Analysis of an Immoblised Enzyme Reactor with Catalysts Activation

2010 ◽  
Vol 4 (3) ◽  
Author(s):  
Mark I Nelson ◽  
Harvinder S Sidhu ◽  
Adesoji A Adesina
Keyword(s):  
Steady State ◽  
Immobilized Enzyme ◽  
Flow Reactor ◽  
Reaction Vessel ◽  
Operating Conditions ◽  
Residence Times ◽  
Enzyme Reactor ◽  
Steady State Analysis ◽  
Product Species ◽  
Enzyme Species

We investigate the behavior of a reaction described by Michaelis-Menten kinetics in an immobilized enzyme reactor (IER). The IER is treated as a well stirred flow reactor, in which the immobilized bounded and unbounded enzyme species are constrained to remain within the reaction vessel. The product species leaves the IER in the reactor outflow. Before the substrate can react with the enzyme, the enzyme must first be activated by absorption of an activator. We use steady state analysis to identify the best operating conditions or the reactor. To this end, we show that the concentration of product is maximized at low residence time whereas the productivity of the reactor is maximized at high residence times.

scholarly journals Analysis of the Michaelis-Menten mechanism in an immobilised enzyme reactor

2005 ◽  
Vol 47 (2) ◽  
pp. 173-184 ◽  
Author(s):  
M. I. Nelson ◽  
X. D. Chen ◽  
M. J. Sexton
Keyword(s):  
Flow Reactor ◽  
Reaction Vessel ◽  
High Flow ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Low Flow ◽  
Enzyme Reactor ◽  
Flow Rates ◽  
Periodic Behaviour ◽  
Enzyme Species

AbstractWe investigate the behaviour of a reaction described by Michaelis-Menten kinetics in an immobilised enzyme reactor (IER). The IER is treated as a well-stirred flow reactor, with the restriction that bounded and unbounded enzyme species are constrained to remain within the reaction vessel. Our aim is to identify the best operating conditions for the reactor.The cases in which an iminobilised enzyme reactor is used to either reduce pollutant emissions or to synthesise a product are considered. For the former we deduce that the reactor should be operated using low flow rates whereas for the latter high flow rates are optimal. It is also shown that periodic behaviour is impossible.

Jet Engine Gas Path Analysis Based on Takeoff Performance Snapshots

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
A. Putz ◽  
S. Staudacher ◽  
C. Koch ◽  
T. Brandes
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Performance Model ◽  
Operating Conditions ◽  
Medium Size ◽  
Jet Engines ◽  
Transient Effects ◽  
Steady State Analysis ◽  
Simulation Results ◽  
State Analysis

Current engine condition monitoring (ECM) systems for jet engines include the analysis of on-wing gas path data using steady-state performance models. Such data, which are also referred to as performance snapshots, usually are taken during cruise flight and during takeoff. Using steady-state analysis, it is assumed that these snapshots have been taken under stabilized operating conditions. However, this assumption is reasonable only for cruise snapshots. During takeoff, jet engines operate in highly transient conditions with significant heat transfer occurring between the fluid and the engine structure. Hence, steady-state analysis of takeoff snapshots is subject to high uncertainty. Because of this, takeoff snapshots are not used for performance analysis in current ECM systems. We quantify the analysis uncertainty by transient simulation of a generic takeoff maneuver using a performance model of a medium size two-shaft turbofan engine with high bypass ratio. Taking into account the influence of the preceding operating regimes on the transient heat transfer effects, this takeoff maneuver is extended backward in time to cover the aircraft turnaround as well as the end of the last flight mission. We present a hybrid approach for thermal calculation of both the fired engine and the shutdown engine. The simulation results show that takeoff derate, ambient temperature, taxi-out (XO) duration and the duration of the preceding aircraft turnaround have a major influence on the transient effects occurring during takeoff. The analysis uncertainty caused by the transient effects is significant. Based on the simulation results, we propose a method for correction of takeoff snapshots to steady-state operating conditions. Furthermore, we show that the simultaneous analysis of cruise and corrected takeoff snapshots leads to significant improvements in observability.

scholarly journals Accelerating Biocatalytic Hydrogenations using the H-Cube Flow Reactor

2020 ◽  
Author(s):  
Barnabas Poznansky ◽  
Lisa Thompson ◽  
Holly Reeve ◽  
Kylie Vincent
Keyword(s):  
High Activity ◽  
Room Temperature ◽  
Immobilized Enzyme ◽  
Flow Reactor ◽  
Residence Times ◽  
Supported Metal Catalysts ◽  
Mild Conditions ◽  
Enzyme Systems ◽  
Hydrogenation Reactions ◽  
Redox Biocatalysis

Translation of redox biocatalysis into a commercial H-Cube hydrogenation flow reactor was achieved using immobilized enzyme systems for biocatalytic hydrogenations. Carbon-supported enzymes for H2-driven NADH recycling and NADH-dependent C=O reductions were handled comparably to supported metal catalysts. High activity at room temperature with 2 bar H2 was attained, highlighting that biocatalytic strategies enable implementation of hydrogenation reactions under mild conditions. High conversions were achieved in short residence times (< 2 s), with high biocatalyst turnover frequencies (1,420 min-1) and space-time yields (7.9 kg L-1 h-1). These results represent the first example of direct biocatalytic hydrogenation in a commercial flow reactor.

