• 한국유변학회:학술대회논문집
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• 한국유변학회 2006년도 춘계 학술발표회 논문집
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• pp.81-84
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• 2006

Slot coating process, in continuous and patch modes, has been applied for the many precise coating products, e.g., flat panel displays and second batteries. However, manufacturing uniform coating products is not a trivial task at high-speed operations because various flow instabilities or defects such as leaking, bubbles, ribbing, and rivulets are frequently observed in this process. It is no wonder, therefore, that many efforts to understand the various aspects of dynamics and coating windows of this process have been made both in academia and industry. In this study, as the first topic, flow dynamics within the coating bead in slot coating process has been investigated using the one-dimensional viscocapillary model by lubrication approximation and two-dimensional model by Flow-3D software. Especially, operability windows in both 1D and 2D cases with various slot die lip designs have been successfully portrayed. Also, effects of process conditions like viscosity and coating gap size on slot coating window have been analyzed. Also, some experiments to find minimum coating thickness and coating windows have been conducted using slot die coater implemented with flow visualization device, corroborating the numerical results. As the second topic, flow dynamics of both Newtonian and Non-Newtonian fluids in patch or pattern slot coating process, which is employed in manufacturing IT products such as secondary batteries, has been investigated for the purpose of optimal process designs. As a matter of fact, the flow control in this system is more difficult than in continuous case because od its transient or time-dependent nature. The internal die and die lip designs for patterned uniform coating products have been obtained by controlling flow behaviors of coating liquids issuing from slot. Numerical simulations have been performed using Fluent and Flow-3D packages. Flow behavior and pressure distribution inside the slot die has been compared with various die internal shapes and geometries. In the coating bead region, efforts to reduce irregular coating defects in head and tail parts of one patterned coating unit have been tried by changing die lip shapes. It has been concluded that optimal die internal design gas been developed, guaranteeing uniform velocity distribution of both Newtonian and shear thinning fluids at the die exit. And also optimal die lip design has been established, providing the longer uniform coating layer thickness within one coating unit.

• 한국응용과학기술학회지
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• 제35권4호
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• pp.985-994
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• 2018

바이오중유란 다양한 동 식물성 유지, 지방산 메틸에스테르, 지방산 에틸에스테르 및 그 부산물을 혼합하여 제조된 제품이며, 국내 기력 중유발전기의 연료(B-C)로 사용되고 있다. 그러나 이러한 바이오중유의 원료 조성 때문에 발전기의 보일러로 이송되는 연료펌프, 유량펌프, 인젝터 등의 연료 공급시스템에서 마찰마모를 유발할 경우 심각한 피해를 초래 할 수 있다. 따라서, 본 연구에서는 발전용 바이오중유의 다양한 원료들의 연료특성과 이에 따른 윤활성을 평가하고, 발전기의 마찰마모 저감을 위한 발전용 바이오중유의 연료 구성 방안을 제시하였다. 발전용 바이오중유 원료물질의 윤활성(HFRR)은 평균 $137{\mu}m$이며, 원료물질에 따라 차이가 있으나 $60{\mu}m{\sim}214{\mu}m$ 분포를 보이고 있다. 이 중 윤활성이 좋은 순서는 Oleo pitch > BD pitch > CNSL > Animal fat > RBDPO > PAO > Dark oil > Food waste oil이다. 발전용 바이오중유의 원료 물질 3종으로 구성된 바이오중유 평가시료 5종에 대한 윤활성은 평균 $151{\mu}m$이며, $101{\mu}m{\sim}185{\mu}m$ 분포를 보이고 있다. 이 중 윤활성이 좋은 순서는 Fuel 1 > Fuel 3 > Fuel 4 > Fuel 2 > Fuel 5이다. 바이오중유 평가시료(평균 $151{\mu}m$)는 C중유($128{\mu}m$) 대비 낮은 윤활성을 나타내었다. 이는 발전용 바이오중유가 지방산 물질로 구성되어 있어 C중유보다 파라핀, 방향족 성분 함량이 낮아 점도가 낮고, 산가가 높기 때문에 산성 성분에 의한 윤활막 형성 저해에 따른 것으로 판단된다. 따라서, 적정 수준의 마찰마모 저감을 위해 윤활성을 증가 시킬 수 있는 바이오중유의 원료로서 Oleo pitch, BD pitch를 60% 이상 함유할 경우 연료 제조 시 윤활성 증가가 예상된다.