• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.56-62
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• 2008

Characteristics of heat transfer were investigated in a three-phase swirling fluidized bed whose diameter was 0.102 m and 2.5 m in height. Effects of gas and liquid velocities, particle size and liquid swirling ratio ($R_S$) on the immersed heater-to-bed overall heat transfer coefficient were examined. The heat transfer characteristics between the immersed heater and the bed was well analyzed by means of phase space portraits and Kolmogorov entropy(K) of the time series of temperature difference fluctuations. The phase space portraits of temperature difference fluctuations became stable and periodic and the value of Kolmogorov entropy tended to decrease with increasing the value of liquid swirling ratio from 0.1 to 0.4. The value of Kolmogorov entropy exhibited its minimum with increasing liquid swirling ratio. The value of overall heat transfer coefficient (h) showed its maximum with the variation of liquid velocity, bed porosity or liquid swirling ratio, but it increased with increasing gas velocity and particle size. The value of K exhibited its maximum at the liquid velocity at which the h value attained its maximum. The overall heat transfer coefficient and Kolmogorov entropy were well correlated in terms of dimensionless groups and operating variables.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.625-631
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• 2014

In this study, according to increase of thermoelectric power plants that use LNG, LNG-FSRU(Floating-Storage and Regasification Unit) appeared and it is installed on the Topside in order to deliver in a gaseous state to consumers who are in the shore. This study about the study on the characteristics analysis of the system depending on changes in performance with the vaporization and temperature of the heat source. For the characteristics analysis of the system, we devided vaporization method into Ethylene glycol water vaporization method and sea water as a heat source. Then the system that can vaporize 200ton per hour of LNG of $-157.9^{\circ}C$ and 10,400kPa was configured, and according to the temperature of supplied sea water, required minimum flow rate value was calculated. Also in case of using Ethylene glycol Water as a vaporization method, providing for regional and seasonal factors such as decrease of temperature of water. The system is configured by adding a steam boiler of $174.5^{\circ}C$, 775kPa as heat source. The generation amount of the steam required according to the performance of the vaporizer compared to the water temperature changes in the steam boiler and the amount of required evaporative performance due to changes in the quantity of steam and Ethylene glycol Water was confirmed.

• Solar Energy
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• v.17 no.3
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• pp.43-49
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• 1997

Cycle simulaton of the double effect parallel flow model is applied to a Lithium-Bromide/water system, with the objective of evaluation the possibilities of effectively utilizing waste-heat as a secondary heat source for the low-temperature generator. In this study, cycle simulation has been carried out to clarify the effect heat exchange in order to predict the performance of absorption refrigeration cycles using waste heat.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.3
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• pp.233-238
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• 2002

본 논문에서는 유도가열조리기의 효과적인 설계를 위하여 입력주파수 변화에 따른 유도가열조리기의 자계와 열계 해석 방법을 제시하였다. 유도가열조리기의 내부자계는 3차원 축대칭 유한요소법을 사용하여 해석하였으며, 열원은 유도가열조리기의 내부에서 유도된 와전류에 의하여 발생되고, 열은 열원과 열방정식을 사용하여 계산되어진다. 또한, 유도가열조리기의 온도특성을 스테인레스와 알루미늄 각각에 대하여 주파수와 투자율에 따라 제시하였다.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.27-29
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• 2003

최근 레이저와 아크를 동시에 사용하여 용접 속도와 품질을 향상시킬 수 있는 하이브리드 용접 기술이 개발되어 활발히 연구가 진행되고 있다. 레이저와 아크를 동시에 사용하게 되면 각각의 열원이 서로 영향을 주어 새로운 용접 열원으로서 동작하게 되는데 특히 레이저에 의해서 발생하는 모재의 금속 증기는 아크 플라즈마의 안정화를 가져오는 것으로 알려져 있다. 또한 금속 증기 속의 이온과 전자가 아크 플라즈마의 음극점을 형성하는데 도움을 줌으로써 플라즈마의 국부적인 온도 상승을 가져오게 된다. 본 연구에서는 effective electrical potential 개념을 도입하여 이러한 현상을 해석하였고 용접 조건에 따른 플라즈마의 거동 변화를 시뮬레이션 하였다.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.1
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• pp.83-95
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• 2020

The economic issue of the period of return versus investment has emerged to efficiently utilize the thermal energy of public resource recovery facilities using waste and private thermal source facilities using BIO-SRF. Accordingly, the optimum temperature and pressure facilities are required beyond the traditional designed, constructed and operated. In this study, we analyzed current energy output by different heat and pressure model in domestic facilities, and calculated the characteristics of green-house gas emission. In order to, utilize the thermal energy producing facilities using waste and biomass fuel more efficiently, it is temperature and pressure, which will lead to more lucrative investment and return as well.

• Tunnel and Underground Space
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• v.9 no.1
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• pp.27-35
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• 1999

The characteristics of heat conduction for the heat source boundary like an arch shape cavern are different from those for the semi-infinite or circular boundary which can be driven theoretically. A new form of transient heat conduction equation in rock mass around the arch shape cavern is evaluated with analyzing the pattern of the rock temperature distribution measured at the cold storage pilot plant. The new equation, which is driven by adopting a shape function, $SF=\sqrt{logx_0/log(x_0+x)}$ to the solution for a semi-infinite boundary, has the semi-radial form of temperature variation with distance. And, thermal properties of rock mass are estimated by comparing the rock temperature distributions by this equation with those by measurement. Thermal conductivity and specific heat of rock mass are estimated as giving the difference of 20~25% compared to those of laboratory scale. This difference seems to be caused by discontinuity like joint and water content in rock mass.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.11a
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• pp.124-126
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• 2006

마이크로파 에너지의 열원을 이용하여 흡착된 톨루엔을 탈착함으로써 활성탄의 재생에 관한 실험을 실시하였다. 마이크로파를 조사함에 따라 흡착제의 온도가 급격히 상승하여 톨루엔이 탈착할수 있는 온도까지 빠른 시간에 도달하였으며, 이 열에 의하여 톨루엔이 탈착함을 알수 있었다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1107-1108
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• 2011

본 논문에서는 전력용 변압기 온도상승을 예측하기 위해 CFD 상용 프로세서인 Fluent를 이용하였다. 온도상승의 원인이 되는 전력손실은 자계 상용 프로세서인 Maxwell을 이용하였으며, 자계해석에 의해 얻은 전력손실을 유체역학과 열전달을 동시에 고려한 열유동해석의 열원으로 적용하였다. 해석의 정확도를 향상시키기 위해 변압기 권선의 형상을 실제형상과 유사하게 모델링하였으며, 해석결과의 타당성을 검증하기 위해 온도 상승 시험을 통해 얻은 측정값과 비교하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.818_819
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• 2009

본 논문에서는 온도상승의 열원이 되는 권선과 철심의 전력손실을 유한요소법을 이용한 전자계해석과 스타인메츠실험식으로 산정하였다. 온도에 대한 자연대류 열전달계수를 산정하여 경계면에서의 경계조건으로 적용하였다. 열전달 해석을 위해 전력용변압기를 3차원 형상으로 모델링한 후 유한요소법을 이용해 권선과 철심에서의 온도분포를 해석하였다.