• Title/Summary/Keyword: Vapor injection

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Macroscopic Characteristics of Evaporating Dimethyl Ether(DME) Spray (Dimethyl Ether(DME)의 증발과 거시적 분무 특성)

  • Yu, Jun;Lee, Ju-Kwang;Bae, Choong-Sik
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.3
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    • pp.58-64
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    • 2003
  • Dimethyl Ether(DME) has been considered as one of the most attractive alternative fuels for compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the physical properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-hole sac type injector was performed in a constant volume vessel pressurized by nitrogen gas. Spray cone angles and penetrations of the DME spray were characterized and compared with those of diesel. For evaluation of the evaporating characteristics of the DME, shadowgraphy technique employing an Ar-ion laser and an ICCD camera was adopted. Tip of the DME spray was formed in mushroom-like shape at atmospheric chamber pressure, which disappeared in higher chamber pressure. Spray tip penetration and spray cone angle of the DME became similar to those of diesel under 3MPa of chamber pressure. Higher injection pressure provided wider vapor phase area while it decreased with higher chamber pressure condition.

Electrical Characteristics of Organic Light Emitting Diodes (OLED) using the Alkali Metal Complex as New Electron Injection Layers (알칼리 금속 전자 주입층을 사용한 유기 전기 발광 소자 (OLED)의 전기적 특성)

  • Lee, Hyun-Koo;Kim, Jun-Ho;Kim, Young-Kwan
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07b
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    • pp.1015-1018
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    • 2004
  • We investigate the influence of the New Electron Injection Layers (EIL) on the performance of the Alkali Metal Complex vapor-deposited Organic Light Emitting Diodes(OLED). Two different Alkali Metal Complex were used; Lithium Quinolate (Liq), and Sodium Quinolate (Naq). In all cases, $Alq_3$ was the Electron Transporting Layer (ETL). We measure and compare the current density-voltage (J-V) and luminance-voltage (L-V) characteristics. We concluded that the turn-on voltage, and luminance efficiency are controlled by the type of EIL material used. We show the longer life-time OLED with Alkali Metal Complex EIL than OLED with LiF EIL. And we show the Optimized Alkali Metal Complex thickness is 3nm. Existent LiF to because is inorganic material, there is trouble to do epitaxy into thin layers but regulates the thickness in case of Alkali Metal Complex matter characteristic that is easy be. Alkali Metal Complex also appeared by sensitive thing in thickness than LiF If utilize this material, It is thought much advantages may be at common use of OLED.

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Evaporation Rate of Lead in Molten Copper Alloy by Gas Injection (가스취입에 의한 용융 동 합금 중 납의 증발속도)

  • Kim, Hang-Su;Jeong, Seong-Yeop;Jeong, U-Gwang;Yun, Ui-Han;Son, Ho-Sang
    • Korean Journal of Materials Research
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    • v.12 no.1
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    • pp.68-74
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    • 2002
  • The lead has to be removed for the recycling of copper alloy. The lead cannot be removed from the copper alloy by oxidation. It can be removed by the evaporation because of its high vapor pressure. However, rare information is found on removal of lead from copper alloy. The purpose of present work is to provide a fundamental knowledges on the removal of lead from the copper alloy by evaporation. Gas injection was made in molten copper alloy, and the evaporation rate of lead was measured. The influence of Ar gas flow rata(2~4 L/min), initial contents of lead(2~4wt%Pb), temperature(1200~140$0^{\circ}C$) was investigated based on the thermodynamic and the kinetics. The rate constant is increased with increasing flow rate of Ar and temperature. Though amount of lead removed is increased with higher initial lead concentration, the rate constant is not changed significantly. The activation energy is estimated from the temperature dependence of the rate constant. Also removal of lead from the copper by adding chloride was made for the comparison.

High functional surface treatments for rapid heating of plastic injection mold (급속가열용 플라스틱 사출금형을 위한 고기능성 표면처리)

  • Park, Hyun-Jun;Cho, Kyun-Taek;Moon, Kyoung-Il;Kim, Tae-Bum;Kim, Sang-Sub
    • Design & Manufacturing
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    • v.15 no.3
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    • pp.7-12
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    • 2021
  • Plastic injection molds used for rapid heating and cooling must minimize surface damage due to friction and maintain excellent thermal and low electrical conductivity. Accordingly, various surface treatments are being applied. The properties of Al2O3 coating and DLC coating were compared to find the optimal surface treatment method. Al2O3 coating was deposited by thermal spray method. DLC films were deposited by sputtering process in room temperature and high temperature PECVD (Plasma enhanced chemical vapor deposition) process in 723 K temperature. For the evaluation of physical properties, the electrical and thermal conductivity including surface hardness, adhesion and wear resistance were analyzed. The electrical resistance of the all coated samples was showed insulation properties of 24 MΩ/sq or more. Especially, the friction coefficient of high temp. DLC coating was the lowest at 0.134.

