• Title/Summary/Keyword: Solid height

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Experimental Study of Close-Contact Melting of Phase-Change Medium Partially Filled in a Horizontal Cylinder (수평원관내 부분적으로 채원진 상변화물질의 융해과정)

  • 서정세;노승탁
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.9
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    • pp.2249-2260
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    • 1995
  • An experiment of close contact melting of phase-change medium partially filled in an isothermally heated horizontal cylinder is performed which involves the volume expansion of liquid induced by the solid-liquid density difference. The solid-liquid interface motion and the free surface behavior of liquid were reported photographically. The experimental results show that the curvature of upper solid-liquid interface varied to flat as melting progresses. In addition to the varying interface shape, the melting rate increases with the lower initial height of solid and the free surface height of liquid increases linearly. The experimental results of molten mass fraction were expressed in a function of dimensionless time Fo.Ste$^{3}$4/ and agreed well with the analytical solutions.

Solid Circulation Characteristics in a 3 kW Chemical-looping Combustor (3 kW급 매체순환식 가스연소기의 고체순환특성)

  • Ryu, Ho-Jung;Park, Jaehyeon;Kim, Hong-Ki;Park, Moon-Hee
    • Korean Chemical Engineering Research
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    • v.46 no.6
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    • pp.1057-1062
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    • 2008
  • To overcome disadvantages of conventional two interconnected fluidized beds system, a novel two-interconnected fluidized bed process has been adopted to 3kW chemical-looping combustor. This system has two bubbling beds, solid injection nozzles, solid conveying lines, and downcomers. In this study, effects of operating variables such as gas velocity through the solid injection nozzle, fluidizing velocity, solid height, geometry of solid intake hole, bed temperature on solid circulation rate have been investigated in a 3kW chemical-looping combustor. The solid circulation rate increased as the solid height and the opening area of solid intake holes increased. The effect of the fluidizing velocity and the bed temperature were negligible. Moreover, long-term operation of continuous solid circulation up to 50 hours has been performed to check feasibility of stable operation. The pressure drop profiles in the bubbling beds and the downcomers were maintained steadily and solid circulation was smooth and stable.

Ignition of a solid fuel by thermal radiation (열복사에 의한 고체연료 점화 연구)

  • Kim, Myeong-Hyo;Baek, Seung-Uk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.3
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    • pp.294-302
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    • 1998
  • Ignition characteristics of a vertical solid fuel plate with block have been investigated experimentally. For low radiant heat flux, ignition does not occur in a vertical solid fuel plate without block. In the case with the block on a vertical fuel plate, however, ignition can occur by increasing the residence time and the time to absorb the incident radiation flux by fuel vapor in gas phase. The ignition occurs below block and the point varies according to the block location and the block height. As the block height increases, the block locates at higher position, and the hot wall temperature increases, the ignition delay time decreases. Also as the initial temperature of fuel plate rises, the ignition delay time of the solid fuel plate decreases. The temperature distribution of solid fuel plate with block is nearly proportional to the radiant heat flux distribution. Therefore, the effect temperature by natural convection heat transfer is of the same order as that of inhibition of temperature increase by pyrolysis.

Numerical Analysis in a 1 kWe SOFC Stack for Variation of the Channel Height in Separators (분리판의 채널 높이에 따른 1 kWe 급 고체산화물 연료전지 스택 수치 해석)

  • YIN, HAOYUAN;KIM, YOUNG JIN;YI, KUNWOO;KIM, HYEON JIN;YUN, KYONG SIK;YU, JI HAENG
    • Journal of Hydrogen and New Energy
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    • v.33 no.5
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    • pp.550-556
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    • 2022
  • In this study, the flow uniformity was analyzed by performing numerical analysis on the 1 kWe internal manifold type solid oxide fuel cell stack according to the channel height of the separator. Also, it was examined by varying the fuel utilization rate and oxygen utilization rate. From the calculation results, we found that as the channel height of the separator decreased, the pressure drop increased exponentially. In addition, it was found that as the channel height of the separator decreased, the gas flow resistance inside the unit cell increased, and the flow resistance increased the pressure drop, thereby improving the flow uniformity inside the stack. Finally, the calculation results showed that as the fuel and oxygen utilization increased, the flow uniformity also improved.

