• Title/Summary/Keyword: Heat Input

Search Result 1,043, Processing Time 0.436 seconds

A Study on Application of Warm Air Circulator by Using the Carbon Heating Element with Particle Type (입상 탄소 발열체의 열원을 이용한 온풍기의 적용에 관한 연구)

  • Bae, K.Y.;Lee, K.S.;Kong, T.W.;Chung, H.S.;Jeong, H.Y.;Chung, H.T.
    • Journal of Power System Engineering
    • /
    • v.7 no.4
    • /
    • pp.31-37
    • /
    • 2003
  • This paper is a study on application of warm air circulator by using the carbon heating element with particle type. The main variables are the input current and amount of carbon heating source for experimental characteristics. The experimental results are obtained as follows. As the input current and temperature are increased, the resistance of heat source is decreased about $20{\sim}25%$ by the effect of negative resistance. As the amount of heating source is small, Joule heat is large with the input current. When the amount of heating source is 300 and the input current is 15A, the value of Joule heat is about 4604.6kJ/h. The heat production efficiency of carbon heating source is larger about 10% than the sheath heater.

  • PDF

Study on Fracture Toughness and Heat Input in Weld HAZ of Cr-Mo Steel (I) (welding structure) (Cr-Mo강 용접열영향부의 파괴인성과 용접입열량에 관한 연구(I) (HAZ 고유조직을 중심으로))

  • 임재규;정세희
    • Journal of Welding and Joining
    • /
    • v.2 no.2
    • /
    • pp.54-61
    • /
    • 1984
  • Construction of welding structure is greatly dependent upon welding heat cycle. Fracture toughness is decreased remarkablely due to coarse grained HAZ and inequal residual stress of three dimensions to originate in welding. Post weld heat treatment(PWHT) is carried out to increase the fracture toughness of HAZ and to remove the residual stress. There occur some problem such as toughness decrement and stress relief cracking(SRC) in the coarse grained HAZ subject to the effect of tempering treatment. Therefore, in this paper, the effect of heat inputs affecting cooling rate and PWHT under the no stress on fracture toughness were evaluated by crack opening displacement (COD), SEM and micro-hardness test. Experimental results are as follows; 1. Fracture toughness of weld HAZ is dependent upon weld heat cycle and it is decreased with increment of heat input, but the degree of improvement of fracture toughness after PWHT was linearly increased with heat input. 2. Hardness of the parent metal is not changed, but the softening of coarse grained HAZ is remarkable due to PWHT. 3. Fracture surface of as-weld show the perfect brittle fracture with the cleavage fracture, but after PWHT they appear the ductile fracture surface with dimple.

  • PDF

A Study on the Performance Evaluation of a Hybrid Desiccant Cooling System (하이브리드 제습냉방시스템의 성능평가 연구)

  • Hwang, Won-Baek;Kim, Young-Chan;Lee, Dae-Young
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.24 no.2
    • /
    • pp.121-128
    • /
    • 2012
  • Improvement in the energy efficiency has been studied of the desiccant cooling system by applying a vapor compression type heat pump to modify the system into a hybrid system. The cycle simulation was performed and the results were compared between a reference desiccant cooling system composed of a desiccant rotor, a sensible rotor and a regenerative evaporative cooler, and a hybrid desiccant cooling system with the sensible rotor being replaced by a heat pump. Though the electric consumption increases as much as the compressor power consumption, the total cooling capacity increases and the thermal energy input decreases by the addition of the heat pump. Therefore, the total energy efficiency can be improved if the increase in the electric consumption can be compensated with the increase in the cooling capacity and the decrease in the thermal energy input. The results showed that the total energy efficiency is optimized at a certain heat pump capacity. When the heat from the CHP plant is used for the thermal energy input, the energy consumption of the hybrid system is reduced by 20~30% compared with the reference system when the heat pump shares 30~40% of the total cooling capacity.