The Effective Evaluation of Soil Remediation Technology by Gas Phase Concentration Trend (가스상 물질의 농도변화를 이용한 오염토양 복원의 타당성 평가)

  • Park, Duck-Shin;Jung, Woo-Sung;Kang, Sun-Ki;Kim, Moo-Hoon
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.7
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    • pp.1233-1241
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    • 2000
  • The purpose of this study is to see the remediability and pilot system operating condition on diesel contaminated areas. Air permeability(k) and trend of gas phase ($O_2/CO_2/VOCs$) concentration to determine the remediation rate of the contaminated sites are very important. So we tested air permeability and trend of gas phase concentration. Throughout soil vapor extraction(SVE) and bioventing hybrid pilot test on different conditions, the range of air permeability(k) was 1985~1194 darcy. The tests result in soil vapor extraction and bioventing hybrid system was appropriate on this test sites, and the suitable injection air flow rate was $3.5m^3/hr$.

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Deposition mechanism of $Bi_4Ti_3O_{12}$ films on Si by MOCVD and property improvement by pulse injection method (MOCVD $Bi_4Ti_3O_{12}$ 박막의 실리콘 위에서의 증착기구 및 유기 금속원료의 펄스주입법에 의한 박막 특성 개선)

  • 이석규;김준형;최두현;황민욱;엄명윤;김윤해;김진용;김형준
    • Journal of the Korean Vacuum Society
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    • v.9 no.4
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    • pp.373-378
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    • 2000
  • There was a great difference in the formation kinetics of $TiO_2$ and $Bi_2O_3$ on silicon, but the growth of bismuth titanate (BIT) thin film was mainly limited by the formation of $TiO_2$. As a result, the BIT film was easy to be lack of bismuth. The pulse injection metalorganic chemical vapor deposition (MOCVD) process was introduced in order to overcome this problem by recovering the insufficient bismuth content in the film. By this pulse injection method, bismuth content was increased and also the uniform in-depth composition of the film was attained with a abrupt $Bi_4Ti_3O_{12}/Si$ interface. In addition, the crystallinity of $Bi_4Ti_3O_{12}$ thin film prepared by pulse injection process was greatly improved and the leakage current density was lowered by 1/2~1/3 of magnitude. Clockwise hysteresis of C-V was observed and the ferroelectric switching was confirmed for $Bi_4Ti_3O_{12}$ film deposited by pulse injection method.

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Comparison of Macroscopic Spray Characteristics of Dimethyl Ether with Diesel (Dimethyl Ether와 디젤의 거시적 분무 특성 비교)

  • Yu, J.;Lee, J. K.;Bae, C. S.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.5
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    • pp.73-80
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    • 2002
  • Dimethyl ether (DM) is one of the most attractive alternative fuel far compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-holes sac type injector (hole diameter 0.168 ㎜/hole) was performed in a high pressure chamber pressurized with nitrogen gas. A CCD camera was employed to capture time series of spray images followed by spray cone angles and penetrations of DME were characterized and compared with those of diesel. Under atmospheric pressure condition, regardless of injection pressure, spray cone angles of the DME were wider than those of diesel and penetrations were shorter due to flash boiling effect. Tip of the DME spray was farmed in mushroom like shape at atmospheric chamber pressure but it was disappeared in higher chamber pressure. On the contrary, spray characteristics of the DME became similar to that of diesel under 3MPa of chamber pressure. Hole-to-hole variation of the DME spray was lower than that of diesel in both atmospheric and 3MPa chamber pressures. At 25MPa and 40MPa of DME injection pressures, regardless of chamber pressure, intermittent DME spray was observed. It was thought that vapor lock inside the injector was generated under the two injection pressures.

