtilis culture and control. Bacillus licheniformis culture increased total rumen microorganism （P〈0.05）, decreased the ammonia N concentration at 2, 4 h （P〈0.05）. Bacillus licheniformis culture increased the total volatile fatty （P〉0.05）, increased the rate of acetic acid to propionic acid （P〉0.05）. Bacillus licheniformis culture decreased the methane production （P〈0.05）.展开更多
基金Projects(91330106,11171190)supported by the National Natural Science Foundation of ChinaProjects(15CX05065A,15CX05003A)supported by the Fundamental Research Funds for the Central Universities,China
文摘Coalbed gas non-Darcy flow has been observed in high permeable fracture systems,and some mathematical and numerical models have been proposed to study the effects of non-Darcy flow using Forchheimer non-Darcy model.However,experimental results show that the assumption of a constant Forchheimer factor may cause some limitations in using Forchheimer model to describe non-Darcy flow in porous media.In order to investigate the effects of non-Darcy flow on coalbed methane production,this work presents a more general coalbed gas non-Darcy flow model according to Barree-Conway equation,which could describe the entire range of relationships between flow velocity and pressure gradient from low to high flow velocity.An expanded mixed finite element method is introduced to solve the coalbed gas non-Darcy flow model,in which the gas pressure and velocity can be approximated simultaneously.Error estimate results indicate that pressure and velocity could achieve first-order convergence rate.Non-Darcy simulation results indicate that the non-Darcy effect is significant in the zone near the wellbore,and with the distance from the wellbore increasing,the non-Darcy effect becomes weak gradually.From simulation results,we have also found that the non-Darcy effect is more significant at a lower bottom-hole pressure,and the gas production from non-Darcy flow is lower than the production from Darcy flow under the same permeable condition.
基金Project(2014BAC31B01)supported by the National Science&Technology Support during the 12th Five-Year Plan Period,ChinaProjects(2015GSF117016,2015GSF115037)supported by the Key Research&Development Project of Shandong Province,China
文摘The easy acidification and high hydrogen sulfide （H2S） production during anaerobic digestion of macroalgae limited its application in biomethane production. In order to investigate the effects of ceramsite on methane and HzS productions during anaerobic digestion of macroalgae, batch experiments ofMacrocystis pyrifera were carried out. Four groups named C0, C1, C2 and C3 added with 0, 1.5, 3.0 and 4.5 g/g substrate of ceramsite, respectively, were studied and compared. The highest cumulative methane yield of 286.3 mL/g substrate is obtained in C2, which is 40.11% higher than that of CO. The cumulative HzS yields of C1, C2 and C3 are 32.67%, 44.66% and 53.21% lower than that of CO, respectively. Results indicate that ceramsite addition permits higher methane yields, shorter lag-phase time and lower HzS yields during anaerobic digestion of Macrocystispyrifera.
基金Supported by National Programs for Dairy Cattle Cow(2002BA518A02-05)
文摘Two parts were involved in this experiment. In experiment 1, 32 Chinese Holstein cows with relatively similar body condition, lactation number and days in milk were selected. The cows were assigned in a randomized complete block design trial to determine the effect of supplemental Bacillus cultures to diet on production performance in dairy cattle. Four treatments, i.e., Bacillus licheniformis （strain number 1.813） group, Bacillus subtilis （strain number 1.1086） group, Bacillus cereus var. mycoides （strain number 1.260） group and control group. Each treatment had eight replicates, each replicate had one cow, 50 g per head per day. Results showed that Bacillus licheniformis group increased the milk yield （P〈0.05）. The other two groups didn＇t have significant effect on milk yield than the control group （P〉0.05）. In experiment 2, 3 Chinese Holstein cows with permanent fistulas were used. 3×3 Latin squares were assigned to three diets： Bacillus lincheniformis culture, Bacillus subtilis culture and control. Bacillus licheniformis culture increased total rumen microorganism （P〈0.05）, decreased the ammonia N concentration at 2, 4 h （P〈0.05）. Bacillus licheniformis culture increased the total volatile fatty （P〉0.05）, increased the rate of acetic acid to propionic acid （P〉0.05）. Bacillus licheniformis culture decreased the methane production （P〈0.05）.
