• Title/Summary/Keyword: Temperature Control of Fuel

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A Study on High Efficiency Geothermal Heat Pump System by Improving Flow of Heat Exchanger (열교환기의 흐름개선을 통한 고효율 지열 히트펌프 시스템에 관한 연구)

  • Ahn, Sung-Hwan;Choi, Jae-Sang;Kim, Sang-Bum;Ahn, Hyung-Hwan
    • Journal of the Korean Institute of Gas
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    • v.21 no.4
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    • pp.42-46
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    • 2017
  • As $CO_2$ emission with imprudent using fossil fuel, annual mean temperature of earth is increased in every year. Geothermal energy is inexhaustible energy resource to solve this problem. Heat pump performance and heat exchange efficiency of ground loop are important to distribute widely. Thus, this study are performed to increase heat pump performance and heat exchange efficiency of ground loop with dual expansion valves and spacer. As a results, COP of cooling & heating is obtained improvement up to 11.4% using dual expansion valves, and heat exchange efficiency is increased up to 17.5% using spacer. It will be reduced initial installation cost due to increasing heat pump performance and heat exchange efficiency of ground loop.

Recent Research Works on Chemiluminescence as Measures of Combustion Characteristics (화학발광을 활용한 연소계측 연구동향)

  • Seo, Seonghyeon;Moon, Insang
    • Journal of the Korean Society of Propulsion Engineers
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    • v.18 no.1
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    • pp.73-84
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    • 2014
  • The present paper includes recent research works on the estimation of physical properties like equivalence ratio and heat release rate of flame through chemiluminescence measurement. Modern combustion devices require a precise control to increase combustion stability as well as to suppress pollutant emissions. The determination of combustion characteristics from chemiluminescence provides practical advantages over other techniques. However, the technique is dependent on equivalence ratio, combustion pressure, inlet temperature, turbulent intensity and fuel type. The intensity ratio of $OH^*$ and $CH^*$ has a strong relation with an equivalence ratio for methane/air premixed flames. The global measurement of chemiluminescence is accepted as a good indicator for a global heat release rate.

A Carbon Cycle Model Based Method for Carbon Neutrality Assessment (탄소순환 모델기반 탄소중립 평가방법)

  • Choi, Soo Hyoung
    • Korean Chemical Engineering Research
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    • v.60 no.3
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    • pp.433-438
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    • 2022
  • A carbon cycle model based method is proposed in order to evaluate the effectiveness of various policies and projects to achieve carbon neutrality. The proposed model was validated by properly reproducing the increase in the concentration of carbon dioxide in the atmosphere and the rise of the global average temperature from the data of anthropogenic carbon emissions and deforestation since the industrial revolution. As a case study, a carbon cycle impact assessment was performed for deforestation, reforestation, and afforestation. It was verified that the increase of carbon dioxide in the atmosphere is attributed not only to fossil fuel usage, but also to deforestation, and that even if deforestation is immediately followed by reforestation, it takes very long to return to the initial concentration. The proposed method is expected to be eventually applicable to simulation of potential climate control in the future, contributing to safety verification of various climate engineering techniques.

A Study on the BEMS Installation and performance Evaluation Method for Energy Monitoring(Measuring) of New Building (신축건물 에너지효율관리를 위한 환경 및 에너지모니터링(계측) 방법론)

  • Kwon, Won Jung;Yoon, Ji Hye;Kwon, Dong Myung
    • Journal of Energy Engineering
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    • v.27 no.2
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    • pp.32-48
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    • 2018
  • Monitoring of energy use should be a priority in order to efficiently manage building energy use. Energy use in buildings can be managed by dividing them into energy sources, uses, and ZONE. By energy source, electricity, gas, fuel, and district heating are supplied to run the building's facilities. The purpose can be divided into five main applications, including cooling, heating, lighting, hot water and ventilation, but not many elevators and electric heaters that are difficult to include in the five applications are classified. ZONE Star refers to the comparison or separate management of areas for which the purpose of the building is similar or different. In addition, energy efficiency management requires control of the temperature, humidity, and people who will be measuring energy in the building, and the recent problem of fine dust should directly affect the ventilation of the building.

An experimental study on development of water mist fire-fighting systems for Ro-Ro spaces (Ro-Ro 구역용 미분무 소화설비의 개발을 위한 실험적 연구)

  • Kwark, Ji-Hyun;Kim, Young-Han
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.8
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    • pp.946-952
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    • 2013
  • Large scale fire tests were conducted to develop water mist nozzles as a component of fixed water- based fire fighting systems for Ro-Ro spaces and special category spaces. Fire scenarios for this system consist of two cases which are for cargo fire in a simulated truck and for passenger vehicle fire, and each case has 3 different tests according to the position between fixed water mist nozzles and fire source. Every experiment proceeded for 30 minutes and acceptance criteria were based on gas temperature, fuel package's damage and ignition of targets. This study primarily dealt with the experimental results of cargo fire and focused on fire suppression capability in accordance with discharge pressure, flow rate and flow characteristics like swirl and penetration of the developed water mist nozzles. It appeared that low pressure water mist nozzles with about 40 L/min were able to control fire occurred in Ro-Ro spaces.

