Oxygen transfer to cassava starch solutions in an aerated, well-mixed bioreactor: Experimental and mass transfer studies

Agus Saptoro,Morgan Ting Hock Herng,Emily Liew Wan Teng 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.4

Experimental and mass transfer studies of oxygen transfer to cassava starch solution in an aerated, wellmixedbioreactor of 2 L have been carried out. The volumetric mass transfer coefficient was estimated and parametricstudies were performed to study the effect of process variables of stirring rate, aeration rate, concentration of starchand temperature on the volumetric mass transfer coefficient. From the experimental results, it is evident that the firsttwo and the last variables are directly proportional to the volumetric mass transfer coefficient. However, the volumetricmass transfer coefficient is inversely proportional to the concentration of the starch. Also, the saturation dissolved oxygenconcentration is greatly affected by temperature and starch solution concentration. Whereas, stirring and aerationrates have neutral impacts on saturation dissolved oxygen concentration. Simulated data generated from obtained volumetricmass transfer coefficient agrees well with the experimental data, which indicates the accuracy of the coefficient.

Comparative Study of Mass Transfer and Bubble Hydrodynamic Parameters in Bubble Column Reactor

Prajak Sastaravet,Chomthisa Chuenchaem,Nawaporn Thaphet,Nattawin Chawaloesphonsiya,Pisut Painmanakul 대한환경공학회 2014 Environmental Engineering Research Vol.19 No.4

In this paper, effects of physical configurations and operating conditions on bubble column performance were analyzed in terms of bubble hydrodynamic and mass transfer parameters. Bubble column with 3 different dimensions and 7 gas diffusers (single / multiple orifice and rigid / flexible orifice) were applied. High speed camera and image analysis program were used for analyzing the bubble hydrodynamic parameters. The local liquid-side mass transfer coefficient (kL) was estimated from the volumetric mass transfer coefficient (kLa) and the interfacial area (a), which was deduced from the bubble diameter (DB) and the terminal bubble rising velocity (UB). The result showed that the values of kLa and a increased with the superficial gas velocity (Vg) and the size of bubble column. Influences of gas diffuser physical property (orifice size, thickness and orifice number) can be proven on the generated bubble size and the mass transfer performance in bubble column. Concerning the variation of kL coefficients with bubble size, 3 zones (Zone A, B and C) can be observed. For Zone A and Zone C, a good agreement between the experimental and the predicted KL coefficients was obtained (average difference of 짹 15%), whereas the inaccuracy result (of 짹 40%) was found in Zone B. To enhance the high kLa coefficient and absorption efficiency in bubble column, it was unnecessary to generate numerous fine bubbles at high superficial gas velocity since it causes high power consumption with the great decrease of kL coefficients.

Enhancing gas–liquid volumetric mass transfer coefficient

Dongil Ho,Kwangmin Kim,Taeshik Earmme,Choongik Kim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.87 No.-

Methane-based biorefineries for biofuel production by microorganisms has gained interest due to theworldwide development of shale gas as an alternative source for fossil fuels. For the practical applicationof biological conversion process to industrial scale, enhancement of the gas–liquid volumetric masstransfer coefficient (kLa) in a gas diffusing system is crucial. This review article provides an overview ofthe developments on gas–liquid volumetric mass transfer enhancement through increasing the gas–liquid mass transfer coefficient term ‘kL’ and/or increasing the gas–liquid interfacial area term ‘a’. Twomajor enhancement methods which are summarized and discussed here include the most recentaccomplishments in gas–liquid mass transfer engineering of gas diffusing systems. The most up-to-datemechanical modification of reactor and additive employment rationales and discussions providing astrong understanding of gas–liquid volumetric mass transfer relationships are presented. Thus, thisreview is expected to inspire new research for future developments and applications in gas–liquid masstransfer engineering for gas diffusing systems.

