• Title/Summary/Keyword: Heat Generation

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Characteristics of Heat Generation during Transormation in Carbon Steels (일반탄소강의 상변태 중 발열 특성 해석)

  • 한흥남
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.04a
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    • pp.196-201
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    • 2000
  • A thermodynamic model was developed to analyze the characteristics of the heat generation during transformation of austenite in 0.186wt% and 0.458 wt%. carbon steels. The heat capacity and the heat evolved during transformation were formulated as functions of temperature and chemical composition for ferrite bainite and pearlite. in addition using the transformation dilatometer the transformation heat evolved during cooling was measured and the transformation behavior was observed. It was found that the heat capacity of ferrite was similar to those of pearlite and bainite. The heat capacity of ferrite was greater than that of bainite which was greater than that of pearlite. The molar heat of transformation to pearlite was greater than that to bainite which was greater than that to ferrite. The heats were found to be increased with decreased temperature and increasing the carbon content, It was also observed that the thermodynamic model. The heat of transformation in the higher carbon steel was greater than that in the lower carbon one. This was attributed to the lower transformation temperature and the greater amount of transformed pearlite in the higher carbon steel.

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The Characteristics of Hydration Heat Generation of Low Heat Concrete using Hydration Heat Reducing Admixtures (분말형 수화열저감재를 사용한 저발열 콘크리트의 수화발열 특성)

  • Kim, Yong-Ro;Jung, Yang-Hee;Lee, Sang-Ho;Kim, Do-Su;Khil, Bae-Su;Kim, Won-Ki
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.709-712
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    • 2006
  • It is necessary to develop a new technology for controling thermal cracking by hydration heat according to the increase construction of massive concrete structures, high strength concrete and early strength concrete. Therefore, it was investigated the characteristics of hydration heat generation of low heat concrete using hydration heat reducing admixtures in this study. To investigate the performance of hydration heat reducing admixtures, it was evaluated hydration heat according to the kind and replacement ratio of phase change material series I, II and the way of using hydration heat reducing admixtures in series III.

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A Study on the Heat Generation and Thermal Conductivity of Crustal Rocks (지각 구성 암석의 열생산량과 열전도도에 관한 연구)

  • Han, Uk
    • Economic and Environmental Geology
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    • v.26 no.3
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    • pp.371-382
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    • 1993
  • Compilations of thermal conductivity and radiogenic heat production on 20 typical rock types provide a convenient summary. These compilations allow estimates to be made of the radioactive heat generation for the continental crust and thus heat flow anomalies of tectonic origin to be isolated.

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Performance Characteristics of a Combined Regenerative Ammonia-Water Based Power Generation Cycle Using LNG Cold Energy (LNG 냉열을 이용하는 암모니아-물 복합 재생 동력 사이클의 성능 특성)

  • Kim, Kyounghoon;Oh, Jaehyeong;Jeong, Youngguan
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.6
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    • pp.510-517
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    • 2013
  • The ammonia-water based power generation cycle utilizing liquefied natural gas (LNG) as its heat sink has attracted much attention, since the ammonia-water cycle has many thermodynamic advantages in conversion of low-grade heat source in the form of sensible energy and LNG has a great cold energy. In this paper, we carry out thermodynamic performance analysis of a combined power generation cycle which is consisted of an ammonia-water regenerative Rankine cycle and LNG power generation cycle. LNG is able to condense the ammonia-water mixture at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the thermodynamic models, the effects of the key parameters such as source temperature, ammonia concentration and turbine inlet pressure on the characteristics of system are throughly investigated. The results show that the thermodynamic performance of the ammonia-water power generation cycle can be improved by the LNG cold energy and there exist an optimum ammonia concentration to reach the maximum system net work production.

A Study on Optimal Control of Slab Cooling Storage Considering Stochastic Properties of Internal Heat Generation (내부발열의 확률적 성상을 고려한 슬래브축냉의 최적제어)

  • Jung, Jae-Hoon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.6
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    • pp.313-320
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    • 2015
  • In this paper, a method to obtain the probability distribution of room temperature and cooling load is presented, when the internal heat generation is applied to the system as a disturbance in the air conditioning system with slab cooling storage. The probability distribution of room temperature and the cooling load due to the disturbance were examined in one room of an office building. When considering only the electric power consumption as a probability component, it was found that the effect on room temperature and cooling load is small, because the probability component of the measured electric power consumption in the building is small. On the other hand, when considering the stochastic fluctuations of electric power consumption together with the heat generated by human bodies, the mean value of the cooling load was about 2,300 W and the ratio of the standard deviations was 19% (10 o'clock in second day). It was revealed that the stochastic effects of internal heat generation acting on the air conditioning system with slab cooling storage are not small.

