• Title/Summary/Keyword: Heat & Mass Transfer

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Simulation of Rough Rice Drying by Natural Air(I) (자연공기(自然空氣)에 의한 벼건조(乾燥) 시뮤레이션(I))

  • Chang, D.I.;Chung, D.S.;Pfost, H.B.;Calderwood, D.L.
    • Korean Journal of Agricultural Science
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    • v.10 no.1
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    • pp.118-128
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    • 1983
  • Simulation model of natural air grain drying was discussed and modified to predict the changes of grain moisture content and dry matter loss of rough rice drying. The modified simulation model was then validated using actual test data. A series of simulated drying tests using official weather data for 15 years from Beaumont, Texas, was taken to make minimum airflow rate and maximum bed depth of rough rice drying by natural air, under different conditions of initial moisture content of rough rice, airflow rate and harvest date.

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A Reaction Kinetic for Selective Catalytic Reduction of NOx with NH3 over Manganese Oxide (NMO, MnO2, Mn2O3) at Low Temperature (망간산화물(NMO, MnO2, Mn2O3)을 이용한 저온에서의 NH3-SCR의 반응속도 연구)

  • Kim, Min Su;Hong, Sung Chang
    • Clean Technology
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    • v.24 no.4
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    • pp.307-314
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    • 2018
  • In this study, NMO (Natural Manganese Ore), $MnO_2$, and $Mn_2O_3$ catalysts were used in the selective catalytic reduction process to remove nitrogen oxides (NOx) using $NH_3$ as a reducing agent at low temperatures in the presence of oxygen. In the case of the NMO (Natural Manganese Ore), it was confirmed that the conversion of nitrogen oxides in the stability test did not change even after 100 hours at 423 K. The Kinetics experiments were carried out within the range where heat and mass transfer were not factors. From a steady-state Kinetics study, it was found that the low-temperature SCR reaction was zero order with the respect to $NH_3$ and 0.41 ~ 0.57 order with the respect to NO and 0.13 ~ 0.26 order with the respect to $O_2$. As temperature increases, the reaction order decreases as a result of $NH_3$ and oxygen concentration. It was confirmed that the reaction between the $NH_3$ dissociated and adsorbedon the catalyst surface and the gaseous nitrogen monoxide (E-R model) and the reaction with the adsorbed nitrogen monoxide (L-H model) occur.

Study on the Storage of Chestnut (밤 저장(貯藏)에 관(關)한 연구(硏究))

  • Yim, Ho;Kim, Choung-Ok;Shin, Dang-Wha;Suh, Kee- Bong
    • Korean Journal of Food Science and Technology
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    • v.12 no.3
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    • pp.170-175
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    • 1980
  • A mass production of chestnut necessiates the development of economic long-term storage method. The main objective of this study was to confirm the technical aspect of the chestnut storage method which was developed by two year project and to review the method of commercial application. The chestnut used for the experiments were separated in brine $(5.5{\sim}6.0^{\circ}\:B{\acute{a}}ume)$ into matured and unmatured lots and fumigated with $CS_2$ at a 5 $lb/27\;m^3$ level for $25{\sim}30\;hrs.$ The chestnuts were packed in wooden boxes with sawdust (50% moisture) in the ratio of 1 : 1 by volume. The boxes were stored in the cold room $(1{\pm}1^{\circ}C,\;85{\sim}95%\;RH)$ and the cellar ($0{\sim}10^{\circ}C$, controlled only by circulating night cool air). The results obtained were as follows: 1. Fully matured chestnut could be successfully preserved $8{\sim}9\;months$ at a l0% decay level in the cold room and $4{\sim}5\;months$ months in cellar. 2. Immatured chestnuts wire inferior to the matured in storage stability. At the maximum storage period, its storage life was two months shorter. 3. The heat transfer equation of piled chestnuts with sawdust can be suggested as $T_{\infty}-T_0=(T_{\infty}-T_0){\cdot}10^{-t/320}$ and j and $f_h$ values were 1 and 320 min, respectively. 4. The chestnuts in the package of storage unit had longer shelf life than naked chestnut during the retail distribution at ambient temperature.

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