• 제목/요약/키워드: drying energy

검색결과 536건 처리시간 0.022초

진해지역 30년생 편백 인공림의 지상부 현존량 (Aboveground Biomass of 30 Years Old Chamaecyparis obtusa Plantation in Jinhae)

  • 이광수;정영교
    • 임산에너지
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    • 제22권1호
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    • pp.49-57
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    • 2003
  • 경상남도 진해지역 30년생 편백 조림지를 대상으로 현존량을 추정하기 위하여 Urich II법에 의하여 수관급에 따른 부위별 현존량을 측정하여 생산구조를 해석하고 시료채취의 효율성을 높이기 위한 방법을 탐색하였다. 지상부 총 물질생산량은 137.3 ton/ha을 보유하고 있었으며, 이들 임목의 부위별 구성비는 줄기 71.8%, 가지 15.4%, 잎 12.8%로 나타났다. 임분에서 엽생산량은 수고 9.2∼11.2m에서 최대치를 보였으며, 현존량의 구성비는 우세목과 준우세목에서는 줄기>가지>잎, 열세목에서는 줄기>잎>가지 순으로 나타났다. 부위별 건조비는 줄기 47.3∼49.2%, 가지 48.8∼52.9%, 잎 39.2∼40.8%, 고사지 0.78%∼0.89%의 범위를 보였다. 표준목 전건비중(basic wood density)은 0.49∼0.53으로 나타났으나 수관급에 따른 표준목간 유의차는 나타나지 않았다.

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마이크로웨이브에 의한 하수 슬러지 이산화탄소 가스화 특성 (Characteristics of Carbon Dioxide Gasification for Sewage Sludge in Microwave)

  • 정벼리;윤수혁;전영남
    • 한국수소및신에너지학회논문집
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    • 제27권2호
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    • pp.192-200
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    • 2016
  • A characteristics of microwave drying-gasification was analyzed for converting a dewatered sewage sludge generated a wastewater treatment plant. Gas (60%) was the largest component of the product of microwave gasification, followed by sludge char (33%) and tar (2%). The main components of the producer gas were hydrogen (33%) and carbon monoxide (40%), and there was some methane and hydrocarbons ($C_2H_4$, $C_2H_6$, $C_3H_8$). Larger nitrogen and smaller oxygen amounts were generated. Gravimetric tar generated $414g/m^3$. This means a total tar which is a heavy hydrocarbons from the volatile organic substance in the sewage sludge. Selected light tars were benzene, anthracene, naphthalene, pyrene, showing lower concentrations as 2.62, 0.37, 0.49, $0.28g/m^3$, respectively. Sludge char has larger meso pores which is a mean pore size of $50.85{\AA}$ and has high adsorptivity. An amount of adsorption was $228.71cm^3/g$, showing higher quantity than acommercial adsorbers. This indicates that the gas obtained from the microwave gasification of wet sewage sludge can be used as fuel, but the heavy tar in the gas must be treated. Sludge char can be used as a tar reduction adsorbent in the process, and then burns as a solid fuel.

고정 부하를 갖는 PEM 연료전지 발전기에 있어서의 수분 평형에 관한 연구 (A Study on Water Balance in Stationary Load Proton Exchange Membrane(PEM) Fuel Cell Power Generator)

  • 아궁 박타아르;오후규;윤정인;김영복;최광환
    • 한국태양에너지학회 논문집
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    • 제31권4호
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    • pp.128-135
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    • 2011
  • 일반적으로 PEM 연료전지에서는 수분 균형이 시스템의 효율에 결정적으로 영향을 미치기 때문에, 이에 대한 균형(balance)을 잡는 것이 매우 중요하다. 특히, 촉매 층에서 물이 넘치는 익수현상(flooding)이나 건조현상(drying)이 발생하게 되면 연료전지의 효율이 급격하게 저하하므로, 항상 수분의 균형이 잡히도록 시스템을 제어하는 것이 일반적이다. 이 때,수분의 익수현상이나 건조현상은 PEM 연료전지의 용량과 주위의 환경, 즉 온도와 습도에 많은 영향을 받게 된다. 금번 논문에서는 가정용 규모인 3kW급에서 10kW급까지의 PEM 연료전지를 설치하였을 때, 주위의 환경(온도와 습도)이 수분 이동에 어떠한 영향을 미치는 지를 시간에 따라서 시뮬레이션(simulation)한 결과를 보여주고 있다. 결과에서 유입공기의 온도가 $50^{\circ}C$ 이하일 경우, 고정부하가 5kW급 이하이면 대부분이 건조현상이 발생하였으나, 고정부하가 6kW급 이상이 되면 익수현상이 운전시간이 20분 이내에서 발생하였다. 또한 고정부하를 최고 10kW급까지 올린 경우, 유입공기의 온도가 $50^{\circ}C$까지는 익수현상이 발생하였으나 $60^{\circ}C$ 이상인 경우에는 거의 건조현상이 발생함을 알 수 있었다.

