• Title/Summary/Keyword: $CO_2$ thermal system

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An Experimental Study of a Water Type PV/Thermal Combined Collector Unit (액체식 PV/Thermal 복합모듈의 성능실험연구)

  • Lee, Hyun-Ju;Kim, Jin-Hee;Kim, Jun-Tae
    • Journal of the Korean Solar Energy Society
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    • v.27 no.4
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    • pp.105-111
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    • 2007
  • Hybrid PV/Thermal systems consisting of photovoltaic module and thermal collector can produce the electricity and thermal energy. The solar radiation increases the temperature of PV modules, resulting in the decrease of their electrical efficiency. Accordingly hot air can be extracted from the space between the PV panel and roof, so the efficiency of the PV module increases. The extracted thermal energy can be used in several ways, increasing the total energy output of the system. This study describes a basic type of PV/T collector using water. In order to analyze the performance of the collector, the experiment was conducted. The result showed that the thermal efficiency was 17% average and the electrical efficiency of the PV module was about $10.2%{\sim}11.5%$, both depending on solar radiation, inlet water temperature and ambient temperature.

Sintered body characteristics of LAS by addition of CaCO3 and ZrO2 using a solid-state reaction (고상반응법을 이용한 LAS계의 CaCO3와 ZrO2 첨가에 따른 소결체 특성 연구)

  • Kim, Sang-Hun;Kang, Eun-Tae;Kim, Ung-Soo;Hwang, Kwang-Taek;Cho, Woo-Seok
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.21 no.5
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    • pp.218-224
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    • 2011
  • LAS ($Li_2O-Al_2O_3-SiO_2$) ceramics were sintered by a solid-state reaction. $CaCO_3$ and $ZrO_2$ were added to the ${\beta}$-spodumene ($Li_2O-Al_2O_3-4SiO_2$) composition of the LAS system for enhancement of sintering behavior and mechanical strength, respectively. We have investigated the sintering characteristics, microstructures, mechanical properties and thermal expansion characteristics according to the change of the amount of additive and sintering temperature of the ${\beta}$-spodumene. At 0.1 mol% $CaCO_3$, the densification of ${\beta}$-spodumene was significantly improved. At 0.04 mol% $ZrO_2$, the strength of ${\beta}$-spodumene was also improved. For all the selected all compositions, the thermal expansion coefficient was measured by a dilatometer, which revealed 1.2 to $1.7{\times}10^6/^{\circ}C$.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 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.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. 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 fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are 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 general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, 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 is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Microwave Thermal Decomposition of CF4 using SiC-Al2O3 (SiC-Al2O3 촉매를 이용한 CF4의 마이크로파 열분해)

  • Choi, Sung-Woo
    • Journal of Environmental Science International
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    • v.22 no.9
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    • pp.1097-1103
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    • 2013
  • Tetrafluoromethane($CF_4$) have been widely used as etching and chemical vapor deposition gases for semiconductor manufacturing processes. $CF_4$ decomposition efficiency using microwave system was carried out as a function of the microwave power, the reaction temperature, and the quantity of $Al_2O_3$ addition. High reaction temperature and addition of $Al_2O_3$ increased the $CF_4$ removal efficiencies and the $CO_2/CF_4$ ratio. When the SA30 (SiC+30wt%$Al_2O_3$) and SA50 (SiC+50wt%$Al_2O_3$) were used, complete $CF_4$ removal was achieved at $1000^{\circ}C$. The $CF_4$ was reacted with $Al_2O_3$ and by-products such as $CO_2/CF_4$ and $AlF_3$ were produced. Significant amount of by-product such as $AlF_3$ was identified by X-ray powder diffraction analysis. It also showed that the ${\gamma}-Al_2O_3$ was transformed to ${\alpha}-Al_2O_3$ after microwave thermal reaction.

An implementation of NDIR type $CO_2$ gas sample chamber and measuring hardware for capnograph system in consideration of the time response characteristics (시간응답특성을 고려한 2광원 1센서 방식의 capnograph 시스템용 NDIR식 $CO_2$ 가스 챔버 설계 및 측정 회로의 구현)

  • Park, I.Y.;Lee, I.K.;Lee, S.K.;Kang, K.M.;Kang, S.W.;Cho, J.H.
    • Journal of Sensor Science and Technology
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    • v.10 no.5
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    • pp.279-285
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    • 2001
  • The capnograph system for determining the partial pressure of carbon dioxide in the blood of a patient was developed based on the NDIR(non-dispersive infrared) absorption technology. NDIR gas analyzing method requires an optical absorption chamber and signal processing hardware. In this paper, we have designed and implemented NDIR type $CO_2$ gas chamber in consideration of the time response characteristics and lamp chopping frequency. And we have implemented signal processing hardware using two infrared sources to reduce the thermal background effect. The implemented gas chamber and signal processing hardware were tested in the temperature variation experiment and human expiratory experiment. The results showed that the system could produce a stable output signal and a good $CO_2$ gas concentration curve like a typical capnogram.

