• Title, Summary, Keyword: heating loss

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Strength loss contributions during stages of heating, retention and cooling regimes for concretes

  • Yaragal, Subhash C.;Warrier, Jishnu;Podila, Ramesh
    • Advances in materials Research
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    • v.4 no.1
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    • pp.13-22
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    • 2015
  • Concrete suffers strength loss when subjected to elevated temperatures during an accidental event such as fire. The loss in strength of concrete is mainly attributed to decomposition of C-S-H gel and release of chemically bound water, which begins when the temperature exceeds $500^{\circ}C$. But it is unclear about how much strength loss occurs in different stages of heating, retention and cooling regimes. This work is carried out to separate the total strength loss into losses during different stages of heating, retention and cooling. Tests were carried out on both Ordinary Portland Cement (OPC) based concrete and Ground Granulated Blast Furnace Slag (GGBFS) blended concrete for $200^{\circ}C$, $400^{\circ}C$, $600^{\circ}C$ and $800^{\circ}C$ with a retention period of 1 hour for each of these temperature levels. Furnace cooling was adopted throughout the experiment. This study reports strength loss contribution during heating, retention and cooling regimes for both OPC based and GGBFS based concretes.

Evaluation on Weight Loss of Spalling Control Fiber by Heating Rate (폭렬저감을 위한 섬유의 가열속도에 따른 중량감소평가)

  • Yu, Sung-Il;Kim, Gyu-Yong;Choe, Gyeong-Cheol;Yoon, Min-Ho;Lee, Young-Wook;Kim, Hong-Seop
    • Proceedings of the Korean Institute of Building Construction Conference
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    • pp.32-33
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    • 2014
  • In this study, evaluation on weight loss properties of spalling control fiber with heating rates has been conducted. For evaluation of this study, 3types of organic fibers(Polyethylene, Polypropylene, Nylon) are used as spaling control fiber. Also, to evaluate the effect of heating rate to spallin control fiber, heating rates are set as 10, 25℃/min. As a result, the start time of weight loss of fiber with various heating rate was delayed as heating rate was increased.

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A Study on the Improvement of Subsidy Program for CHP Plant Connected with Capital Region District Heating System (수도권 지역난방연계 열병합발전소의 기반기금 지원과 개선방안)

  • 김창수;이창호
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.53 no.2
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    • pp.97-103
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    • 2004
  • CHP system supplies electricity and heating together with high efficiency. Current utility's CHP system uses electric power by itself and sells thermal energy to KDHC(Korea District Heating Corporation). CHP's operation cost except sales revenue of heating was covered by the sale revenue of electricity. Thus Electric generation cost in district Heating CHP system has close relationship with the level of heating price. However, after the restructuring of electricity industry, the operation cost could not be covered by sales revenue of heating and electricity. This loss was compensated by energy subsidy program in the electric power industry infrastructure fund. This paper suggests reasonable evaluation and improvement methods of the loss calculation of CHP system utilizing the infrastructure fund efficiency In terms of the direction of support by the fund, it provides the methods to prevent inefficient operation through setting up the upper limit of subsidy and to improve the loss calculation. Moreover, it suggest fixed rate support by heating supply level and reducing subsidy gradually for an efficient operation of CHP system.

A Study on Solar Radiation Analysis and Saving Elements of Heating Load according to the Location and Type of Housing in Multi-family Apartments (공동주택 주동형태별 세대위치에 따른 일사분석 및 난방부하 절감요소에 관한 연구)

  • Kim, Soo-Jeong;Park, Doo-Yong;Kim, Kang-Soo
    • KIEAE Journal
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    • v.13 no.1
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    • pp.47-55
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    • 2013
  • This study aims to evaluate the correlation between vertical solar radiation and the level of heating load according to the location and type of housing in multi-family apartments. This study shows that heating load is related with factors such as wall loss, window loss, ventilation loss and solar radiation gain. The heating load increases in the order of the middle floors, the highest floors and the lowest floors. The lowest and the highest floors are the most vulnerable floors, and it should be as emphasized as the middle floors. The heating load saving proposal contains 52 Alt. that shows heating load savings from min. 4% to max. 49%. The goal is to reduce the heating load of the highest and the lowest floors to the level of the middle floors. The result showed that there are 3 Alt. for the lowest floors and 16 Alt. for the highest floors as the heating load saving proposal. This study suggests integrated application to compose saving elements of heating load. so it could be utilized as a data for the construction of passive houses.

A Heating Apparatus for Semiconductor Manufacturing using Direct Heating Method (직접 가열 방식을 이용한 반도체 제조용 히팅 장치)

  • Jung, Soon-Won;Koo, Kyung-Wan
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.57 no.4
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    • pp.408-411
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    • 2008
  • As to this research is new structure of the semiconductor substrate heating apparatus. The fast thermoresponsive according to the direct heating structure of the heating plate layer adhering closely to the floor side of a substrate and the fast heat loss minimization can be accomplished. Moreover, the contact area of the sheath heater, which is the heating plate layer built-in heating apparatus, is increased, so that it has more heating valid area. For this, it adheres closely to the substrate, in which the photosensitive film is coated and the heating plate layer, adhering closely to the floor side of a substrate the mica layer which adheres closely to the floor side of the upper heating plate layer in order to minimize an insulation and heat loss, and the lower part of the mica layer and it is comprised of the floor plate layer. The heating plate layer forms the continued groove portion over the floor side whole. The sheath heater for heating a substrate is inserted with the groove portion and the heating plate layer is comprised. It is confirmed that by using the new substrate heating structure, the temperature change of the heating plate against the time is observed. Then, there is the electric power saving effect of about 40% in comparison with the existing method.