균일용액침전법에서 수세여부와 건조온도가 망간이 첨가된 바륨헥사알루미네이트의 제조에 미치는 영향 (Effect of Water Wash and Dry Temperature in Homogeneous Precipitation Method on the Manufacture of Mn-added Barium Hexaaluminates)

  • 박지윤;김서영;이영우
    • Korean Chemical Engineering Research
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    • 제59권3호
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    • pp.435-442
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    • 2021
  • 요소를 이용한 균일용액침전법으로 망간이 첨가된 바륨 헥사알루미네이트를 제조하였다. 합성 후 수세 여부와 건조온도에 따른 영향을 열중량분석, X선 회절분석과 장방출 주사현미경으로 분석하였다. 수세하지 않은 여과단계만 거친 소성촉매가 수세단계를 거친 소성촉매보다 순수한 헥사알루미네이트 상을 얻을 수 있었다. 건조과정 동안 합성 후 잔존한 요소가 전구체에 탈수과정을 도와 주요 금속종인 깁사이트를 순수한 헥사알루미네이트로 변환되기 쉬운 보에마이트로 상변이에 영향을 주었다. 제조된 촉매의 메탄 연소성능 평가는 WO200이 가장 우수하였으며, 모든 촉매연소반응에서 NOx가 배출되지 않았다. 헥사알루미네이트는 최고 CO 배출량을 감소시키는데 영향을 주는 것으로 확인되었다.

Coping with large litters: the management of neonatal piglets and sow reproduction

  • Peltoniemi, Olli;Yun, Jinhyeon;Bjorkman, Stefan;Han, Taehee
    • Journal of Animal Science and Technology
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    • 제63권1호
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    • pp.1-15
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    • 2021
  • As a result of intensive breeding, litter size has considerably increased in pig production over the last three decades. This has resulted in an increase in farrowing complications. Prolonged farrowing will shorten the window for suckling colostrum and reduce the chances for high-quality colostrum intake. Studies also agree that increasing litter sizes concomitantly resulted in decreased piglet birth weight and increased within-litter birth weight variations. Birth weight, however, is one of the critical factors affecting the prognosis of colostrum intake, and piglet growth, welfare, and survival. Litters of uneven birth weight distribution will suffer and lead to increased piglet mortality before weaning. The proper management is key to handle the situation. Feeding strategies before farrowing, management routines during parturition (e.g., drying and moving piglets to the udder and cross-fostering) and feeding an energy source to piglets after birth may be beneficial management tools with large litters. Insulin-like growth factor 1 (IGF-1)-driven recovery from energy losses during lactation appears critical for supporting follicle development, the viability of oocytes and embryos, and, eventually, litter uniformity. This paper explores certain management routines for neonatal piglets that can lead to the optimization of their colostrum intake and thereby their survival in large litters. In addition, this paper reviews the evidence concerning nutritional factors, particularly lactation feeding that may reduce the loss of sow body reserves, affecting the growth of the next oocyte generation. In conclusion, decreasing birth weight and compromised immunity are subjects warranting investigation in the search for novel management tools. Furthermore, to increase litter uniformity, more focus should be placed on nutritional factors that affect IGF-1-driven follicle development before ovulation.

Improvement of Electrochemical Performance of Lithium-ion Secondary Batteries using Double-Layered Thick Cathode Electrodes

  • Phiri, Isheunesu;Kim, Jeong-Tae;Kennedy, Ssendagire;Ravi, Muchakayala;Lee, Yong Min;Ryou, Myung-Hyun
    • 전기화학회지
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    • 제25권1호
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    • pp.32-41
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    • 2022
  • Various steps in the electrode production process, such as slurry mixing, slurry coating, drying, and calendaring, directly affect the quality and, consequently, mechanical properties and electrochemical performance of electrodes. Herein, a new method of slurry coating is developed: Double-coated electrode. Contrary to single-coated electrode, the cathode is prepared by double coating, wherein each coat is of half the total loading mass of the single-coated electrode. Each coat is dried and calendared. It is found that the double-coated electrode possesses more uniform pore distribution and higher electrode density and allows lesser extent of particle segregation than the single-coated electrode. Consequently, the double-coated electrode exhibits higher adhesion strength (74.7 N m-1) than the single-coated electrode (57.8 N m-1). Moreover, the double-coated electrode exhibits lower electric resistance (0.152 Ω cm-2) than the single-coated electrode (0.177 Ω cm-2). Compared to the single-coated electrode, the double-coated electrode displays higher electrochemical performance by exhibiting better rate capability, especially at higher C rates, and higher long-term cycling performance. Despite its simplicity, the proposed method allows effective electrode preparation by facilitating high electrochemical performance and is applicable for the large-scale production of high-energy-density electrodes.

