• 한국수소및신에너지학회논문집
• /
• 제31권1호
• /
• pp.105-111
• /
• 2020

The organic Rankine cycle (ORC) and the Kalina cycle system (KCS) are being considered as the most feasible and promising ways to recover the low-grade finite heat sources. This paper presents a comparative exergetical performance analysis for ORC and Kalina cycle using ammonia-water mixture as the working fluid for the recovery of low-grade heat. Effects of the system parameters such as working fluid selection, turbine inlet pressure, and mass fraction of ammonia on the exergetical performance are parametrically investigated. KCS gives lower lower exergy destruction ratio at evaporator and higher second-law efficiency than ORC. The maximum exergy efficiency of ORC is higher than KCS.

• 한국응용과학기술학회지
• /
• 제27권2호
• /
• pp.208-215
• /
• 2010

EAF dust which is contained around 30% of zinc, 15% of iron and 3% of lead individually, is chemically treated by ammonium chloride, ammonia water, ammonia gas and carbon dioxide, and also tested and identified the ratios of the recovery of In by applied the variations of particle size, pH and heating temperature as well, in order to getting optimized recovery of the In metal after performing all of those processes. Experimental results showed that the rate of Zn recovery is 97% when the mixture of 1.3 of $NH_4Cl$/EAF is heated to the temperature of $400^{\circ}C$ and leached by water, and 95% recovery of In when ammonia gas and carbon dioxide is added simultaneously and adjust the 9.5 of pH to the same mixture above. For the purpose of remove the impurities in the mixed sample, which is prepared by the two samples, indicated above showing as the ratio of 95% and 97% recovery, in case of applied the cementation process to it, and also by electrolytic process, produced the In plate of 95~97%, and acquired 99-99.5% of In metal ingot finally by applied the heating process at $470{\sim}500^{\circ}C$.

• 한국토양비료학회지
• /
• 제4권2호
• /
• pp.137-141
• /
• 1971

토양(土壤)의 첨가(添加)가 화훼액비(花卉液肥), 유박(油粕)(참깨묵)의 부숙(腐熟) 및 비효에 미치는 영향을 밝히고저 실험실내(實驗室內)에서 한개의 부숙시험(腐熟試驗)을 실시(實施)하는 외(外)에, Petunia hybrida를 표식식물(標識植物)로 분재배(盆栽培)를 하였다. 표식식물(標識植物)은 4엽(葉)이 나왔을 때 이식(移植)한 것이며, 비료(肥料)는 추비(追肥)로만 시용(施用)했는데, 시험결과(試驗結果)는 다음과 같다. 1. 유박(油粕)에 토양(土壤)을 혼합(混合)하여 담수(湛水)한 것이 토양(土壤)의 첨가(添加)없이 담수(湛水)한 것보다 부숙(腐熟)이 빠르고 더 많은 암모니아태질소(態窒素)를 생성(生成)했으며, Petunia hybrida에 대한 비효도 컸다. 토양(土壤)의 첨가(添加)는 담수초기(湛水初期)에 혼합물(混合物)의 pH를 높임으로써 뒤따르는 유박(油粕)의 분해(分解)를 촉진(促進)한 것으로 생각되었다. 2. 야간온도(夜間溫度)가 때로는 $15^{\circ}C$ 이하(以下)에 달(達)하는 저온(低溫)에서는 부숙액(腐熟液)의 pH가 상승(上昇)하지 않고 암모니아태질소(態窒素)의 생성(生成)의 고온(高溫)($30^{\circ}C$)에서 보다 현저히 낮았다. 그러나 토양(土壤)을 첨가(添加)하여 부숙(腐熟)시킨 것이 그렇게 하지 않았던 것보다 많은 암모니아를 생성(生成)했고, Petunia hybrida의 생육(生育)에도 좋은 영향을 주었다.

