Chemical reaction modeling in a selenization process of CIGS thin film solar cells

Taejong Yu(유태종),Donghyun You(유동현) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

Integrated simulation of turbulent convection, radiation and conduction during a selenization process for large-scale CIGS thin films

Yu, Taejong,Yoon, Daegeun,You, Donghyun Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.125 No.-

<P><B>Abstract</B></P> <P>A numerical methodology for simulations of multi-mode heat transfer during a selenization process for CIGS (Copper Indium Gallium Selenide) solar cell films has been developed. Turbulent fluid dynamics and convective heat transfer are simulated using a finite-volume large-eddy simulation (LES) technique while thermal conduction and radiation are predicted using finite-element methods. The computational methodology is validated for three heat transfer modes. Using the technique, a numerical study of heat transfer during the selenization process for deposition of a CIGS layer is performed to analyze the thermo-fluid phenomena occurring during the process. The present method is found to well predict temperature distribution on substrates as a function of both space and time. It is also analyzed that how turbulent fluid motions alter temperature distributions on the substrate during the selenization process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A numerical methodology for multi-mode heat transfer during a selenization process for CIGS thin films has been developed. </LI> <LI> A numerical study of thermo-fluid phenomena during the selenization process is performed. </LI> <LI> Effects of thermo-fluid phenomena on the uniformity of CIGS deposition are investigated. </LI> </UL> </P>

淨水場 汚泥의 發生量 推定

류태종 광주대학교 1996 産業技術硏究 Vol.7 No.-

In this study, experiments to estimate the amount of alum sludge production were conducted in two different ways. The one of the two estimation method is based on the alum dosage and raw water turbidity, the other is based on the the ratio of alum dosage to aluminum concentration in the sludge. In the first experiment, sludge production was observed to be 1.234-2.262㎎/L per unit turbidity for raw waters from three water treatment plants around the Kwangju metropolitan area. It was considered to be reasonable that sludge production caused by the addition of alum was 0.273㎎/L per 1 ppm addition of filter alum(1mL/m3 as 8% Al203). The sludge production estimated from the ratio of alum dosage to aluminum concentration in the sludge from three water treatment facilities and that estimated from the turbidity and alum dosage showed good agreement with each other, indicating that both methods are reliable.

회수 알럼 재이용의 경제성 평가

류태종 광주대학교 1998 産業技術硏究 Vol.11 No.-

정수처리장에서 발생되는 알럼오니를 처리하는 방법은 여러 가지가 있는데, 그중 한 방법이 알럼오니를 산처리한 후 회수알럼을 재사용하는 방법이다. 본 연구에서는 회수된 알럼을 정수처리장에서 응집제로써 재사용하는 것에 대해서 경제성 평가를 행하였는데, 그 전제 조건은 다음과 같다. ①회수 알럼의 시판알럼에 대한 응집 효율 : 90% ②발생오니 산처리 비율 : 100% ③탈수케이크의 함수율 : 80% ④산처리에서의 pH : 2.0 ⑤황산 구입단가 : 83,000원/ton ⑥시판알럼 구입단가 : 78,100원/m3 ⑦해양투기 처분비용 : 43,000원/m3 There are many methods of treating alum sludge generated from water treatment plant. One of the methods is acidification of the alum sludge and reuse of recovered alum. In this study, the economic analysis was conducted to evaluate the reuse of the recovered alum as a coagulant in water treatment plant. Assumption of analysis are as follows ①Effectiveness of recovered alum (compared with commercial alum) : 90% ②Percent of sludge acidified : 100% ③Water content of dewatered cake : 80% ④pH of recovered alum : 2.0 ⑤Price of H2SO4 : ￦83,000/m3 ⑥Price of commercial alum : 78,100원/m3 ⑦Disposal cost of alum sludge: ￦43,000/m3

정수오니의 산처리·알칼리처리 특성

유태종 광주대학교 산업기술연구소 1995 産業技術硏究 Vol.5 No.-

In advanced countries, alum recovery from alum sludge by its acidification has recently gained more attention because many water utilities need to improve their sludge handling and disposal practices. As part of an overall sludge management program, alum recovery can reduce the amount of solids and allow for reuse of recovered alum as a coagulant in the water treatment plant. It also has other potential uses such as phophorus removal at wastewater treatment plant. In this study, sludges of five water treatment plants around Kwangju area were used to analyze their chemical and physical characteristics and to determine the concentration of impurities in the recovered alum. The acidified or alkalyzed residual sludges were used to evaluate the chracteristics of their thickening, settleability and dewaterability.