Heating Performance Characteristics of Heat Pump with VI cycle using Re-Heater and Solar-Assisted (태양열과 재열기를 사용한 VI heat pump의 성능 특성에 관한 연구)

  • Lee, Jin-Kook;Choi, Kwang-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.35 no.6
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    • pp.25-33
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    • 2015
  • In this study, heating performance of the air-cooled heat pump with vapor-injection (VI) cycles, re-heater and solar heat storage tank was investigated experimentally. Devices used in the experiment were comprised of a VI compressor, re-heater, economizer, variable evaporator, flat-plate solar collector for hot water, thermal storage tank, etc. As working fluid, refrigerant R410A for heat pump and propylene glycol (PG) for solar collector were used. In this experiment, heating performance was compared by three cycles, A, B and C. In case of Cycle B, heat exchange was conducted between VI suction refrigerant and inlet refrigerant of condenser by re-heater (Re-heater in Fig. 3, No. 3) (Cycle B), and Cycle A was not use re-heater on the same operating conditions. In case of Cycle C, outlet refrigerant from evaporator go to thermal storage tank for getting a thermal energy from solar thermal storage tank while re-heater also used. As a result, Cycle C reached the target temperature of water in a shorter time than Cycle B and Cycle A. In addition, it was founded that, as for the coefficient of heating performance($COP_h$), the performance in Cycle C was improved by 13.6% higher than the performance of Cycle B shown the average $COP_h$ of 3.0 and by 18.9% higher than the performance of Cycle A shown the average $COP_h$ of 2.86. From this results, It was confirmed that the performance of heat pump system with refrigerant re-heater and VI cycle can be improved by applying solar thermal energy as an auxiliary heat source.

A Study on the Characteristics of Heating Performance of High-Performance Heat Pump with VI cycle using Re-Heater (재열기를 사용한 고성능 VI 사이클 열펌프의 난방 성능 특성에 관한 연구)

  • Lee, Jin-Kook;Choi, Kwang-Hwan
    • Journal of Power System Engineering
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    • v.19 no.4
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    • pp.69-75
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    • 2015
  • In this study, the characteristics of heating performance of a high-performance air-cooled heat pump with vapor-injection(VI) cycle using re-heater was investigated experimentally. Devices used in the experiment is consist of a VI compressor, condenser, oil separator, refrigerant (economizer outlet refrigerant) re-heater, economizer, evaporator. And R410A was used as a working fluid. The experiment was conducted with two cycles(cycles A and B) for investigating heating performance. In case of cycle B, heat exchange was conducted by re-heater between outlet refrigerant of compressor and suction refrigerant of the VI system(Fig.1, re-heater). But the re-heater was not used in case of cycle A. As a result of this experiment, discharge temperature of refrigerator in compressor was shown higher value, when the cycle B was conducted, because of the heat exchange between suction refrigerant of VI cycle and outlet refrigerant of compressor in the re-heater than cycle A that was not use re-heater. it means that liquid hammer and the decrement of heating performance can be decreased by using re-heater. Also, Heating coefficient of performance(COPh) was shown about 2.98 in Cycle B which was 4% higher than Cycle A and from these results, It was confirmed that the improvement of the heating performance of heat pump with VI cycle can be achieved by applying re-heater.

Quantitative Approaches for the Determination of Volatile Organic Compounds (VOC) and Its Performance Assessment in Terms of Solvent Types and the Related Matrix Effects

  • Ullah, Md. Ahsan;Kim, Ki-Hyun;Szulejko, Jan E.;Choi, Dal Woong
    • Asian Journal of Atmospheric Environment
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    • v.11 no.1
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    • pp.1-14
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    • 2017
  • For the quantitative analysis of volatile organic compounds (VOC), the use of a proper solvent is crucial to reduce the chance of biased results or effect of interference either in direct analysis by a gas chromatograph (GC) or with thermal desorption analysis due to matrix effects, e.g., the existence of a broad solvent peak tailing that overlaps early eluters. In this work, the relative performance of different solvents has been evaluated using standards containing 19 VOCs in three different solvents (methanol, pentane, and hexane). Comparison of the response factor of the detected VOCs confirms their means for methanol and hexane higher than that of pentane by 84% and 27%, respectively. In light of the solvent vapor pressure at the initial GC column temperature ($35^{\circ}C$), the enhanced sensitivity in methanol suggests the potential role of solvent vapor expansion in the hot injector (split ON) which leads to solvent trapping on the column. In contrast, if the recurrent relationships between homologues were evaluated using an effective carbon number (ECN) additivity approach, the comparability assessed in terms of percent difference improved on the order of methanol (26.5%), hexane (6.73%), and pentane (5.24%). As such, the relative performance of GC can be affected considerably in the direct injection-based analysis of VOC due to the selection of solvent.