scholarly journals TOWARDS KINETIC REGIME OF REVERSE FLOW OPERATION

2018 ◽  
Vol 4 (3) ◽  
pp. 322
Author(s):  
Yogi Budhi
Keyword(s):  
Steady State ◽  
Flow Reactor ◽  
Switching Time ◽  
Reverse Flow ◽  
Fixed Bed ◽  
Operating Conditions ◽  
Fixed Bed Reactor ◽  
Kinetic Regime ◽  
Steady State Operation ◽  
Reverse Flow Reactor

An analysis of reverse flow operation and its experimental study for ammonia oxidation to produce either N2, N2O, and NO have been carried out. An experimental set-up of reverse flow reactor was constructed for a laboratory scale. The experiment under steady state operation was performed as a base case in order to judge the potential during the reverse flow operation. Aim was to investigate the behavior of reverse flow operation and to observe the reactor performance. Focus was on the comparison of the steady state and reverse flow operations. The experiments show that the behavior of reverse flow reactor is strongly influenced by the ratio of the switching time over the residence time. The ammonia conversion during the regular reverse flow operation shows lower values compared to the steady state operation which is even worse during asymmetric mode. The product distributions may change under flow reversal, depending on the operating conditions, regime of operation, and operation mode.Keywords : Reverse Flow Operation, Fixed Bed Reactor, Selectivity Manipulation, Steady State Operation, Ammonia OxidationAbstrak Sebuah analisis operasi aliran bolak-balik dan studi eksperimental oksidasi amoniak untuk menghasilkan baik N2., N2O, dan NO telah dilakukan. Sebuah perangkat eksperimen reaktor aliran bolak-balik dikonstruksi untuk skala laboratorium. Eksperimen dalam operasi keadaan tunak dilakukan sebagai kasus dasar untuk menilai potensi operasi aliran bolak-balik. Tujuan penelitian ini adalah untuk meneliti kelakuan operasi aliran bolak-balik dan untuk mengamati kinerja reaktor. Kajian ini dititikberatkan pada perbandingan operasi keadaan tunak dan operasi aliran bolak-balik. Hasil percobaan menunjukkan bahwa kelakuan reaktor aliran bolak-balik sangat dipengaruhi oleh nisbah waktu pembalikan arah aliran (switching time) terhadap waktu tinggal. Konversi amomiak dalam operasi aliran bolak-balik menunjukkan nilai yang lebih rendah dibandingkan dengan operasi keadaan tunak dan dalam mode asimetrik konversinya bahkan lebih rendah lagi. Distribusi produk dapat berubah dalam pembalikan aliran yang bergantung pada kondisi-kondisi operasi, daerah operasi, dan mode operasi.Kata Kunci : Operasi Aliran Bolak-balik, Reaktor Fixed Bed, Manipulasi Selektivitas, Operasi Tunak, Oksidasi Amoniak

scholarly journals Accelerating Biocatalytic Hydrogenations using the H-Cube Flow Reactor

2020 ◽  
Author(s):  
Barnabas Poznansky ◽  
Lisa Thompson ◽  
Holly Reeve ◽  
Kylie Vincent
Keyword(s):  
High Activity ◽  
Room Temperature ◽  
Immobilized Enzyme ◽  
Flow Reactor ◽  
Residence Times ◽  
Supported Metal Catalysts ◽  
Mild Conditions ◽  
Enzyme Systems ◽  
Hydrogenation Reactions ◽  
Redox Biocatalysis

Translation of redox biocatalysis into a commercial H-Cube hydrogenation flow reactor was achieved using immobilized enzyme systems for biocatalytic hydrogenations. Carbon-supported enzymes for H2-driven NADH recycling and NADH-dependent C=O reductions were handled comparably to supported metal catalysts. High activity at room temperature with 2 bar H2 was attained, highlighting that biocatalytic strategies enable implementation of hydrogenation reactions under mild conditions. High conversions were achieved in short residence times (< 2 s), with high biocatalyst turnover frequencies (1,420 min-1) and space-time yields (7.9 kg L-1 h-1). These results represent the first example of direct biocatalytic hydrogenation in a commercial flow reactor.

scholarly journals Temperature rise characteristics for angular-contact ball bearings with oil-air lubrication based on fluid-solid conjugate heat transfer

2021 ◽  
Vol 13 (1) ◽  
pp. 168781402199092
Author(s):  
Miaomiao Li ◽  
Yu Wang ◽  
Weifang Chen ◽  
Rupeng Zhu
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Flow Field ◽  
Temperature Rise ◽  
Conjugate Heat Transfer ◽  
Operating Conditions ◽  
Ball Bearings ◽  
Analysis Model ◽  
Steady State Analysis ◽  
State Analysis

At present, the thermal analysis of oil-air-lubricated angular-contact ball bearings uses empirical heat transfer coefficients to calculate heat transfer. This approach presents problems such as simulating the actual lubrication flow field and ignoring the internal heat conduction in the bearing ring. This paper proposes a CFD steady-state analysis model of oil-air-lubricated angular-contact ball bearings based on fluid-solid conjugate heat transfer to analyze the flow field and temperature field. A temperature rise test of oil-air-lubricated angular-contact ball bearings was carried out to verify the positive determination of the simulation analysis results. Based on a fluid-solid conjugate heat transfer steady-state analysis model, the effects of lubrication parameters, operating conditions, and rolling element materials on the temperature rise characteristics of oil-air-lubricated angular-contact ball bearings were studied. The research results provide a method for analyzing the temperature rise characteristics of oil-lubricated bearings and provide a basis for the analysis of oil-lubricated bearing life.

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