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CO<sub>2</sub>-Hydrate와 CO<sub>2</sub> 가스 혼합물의 전달물성과 관내측 열전달계수 및 압력강하 예측
윤린,Yun, Rin 대한설비공학회 2013 설비공학 논문집 Vol.25 No.5
The Thermophysical properties of thermal conductivity, viscosity, and heat capacity for $CO_2$ slurry ($CO_2$ gas and $CO_2$-hydrate mixture) having a high gas phase volume fraction were predicted using the conventional mixture models and the TRAPP model under hydrate formation conditions. Based on the calculated thermophysical properties, the heat transfer coefficient and pressure drop of the $CO_2$ slurry in the tube were predicted. The thermal conductivity of $CO_2$ slurry ranged from 0.02 to 0.2 W/m-K, and the mixture viscosity was larger than that of pure $CO_2$ by 1.9~2.7 times. The heat capacity of $CO_2$ slurry ranged from 63 to 68% of that for pure $CO_2$. The predicted heat transfer coefficient of $CO_2$ slurry was 6 times higher than that of pure $CO_2$. In the separate model, the estimated pressure drop increased with an increase of $CO_2$-hydrate mole fraction, and was 60% of that of pure $CO_2$.
수평원관 내 CO<sub>2</sub> R-22 및 R-134a의 증발열전달 특성에 관한 실험적 연구
윤린,황준현,최영돈,김용찬,Yun, Rin,Hwang, Jun-Hyeon,Choi, Young-Don,Kim, Yong-Chan 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.7
Evaporation heat transfer coefficients of carbon dioxide($CO_2$), R-22, and R-134a in a horizontal smooth tube were measured and analyzed as a function of heat flux, mass flux, and evaporating temperature. The experiments were carried out by varying heat flux from 10 to 20 $kW/m^2$, mass flux from 170 to 340 $kg/m^2s$, and saturation temperatures of 5 and $10^{\circ}C$. It was found that the heat transfer coefficient of $CO_2$ decreased with a rise of quality due to an earlier liquid-film dryout as compared to R-22 and R-134a. Averaged heat transfer coefficients of $CO_2$ were 22-63% higher than those of R-22 and R-134a at all test conditions. The effects of mass flux and heat flux on averaged heat transfer coefficients were much greater in $CO_2$ than in R-22 and R-134a. When comparing $CO_2$ test results with the correlations in the literature, the existing models yielded large deviations at medium and high qualities. Therefore, a generalized correlation for $CO_2$evaporation heat transfer needs to be developed by including the effects of dryout phenomenon.
흡수식 칠러를 장착한 마이크로터빈 구동 열병합시스템의 성능 해석
윤린(Rin Yun),한승동(Seungdong Han) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.7
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 ㎾, 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.
첨가물이 존재하는 CO₂ Hydrate 형성의 CFD 모델링
윤린(Rin Yun),Benedict Prah,이광빈(Kwangbin Lee) 대한설비공학회 2021 설비공학 논문집 Vol.33 No.12
CO₂ hydrate formation with additives in the pipeline was simulated by the CFD tool of the COMSOL Multiphysics. The length and diameter of the pipeline for the hydrate formation simulation were 1 m and 0.0347 m, respectively. The 3D axis-symmetric geometric structure was implemented. The Eulerian multiphase flow model was introduced for the modelling of the hydrate formation processes composed of complex multi-physical phenomena such as mass transfer, heat transfer, and phase change. The validity of the simulation results was proved by comparing them with previous experimental data in terms of hydrate formation rate. As a result, hydrate velocity and volume fraction along length direction were calculated. The average hydrate mass fraction increased from 8% to 12% by additive.
CHP Capacity Optimizer를 이용한 건물 열병합 시스템의 경제성 평가
윤린(Rin Yun) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.5
This paper presents and analyzes the effects of on-grid electricity cost, fuel price and initial capital cost of a CHP system, on the optimum DG and AC capacity and NPV, by using the ORNL CHP Capacity Optimizer, which was applied to a library in a university. By considering the current domestic energy cost and initial capital cost, it is shown that the installation and operation of the CHP system is not economical. However, with the current domestic CHP installation cost and fuel price, the NPV achieved by the installation of CHP system is greater when the on-grid electricity price is a factor of x1.5 the present value. Regarding the initial capital cost of the CHP system, the reduction of the DG cost is much more economical than that of the AC cost, with respect to NPV. Electricity cost and fuel price have opposite effects on NPV, and NPV is more sensitive to an increase of the electricity cost than an increase of the fuel price.