• Title/Summary/Keyword: Heat Control

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Experimental Study on the Generation of Hydration Heat of Binder using Latent Heat Material (잠열재를 사용한 결합재의 수화발열 특성에 관한 실험적 연구)

  • Kim, Yong-Ro;Kim, Do-Su;Khil, Bae-Su;Kim, Ook-Jong;Lee, Do-Bum
    • Journal of the Korea Institute of Building Construction
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    • v.9 no.3
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    • pp.103-107
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    • 2009
  • It is necessary to develop a new technology for effectively controlling thermal crack caused hydration heat according to the increasing construction of large size massive concrete structures such as mat foundation of high-rise building. Therefore, to develop a new technology for reducing hydration heat of large size massive concrete in this study, it was investigated hydration heat generation properties of binder using latent heat materials. As a test result, it was confirmed that latent heat materials were advanced on the reduction of hydration heat and control of thermal crack. It is expected to be applied as the excellent technology on the management of hydration heat and thermal crack in large size massive concrete structures.

Heat Shock Treatments Induce the Accumulation of Phytochemicals in Kale Sprouts (열처리에 의한 케일 새싹의 기능성물질 축적)

  • Lee, Min-Jeong;Lim, Sooyeon;Kim, Jongkee;Oh, Myung-Min
    • Horticultural Science & Technology
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    • v.30 no.5
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    • pp.509-518
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    • 2012
  • The objective of this study was to determine the effect of heat shock treatments on the phytochemicals including antioxidants and anticancer materials in kale (Brassica oleracea L. var. acephala) sprouts. In study I, kale sprouts grown under the growing system for four days were soaked at 40, 50, or $60^{\circ}C$ distilled water for 10, 30, or 60 seconds, and in study II, kale sprouts were soaked at $50^{\circ}C$ distilled water for 10, 20, 30, 45, or 60 seconds. After the heat shock treatments, the sprouts were transferred into normal growing conditions and recovered there for two days. Fresh and dry weights, electrolyte leakage, total phenolic concentration, antioxidant capacity, total flavonoid concentration, phenylalanine ammonia-lyase (PAL) activity, and glucosinolates content of the sprouts were measured before and after the heat shock treatments. As a result, there was a significant decrease in the fresh and dry weight of kale sprouts treated with heat shock compared with control at harvest in study I. Especially, heat shock at $60^{\circ}C$ lead to more pronounced growth inhibition compared with heat treatments at 40 and $50^{\circ}C$. Electrolyte leakage by cell collapse was the highest in the sprouts exposed to $60^{\circ}C$ distilled water, which agreed with the growth results. Heat shock at $50^{\circ}C$ significantly induced the accumulation of phenolic compounds. In study II, fresh weight of kale sprouts at $50^{\circ}C$ heat shock showed a significant decrease compared with the control at one and two days after the treatment. However, the decrease was minimal and dry weight of kale sprouts was not significantly different from that in control. In contrast, the heat shock-treated kale sprouts had higher level of total phenolic concentration than control at harvest. Heat shock treatments at $50^{\circ}C$ for 20 seconds or more showed at least 1.5 and 1.2 times higher total phenolic concentration and antioxidants capacity than control, respectively. The change of the total flavonoid concentration was similar with that of antioxidants. PAL activity after 24 hours of heat shock was higher in all the heat shock-treated sprouts than that in control suggesting heat shock may stimulate secondary metabolic pathway in kale sprouts. Seven glucosinolates were identified in kale sprouts and soaking the sprouts with $50^{\circ}C$ water for 20 seconds had a pronounced impact on the accumulation of total glucosinolates as well as two major glucosinolates, progoitrin and sinigrin, at harvest. In conclusion, this study suggests that heat shock using hot water would be a potential strategy to improve nutritional quality of kale sprouts by inducing the accumulation of phytochemicals with antioxidant and anticancer properties.

Heat Treatment of Superalloys for High Temperature Applications (고온구조용 초내열합금 열처리)

  • Park, Nho-Kwang
    • Journal of the Korean Society for Heat Treatment
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    • v.16 no.6
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    • pp.341-348
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    • 2003
  • Superalloys which can be devided into three categohes, i.e. Ni-base, Co-base, and Fe-base alloys are widely used for high temperature applications. Since superalloys contain many alloying elements and precipitates, its chemistry and processing parameters need to be carefully designed. In this review, current state-of-the art in the superalloy technologies is described with special attention to the heat-treatment for the control of the microstructures and mechanical properties.

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.