Process Design for the Tubular Hydroforming at Elevated Temperatures (온간 하이드로포밍 공정을 위한 시스템 설계)

  • Kim, B.J.;Park, K.S.;Sohn, S.M.;Lee, M.Y.;Moon, Y.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.226-229
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    • 2006
  • Process design has been performed for the warm hydroforming of light weight alloy tubes. For the heating of tubes, specially designed induction heating system has been adopted to ensure rapid heating of tubes. The induction heating system uses 30kHz frequency induction coil in order to concentrate the energy in the tube and prevent the energy loss. But the induced heat by the integrated heating system, consisting of induction coil, tube, pressure oil and dies, was normally not equally distributed over the length and circumference of the tube specimen, and consequent temperature distribution was non-uniform. So additional heating element has been inserted into the inside of the tube to maintain the forming temperature and reduce temperature drop due to heat loss to the molds. And for that heat loss, a heat insulation system has also been installed. The drop in flow stress at elevated temperatures results in lower internal pressure for hydroforming and lower clamping forces. The proposed warm hydroforming process has been successfully implemented when applying 6061 aluminum extruded tubes.

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Study on the Development of Multi Heat Supply Control Algorithm in Apartment Building of District Heating Energy (지역난방 에너지 공동주택의 다중 열공급 제어 알고리즘 개발에 관한 해석적 연구)

  • Byun, J.K.;Choi, Y.D.;Park, M.H.;Shin, J.K.
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.2
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    • pp.63-70
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    • 2011
  • In the present study, we developed optimal heat supply algorithm which minimizes the heat loss through the distribution pipe line in group energy apartment. Heating load variation of group energy apartment building in accordance with outdoor air temperature was predicted by the correlation obtained from calorimeter measurements of whole households of apartment building. Supply water temperature and mass flow rate were conjugately controlled to minimize the heat loss rate through distribution pipe line. Group heating apartment located in Hwaseong city, Korea, which has 1,473 households divided in 4 regions, was selected as the object apartment for verifying the present heat supply control algorithm. Compared to the original heat supply system, 10.4% heat loss rate reduction can be accomplished by employing the present control algorithm.

A Study on the Influence Factor in Measuring the Dynamic Stiffness and Loss Factor of Damping Materials (완충재의 동탄성 및 손실계수 측정 시 영향인자에 관한 연구)

  • Lee, S.H.;Jeong, G.C.;Chung, J.Y.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.279-282
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    • 2005
  • The aim of this study is to suggest the method of measuring the dynamic stiffness and loss factor of materials used under floating floors in the dwelling by korea standard (KS F 2868). According to the results, the amplitude change of an impact source have no effect on the variation of the dynamic stiffness and loss factor. Comparing with the heating before, heating makes lower the dynamic stiffness except the EPS. In EVA material, the loss factor is increased by heating.

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Mechanical Property and Process Variables Optimization of Tube-to-Tube Friction Welding for Steel Pipe with 36 mm External Diameter (외경 36mm 강관의 관대관 마찰용접 특성과 공정 변수 최적화)

  • Kong, Yu-Sik;Park, Young Whan
    • Journal of Power System Engineering
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    • v.18 no.2
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    • pp.50-56
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    • 2014
  • Friction welding is a very useful joining process to weld metals which have axially symmetric cross section. In this paper, for the friction welding with tube-to-tube shape, the feasibility of industry application was determined using analyzing mechanical properties of weld and optimized welding variables was suggested. In order to accomplish this object, rotating speed, friction heating pressure, and friction heating time were selected as the major process variables and the experiment was performed in three levels of each parameter. Weld characteristic was investigated in terms of weld shape and metal loss, and 7mm of metal loss was regarded as the optimal metal loss. By tensile test, tensile strength and yielding strength was measured and fracture was occurred at base metal. In order to optimize the welding condition, fitness function was defined with respect to metal loss and yielding strength and the fitness values for each welding condition could be calculated in experimental range. Consequently, we set the optimal welding condition as the point which had maximum value of fitness function. As the result of this paper the optimal welding variables could be suggested as rotating speed was 1300 rpm, friction heating pressure was 15 MPa, and friction heating time was 10 sec.

Development of On-site Heat Loss Audit and Energy Consulting System for Greenhouse

  • Kwon, Jin Kyung;Kang, Geum Choon;Lee, Seong Hyun;Sung, Je Hoon;Yun, Nam Kyu;Moon, Jong Pil;Lee, Su Jang
    • Journal of Biosystems Engineering
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    • v.38 no.4
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    • pp.287-294
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    • 2013
  • Purpose: Greenhouses for a protected horticulture covered with a plastic or glass are easy to have weakness in a heat loss by deterioration, damage, poor construction, and so on. To grasp the vulnerable points of heat loss of the greenhouses is important for heating energy saving. In this study, an on-site heat loss audit and energy consulting system were developed for an efficient energy usage of a greenhouse. Method: Developed system was mounted with infrared thermal and visual cameras to grasp the heat loss from the greenhouse quickly and exactly, and a trial calculation program of heating load of greenhouse to provide farmers with the information of heating energy usage. Results: Developed system could print out the reports about the locations and causes of the heat losses and improvement methods made up by an operator. The mounted trial calculation program could print out the information of the period heating load and fuel cost according to the conditions of greenhouse and cultivation. The program also mounted the databases of the information on the 13 horticultural energy saving technologies developed by the Korea Rural Development Administration and simple economic analysis sub-program to predict the payback period of the technologies. Conclusion: The developed system was expected to be used as the basic equipment for an instructors of district Agricultural Technology and Extension Centers to conduct the energy consulting service for the farmers within the jurisdiction.