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The Effect of Sn on the Glass Formation Ability of the Zr-based Amorphous Alloy (Zr-based 비정질 합금의 비정질 특성에 미치는 Sn의 영향)

  • Lee, Byung-Chul;Park, Heong-Il;Park, Bong-Gyu;Kim, Sung-Gyoo
    • Journal of Korea Foundry Society
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    • v.34 no.2
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    • pp.49-53
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    • 2014
  • In commercial Zr-Nb-Cu-Ni-Al amorphous alloys, expensive element, Zr, was substituted to Sn which was cheaper one, and then, glass forming ability, compressive strength and hardness of them were estimated. Even though the Sn was added up to 1.5%, resulting phase was not changed to the crystalline form. It was confirmed by X-ray diffraction and thermal analyses. In the X-ray profiles, there were no peaks for crystalline phases and typical halo pattern for amorphous phase was appeared at the diffraction angle of $35^{\circ}{\sim}45^{\circ}$. Thermal analyses also showed that the Sn modified alloys were corresponded to the amorphous standards where ${\delta}T$(= Tx - Tg) and Trg(= Tg/Tm) affecting to the amorphous forming ability were more than 50K and 0.60 respectively. Compressive strengths were 1.77 GPa, 1.63 GPa, 1.65 GPa and 1.77 GPa for 0%Sn, 0.5%Sn, 1.0%Sn and 1.5%Sn respectively. Hardnesses of the Sn modified alloys were decreased from 752 Hv to 702 Hv in 1.0%Sn and recovered to 746 Hv in 1.5%Sn.

High-Temperature Corrosion Characterization for Super-Heater Tube under Coal and Biomass Co-firing Conditions (석탄-바이오매스 혼소에 따른 슈퍼히터 튜브 고온 부식 특성 연구)

  • Park, Seok-Kyun;Mock, Chin-Sung;Jung, Jin-Mu;Oh, Jong-Hyun;Choi, Seuk-Cheun
    • Journal of Power System Engineering
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    • v.22 no.1
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    • pp.79-86
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    • 2018
  • Many countries have conducted extensive studies for biomass co-firing to enhance the durability of reactor on high-temperature corrosion. However, due to the complicated mechanisms of biomass co-firing, there have been limitations in accurately determining the current state of corrosion and predicting the potential risk of corrosion of power plant. In order to solve this issue, this study introduced Lab-scale corrosion system to analyze the corrosion characteristics of the A213 T91 material under the biomass co-firing conditions. The corrosion status of the samples was characterized using SEM/EDS analysis and mass loss measurement according to various biomass co-firing conditions such as corrosion temperature, $SO_2$ concentration, and corrosion time. As a result, the corrosion severity of A213 T91 material was gradually increased with the increase of $SO_2$ concentration in the reactor. When $SO_2$ concentration was changed from 0 ppm to 500 ppm, both corrosion severity and oxide layer thickness were proportionally increased by 15% and 130%, respectively. The minimum corrosion was observed when the corrosion temperature was $450^{\circ}C$. As the temperature was increased up to $650^{\circ}C$, the faster corrosion behavior of A213 T91 was observed. A213 T91 was observed to be more severely corroded by the effect of chlorine, resulting in faster corrosion rate and thicker oxide layer. Interestingly, corrosion resistance of A213 T91 tended to gradually decrease rather than increases as the oxide layer was formed. The results of this study is expected to provide necessary research data on boiler corrosion in biomass co-firing power plants.

Development of a Virtual Machine Tool - Part 2: Dynamic Cutting Force Model, Thermal Behavior Model, Feed Drive System Model, and Comprehensive Software Environment

  • Ko, Jeong-Hoon;Yun, Won-Soo;Kang, Seok-Jae;Cho, Dong-Woo;Ahn, Kyung-Gee;Yun, Seung-Hyun
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.3
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    • pp.42-47
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    • 2003
  • In Part 2 of this paper, the dynamic cutting force model, thermal behavior model, and feed drive model used in the development of a virtual machine tool (VMT) are briefly described. Some results are presented to verify the proposed models. Experimental data agreed well with the predicted results fer each model. A comprehensive software environment to integrate the models into a VMT is also proposed.

Effects of Air Flow Nonuniformity on the Thermal Performance of a Compact Evaporator for Natural Working Fluids (밀집형 자연냉매 증발기의 열성능에 미치는 불균일 공기유동분포의 영향)

  • 박병규;김근오;김무근
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.11
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    • pp.1114-1124
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    • 2001
  • The application of carbon dioxide as an attractive natural working fluid in air cooling and heating system is increasingly important in view of the CFC substitution problem. The thermal performance of compact evaporator was analyzed using section-by-section method. The effects of the two-dimensional nonuniformity of air flow through the evaporator is presented. The detrimental effect of the aid flaw nonuniformity on the thermal performance of the evaporator is found to be significant for many typical applications. It is shown that total heat transfer rate of evaporator using $CO_2$ is higher than that using R134a at the simulation conditions.

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The Formation and Deliveries of CO in Reconstituted Tobacco Leaves by Decreasing of Combustion Temperature (제지식 판상엽으로 제조된 권련에서 연소점 온도 내림이 CO의 생성과 이행에 미치는 영향)

  • 김대종;송태원;이문수;제병권
    • Journal of the Korean Society of Tobacco Science
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    • v.19 no.1
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    • pp.64-69
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    • 1997
  • Deliveries of tar, nicotine, CO and $CO_2 in main stream smoke decreased as the potassium salt content of reconstituted tobacco leaves increased. The peak temperatures of the central region of a burning cone during a puff was in the range 940$^{\circ}C$∼430$^{\circ}C$ by IR thermal video system. The exogenous Potassium salt contents influenced the reduction of carbon-monoxide delivery through a decrease in the Peak temperature of the burning cone. Consequently, the amount of CO formed in the combustion Process was reduced by potassium salt. Moreover, the temperature of the burning cone was lowered, and the CO formed from carbonaceous reduction was decreased.

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