• 한국재료학회지
• /
• 제10권6호
• /
• pp.445-449
• /
• 2000

가압 경수형 원자로 (pressurized light water reactor) 냉각재 계통 내의 주된 분식 생성물로 알려져 있는 nickel ferrite의 거동에 대해 고찰하기 위해 모의 nickel ferrite($Ni_{0.75}Fe_{2.25}O_4$)를 공침법으로 제조하였다. 수용액-pH-조절로는 am-monia 또는 potassium carbonate를, 공침물-세척제는 ammonia 수용액이나 potassium carbonate 수용액 또는 2차 증류수를 사용하였다. Nickel ferrite의 생성 및 수용액-pH-조절제와 공치물-세척제가 최종 생성물의 Ni-Fe 몰 비에 따른 수율 및 특성에 미치는 영향은 EDX, XPS, XRD 및 SEM으로 고찰하였다. 반응 전.후 Ni/Fe 몰 비에 따른 수율은, pH를 potassium carbon-ate로 조절한 후 2차 증류수로 공침물을 세척한 경우가 0.994로 가장 높이 나왔으며, pH-조절제로 potassium carbonate를 사용한 경우가 ammonia를 사용한 경우에 비해 높은 수율을 나타냈다. 이러한 차이는 공침 시에 수용액 내에서 ammonia가 보여주는 상대적으로 큰 $Na_{2+}{\leftarrow}NH_3$ 착화 효과와 더불어 공침물-세척제의 pH에 기인하는 것으로 해석하였다.

• 태양에너지
• /
• 제19권3호
• /
• pp.101-113
• /
• 1999

Thermodynamic performance of a simple Rankine cycle, regenerative Rankine cycle, and Kalina cycle for Ocean thermal Energy Conversion(OTEC) is evaluated under the same condition with various working fluids. The evaporator and condenser are modeled by a UA and LMTD method while the turbine and pump are modeled by considering isentropic efficiencies. As for the working fluids, R22, R134a, R32, propylene, ammonia are used for the Rankine cycles while ammonia/water and R32/R134a mixtures are used for Kalina cycle. Calculated results show that newly developed fluids such non-ozone depleting refrigerants as R134a and R32 perform as well as R22 and ammonia. The regenerative Rankine cycle showed a 1.2 to 2.8% increase in energy efficiency as compared to the simple Rankine cycle while the Kalina cycle with ammonia/water mixture showed a 1.8% increase in energy efficiency. The efficiency of the Kalina cycle with R32/R134a mixtures is the same as that of a simple Rankine cycle using R22. Therefore, the regenerative Rankine cycle turns out to be best choice for OTEC applications.

• 한국자동차공학회논문집
• /
• 제20권6호
• /
• pp.73-82
• /
• 2012

The main and side reactions of the three selective catalytic reduction (SCR) reactions with ammonia over a vanadium-based catalyst have been investigated using synthetic gas mixtures in the temperature range of $170{\sim}590^{\circ}C$. The three SCR reactions are standard SCR with pure NO, fast SCR with an equimolar mixture of NO and $NO_2$, and $NO_2$ SCR with pure $NO_2$. Vanadium based catalyst has no significant activity in NO oxidation to $NO_2$, while it has high activity for $NO_2$ decomposition at high temperatures. The selective catalytic oxidation of ammonia and the formation of nitrous oxide compete with the SCR reactions at the high temperatures. Water strongly inhibits the selective catalytic oxidation of ammonia and the formation of nitrous oxide, thus increasing the selectivity of the SCR reactions. However, the presence of water inhibits the SCR activity, most pronounced at low temperatures. In this study, the experimental results are analyzed by means of a dynamic one-dimensional isothermal heterogeneous plug-flow reactor (PFR) model according to the Eley-Rideal mechanism.

• 환경위생공학
• /
• 제14권4호
• /
• pp.35-40
• /
• 1999

For application of a yellow pigment as food additives, stability of a water-soluble yellow pigment from Bacillus sp. PY123 was investigated. The yellow pigment from Bacillus sp. PY123 was purified with pH treatment, activated carbon and silica gel column chromatography. The partial purified yellow pigment appeared only one spot on silica gel TLC after 12 evaporation and under irradiation of UV 253nm at dark room. Rf value of the pigment was measured at 0.04 and 0.12 with development of a solvent mixture (Butanol : Acetic acid : water = 4 :1:5) and a solvent mixture (Isopropanol : Ammonia : Water = 9 :1: 2), respectively, The partial purified pigment appeared a white fluorescence under UV365nm irradiation. The partial purified yellow pigment had a main peak and a minor peak on HPLC using 20mM phosphate buffer(pH 7.0) at 1ml/min flow rate. The partial purified pigment was stable at heat treatment, acidic pH, oxide-reductants and surfactants.

