수평원관 내 CO₂ 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.

CO₂-Hydrate와 CO₂ 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 $CO_2$.

가스-하이드레이트 기반 이산화탄소 수송 및 포집

윤린(Rin Yun),베네딕트 프라(Benedict Prah) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.5

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.

CO₂-Hydrate와 CO₂ 가스 혼합물의 전달물성과 관내측 열전달계수 및 압력강하 예측

윤린(Rin Yun) 대한설비공학회 2013 설비공학 논문집 Vol.25 No.5

The Thermophysical properties of thermal conductivity, viscosity, and heat capacity for CO₂ slurry (CO₂ gas and CO₂-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 CO2 slurry in the tube were predicted. The thermal conductivity of CO₂ slurry ranged from 0.02 to 0.2 W/m-K, and the mixture viscosity was larger than that of pure CO₂ by 1.9~2.7 times. The heat capacity of CO₂ slurry ranged from 63 to 68% of that for pure CO₂. The predicted heat transfer coefficient of CO2 slurry was 6 times higher than that of pure CO₂. In the separate model, the estimated pressure drop increased with an increase of CO₂-hydrate mole fraction, and was 60% of that of pure CO₂.

트랜시스를 이용한 복합열원과 BTES 결합 건물 공조시스템 모델링

윤린(Rin Yun),오선희(Sun Hee Oh),허재혁(Jaehyeok Heo),윤석만(Seok Mann Yoon) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.4

낮은 오일 농도에서 CO₂-PEC9 혼합물의 밀도와 점성예측

윤린(Rin Yun) 대한설비공학회 2008 설비공학 논문집 Vol.20 No.11

Due to environmental concerns CO₂ has been reintroduced as a potential candidate to replace HFCs in refrigeration systems. Oils are always required in a vapor-compression cycle, and thus it is necessary to precisely estimate the thermodynamic mixture properties of CO₂-lubricant oil. In the present study, the density and the viscosity of the mixture was calculated by the Redlich and Kwong type EoS and the modified Peng and Robinson type viscosity EoS, respectively. The viscosity model was based on the similarity between P-v-T and T-u-P relationships. The predicted results were compared with the experimental data of Pensado et al. whose test conditions were 100~650 bar of pressure and 303 K ~353 K of temperature with the CO₂-POEs mixtures under 92.2 wt.% and 83.3 wt.% of CO₂ concentration. The mean deviations of the mixture density were 7.93% and 8.32% for 92.2 wt.% and 83.3 wt.% of CO₂ concentration, respectively. Concerning the viscosity, the mean deviations were 4% and 10% for 92.2 wt.% and 83.3 wt.% of CO₂ concentration under the Pensado et al.'s test conditions.

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.

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.

The heat transfer characteristics of CO₂ and CO₂-oil mixture in tubes

Rin Yun(윤린) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

The heat transfer characteristics of CO₂ and CO₂-oil mixture in tubes including convective flow boiling, gas cooling, and condensation are investigated. Two-phase flow patterns are thoroughly investigated based on physical phenomena, which show the early flow transition to intermittent or annular flow especially for small diameter tube. The physical phenomena for nucleate boiling of CO₂ follow the same trends with other organic fluids under the same reduced pressure. The gas cooling heat transfer is critically dependent on the turbulent diffusivity related with buoyancy force due to the large density difference. Under the oil presence conditions, the interaction of oil rich layer and bubble formation is the physical mechanism for the CO₂-oil mixture convective boiling. Besides, the gas cooling phenomena with oil should be investigated based on the flow patterns formed by CO₂ and oil, and the oil rich layer, whose thickness are depends on the solubility of CO₂ to oil explains the physical mechanisms of heat transfer. The thermodynamic properties of CO₂-oil were estimated by the general model based on EOS, and they are utilized to estimate the properties for oil rich layer and oil droplet vapor core. Through these predicted properties, the convective boiling and gas cooling heat transfer coefficients and pressure drop theoretically estimated. Condensation of CO₂ is not so different from the existing one, so the heat transfer coefficients and pressure drop are well estimated by the existing one developed for other fluids.