Determination of volumetric mass transfer coefficient of methane in newly developed reactor

이재원,김충익 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

Biological conversion of methane gas has been attracting considerable recent interest. However, methanotropic bioreactor is limited by low solubility of methane gas in aqueous solution. Although a large mass transfer coefficient of methane in water could possibly overcome this limitation, no dissolved methane probe in aqueous environment is commercially available. We have developed a reactor enabling the measurement of aqueous phase methane concentration and mass transfer coefficient (k L a). The feasibility of the new reactor was demonstrated by measuring k L a values as a function of spinning rate of impeller and flow rate of methane gas. Especially, at spinning rate of 300 rpm and flow rate of 3.0 L/min, a large k L a value of 102.9 h-1 was obtained.

오리피스 노즐 수직 2 상 유동의 물질전달 특성

김동준(Dong Jun Kim),양희천(Hei Cheon Yang) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.10

본 논문은 수직 오리피스 노즐의 유동 및 물질전달 특성에 대한 실험적 연구를 목적으로 한다. 구동유체 및 부유체의 유량, 용존산소 농도 그리고 소비 전력을 측정하였으며, 고속 카메라를 이용한 직접 촬영 기법으로 수직 혼합유동의 가시화 이미지를 획득하였다. 측정자료를 이용하여 질량비, 총괄 산소전달 계수 그리고 물질전달 성능계수를 도출하였다. 구동압력이 증가하면 질량비는 약간 감소하는 반면에, 산소전달 계수와 소비전력은 증가하였다. 구동압력이 증가하고 질량비가 작아지면, 기포의 미세화가 촉진되고 확산도가 증대되기 때문에 산소 전달율이 증가하였다. Experiments were carried out to investigate the flow and mass transfer characteristics of an orifice nozzle. Measurements of primary and suction flow rates, dissolved oxygen concentration, and electric power were obtained. Vertically injected mixed-jet images were captured by a direct visualization technique with a high speed camera unit. The mass ratio, volumetric mass transfer coefficient, and mass transfer performance were calculated using the measured data. As the primary flow pressure increases, the mass ratio decreases slightly, while the volumetric mass transfer coefficient and electric power increase. As the primary flow pressure increases and the mass ratio decreases, the mass transfer rate increases because of the fine bubbles and wider distribution of the bubbles.

Enhancement of methane-water volumetric mass transfer coefficient via bubble coalescence inhibition with electrolyte

김광민,김충익 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

The effect of electrolyte on methane-water volumetric mass transfer coefficient (kLa) was investigated in this study. Various electrolytes including MgSO4, K2SO4, Na2SO4, MgCl2, KCl, NaCl, MgBr2, NaBr, KBr,Mg(NO3)2, KNO3, and NaNO3 were employed and enhancement of kLa from 103 h-1 (in pure water) to 711 h-1 was observed, depending on electrolyte type and concentration. This is the highest methane-water kLa value reported. For all electrolytes, ions with large charge density (charge valency per ionic volume) exhibited larger enhancement in methane-water kLa values. Furthermore, anions exhibited larger influence than cations on the enhancement of kLa. Enhancement of methanewater kLa by electrolytes was due to the inhibition of methane bubble coalescence.

Study of different flexible aeration tube diffusers

Narapong Hongprasith,Natchanok Dolkittikul,Kamolnapach Apiboonsuwan,Wiboonluk Pungrasmi,Pisut Painmanakul 대한환경공학회 2016 Environmental Engineering Research Vol.21 No.3

The research aims to study the different flexible rubber tube diffusers used in urban wastewater treatment processes and aquaculture systems. The experiment was conducted in small-scale aeration tank with different physical properties of the tubes that were used as aerators. The volumetric mass transfer coefficient (kLa), oxygen transfer efficiency (OTE) and aeration efficiency (AE) were measured and determined to compare the diffusers. Moreover, the bubble hydrodynamic parameters were analyzed in terms of bubble diameter (dB) and rising velocity (UB) by a high speed camera (2,000 frames/s). Then the interfacial area (a) and liquid-side mass transfer coefficient (kL) can be calculated. The physical properties (tube wall thickness, tensile strength, orifice size, hardness and elongation) have been proven to be the key factor that controls the performance (kLa and OTE). The effects of hardness and elongation on bubble formation, orifice size and a-area were clearly proved. It is not necessary to generate too much fine bubbles to increase the a-area: this relates to high power consumption and the decrease of the kL. Finally, the wall thickness, elongation and hardness associated of the flexible tube diffuser (tube No. 12) were concluded, to be the suitable properties for practically producing, in this research.

