• Title/Summary/Keyword: Mass Transfer Resistance

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Carbon Dioxide Absorption in a Packed Column Using Guanidine-based Superbase Solution (구아니딘계 초염기 흡수제에 의한 충진탑에서의 이산화탄소 포집 특성)

  • Choi, Young Min;Hong, Yeon Ki;You, Jong Kyun
    • Korean Chemical Engineering Research
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    • v.54 no.5
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    • pp.648-652
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    • 2016
  • The study of $CO_2$ absorption in a packed column by 1,1,3,3-tetramethylguanidine (TMG) dissolved in ethylene glycol is presented. Absorption column of inner diameter 1 in and 0.6 m length was filled with Protruded-packing $0.16in{\times}0.16in$. We investigated the effect of operating conditions on overall mass transfer coefficients as well as on $CO_2$ removal efficiency. The loading values reached at about $1.0mol_{CO2}/mol_{TMG}$. In case of absorbent with lean $CO_2$ loading, the overall mass transfer coefficient was proportional to the concentration of TMG. However, in the range of more than ${\alpha}=0.5molCO_2/molTMG$, the overall mass transfer coefficients decreased with the concentration of TMG. It is due to the increasing of mass transfer resistance in liquid phase as increasing of viscosity at higher loading values.

A Study on the Mass Transfer and Metal Extraction by use of Hydrophobic Membrane (소수성막을 이용한 금속추출 및 물질전달에 관한 연구)

  • Lee, Ryong-Jin;Kim, Young-Il;Park, Dong-Won
    • Applied Chemistry for Engineering
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    • v.9 no.7
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    • pp.1036-1042
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    • 1998
  • It was investigated that the extraction of Cr(VI) from aqueous solution into the organic TDA and the stripping(back extraction) of Cr(VI) from the Cr(VI)-TDA complex into NaOH aqueous solution by hydrophobic hollow fiber membrane. It was found that the mass transfer rates of stripping process were smaller than those of the extraction process. This result was expected that membrane resistance, neglected in the extraction process, acts on the stripping process when organic phase flow in the tube side of the hydrophobic membrane. Hollow fiber modules were made by potting the desired number(60, 100, 150, 300fibers). We also examined the effect of flow rates of aqueous and organic phase on the mass transfer rate in the membrane modules. From these experiments, we identified for the extraction process by using hydrophobic membrane, the effect of flow rate of aqueous phase on the mass transfer rate was significant, but that of organic phase was negligible one. In the stripping process, however, mass transfer rate depend neither flow rate of aqueous(stripping solution) phase nor that of organic(Cr-TDA complex) phase.

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An Experimental Investigation of Heat Transfer in Forced Convective Boiling of R 134a, R 123 and R 134a/R 123 in a Horizontal Tube

  • Lim, Tae-Woo;Kim, Jun-Hyo
    • Journal of Mechanical Science and Technology
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    • v.18 no.3
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    • pp.513-525
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    • 2004
  • This paper reports an experimental study on flow boiling of pure refrigerants R l34a and R l23 and their mixtures in a uniformly heated horizontal tube. The flow pattern was observed through tubular sight glasses with an internal diameter of 10㎜ located at the inlet and outlet of the test section. Tests were run at a pressure of 0.6 MPa in the heat flux ranges of 5-50㎾/㎡, vapor quality 0-100 percent and mass velocity of 150-600㎏/㎡s. Both in the nucleate boiling-dominant region at low quality and in the two-phase convective evaporation region at higher quality where nucleation is supposed to be fully suppressed, the heat transfer coefficient for the mixture was lower than that for an equivalent pure component with the same physical properties as the mixture. The reduction of the heat transfer coefficient in mixture is explained by such mechanisms as mass transfer resistance and non-linear variation in physical properties etc. In this study, the contribution of convective evaporation, which is obtained for pure refrigerants under the suppression of nucleate boiling, is multiplied by the composition factor by Singal et al. (1984). On the basis of Chen's superposition model, a new correlation is presented for heat transfer coefficients of mixture.