Variation of Indoor Air Temperature by using Hot Water Piping in Greenhouse (온수배관에 의한 온실 내부의 온도변화)

  • Yoon, Yong-Cheol;Shin, Yik-Soo;Bae, Seoung-Beom;Kim, Hyeon-Tae;Choi, Jin-Sik;Suh, Won-Myung
    • Journal of agriculture & life science
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    • v.46 no.2
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    • pp.179-190
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    • 2012
  • This study was performed to obtain a heat saving effect and enhance the efficiency of a greenhouse by using a hot water piping in order to minimize the operating costs of a greenhouse as oil prices continue to rise. This method also reduces the likelihood of accidents caused by snowdrifts in regions with heavy snowfall. In general, the experimental plot was $2.0{\sim}6.0^{\circ}C$ higher than the control plot. When the skylight felt was opened, the minimum temperature was in the range of $3.0{\sim}12.0^{\circ}C$. Therefore, we judged that damage caused by snowdrifts may be prevented partly by active heating. The temperature difference inside of the greenhouse by height was insignificant. The maximum heating load of the greenhouse according to crop was respectively about $37,000kcal{\cdot}h^{-1}$ and $41,700kcal{\cdot}h^{-1}$. During the experiment, the heat value of each designed temperature in the range of the minimum ambient temperature $-11.9{\sim}4.0^{\circ}C$ was about 95,000~322,000 kcal and it was in the range of $6,050{\sim}20,900kcal{\cdot}h^{-1}$. If it is compared with the maximum heating load, it can be shown that about 15~56% of the heating energy can be supplied. The total heat value and the amount of power consumption were 2,629,025 kcal and 677.3 kWh respectively during the experiment. If it is heated with diesel, a fossil fuel, the consumption during the experiment was 291 L and the cost was 331,700won. Total cost of using electric power was about 24,400 won and it is shown that it is about 7.5% of the cost of diesel consumption. Also, if the total amount of power consumption is converted into energy, it is approximately 582,200 kcal and the energy was just about 22% of the total heat value.

An Electrochemical Reduction of TiO2 Pellet in Molten Calcium Chloride (CaCl2 용융염에서 TiO2 펠렛의 전기화학적 환원반응 특성)

  • Ji, Hyun-Sub;Ryu, Hyo-Yeol;Jeong, Ha-Myung;Jeong, Kwang-Ho;Jeong, Sang-Mun
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.10 no.2
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    • pp.97-104
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    • 2012
  • A porous $TiO_2$ pellet was electrochemically converted to the metallic titanium by using a $CaCl_2$ molten salt system at $850^{\circ}C$. Ni-$TiO_2$ and graphite electrodes were used as cathode and anode, respectively. The electrochemical behaviour of $TiO_2$ pellet was determined by a constant voltage control electrolysis. Various reaction intermediates such as $CaTiO_3$, $Ti_2O$ and $Ti_6O$ were observed by XRD analysis during electrolysis of the pellet. Once $TiO_2$ pellet was converted to a porous metallic structure, the porous structure disappeared by sintering and shrinking with increasing the reaction time at high temperature.

Effect of Growing Part Following Local Heating for Cherry Tomato on Temperature Distribution of Crop and Fuel Consumption (방울토마토 생장부 추종 국소난방이 군락 온도분포 및 연료소비에 미치는 영향)

  • Kwon, Jin Kyung;Kang, Geum Chun;Moon, Jong Pil;Lee, Tae Seok;Lee, Su Jang
    • Journal of Bio-Environment Control
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    • v.24 no.3
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    • pp.217-225
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    • 2015
  • Local heating system providing hot air locally to growing parts including shoot apex and flower cluster which were temperature-sensitive organs of cherry tomato was developed to reduce energy consumption for greenhouse heating without decline of crop growth. Growing part following local heating system was composed of double duct distributer which connected inner and outer ducts with hot air heater and winder which moved ducts up and down following growing parts with plant growth. Growing part local heating system was compared with conventional bottom duct heating system with respect to distributions of air and leaf surface temperatures according to height, growth characteristics and energy consumption. By growing part local heating, air temperature around growing part was maintained $0.9{\sim}2.0^{\circ}C$ higher than that of lower part of crop and leaf surface temperature was also stratified according to height. Investigations on crop growth characteristics and crop yield showed no statistically significant difference except for plant height between bottom duct heating and growing part local heating. As a result, the growing part local heating system consumed 23.7% less heating energy than the bottom duct heating system without decrease of crop yield.

Synthesis and Electrochemical Properties of (La0.6Sr0.4)(Co0.2Fe0.8)O3 cathode for SOFC on pH Control Using Modified Oxalate Method (Modified Oxalate Method 의해 합성한 SOFC용(La0.6Sr0.4)(Co0.2Fe0.8)O3 Cathode의 pH 변화에 따른 특성)

  • Lee, Mi-Jai;Choi, Byung-Hyun;Kim, Sei-Ki;Park, Sang-Sun;Lee, Kyung-Hee
    • Journal of the Korean Electrochemical Society
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    • v.10 no.4
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    • pp.288-294
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    • 2007
  • The LSCF cathode far Solid Oxide Fuel Cell was investigated to develop high performance unit cell at intermediate temperature by modified oxalate method with different electrolytes and different pH. The LSCF powders employed La, Sr, Co and Fe oxides, oxalic acid, ethanol and $NH_4OH$ solution were synthesized with pH controlled as 2, 6, 7, 8, 9 and 10 at $80^{\circ}C$ Single crystalline phase was obtained from pH $2{\sim}9$. on the other hand, $La_2O_3$ appeared from pH 10. Very fine powder with particle size of 50 nm was obtained at calcination temperature of $800^{\circ}C$ for 4 hours. LSCF cathode synthesized at pH 7 showed the highest electric conductivity in the temperature range of $600^{\circ}C$ to $900^{\circ}C$ its value was 950 S/cm at $900^{\circ}C$ Under same synthesis conditions, polarization resistance of each LSCF cathode was changed with different calcination temperatures. As-prepared powder presented 2.52, 1.54 and $2.58\;{\Omega}$ at $600^{\circ}C$ with ScSZ, 8Y-YSZ and GDC as its electrolyte respectively after calcination at $800^{\circ}C$ for 4 hours.

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 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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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.