Thermal Conductivity Effect of Heat Storage Layer using Porous Feldspar Powder (다공질 장석으로 제조한 축열층의 열전도 특성)

  • Kim, Sung-Wook;Go, Daehong;Choi, Eun-Kyeong;Kim, Sung-Hwan;Kim, Tae-Hyoung;Lee, Kyu-Hwan;Cho, Jinwoo
    • Economic and Environmental Geology
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    • v.50 no.2
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    • pp.159-170
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    • 2017
  • The temporal and spatial temperature distribution of the heat storage mortar made of porous feldspar was measured and the thermal properties and electricity consumption were analyzed. For the experiment, two real size chambers (control model and test model) with hot water pipes were constructed. Two large scale models with hot water pipes were constructed. The surface temperature change of the heat storage layer was remotely monitored during the heating and cooling process using infrared thermal imaging camera and temperature sensor. The temperature increased from $20^{\circ}C$ to $30^{\circ}C$ under the heating condition. The temperature of the heat storage layer of the test model was $2.0-3.5^{\circ}C$ higher than the control model and the time to reach the target temperature was shortened. As the distance from the hot water pipe increased, the temperature gap increased from $4.0^{\circ}C$ to $4.8^{\circ}C$. The power consumed until the surface temperature of the heat storage layer reached $30^{\circ}C$ was 2.2 times that of the control model. From the heating experiment, the stepwise temperature and electricity consumption were calculated, and the electricity consumption of the heat storage layer of the test model was reduced by 66%. In the cooling experiment, the surface temperature of the heat storage layer of the test model was maintained $2^{\circ}C$ higher than that of the control model. The heat storage effect of the porous feldspar mortar was confirmed by the temperature experiment. With considering that the time to reheat the heat storage layer is extended, the energy efficiency will be increased.

Temperature distribution of top and back surface in GMA welding process (GMA 용접공정에서 용접부의 표면 및 이면의 온도분포)

  • 김영선;조형석
    • 제어로봇시스템학회:학술대회논문집
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    • 1996.10b
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    • pp.1408-1411
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    • 1996
  • In arc welding processes, because of the complexity and nonlinearity of heat transfer phenomena, it is often difficult to design an effective control system based upon an exact mathematic model. In this paper, we simulated the welding process for various welding conditions and positions to investigate the variations of temperature distribution for those cases. Those will be used as a preinformation for developing quality control system for arc welding process.

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An Application Study on Quality Control of Re-Mi-Con for Using the Early Estimating Method of Concrete Strength with the Test of Solution Heat of Hychrochioric Acid (염산용해열법의 콘크리트 강도 조기추정에 의한 레미콘 품질관리의 적용성 연구 -Fc=180Kg/$\textrm{cm}^2$를 중심으로-)

  • 한천구;윤기원
    • Proceedings of the Korea Concrete Institute Conference
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    • 1990.10a
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    • pp.101-106
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    • 1990
  • To estimate the concrete strength at fresh state is very important problem in quality control. So, this study is designed for analyzing the quality control application of practical use Re-Mi-Con with the early estimation method of concrete strength using the test of solution heat of hydrochloric acid.

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Process Management System using a PC (PC를 이용한 공정관리시스템 개발)

  • Song, Joon-Yeob;Lee, Seung-Woo;Lee, Hyun-Yong
    • IE interfaces
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    • v.6 no.2
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    • pp.171-181
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    • 1993
  • In this study, a process management system is designed that can automatically control the heat treating atmosphere, and a managment software is developed to monitor and control continously the heat treating process using a n interface device. Especially, a communication protocol is developed to control and monitor atmosphere condition, temperature, surrounding gas, and time. The developed interface device, called COMPORT SELECTOR is to send and receive information from PID controllers and PLC via RS-232C communication. This system will reduce manufacturing cost and cycle time, and improve the effectiveness of working process and quality.

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A Study on Thermal Heating Control Performance of Automatic Thermostatic Valves in Floor Radiant Heating System (바닥난방 시스템의 열환경 개선을 위한 제어방안 연구)

  • Song, Jae-Yeob;Ahn, Byung-Cheon;Kim, Kyung-Chul;Jang, Sa-Yun
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.973-978
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    • 2009
  • In this study, the thermal environment characteristics of On-Off control and thermal difference proportional control method in floor radiant heating system were researched by computer simulation. For the analysis of unsteady heat transfer phenomena in household, the method of using electrical equivalent R-C circuit is applied, and radiation heat transfer between panel, ceiling and walls in household is calculated by enclosure analysis method. The parametric study on two control methods, conventional on-off control and temperature error based time control(T.E.B.T.C.) method, are performed to compare thermal heating control performances, respectively.

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EEV Superheat Control of a Multi-type Heat Pump by Using Dither Signal (멀티형 히트펌프 전자팽창밸브의 디더 신호를 적용한 과열도 제어)

  • 한도영;표수환
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.11
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    • pp.948-953
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    • 2002
  • The electronic expansion valve (EEV) may be used to control the refrigerant flow rate for the multi-type heat pump. Stepping motor driven EEV may precisely control the refrigerant flow rate to meet each internal load requirement. To control the EEV, PI algorithm may be used. But the hysteresis of EEV deteriorates the performance of superheat control. To reduce the performance degradation, the PI algorithm along with the dither signal may be used. The dither signal, with about 10 times higher frequency than the system crossover frequency and about 10 times larger magnitude than the deadband of hysteresis, was selected for the superheat control of EEV. Experimental results showed the improvement of EEV control by adding the dither signal to the PI algorithm.