OPTIMZATION OF A PIN FIN BASED ON THE INCREASING RATE OF HEAT LOSS

  • Kang, Hyung-Suk
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.12 no.1
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    • pp.25-32
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    • 2008
  • A pin fin is optimized based on the increasing rate of heat loss by using a two-dimensional analytic method. The optimum heat loss, corresponding optimum thermal resistance and fin length are presented as a function of the fin base thickness, convection characteristic numbers ratio, fin outer radius and ambient convection characteristic number. One of the results shows that both the optimum heat loss and fin length decrease linearly whereas the optimum thermal resistance increases very slightly with increase of the fin base thickness.

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A Study on the Heat Transfer Enhancement of Miniature loop Heat Pipes by Using the Cu Nanofluids

  • Kim, Young-Sik;Jeong, Hyo-Min;Chung, Han-Shik;Tanshen, Md.Riyad;Lee, Dae-Chul;Ji, Myoung-Kuk;Bae, Kang-Youl
    • Journal of Power System Engineering
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    • v.17 no.2
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    • pp.70-77
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    • 2013
  • An experimental study was carried out to understand the heat transfer performance of a miniature loop heat pipes using water-based copper nanoparticles suspensions as the working fluid. The suspensions consisted of deionized water and copper nanoparticles with an average diameter of 80 nm. Effects of the cupper mass concentration and the operation pressure on the average evaporation and condensation heat transfer coefficients, the critical heat flux and the total heat resistance of the mLHPs were investigated and discussed. The pressure frequency also depends upon the evaporator temperature which has been maintained from $60^{\circ}C$ to $90^{\circ}C$. The Investigation shows 60% filling ratio gives the highest inside pressure magnitude of highest number pressure frequency at any of setting of evaporator temperature and 5wt% results the lowest heat flow resistance.

Preparation of PVDF Hollow Fiber Membrane and Absorption of SO2 from Flue Gas Using Bench Scale Gas-Liquid Contactor (PVDF 중공사막 제조 및 벤치규모 기-액 접촉기를 이용한 SO2 흡수특성)

  • Park, Hyun-Hee;Jo, Hang-Dae;Kim, In-Won;Lee, Hyung-Keun
    • Korean Chemical Engineering Research
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    • v.46 no.3
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    • pp.521-528
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    • 2008
  • The micro-porous asymmetric PVDF hollow fiber membranes for gas-liquid contactor were prepared by the dry-jet wet phase inversion process and the characteristics of hollow fiber membranes were evaluated by the gas permeation method and scanning electron microscope. The chemical absorbent for removal of $SO_2$ gas was sodium hydroxide at bench scale hollow fiber membrane contactor. The experiments were performed in a counter-current mode of operation with gas in the shell side and liquid in the fiber lumen of the module to examine the effect of various operating variables such as concentration of absorbent, gas flow rate, L/G ratio and concentration of inlet $SO_2$ gas on the $SO_2$ removal efficiency using PVDF hollow fiber membrane contactor. Membrane mass transfer coefficient($k_m$) was calculated by mathematical modeling. The volumetric overall mass transfer coefficient increased with increasing the concentration of absorbent and L/G ratio. The increase of the absorbent concentration and L/G ratio not only provides more sufficient alkalinity but also decreases liquid phase resistance. The volumetric overall mass transfer coefficient increased with increasing gas flow rate due to decreasing the gas phase resistance.

An Experimental Study on the Effects of Porous Layer Treatment on Evaporative Cooling of an Inclined Surface (다공물질 표면처리가 경사판의 증발냉각에 미치는 영향에 관한 실험적 연구)

  • Lee Dae Young;Lee Jae Wan;Kang Byung Ha
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.1
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    • pp.25-32
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    • 2005
  • Falling film heat transfer has been widely used in many applications in which heat and mass transfer occur simultaneously, such as evaporative coolers, cooling towers, absorption chillers, etc. In such cases, it is desirable that the falling film spreads widely on the surface forming thin liquid film to enlarge contact surface and to reduce the thermal resistance across the film and/or the flow resistance to the vapor stream over the film. In this work, the surface is treated to have thin porous layer on the surface. With this treatment, the liquid can be spread widely on the surface by the capillary force resulting from the porous structure. In addition to this, the liquid can be held within the porous structure to improve surface wettedness regardless of the surface inclination. The experiment on the evaporative cooling of an inclined surface has been conducted to verify the effectiveness of the surface treatment. It is measured that the evaporative heat transfer increases about $50\%$ by the porous layer treatment as compared with that from orignal bare surfaces.

