• Title/Summary/Keyword: Constant pressure mixing

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Liquefaction Characteristics of Polypropylene-Polystyrene Mixture by Pyrolysis at Low Temperature (Polypropylene-Polystyrene 혼합물의 저온 열분해에 의한 액화특성)

  • Cho, Sung-Hyun;Kim, Chi-Hoi;Kim, Su-Ho;Lee, Bong-Hee
    • Clean Technology
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    • v.16 no.1
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    • pp.26-32
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    • 2010
  • The low temperature pyrolysis of polypropylene (PP), polystyrene (PS) and polypropylene-polystyrene (PP-PS) mixture in a batch reactor at the atmospheric pressure and $450^{\circ}C$ was conducted to investigate the synergy effect of PP-PS mixture on the yield of pyrolytic oil. The pyrolysis time was varied from 20 to 80 mins. The products formed during pyrolysis were classified into gas, gasoline, kerosene, gas oil and heavy oil according to the petroleum product quality standard of Ministry of Knowledge Economy. The analysis of the product oils by GC/MS(Gas chromatography/Mass spectrometry) showed that new components were not detected by mixing of PP and PS. There was no synergy effect according to the mixing of PP and PS. Conversions and yields of PP-PS mixtures were linearly dependent on the mixing ratio of samples except for heavy oil yields. Heavy oil yields showed almost constant regardless of the mixing ratio.

The study of turbulent flow structures in a wavy channel using direct numerical simulation (직접수치모사를 통한 Wavy Channel 내의 난류 유동 구조의 연구)

  • Lee, Dae-Sung;Ha, Man-Yeong;Yoon, Hyun-Sik;Chun, Ho-Hwan;Jeon, Chung-Hwan
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1807-1812
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    • 2004
  • Sinusoidal wavy channel is one of the most commonly used devices in the industry for achieving mixing and heat transfer. Here we report on results obtained from the DNS of flow inside the wavy channel performed using the finite volume technique. As a primary stage to obtain the optimal design for heat transfer and mixing, this study observed the basic flow structures in a wavy channel. The mass flow rate is kept constant with friction Reynolds number of $Re_{\tau}$ = 140 . Time- and space-averaged and instantaneous flow fields are illustrated to observe the flow structures. Although the direct comparison of results between turbulent wavy and flat channel is somehow difficult due to the different flow phenomena derived from different configuration, here the mean streamwise velocity and RMS of velocities at same $Re_{\tau}$ of two different channels are compared. The basic difference between wavy and flat channel flow is the existence of small scale wall vortices along the walls in a wavy channel. These vortices make flow more complex, which will accompany the increase of heat transfer, pressure drop and drag.

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Evaluation of Piezoelectric Properties in Pb(Zr1Ti)O3-PVDF Composites for Thick Film Speaker Application (후막 스피커 응용을 위한 Pb(Zr1Ti)O3-PVDF 복합체의 압전 특성 평가)

  • Son Yong-Ho;Kim Sung-Jin;Kim Young-Min;Jeong Joon-Seok;Ryu Sung-Lim;Kweon Soon-Yong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.10
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    • pp.966-970
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    • 2006
  • We reported on characteristics of the piezoelectric ceramic-polymer composite for the application of the thick-film speaker. The PVDF-PZT composites were fabricated to incorporate the advantages of both ceramic and polymer with various mixing ratios by 3-roll mill mixer. The composite solutions were coated by the conventional screen-printing method on ITO electrode coated PET (Polyethylene terephthalate) polymer film. After depositing the top-electrode of silver-paste, 4 kV/mm of DC field was applied at $120^{\circ}C$ for 30 min to poling the composite films. The value of $d_{33}$ (piezoelectric charge constant) was increased when the PZT weight percent was increased. The maximum value of the $d_{33}$ was 24 pC/N at 70 wt% PZT. But the $g{33}$ (piezoelectric voltage constant) showed the maximum value of $32mV{\cdot}m/N$ at 65 wt% of PZT powder. The SPL (sound pressure level) of the speaker fabricated with the 65:35 composite film was about 68 dB at 1 kHz.