A Study on the High Temperature Tensile Characteristics of Lap Weld of 15Cr Ferritic Stainless Steels (15Cr 페라이트계 스테인리스강의 겹침용접부 고온인장 특성에 관한 연구)

  • Lee, Young-Gi;Lee, Gyeong-Cheol;Kim, Jae-Seong;Han, Do-Seok;Oh, Seung-Taek;Lee, Bo-Young
    • Journal of Welding and Joining
    • /
    • v.26 no.5
    • /
    • pp.60-65
    • /
    • 2008
  • Ferritic stainless steels of the 400 series have been available for automotive exhaust system, heat exchanger, radiater etc. in various industrial because heat resistance, corrosion resistance and strength are excellent. Especially, automotive exhaust system is required good heat resistance because typical temperature of exhaust system exposed during operation of engine is reach up to $800^{\circ}C$. However, research for effect of high temperature in ferritic stainless steels is not enough. In this study, high temperature tensile properties of lap weld of ferritic stainless steels(STS 429) were investigated. In accordance with heat input, lap welds had been produced and were evaluated at high temperature($800^{\circ}C$) to compare high temperature tensile properties. In addition, room temperature tensile tests were carried out for non-aging and aging specimens. As a result of R.T tensile test, non-aging specimens were fractured in base metal except for low heat input specimen and aging specimens were fractured in weld metal. Also high temperature tensile test were carried out by aging specimen. After high temperature tensile test, fracture of aged specimen was occurred in base metal except for low heat input specimen. Fracture surface of low heat input specimen in weld metal was confirmed as brittle fracture with observation using scanning electron microscope(SEM). Significant decrease in ultimate tensile strength (between 82 and 85%) was observed for aged ferritic stainless steels(STS 429) when tested at high temperature.

The effect of PWHT on the mechanical properties of HSB600 steel (HSB600강의 용접 후 열처리에 따른 기계적 특성 변화 연구)

  • Lim, Young-Min;Ju, Dong-Hwi;Kim, Nam-Hoon;Koh, Jin-Hyun
    • Proceedings of the KAIS Fall Conference
    • /
    • /
    • pp.679-682
    • /
    • 2011
  • The effects of heat input(1.5~3.6kJ/mm) and postweld heat treatment(PWHT, $600^{\circ}C$, 40hr.) on the TMCP HSB600 steel weldments made by GMAW process were investigated. The tensile strength and CVN impact energy of as-welded specimens decreased with increasing heat input. The fine-grained acicular ferrite was mainly formed in the low heat input while polygonal and side plate ferrites were dominated in the high inputs. Meanwhile, tensile strength and hardness of PWHT weldments decreased due to the coarsening of microstructure and reduction of residual stresses.

  • PDF

Effect of Welding Heat Input on Mechanical Properties of Underwater Welded Joints of KR Grade A-1 Steel Plates (국산 선급 A-1 강판의 수중용접 입열량이 기계적 특성에 미치는 영향에 관한 연구)

  • 오세규;이종석;한상덕
    • Journal of Ocean Engineering and Technology
    • /
    • v.1 no.1
    • /
    • pp.120-126
    • /
    • 1987
  • In this paper, the optimizing investigation of characteristics of underwater welding by a gravity type arc welding process is experimentally carried out by using the .phi. 4mm ilmenite type of domestic coated welding electrodes for welding the domestic marine structural steel plates of 8mm thickness in order to develop the underwater welding techniques in practical use, resulting in the quantitative analysis possibility for the relationship between the mechanical propernical properties of underwater welded joint HAZ and the welding heat input.