회수 알럼의 품질평가

류태종 광주대학교 1998 産業技術硏究 Vol.11 No.-

회수알럼에 대한 중요 평가인자로는 회수율, 회수 알럼의 농도, 회수알럼액상내에 존재하는 불순물의 농도등이다. 알럼 회수율은 알럼의 용해도와 고액분리공정의 효율에 따라 달라질수 있다. 본 연구에서는 광주인근 3개정수장에서 발생되는 알럼오니를 산처리하여 알럼을 회수한 후 다음과 같은 분석을 행하여 응집제로써의 회수알럼의 품질을 평가하고자 하였다. ① 알럼 회수율 ② 철, 망간등의 불순물 농도 분석 결과로부터 얻을 수 있었던 결론은 농축에 의한 알럼의 회수율은 61∼63.7% 이었고, 기계식 탈수에 의한 알럼의 회수율은 81.6∼94.4%정도로 나타났다. 또한 회수알럼내에 포함된 불순물의 농도는 응집제로써 재사용되기에 충분할 정도의 저농도로 나타났다. The important evaluation factor of recovered alum are recovery percent, recovered Al concentration, concentrations of impurities included in recovered alum. Recovery percent depends on the alum solubility and the effectiveness of solid-liquid separation process. In this study, alum sludges generated from water treatments around Kwangju metropolitan city area were acidified and alum was recovered from acidified alum sludge in the form of supernatant. The following analysis were conducted to evaluate the quality of recovered alum as a coagulant. ① Alum recovery percent ② Concentration of impurities such as Fe, Mn.... From the reults of analysis, alum recovery by thickening and mechanical dewatering were 61∼63.7% and 81.6∼94.4 respectively. The concentration of impurities were low enough to be reused as a coagulant in water treatment plant.

생물학적 인 처리 공정의 설계

유태종 광주대학교 1998 産業技術硏究 Vol.10 No.-

본 논문은 wisconsin주에 소재한 Marathon시에서 발생되는 하수로부터 인을 제거 위한 처리공정을 설계하기 위해 하수의 성상 분석을 행하고 생물학적인 공정에 의해 인의 처리가 가능한지의 여부(BPR test)를 조사하였다. 조사 분석된 하수의 성상 자료를 자동설계 프로그램인 ENBIR에 입력하여 모의함으로서 Marathon시에서 발생되는 하수의 고도 처리시설의 설계를 행하였으며, 생물학적 인 처리 공정 중에서 A/O, A2/O, UCT, Phoredox등을 비교하여 각 공정의 적합성을 조사하였다.

A 3D-printed flow distributor with uniform flow rate control for multi-stacked microfluidic systems

Park, Young-June,Yu, Taejong,Yim, Se-Jun,You, Donghyun,Kim, Dong-Pyo The Royal Society of Chemistry 2018 Lab on a chip Vol.18 No.8

<P>In the scale-up of chemical production in a microfluidic system, it is challenging to prevent flow maldistribution from a single inlet into stacked multiple microchannel exits. In the present study, a compact flow distributor equipped with a fluidic damper is developed by computational fluid dynamics (CFD) along with experimental validation. A microfluidic flow distributor, which is equipped with an optimized fluidic damper and consists of 25 exit channels, is fabricated as an integrated body using a digital light processing (DLP) type 3D printer. The 3D printed flow distributor with a CFD-optimized fluidic damper is found to achieve a low maldistribution factor (MF) of 2.2% for the average flow rate over 25 exit channels while inducing only a minor increment (<6%) in the pressure drop. A generalized manual is proposed for the design of optimal flow distributors with different scale-up dimensions. Using the manual, an optimal flow distributor with 625 stacked microchannels with a MF of only 1.2% is successfully designed. It is expected that the design manual and the rapid printing platform will allow the efficient development of multi-channel stacked micro-devices such as those in drug delivery and energy conversion systems where equidistribution of fluid flow is highly demanded.</P>

Kinetic modeling and dynamic simulation for the catalytic wet air oxidation of aqueous ammonia to molecular nitrogen

Deuk Ki Lee,Jeong Shik Cho,Taejong Yu,Yong Su Lee,Jae Wan Choe,Sang Soo Lee 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.11

A kinetic model for the catalytic wet air oxidation of aqueous ammonia over Ru/TiO2 catalyst was developed considering the consecutive reaction steps as follows: (i) formation of active oxygen sites O* by the dissociative adsorption of aqueous O2 on the catalyst, (ii) oxidation of aqueous NH3 by the reaction with three O* sites to produce HNO2, (iii) aqueous phase dissociation of HNO2 into H+ and NO2 −, (iv) formation of NH4 + by the association of NH3 with the HNO2-dissociated H+, (v) formation of N2 by the aqueous phase reaction between NO2 − and NH4 +, (vi) formation of NO3 by the reaction of NO2 − with an O* site. For each reaction step, a rate equation was derived and its kinetic parameters were optimized by experimental data fitting. Activation energies for the reactions (ii), (v), and (vi) were 123.1, 76.7, and 54.5 kJ/mol, respectively, suggesting that the oxidation reaction of aqueous NH3 to HNO2 was a ratedetermining step. From the simulation using the kinetic parameters determined, the initial pH adjustment of the ammonia solution proved to be critical for determining the oxidation product selectivity between desirable N2 and undesirable NO3 − as well as the degree of oxidation conversion of ammonia.