Temperature is one of the most important parameters that need to be controlled in photo-fermentation bio-hydrogen production(PFHP)system.Since the high temperature and big temperature fluctuation have adverse impacts ...Temperature is one of the most important parameters that need to be controlled in photo-fermentation bio-hydrogen production(PFHP)system.Since the high temperature and big temperature fluctuation have adverse impacts on bio-hydrogen yield,the system numerical simulation based on the operating conditions and environmental factors is desirable.This research focused on the investigation of heat transfer properties of the PFHP system.Enzymatic hydrolysate from agricultural residues was taken as substrate,and up-flow tubular photo-bioreactor was adopted for PFHP.Temperatures inside the photo-bioreactor were monitored.The experimental design and computational modeling for the determination of the heat transfer behavior in tubular photo-bioreactor was presented.Energy balance analysis was conducted to determine the energy efficiency,and optimize the operation parameters in order to obtain higher energy efficiency.The commercial software FLUENT was also adopted in order to predict the transient temperature distribution in the photo-bioreactor.The results showed that mathematical and computational modeling method has a clear potential for improving the performance of photo-bioreactor in the process of PFHP.Up-flow tubular bioreactor has tiny temperature fluctuant,and is suitable for PFHP.展开更多
Microalgae based biofuel is an emerging natural source of energy alternative to the fossil fuel. As microalgae are photosynthetic microorganisms, light is one of the limiting factors for its culture. Though many resea...Microalgae based biofuel is an emerging natural source of energy alternative to the fossil fuel. As microalgae are photosynthetic microorganisms, light is one of the limiting factors for its culture. Though many researches have been carried out for findings behind suitable culture system for the proper growth of microalgae, those are confined only to tubular Photo-bioreactor (PBR). This paper aims to make comparison among the horizontal loop photo bioreactors with different cross sections based on the analysis of hydrodynamics behavior. Three different geometrical shapes having vertical cross sections of circular, square and hexagonal PBR, have been proposed taking into account light intensity for microalgae culture. In this study, we simulate the flow dynamics of three types of PBRs and discuss the velocity, pressure and shear stress properties as microalgae endurance capacity depends on them. For the dimension of the three PBRs we considered here, each of them have radius of about 0.05 m while the length together with bending portion is approximately 20.5 m for a single loop. From the study, the hydrodynamic behaviors are observed to be quite dissimilar in case of three PBR’s. In the straight portion the velocity profile is quite parabolic in tubular but distorted minimally in case of square and hexagonal PBRs. In the middle of the U-loop, a haphazard fluid distribution is noticed. The velocity magnitude and agitation of microalgae cells are higher in hexagonal than in square and tubular. The shear rate is less in case of tubular compared to square and hexagonal. A linear pressure drop is found from the inlet to the outlet for three PBR’s. From this comparison, it can be said that the tubular one would be the best option for microalgae culture in case of industrial purposes.展开更多
基金the 59th Chinese Postdoctoral Science Foundation(2016M59068)Financial supports from National Natural Science Foundation of China(51376056)Doctoral Scientific Fund Project of the Ministry of Education of China(20134105130001).
文摘Temperature is one of the most important parameters that need to be controlled in photo-fermentation bio-hydrogen production(PFHP)system.Since the high temperature and big temperature fluctuation have adverse impacts on bio-hydrogen yield,the system numerical simulation based on the operating conditions and environmental factors is desirable.This research focused on the investigation of heat transfer properties of the PFHP system.Enzymatic hydrolysate from agricultural residues was taken as substrate,and up-flow tubular photo-bioreactor was adopted for PFHP.Temperatures inside the photo-bioreactor were monitored.The experimental design and computational modeling for the determination of the heat transfer behavior in tubular photo-bioreactor was presented.Energy balance analysis was conducted to determine the energy efficiency,and optimize the operation parameters in order to obtain higher energy efficiency.The commercial software FLUENT was also adopted in order to predict the transient temperature distribution in the photo-bioreactor.The results showed that mathematical and computational modeling method has a clear potential for improving the performance of photo-bioreactor in the process of PFHP.Up-flow tubular bioreactor has tiny temperature fluctuant,and is suitable for PFHP.
文摘Microalgae based biofuel is an emerging natural source of energy alternative to the fossil fuel. As microalgae are photosynthetic microorganisms, light is one of the limiting factors for its culture. Though many researches have been carried out for findings behind suitable culture system for the proper growth of microalgae, those are confined only to tubular Photo-bioreactor (PBR). This paper aims to make comparison among the horizontal loop photo bioreactors with different cross sections based on the analysis of hydrodynamics behavior. Three different geometrical shapes having vertical cross sections of circular, square and hexagonal PBR, have been proposed taking into account light intensity for microalgae culture. In this study, we simulate the flow dynamics of three types of PBRs and discuss the velocity, pressure and shear stress properties as microalgae endurance capacity depends on them. For the dimension of the three PBRs we considered here, each of them have radius of about 0.05 m while the length together with bending portion is approximately 20.5 m for a single loop. From the study, the hydrodynamic behaviors are observed to be quite dissimilar in case of three PBR’s. In the straight portion the velocity profile is quite parabolic in tubular but distorted minimally in case of square and hexagonal PBRs. In the middle of the U-loop, a haphazard fluid distribution is noticed. The velocity magnitude and agitation of microalgae cells are higher in hexagonal than in square and tubular. The shear rate is less in case of tubular compared to square and hexagonal. A linear pressure drop is found from the inlet to the outlet for three PBR’s. From this comparison, it can be said that the tubular one would be the best option for microalgae culture in case of industrial purposes.