Comparative Analysis of Resources Characteristics for Deep Ocean water and Brine Groundwater (해양심층수와 지하염수의 자원특성 비교분석)

  • Mun, Deok-Su;Jeong, Dong-Ho;Kim, Hyeon-Ju
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.10a
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    • pp.333-335
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    • 2003
  • Deep Ocean Water is formed within restricted area including polar sea (high latitude) by cooling of surface seawater and globally circulated in the state of insolation with surface seawater. Although not as obvious as estuaries mixing, Brine groundwater is mixture of recirculated seawater and groundwater. Seawater having high osmotic pressure infiltrate into unconfined aquifer where is connected to the sea. The ions dissolved in seawater are present in constant proportions to each other and to the total salt content of seawater. However deviation in ion proportions have been observed in some brine groundwater. Some causes of these exception to the Rule of constant proportions are due to many chemical reactions between periphery soil and groundwater. While Deep Ocean Water (DOW) have a large quantity of functional trace metals and biological affinity relative to brine groundwater, DOW have relatively small amount of harmful bacteria and artificial pollutants.

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Accuracy and applicable range of a reconstruction technique for hybrid rockets

  • Nagata, Harunori;Nakayama, Hisahiro;Watanabe, Mikio;Wakita, Masashi;Totani, Tsuyoshi
    • Advances in aircraft and spacecraft science
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    • v.1 no.3
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    • pp.273-289
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    • 2014
  • Accuracy of a reconstruction technique assuming a constant characteristic exhaust velocity ($c^*$) efficiency for reducing hybrid rocket firing test data was examined experimentally. To avoid the difficulty arising from a number of complex chemical equilibrium calculations, a simple approximate expression of theoretical $c^*$ as a function of the oxidizer to fuel ratio (${\xi}$) and the chamber pressure was developed. A series of static firing tests with the same test conditions except burning duration revealed that the error in the calculated fuel consumption decreases with increasing firing duration, showing that the error mainly comes from the ignition and shutdown transients. The present reconstruction technique obtains ${\xi}$ by solving an equation between theoretical and experimental $c^*$ values. A difficulty arises when multiple solutions of ${\xi}$ exists. In the PMMA-LOX combination, a ${\xi}$ range of 0.6 to 1.0 corresponds to this case. The definition of $c^*$ efficiency necessary to be used in this reconstruction technique is different from a $c^*$ efficiency obtained by a general method. Because the $c^*$ efficiency obtained by average chamber pressure and ${\xi}$ includes the $c^*$ loss due to the ${\xi}$ shift, it can be below unity even when the combustion gas keeps complete mixing and chemical equilibrium during the entire period of a firing. Therefore, the $c^*$ efficiency obtained in the present reconstruction technique is superior to the $c^*$ efficiency obtained by the general method to evaluate the degree of completion of the mixing and chemical reaction in the combustion chamber.

Estimate Minimum Amount of Methane for Explosion in a Confined Space (밀폐공간에서 메탄 폭발사고의 최소 가스누출량 예측)

  • Jo, Young-Do
    • Journal of the Korean Institute of Gas
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    • v.21 no.4
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    • pp.1-5
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    • 2017
  • Leaking of natural gas, which is mostly methane, in a confined living space creates flammable atmosphere and gives rise to explosion accident. The minimum amount of leaked methane for explosion is highly dependent on the degree of mixing in the confined space. This paper proposes a method for estimating minimum amount of flammable gas for explosion by using Gaussian distribution explosion model(GDEM) and experimental explosion data. The explosion pressure in the confined space can be estimated by assuming the Gaussian distribution of flammable gas along the height of an enclosure and estimating the maximum amount of gas within flammable limits, combustion of the estimated gas with constant volume and adiabatic or isothermal mixing in the confined space. The predicted minimum gas amount for an explosion is tied to explosion pressure that results in a given building damage level. The result shows that very small amount of methane leaking in the confined space may results in a serious gas explosion accident. This result could be applied not only to setting the leak criteria for developing a gas safety appliance but also to accident investigating of explosion.