  • PDF

Heat Transfer Simulation and Temperature Measurement for Heat Input Control in Orbital Welding (오비탈 용접에서 입열량 제어를 위한 열전도 시뮬레이션 및 온도측정)

  • 김기정;김진우;강윤배;조상명
    • Proceedings of the KWS Conference
    • /
    • /
    • pp.155-158
    • /
    • 2003
  • Orbital GTA welding is used in the pressure pipe line of auto-mobile, LNG and plant piping. To weld the pipe line safely, to some extent, the back bead must be formed in the root pass. In the plate welding the back bead can be observed, but in the pipe welding, the back bead can not be observed directly. In the welding around circumference, the parameters such as gravity, surface tension and arc force are different at each position. And then D/B for welding condition at each position are required. We also studied about the setting of the optimum orbital welding condition by controlling heat input.

  • PDF

A Study on the Impact Toughness and Microstructure change for High Nitrogen TiN Steel Alloy with Welding Heat Input. (용접 입열량에 따른 고질소 TiN 강재의 용접부 충격인성 및 미세조직 변화에 관한 연구)

  • Gwon Sun Du;Lee Gwang Hak;Park Dong Hwan
    • Proceedings of the KWS Conference
    • /
    • v.43
    • /
    • pp.123-124
    • /
    • 2004
  • This study was investigated on the impact toughness and microstructure of welded metal and heat affected zone for Hi Nitrogen TiN Steel. With welding procedures, welding heat input applied were 30, 79 and 264 kJ/cm. TiN steel has shown very small prior austenite grain size for all the welding heat input applied, which was considered to result from the effect of TiN particles. In case of single SAW and EGW welding, the dilution rate of base metal into the weld was not high, resulting that there were no significant effects of base metal chemical composition on the mechanical properties of welds. However, TSAW with double Ypreparation carried very high dilution rate so that TiN steel has impaired the toughness of weld metal because N content in the weld was increased through the dilution of base metal.

  • PDF

Performance Analysis of Micro-turbine CHP System with Absorption Chiller (흡수식 칠러를 장착한 마이크로터빈 구동 열병합시스템의 성능 해석)

  • Yun, Rin;Han, Seung-Dong
    • Proceedings of the SAREK Conference
    • /
    • /
    • pp.540-545
    • /
    • 2007
  • The performance of microturbine CHP system equipped with an absorption chiller was analyzed by modelling of a microturbine and an absorption chiller. The microturbine having recuperator was simulated by the Brayton cycle model. The mass flow rate and available heat energy of the exhaust gas from the microtubune were simulated, and this results were utilized as input values for the generator of the absorption chiller. The absorption chiller is a single-effect air cooled type having solution heat exchanger. When heat input to the generator increased, the heat transfer rate and UA of the heat exchangers of the absorption chiller proportionally increased. Besides, the COP of the absorption chiller increased with increase of the heat input to the generator under the sufficient size of the evaporator condition. When the capacity of the CHP system increased from 30 to 60 kW, the mass flow rate of the LiBr for the absorption chiller increased by two times, and UA values for evaporator and condenser were increased by 3.9 and 3.4 times, respectively, under the same COP condition.

  • PDF

Performance Analysis of Microturbine CHP System with Absorption Chiller (흡수식 칠러를 장착한 마이크로터빈 구동 열병합시스템의 성능 해석)

  • Yun, Rin;Han, Seung-Dong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.20 no.7
    • /
    • pp.486-491
    • /
    • 2008
  • The performance of a microturbine CHP system equipped with an absorption chiller was analyzed by modeling it. The microturbine with recuperator was simulated with the Brayton cycle model. The mass flow rate and available heat energy of the exhaust gas from the microturbine were simulated. These results were utilized as input values for the generator of the absorption chiller. The absorption chiller is a single-effect air cooled type with a solution heat exchanger. The heat input into the generator was proportional to the heat transfer rate and the UA values of the heat exchangers of the absorption chiller. Furthermore, the COP of the absorption chiller increased with respect to an increase of the heat input into the generator, under the sufficient evaporator capacity condition. When the capacity of the CHP system increased from 30 to 60 kW, the mass flow rate of the LiBr for the absorption chiller doubled, and the UA values for evaporator and condenser increased by factors of x3.9 and x3.4, respectively, under the same COP condition.