• Environmental Engineering Research
• /
• 제24권3호
• /
• pp.376-381
• /
• 2019

In this study, a poly(vinyl) alcohol/sodium alginate (PVA/SA) mixture was used to fabricate core-shell structured gel beads for autotrophic single-stage nitrogen removal (ASNR) using aerobic and anaerobic ammonia-oxidizing bacteria (AAOB and AnAOB, respectively). For stable ASNR process, the mechanical strength and oxygen penetration depth of the shell layer entrapping the AAOB are critical properties. The shell layer was constructed by an interfacial gelling reaction yielding thickness in the range of 2.01-3.63 mm, and a high PVA concentration of 12.5% resulted in the best mechanical strength of the shell layer. It was found that oxygen penetrated the shell layer at different depths depending on the PVA concentration, oxygen concentration in the bulk phase, and free ammonia concentration. The oxygen penetration depth was around $1,000{\mu}m$ when 8.0 mg/L dissolved oxygen was supplied from the bulk phase. This study reveals that the shell layer effectively protects the AnAOB from oxygen inhibition under the aerobic conditions because of the respiratory activity of the AAOB.

• 한국환경보건학회지
• /
• 제2권1호
• /
• pp.5-9
• /
• 1975

For analysis of Xanthene dyes according to the developing solvent and adsorbent was applied to Thin-layer chromatography with silicagel and cellulose plate. Silicagel chromato-plate used were prepared under different condition of activation. Using eight developing solvent, the influence of the condition for activation upon the separation of Xanthene dyes was investigated. The results are shown in Table 3. Methyl ethyl ketone+Acetone+$H_2O$ (10:0.1:0.4) mixture and n-butanol+Ammonia water (4:1) mixture gave clear separation for Xanthene dyes, including Fluorescein, Erythrosine Rhodamin B, Eosine, Rose bengale, phloxine and Acid red those Rf values decrease in the described ordor. Methyl ethyl ketone+Acetone+$H_2O$ (10:0.1:0.4) was applied to two adsorbents which were purchased from different manufactures. The results of Chromatograms are obtained Figure 6.

• Animal Bioscience
• /
• 제36권10호
• /
• pp.1612-1618
• /
• 2023

Objective: In our previous study, we observed that the addition of waste cooking oil (WCO) reduced ammonia (NH₃) emissions during laboratory-scale composting of dairy cattle manure under low-aeration condition. Therefore, this study aimed to evaluate the effect of addition of WCO on NH₃ emissions reduction during pilot-scale composting of dairy cattle manure, which is close to the conditions of practical composting treatment. Methods: Composting tests were conducted using pilot-scale composting facilities (1.8 m³ of capacity). The composting mixtures were prepared from manure, sawdust, and WCO. Two treatments were set: without WCO (Control) and with WCO added to 3 wt% of manure (WCO3). Composting was conducted under continuous aeration at 40 L/min, corresponding to 22.2 L/(min·m³) of the mixture at the start of composting. The changes in temperatures, NH₃ concentrations in the exhaust gases, and contents of the composted mixtures were analyzed. Based on these analysis results, the effect of WCO addition on NH₃ emissions and nitrogen loss during composting was evaluated. Results: During composting, the temperature increase of the composting mixture became higher, and the decreases of weight and water content of the mixture became larger in WCO3 than in Control. In the decrease of weight, and the residual weight and water content of the mixture, significant differences (p<0.05) were detected between the two treatments at the end of composting. The NH₃ concentrations in the exhaust gases tended to be lower in WCO3 than in Control. Nitrogen loss was 21.5% lower in WCO3 than in Control. Conclusion: Reduction of NH₃ emissions by the addition of WCO under low aeration condition was observed in pilot-scale composting, as well as in laboratory-scale composting. This result suggests that this method is effective in reducing NH₃ emissions in practical-scale composting.