Effects on Swirling Chamber and Breaker Disk in Pressurized-Dissolution Type Micro-Bubble Generator

김현식,임지영,박수영,김진한 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.4

This study was performed to investigate the effect on element such as swirling chamber and breaker disk in pressurized-dissolution type micro-bubble generator. And, to show the effect of element measured bubble size distribution, Sauter mean diameter and volumetric mass transfer coefficient as performance indicators of pressurized-dissolution type micro-bubble generator. And the results of experiments was summarized quantitatively. As a results of several experiments, breaker disk was shown up the best efficiency than other cases in aspect of effect on bubble size, which contribution ratio for D50 and Sauter mean diameter are 27.84%, 45.16% respectively. Also, in aspect of effect on volumetric mass transfer coefficient, swirling chamber B was shown up the best efficiency than other cases. The contribution ratio for volumetric mass transfer coefficient was 345.59%. Hence, the composition of additional equipment for improving efficiency of pressurized dissolution type micro-bubble generator was recommended using breaker disk and swirling chamber B type.

Determination of the Process Parameters Relative Influence on kLa Value using Taguchi Design Methodology

Andreja GOR?EK,Marko TRAM?EK 한국공업화학회 2007 Journal of Industrial and Engineering Chemistry Vol.13 No.7

This article describes experimental determination of the relative impact of significant process parameters that influence volumetric oxygen mass transfer coefficient (kLa) using Taguchi design methodology. For this purpose an automated RC1 reaction calorimeter (Mettler-Toledo), which was originally developed for chemical processes, was modified for the bioprocesses. Simple fermentation using Baker’s yeast was studied to illustrate the design procedure. Orthogonal array L25 was selected for the proposed design and ANOVA method was used for recognizing the relative influence of the process parameters. Within the observed range of temperature (), fermentation media volume (VFM), and yeast mass concentration (γY), these process parameters were found to be unimportant compared to the volumetric air flow rate (qV,a) and rotational frequency of the stirrer (fm). The qV,a had a substantial effect on the kLa value (89.2 %) and the fm had just a small one (3.6 %), meanwhile the remain fraction to 100 % represents error. The results refer strictly to the selected case study. Anyhow, the proposed procedure shows that application of the Taguchi approach for analyzing the oxygen mass transfer based on the experimental data obtained from a highly-automated laboratory reactor appears to have potential usage in general biopharmaceutical process design.

Enhanced mass transfer rate and solubility of methane via addition of alcohols for Methylosinus trichosporium OB3b fermentation

김광민,김유진,양정모,하경수,Hakan Usta,이진원,김충익 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.46 No.-

The effect of alcohol on methane–water volumetric mass transfer coefficient (kLa) and solubility ofmethane was investigated in this study. Various alcohols including methanol, ethanol, 1-propanol,butanol, and pentanol were added to aqueous solution and enhancement of both methane–water kLa(from 72 h 1 to 471 h 1) and solubility (from 21.72 mg/L to 30.41 mg/L) was observed, depending onalcohol type and concentration. Among all alcohols, 1-propanol exhibited largest enhancement viabubble coalescence inhibition effect. Enhanced methane–water kLa and methane solubility in aqueoussolution were employed for the fermentation of Methylosinus trichosporium OB3b, and cell growth rateand maximum optical density were increased by 700% and 730%, respectively, by addition of 1-propanol.