A Study on the Thermal Characteristics of the Low Temperature Vacuum Dryer by the Vacuum Chamber Temperature (진공실 온도에 의한 저온진공건조기의 열적 특성에 관한 연구)

  • Choe, S.Y.
    • Journal of Power System Engineering
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    • v.14 no.4
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    • pp.23-28
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    • 2010
  • Of the roughly four million known substances, about 60,000 are processed and sold ; many of these must be dried. Many materials are processed in the liquid state - ideal for mixing and reacting - but most products are needed or wanted as dry, or relatively dry, solids. Usually operation is just below atmospheric pressure, as with direct dryers, but some are built for vacuum operation with pressures as low as 26.66kPa abs.. In spite of the global-class aquiculture agriculture and fisheries technology of our country, the processing technologies are lags behind the other nations relatively. These problems are considered to be caused directly by the lack of drying technologies. This paper is concerned to the experimental results of drying heat transfer characteristics for the green energy type vacuum dryer for the high quality agriculture and fisheries production.

Ion Permeability, Dehydration and Relaxation Times of Hydrated Ions Through Membranes (반투막을 통한 수화된 이온의 투과속도 탈수화율 및 완화시간에 관한 연구)

  • Kim Mu Shik;Lee Hai Bang;Kim Sung Wan;Joseph D. Andrade
    • Journal of the Korean Chemical Society
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    • v.20 no.6
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    • pp.448-452
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    • 1976
  • A simplified statistical mechanical method was developed for the calculation of the dehydration fraction, activation free energy of dehydration, and the relaxation times of hydrated ions. The model used includes the equilibrium constant between hydrated and dehydrated water, a water-ion interaction potential energy term, and a mixing factor for the species present. The agreement between theory and experiment is good. The pressure dependence of ion dehydration is also discussed.

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Effects of DME Additives on Combustion Characteristics and Nano-particle Distributions in a Single Cylinder Compression Ignition Engine (DME 연료에 첨가제를 혼합하였을 때의 연소 특성 및 배출가스 특성에 관한 연구)

  • Kwon, Seok-Joo;Cha, June-Pyo;Kang, Min-Gu;Lee, Chang-Sik;Park, Sung-Wook;Lim, Young-Kwan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.20 no.5
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    • pp.19-25
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    • 2012
  • This study describes effects of DME additives on combustion and exhaust emissions characteristics including nano-particle in a single cylinder compression ignition engine. Considered additives include bio-diesel, n-butanol, and MTBE for increasing kinematic viscosity. Among three additives, n-butanol showed the greatest kinematic viscosity. In addition MTBE showed the highest vapor pressure. In the present study mixing ratios of additives were kept constant at 1 and 10% by volume. Experiments were performed at 1200rpm engine speed and nano-particles were measured by SMPS (Scanning mobility particle sizer) devices. Results of combustion characteristics showed that considered additives had little effects on combustion pressure. However, patterns of heat release rate were dependent on properties of additives. Nano-particles of MTBE were the lowest among considered additives.

Thermally Stratified Hot Water Storage (태양열의 성층축열과 주택이용에 관한 연구(성층축열))

  • Pak, Ee-Tong
    • Solar Energy
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    • v.10 no.3
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    • pp.3-12
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    • 1990
  • This paper deals with experimental research to increase thermal storage efficiency of hot water stored in an actual storage tank for solar application. The effect of increased energy input rate due to stratification has been discussed and illustrated through experimental data, which was taken by changing dynamic and geometric parameters. Ranges of the parameters were defined for flow rate, the ratio of diameter to height of the tank and inlet-exit water temperature difference. During the heat storage, when the flow was lower, the temperature difference was larger and the ratio of diameter to height of the tank was higher, the momentum exchange decreased. As for this experiment, when the flow rate was 8 liter/min, the temperature difference was $30^{\circ}C$ and the ratio of diameter to height of the tank was 3, the momentum exchange was minimized resulting in a good thermocline and a stable stratification. In the case of using inlet ports, if the modified Richardson number was less than 0.004, full mixing occured and so unstable stratification occured, which mean that this could not be recommended as storage through thermal stratification. Using a distributor was better than using inlet ports to form a sharp thermocline and to enhance the stratification. It was possible to get storage efficiency of 95% by using the distributor, which was higher than a storage efficiency of 85% obtained by using inlet ports in same operation condition. Furthermore, if the distributor was manufactured so that the mainpipe decreases in diameter toward the dead end to maintain constant static pressure, it might be predicted that further stable stratification and higher storage efficiency are obtainable(ie:more than 95%).

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