Simulation of the Kalina cycle for a Geothermal Power Generation (지열발전을 위한 칼리나 사이클의 시뮬레이션)

  • Baik, Young-Jin;Kim, Min-Sung;Chang, Ki-Chang;Lee, Young-Soo;Park, Seong-Ryong;Ra, Ho-Sang
    • Proceedings of the SAREK Conference
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    • 2008.06a
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    • pp.782-787
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    • 2008
  • The Kalina cycle simulation study was carried out for a preliminary design of a geothermal power generation system. The Kalina cycle system can be used for the utilization of a low-temperature heat sources such as geothermal and industrial waste heat that are not hot enough to produce steam. The sea/river water can be considered as a cooling media. A steady-state simulation model was developed to analyze and optimize its performance. The model contains a turbine, a pump, an expansion valve and heat exchangers. The turbine and pump were modelled by an isentropic efficiency, while a condenser, an evaporator and a regenerative heat exchanger were modeled by UA-LMTD method with a counter-flow assumption. The simulation results show that the power generation efficiency over 10% is expected when a heat source and sink inlet temperatures are $100^{\circ}C$ and $10^{\circ}C$ respectively.

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Heat Transfer Characteristics of High Temperature molten salt storage for Solar Thermal Power Generation (태양열 발전에서 태양열에너지 수송을 위한 고온 축열 물질의 열절달 특성)

  • Mao, Aiming;Kim, Ki-Man;Kang, Yong-Heack;Han, Gui-Young
    • 한국신재생에너지학회:학술대회논문집
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    • 2008.05a
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    • pp.190-193
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    • 2008
  • The heat transfer characteristics of molten salt storage system for the solar thermal power generation were investigated. Temperature profiles and the heat transfer coefficients during the storage and discharge stage were obtained with the steam as the heat transfer fluid. Two kinds of inorganic salt were employed as the storage materials and coil type of heat exchanger were installed in both tanks to provide the heat transfer surfaces during the storage and discharge stage. The effects of steam flow rates, flow direction of steam in the storage tank and the initial temperature of storage and discharge tank on the heat transfer were tested.

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An Experimental Study on the Characteristics of Hydration Heat Generation of Low Heat Concrete with Binder Types (결합재 종류에 따른 저발열 콘크리트의 수화발열 특성에 관한 실험적 연구)

  • Kim, Yong-Ro;Jung, Yang-Hee;Lee, Sang-Ho;Kim, Do-Su;Khil, Bae-Su;Han, Seung-Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.417-420
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    • 2006
  • Recently, the attention is paid to the problem of thermal crack by hydration heat according to the increase of high strength and mass concrete structures. At this point, various research has been carried out for the control of hydration heat in high strength and mass concrete. As a part of the research, it was investigated application of hydration heat reduction agent (HR) for the control of thermal crack by hydration heat in this study. To investigate the application, it was selected HR which can reduce hydration heat of concrete with effect in series I and II. Also, it was investigated the characteristics of hydration heat generation of low heat concrete using HR with binder types in seriesIII.

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An Experimental Study on Thermoelectric Generator Performance for Waste Coolant Recovery Systems in Vehicles (자동차 냉각수 폐열회수 열전발전 시스템의 성능에 관한 연구)

  • Lee, Dae-Woong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.7
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    • pp.329-334
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    • 2014
  • This study indicated the possibility of energy regeneration from waste coolant heat, by using thermoelectric generation integrated with heat pipe. The internal combustion engine rejects more than 60% wasteful energy to the atmosphere by heat. The thermoelectric generator has recently been studied, to convert the energy from engine waste heat into electricity. For coolant waste heat recovery, a thermoelectric generator was investigated, to find out the possibility of vehicular application. Performance characteristics were conducted with various test conditions of coolant temperature, coolant mass flow rate, air temperature, and air velocity, with the thermoelectric generator installed either horizontally or vertically. Experimental results show that the electric power and conversion efficiency increases according to the temperature difference between the hot and cold side of the thermoelectric generator, and the coolant flow rate of the hot side heat exchanger. Performance improvement can be expected by optimizing the heat pipe design.

A Study on the Entropy Generation of Single Fin-Tube Heat Exchanger (단일 핀-관 열교환기에서 엔트로피 생성에 관한 연구)

  • Pak, Hi-Yong;Lee, Kwan-Soo;Kim, Byoung-Kue
    • Solar Energy
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    • v.10 no.1
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    • pp.14-21
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    • 1990
  • The entropy generation rate in a fin-tube heat exchanger is investigated as a basis for thermodynamic optimization associated with single fin-tube heat exchanger. The entropy generation (irreversibility)analysis is used to find the optimum design factor and investigate total entropy generation, optimum dimensions of fin length, tube inner and outer diameters, and fin spacing on the variation of design factors. The results of this study are as follows: As the outer diameter increases, optimum !in spacing and fin length increase but the entropy generation and optimum inner diameter decrease; As fin thickness increases, the entropy generation of system and optimum fin spacing increase; As fin length increases, entropy generation and optimum outer diameter increase.

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