A Study on Two-interconnected Fluidized Beds System for Selective Solid Circulation (선택적 고체순환을 위한 2탑 유동층 시스템 연구)

  • Ryu, Ho-Jung;Jang, Myoung-Su;Kim, Hong-Ki;Lee, Dong-Kyu
    • Korean Chemical Engineering Research
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    • v.47 no.3
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    • pp.337-343
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    • 2009
  • To apply to novel two-interconnected fluidized beds system for selective solid circulation, a solid separator and a solid circulation system were developed. The solid separation rate increased as the gas velocity through the solid injection nozzle, solid height, and diameter of solid injection nozzle increased. However, the effect of the fluidization velocity was negligible. Coarse($212{\sim}300{\mu}m$) and fine($63{\sim}106{\mu}m$) particles were separated using the solid separator and the solid separation rate was ranged from 66 to 453 g/min. The solid circulation rate increased as the gas velocity through the solid injection nozzle, solid height, and the number of solid intake holes increased. However, the effect of the fluidization velocity was negligible. Fine particle was circulated using the solid circulation system and the solid circulation rate was ranged from 65 to 390 g/min. We also proposed two interconnenced fluidized beds system for selective solid circulation equipped with the developed solid separator and the solid circulation system. Long-term operation of continuous solid circulation up to 20 hours has been performed to check feasibility of stable operation. The pressure drop profiles in two beds and the solid separation rate were maintained steadily, and therefore, we could conclude that solid circulation was smooth and stable.

The Effective Factors of n Foam Generation Using Foam Condensate (포말 농축물에 의한 포말 생성의 영향인자)

  • SUH Kuen-Hack;SHIN Jeong-Sik;LEE Ju-Hwa
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.36 no.5
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    • pp.509-514
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    • 2003
  • We performed the experiment to determine the effective factors, such as the initial concentration of protein, pore size of air distributor, SAV (superficial air velocity), pH, salts and temperature related to foaming characteristics. The foam height in a foam generator was increased with the increase of the initial protein concentration and the decrease of pore size. As SAV was increased, the foam height was increased, and the optimum SAV was 0.84 cm/sec. The foam height was highest in the acid region and it was increased with the increase of salt concentration of NaCl and $NaHCO_3.$ The removal efficiencies of TSS (total suspended solid) and turbidity decreased with the increase of the initial protein concentration in the batch foam separator.

Characteristics of Foam Generation in Freshwater and Seawater (담수와 해수에서의 포말 생성 특성)

  • SHIN Jeong-Sik;KIM Byong-Jin;SUH Kuen-Hack
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.37 no.3
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    • pp.179-185
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    • 2004
  • The characteristics of foam generation were assessed for freshwater and seawater using a foam generator. Both in freshwater and seawater, the height of the foam layer increased with initial protein concentrations. The height of the foam layer also increased with pore size of the air distributor. The optimum superficial air velocities (SAV) in freshwater and seawater were 0.84 cm/sec and 0.6 cm/sec, respectively. The height of the foam layer was the highest in pH 3 in freshwater and in the region of pH 5-7 in seawater. The height of the foam layer increased with $NaHCO_3$ concentration in freshwater, and $NaHCO_3$ concentration had little effect in seawater. Removal efficiencies of total suspended solid (TSS) and turbidity decreased with an increase of initial protein concentrations in a batch foam separator both in freshwater and seawater.

A Study on the Effect of Pin Height on Weld Strength in Extru-Rivet Spot Welding of Aluminum Plates (알루미늄 판재의 전기저항가열 압출점접합공정에 있어서 핀의 높이가 접합강도에 미치는 영향에 관한 연구)