Fire Behavior of Reinforced Concrete Filled Square Steel Tube Columns Under Constant Axial Loads

  • Jeeyoung Lee;Seulgi Han;Jinwon Shin;Inrak Choi;Sungmo Choi
    • International Journal of High-Rise Buildings
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    • v.13 no.1
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    • pp.85-95
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    • 2024
  • A composite member made of concrete-filled steel tubes (CFT columns) has been recognized for its fire resistance due to the thermal mass effect of concrete inside the steel tube, as shown in various studies. In this study, the fire resistance performance of reinforced CFT columns under constant axial load was evaluated using finite element analysis with ABAQUS. For this purpose, the variables including cross-section size, steel tube thickness, and concrete cover thickness were set, and the temperature distribution in the column cross-section exposed to a standard fire was investigated using heat transfer analysis. Ultimately, a P-M interaction curve was obtained by evaluating the overall residual strength of columns, and the fire resistance time was determined by evaluating axial displacement-time responses due to the reduction in load capacity during fire through stress analysis.

Characteristics of the Bioreactors of Hydrogen-producing Immobilized Cells (II) -Overall Effectiveness Factor in Continuous Reactors- (수소생산 고정화 생물 반응기의 특성(II) -연속 반응기에서의 총괄 효율인자 -)

  • 이명재;선용호;한정우;조영일
    • Microbiology and Biotechnology Letters
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    • v.16 no.6
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    • pp.510-516
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    • 1988
  • The effects of input substrate concentration and dilution rate on mass transfer resistance in the operation of immobilized cell reactors were investigated using Rhodospirillum rubrum KS-301 immobilized by Ca alginate as reactor element and glucose as growth-limiting substrate. The kinetic parameters were obtained to estimate effectiveness factors. In the packed-bed reactor, internal mass transfer resistance was predominating although external resistance could not be neglected. The overall effectiveness factor was decreased with increase of dilution rate. In the continuous stirred-tank reactor, external resistance was nearly neglected and the overall effectiveness factor was not affected by dilution rate. In this experiment the overall effectiveness factors in PBR and CSTR were estimated to be 0.70 and 0.71 at D$_{i}$ = 0.2/h, R = 0.15 cm, and S$_{i}$ : 1.0g/L, respectively.

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Simulative Calculations of Food Waste Reduction Using Kineto-transport Models (동력학-전달 모델을 활용한 식품 폐기물 감량 해석)

  • Cho, Sun-joo;Kim, Tae-wook;Kwon, Sung-hyun;Cho, Daechul
    • Journal of Environmental Science International
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    • v.30 no.6
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    • pp.429-439
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    • 2021
  • Food waste is both an industrial and residential source of pollution, and there has been a great need for food waste reduction. As a preliminary step in this study, waste reduction is quantitatively modeled. This study presents two models based on kinetics: a simple kinetic model and a mass transport-shrinking model. In the simple kinetic model, the smaller is the reaction rate constant ratio k1, the lower the rate of conversion from the raw material to intermediate products. Accordingly, the total elapsed reaction time becomes shorter. In the mass transport-shrinking model, the smaller is the microbial decomposition resistance versus the liquid mass transfer resistance, the greater is the reduction rate of the radius of spherical waste particles. Results showed that the computed reduction of waste mass in the second model agreed reasonably with that obtained from a few experimantal trials of biodegradation, in which the microbial effect appeared to dominate. All calculations were performed using MATLAB 2020 on PC.