설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제29권6호
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제27권7호
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

Methodology effects on determining the energy concentration and the apparent total tract digestibility of components in diets fed to growing pigs

  • Huang, Chengfei;Li, Ping;Ma, Xiaokang;Jaworski, Neil William;Stein, Hans-Henrik;Lai, Changhua;Zhao, Jinbiao;Zhang, Shuai
    • Asian-Australasian Journal of Animal Sciences
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    • 제31권8호
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    • pp.1315-1324
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    • 2018
  • Objective: An experiment was conducted to investigate the effects of different diet formulations: F1 (Two complicated basal diets containing different crude protein levels plus tested feedstuff) vs F2 (A simple corn soybean meal [SBM] basal diet plus tested feedstuff) combined with total collection (TC) or chromic oxide ($Cr_2O_3$) marker or acid-insoluble ash (AIA) marker method, and freeze-dry or oven-dry (OD) technique on estimation of nutrient digestibility in diets fed to growing pigs. Methods: In F1, twelve barrows were allocated to two $6{\times}4$ Youden Squares. The treatment diets included a high protein basal (HPB) diet, a low protein basal (LPB) diet, a corn diet and a wheat bran (WB) diet formulated based on the HPB diet, and a SBM diet and a rapeseed meal (RSM) diet formulated based on the LPB diet. In F2, eight barrows were allocated to two $4{\times}4$ Latin Squares. The treatment diets included a corn basal diet, a SBM basal diet formulated based on the corn diet, and a WB diet and a RSM diet formulated based on the SBM diet. Results: Concentration of digestible (DE) and metabolizable energy (ME), and the apparent total tract digestibility of gross energy, ash, neutral detergent fibre, and acid detergent fibre determined by $Cr_2O_3$ marker method were greater than those determined by TC and AIA marker methods in HPB, LPB, and RSM diets formulated by F1 and in corn diet formulated by F2 (p<0.05). The DE values in WB and both DE and ME values in SBM and RSM estimated using F1 were greater than those estimated using F2 (p<0.05). Conclusion: From the accuracy aspect, the AIA marker or TC method combined with OD technique is recommended for determining the energy concentration and nutrient digestibility of components in diets fed to growing pigs.

지르코니아볼층 진동을 이용한 스파이스와 석회석 입자의 비중선별 (The Gravity Separation of Speiss and Limestone Granules Using Vibrating Zirconia Ball Bed)

  • 유재경;이민지;김경환;유경근
    • 자원리싸이클링
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    • 제29권3호
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    • pp.36-42
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    • 2020
  • 이 연구에서는 1 mm의 지르코니아볼(5.6 g/㎤)층을 진동시켜 스파이스(6.74 g/㎤)와 석회석 (2.7 g/㎤) 입자가 지르코니아볼층을 매체로 비중선별이 가능한지 조사하였다. 진동세기를 18 Hz부터 26 Hz까지 변화시켜 스파이스와 석회석의 입자개수 증가에 따른 부유율과 분리효율을 분석하였다. 진동 중 지르코니아볼은 용기내부를 순환하며, 스파이스는 지르코니아볼과 함께 가라앉지만 석회석 입자는 지르코니아볼 표면에 잔존하였다. 스파이스와 석회석의 입자 개수가 증가할수록 입자가 가라앉는 경로에 정체현상이 발생하여 입자가 가라앉는 속도가 감소하며, 스파이스 입자와 겹쳐진 석회석 입자가 같이 가라앉는 현상도 발생하였다. 따라서 입자개수가 증가할수록 스파이스와 석회석의 분리효율은 감소하나, 진동세기가 증가하면 정체현상이 해소되어 분리효율이 증가하는 현상이 관찰되었다. 특히 각 3개의 입자를 투입한 경우 22 Hz에서 100 %의 분리효율이 관찰되어 건조공정이 요구되지 않는 건식 비중선별 공정이 가능한 것이 확인되었다.