  • Lee, S.J.;Kim, T.H.;Jin, I.T.
    • Transactions of Materials Processing
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    • v.23 no.5
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    • pp.282-288
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    • 2014
  • It is difficult to control welding variables during spot welding of non-ferrous metals like aluminum because of the low electrical resistance of the material. It has been suggested that a solid state welding process such as friction stir spot welding or extru-spot welding can be used to spot weld aluminum plates. In the extru-spot welding, there is a need to increase the weld strength by improving the shape of the welding die. The current study shows that the weld strength for an extru-spot welding can be increased by using a pin placed on the inside of the upper electrode in the welding die. In the current study, the deformed shape of the insert rivet and the stress distribution in the welding zone were analyzed by simulation. Extru-rivet spot welding experiments were performed by changing the height of pin on the inside of the upper electrode. From the experimental result, it is shown that the weld strength for an extru-rivet spot welding can be increased by adjusting the height of the pin. The optimal shape of the deformed rivet after the extru-rivet spot welding can be observed from the simulation results. The deformed shape of the insert rivet can also be controlled by the height of pin.

Mucoadhesion, Swelling and Drug Release Characteristics of Hydroxypropylcellulose/Carbopol Solid Dispersions (히드록시프로필셀룰로오스/카르보폴 고체분산체의 점막부착성과 팽윤 및 약물방출특성)

  • Kim, Sang-Heon;Yang, Su-Geun;Shin, Dong-Sun;Lee, Min-Suk;Choi, Young-Wook
    • Journal of Pharmaceutical Investigation
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    • v.24 no.3
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    • pp.155-165
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    • 1994
  • Some mucoadhesive polymers such as hydroxypropylcelluose (HPC) and carbopol-934 (CP) have been employed for the preparation of mucoadhesive polymeric systems, and their physical properties including mucoadhesion, swelling, and drug release were evaluated. A new simple experimental technique that can quantitatively measure the bioadhesive properties of various polymeric systems has been developed by the methods of detachment force test. As the polymeric systems, the discs of freeze-dried HPC/CP solid dispersions were prepared. The mucosa used in these tests were upper, middle, and lower parts of small intestine of male rats weighing $300{\sim}350\;g$. Detachment forces were increased as the mole fraction of CP increased in discs of HPC/CP solid dispersions. In the points of intestinal site dependence of mucoadhesion, the solid dispersions revealed non-specific mucoadhesion to the intestine. Swelling and drug release characteristics of mucoadhesive polymeric systems were studied extensively to find out the feasibility for the oral controlled delivery systems. Swelling ratio, expressed as the final height/initial height, has been determined in various pH buffer solutions. Hydrochlorothiazide (HCT) was employed as a model drug for release study. Apparent swelling and drug release rate constants, $K_s$ and $K_r$ respectively, were obtained from the square-root time plot of either swelling ratio or released amount of drug, particularly for the time periods before reaching the equilibrium. As a result, the swelling ratio of HPC/CP solid dispersions was increased as the weight percentage of CP increased. Similarly, the release of HCT from the solid dispersions was dependent on pH changes and CP contents, resulted in the slower release of HCT with the increases of pH and CP contents.

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Effect of Lower Bed Height on Collapse Velocity in the Two-Stage Bubbling Fluidized-Bed with a Standpipe for Solid Transport (고체 수송관이 있는 2 단 기포 유동층에서 붕괴 속도에 대한 하단 층 높이의 영향)

  • Khurram, Muhammad Shahzad;Choi, Jeong-Hoo
    • Korean Chemical Engineering Research
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    • v.56 no.6
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    • pp.864-870
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    • 2018
  • The effect of lower bed height on the collapse velocity was investigated for a two-stage bubbling fluidizedbed (0.1 m in diameter, 1.2 m high) connected with a standpipe (0.025 m in diameter) for solid transport. Air was used as fluidizing gas and mixture of coarse (< $1000{\mu}m$ in diameter and $3625kg/m^3$ in apparent density) and fine (< $147{\mu}m$ in diameter and $4079kg/m^3$ in apparent density) particles as solid particles. Mixing ratio of fine particles, height of the lower bed and the distributor of the upper bed were considered as experimental variables. The collapse velocity increased with static height of the lower bed. However, the effect decreased as the mixing ratio of fine particles increased. The effect seemed to be attributed to the increase in height of the dense layer of coarse particles that prevented the gas from flowing into the standpipe, not in pressure drop for the standpipe, as the bed height increased. The collapse velocity decreased a little as the pressure drop of the distributor of the upper bed increased. An improved correlation was proposed for predicting the collapse velocity.