It is known that increasing the injection pressure reduces the breakup length and the droplet size.Adding pulses,on the other hand,helps to atomize the liquid into finer droplets,similar to airassisted injectors but w...It is known that increasing the injection pressure reduces the breakup length and the droplet size.Adding pulses,on the other hand,helps to atomize the liquid into finer droplets,similar to airassisted injectors but without altering the airtofuel concentration.To further reduce the droplet size and breakup length,a novel injector type,called''Pulsed PressureSwirl"(PPS),is introduced in this work,which is a combination of pressureswirl and ultrasonic pulsed injectors.A pressureswirl atomizer was designed and fabricated specifically for Mazut HFO(Heavy Fuel Oil).The droplet formation process and droplet size distribution have been studied experimentally(by shadowgraphy high speed imaging)and numerically(with the opensource VolumeofFluid code Gerris).Changing liquid injection pressure effect on the spray angle and film thickness has been quantified.These simulations have been used to study the primary breakup process and quantify the droplet size distributions,using different injection pulse frequencies and pressures.The numerical results have revealed that the new injector concept successfully produces finer droplets and results in a decrease in the breakup length,especially when applying high pulse frequencies,with no significant changes in the spray angle.展开更多
In this work, ZSM-5 type chromosilicate samples as K[Cr]ZSM-5(KCS) and Na[Cr]ZSM-5(NCS) were prepared by hydrothermal method and their catalytic properties were investigated for the oxidative dehydrogenation of ethylb...In this work, ZSM-5 type chromosilicate samples as K[Cr]ZSM-5(KCS) and Na[Cr]ZSM-5(NCS) were prepared by hydrothermal method and their catalytic properties were investigated for the oxidative dehydrogenation of ethylbenzene in the presence of CO<sub>2</sub> as an oxidant using a fixed-bed stainless steel reactor. The prepared samples were characterized by their morphology (SEM), structural parameters (XRD), and textural parameters (BET). The performance of these catalysts was evaluated in terms of conversion, styrene yield, and selectivity. The KCS<sub>BW</sub> catalyst (potassium chromosilicate before washing with distilled water) afforded the highest styrene yield, 56.19%, with the selectivity of 96.05% in the presence of CO<sub>2</sub> because of the coexistence of potassium ion and Cr<sub>2</sub>O<sub>3</sub> in its structure and their synergistic effect. The influence of the presence of Cr<sub>2</sub>O<sub>3</sub> and sodium or potassium ion on the catalytic activity of the chromosilicate samples in the catalytic EB dehydrogenation process was discussed in detail. Moreover, according to the results, the catalytic activity of the chromosilicate samples (CS) in EB dehydrogenation was increased by decreasing the surface area.展开更多
文摘It is known that increasing the injection pressure reduces the breakup length and the droplet size.Adding pulses,on the other hand,helps to atomize the liquid into finer droplets,similar to airassisted injectors but without altering the airtofuel concentration.To further reduce the droplet size and breakup length,a novel injector type,called''Pulsed PressureSwirl"(PPS),is introduced in this work,which is a combination of pressureswirl and ultrasonic pulsed injectors.A pressureswirl atomizer was designed and fabricated specifically for Mazut HFO(Heavy Fuel Oil).The droplet formation process and droplet size distribution have been studied experimentally(by shadowgraphy high speed imaging)and numerically(with the opensource VolumeofFluid code Gerris).Changing liquid injection pressure effect on the spray angle and film thickness has been quantified.These simulations have been used to study the primary breakup process and quantify the droplet size distributions,using different injection pulse frequencies and pressures.The numerical results have revealed that the new injector concept successfully produces finer droplets and results in a decrease in the breakup length,especially when applying high pulse frequencies,with no significant changes in the spray angle.
文摘In this work, ZSM-5 type chromosilicate samples as K[Cr]ZSM-5(KCS) and Na[Cr]ZSM-5(NCS) were prepared by hydrothermal method and their catalytic properties were investigated for the oxidative dehydrogenation of ethylbenzene in the presence of CO<sub>2</sub> as an oxidant using a fixed-bed stainless steel reactor. The prepared samples were characterized by their morphology (SEM), structural parameters (XRD), and textural parameters (BET). The performance of these catalysts was evaluated in terms of conversion, styrene yield, and selectivity. The KCS<sub>BW</sub> catalyst (potassium chromosilicate before washing with distilled water) afforded the highest styrene yield, 56.19%, with the selectivity of 96.05% in the presence of CO<sub>2</sub> because of the coexistence of potassium ion and Cr<sub>2</sub>O<sub>3</sub> in its structure and their synergistic effect. The influence of the presence of Cr<sub>2</sub>O<sub>3</sub> and sodium or potassium ion on the catalytic activity of the chromosilicate samples in the catalytic EB dehydrogenation process was discussed in detail. Moreover, according to the results, the catalytic activity of the chromosilicate samples (CS) in EB dehydrogenation was increased by decreasing the surface area.
